Group Title: electroencephalographic and neuroanatomical analysis of the septal syndrome
Title: An electroencephalographic and neuroanatomical analysis of the septal syndrome
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Title: An electroencephalographic and neuroanatomical analysis of the septal syndrome
Physical Description: v, 56 leaves. : ill. ; 28 cm.
Language: English
Creator: Turner, Blair Hamilton, 1938-
Publication Date: 1968
Copyright Date: 1968
Subject: Brain -- Localization of functions   ( lcsh )
Behaviorism (Psychology)   ( lcsh )
Hypothalamus   ( lcsh )
Rats   ( lcsh )
Psychology thesis Ph. D   ( lcsh )
Dissertations, Academic -- Psychology -- UF   ( lcsh )
Genre: bibliography   ( marcgt )
non-fiction   ( marcgt )
Thesis: Thesis--University of Florida, 1968.
Bibliography: Bibliography: leaves 31-32; 54-55.
Additional Physical Form: Also available on World Wide Web
General Note: Manuscript copy.
General Note: Vita.
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Bibliographic ID: UF00097816
Volume ID: VID00001
Source Institution: University of Florida
Holding Location: University of Florida
Rights Management: All rights reserved by the source institution and holding location.
Resource Identifier: alephbibnum - 000561339
oclc - 13515163
notis - ACY7267


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Abstract of Dissertation Presented to the Graduate Council
in Partial Fulfillment of the Requirements for the Degree of
Doctor of Philosophy



Blair H. Turner

December, 1968

J. A. Horel, Chairman
Department of Psychology

An investigation was made of the anatomical localization of

"the septal rage" syndrome and its attenuation by a thalamic lesion.

Destruction of the nucleus accumbens correlated with change in eight

or thirteen measures of emotionality (correlations ranged from +0.43

to --0.77). The medial and lateral septal nuclei and the medial pre-

optic area were correlated with three of the remaining measures, and

in no nucleus did amount of damage correlate with the final two meas-

ures. Lesions in the ventrobasal thalamus and zona incerta were

effective (correlations -0.47 to -0.70) in lowering all measures of


Electroencephalographic abnormalities were obtained from cortical

dural and depth electrodes in rats following lesions of the septal area.

A high amplitude (200 V) burst of 4-5/sec. waves (sigma rhythm) was

elicited upon presentation of a threatening or novel stimulus.

Latency of the sigma rhythm varied from 1.8-7.5 secs. after stimulus

presentation, and was of short duration (1-2 secs.) Sigma rhythm

appeared 1-2 days after surgery, and disappeared in 4-7 days. The

greatest amplitude of response was recorded over posterior cortex.

Electroencephalographic abnormalities were obtained also during sleep

and found to be abnormal in that at no time was theta activity or

sleep spindles observed. High voltage slow and low voltage fast

components were highly intermixed, and the signal was often extremely



The author would like to express his appreciation to James

A. Horel, the chairman of his doctoral committee, and to J. J.

Bernstein, W. W. Dawson, F. A. King, and N. W. Perry, members of the

committee. Thanks are also due John Thornby for statistical consulta-

tion, and Dorothy Robinson for histological assistance.



Acknowledgments ------------------------------------- ii

List of Tables ------------------------------------- iv

List of Figures --------------------------------- v

Chapter I Experiment One:

Localization of the Septal
Syndrome and its Attenuation
by Thalamic Lesions ------ ----- 1

Introduction ---------------- 1
Method ----------------------- 2
Results ----------------- ----- 8
Discussion ----------------- 10
Summary ------------------ 16

Appendix I ------------------------ 26

References Cited in Experiment One 30

Chapter II Experiment Two:

Electroencephalographic Cor-
relates of the Septal Syn-
drome ---------------------------- 33

Introduction ------------------ 33
Method ------------------- 33
Results ---------------------- 36
Discussion ------------------ 41
Summary -------------- ----- 46

References Cited in Experiment Two 54

Biographical Sketch --------------------------------- 56



Discussion of Table I --------------------------- 18

Table I Regression and Multiple Correlation
Coefficients Between Damage to Nuclei
in the Septal Region and Emotionality
Ratings ----------------------- 19

Discussion of Table II ------------------------ 20

Table II Regression and Multiple Correlation
Coefficients Between Damage to Dien-
cephalic Structures and Emotionality
Ratings ---------------------- 21



Experiment One

Discussion of Figure 1. --------------- 22

Figure 1. Nuclear Categories Used for
Statistical Analysis -------------- 23

Discussion of Figure 2. ---------------- 24

Figure 2. Representative Lesions and
Their Effect on Hyperirritability
Which had been Previously Induced
by a Forebrain Lesion ---------- 25

Experiment Two

Discussion of Figure 1. ---------------- 48

Figure 1. Electroencephalograms of Normal
and Septal Animals in Different
Stimulus Situations --------- 49

Discussion of Figure 2. --------------- 50

Figure 2. Electroencephalograms of Lesioned
and Normal Rats in a Novel Envir-
onment ----------------------- 51

Discussion of Figure 3. --------------- 52

Figure 3. Sleep Records from Animals
with Septal Lesions and Normal
Controls -------------------- 53


Experiment One

Localization of the Septal Syndrome
and its Attenuation by Thalamic Lesions


Lesions of the septal area of the rat produce explosive attack

and flight behaviors which have been termed septall rage" or "the septal

syndrome" by King.5 Efforts to localize those nuclei in the septal

region which are crucial for the production of this behavior have so
far been unsuccessful. Experiments relating other forebrain areas to

the syndrome have yielded more positive results. King and Meyer showed
that bilateral lesions of the amygdala attenuate septal rage, while

Yutzey, Meyer,and Meyer found that cortical lesions prolonged it.35

Hilton and Zybrozyna demonstrated that the critical path of excitation

was from hypothalamus to amygdala over the stria terminalis, and then

back to hypothalamus via ventral amygdalofugal fibers.12 Attention

also has been given to elucidation of the peripheral sensory afferents

that participate in septal behavior. Flynn found that section of the

sensory afferents from the mouth area attenuated attack reactions induced
in cats following hypothalamic stimulation, and Forkner and Doty
showed a decrease in pain thresholds in septal rats. These findings

suggest that the most effective stimuli for rage may be mediated by



somesthetic pathways. It follows, therefore, that the ventrobasal

thalamus, site of somesthetic synapse, may be of central importance

to maintenance of the septal syndrome. Examination of the histolog-

ical preparation from a series of rats in a pilot experiment supported

this hypothesis: lesions of the ventrobasal complex of the thalamus

markedly attenuated the septal syndrome, while lesions of the dorsal

and ventral hippocampus, olfactory bulbs, caudate, and anterior and

midline thalamic nuclei did not.

The purpose of this experiment was twofold: first, to identify

the structures in, or adjacent to, the septal area which are primary

contributors to the syndrome; and second, to test the hypothesis that

septal behavior is mediated by the somesthetic system. To achieve

this, the major thalamic station for somesthesis, the ventrobasal

area, was lesioned subsequent to septal injury. Affective behavior

was measured to determine whether the thalamic lesion attenuated

septal rage.


Subjects and experimental method.-- The subjects were male Long-

Evans hooded rats (N=41), 90-120 days of age. Subjects were housed in

individual cages and handled by the experimenter to gentle them. They

were then rated on a modified King Emotionality Scale for at least three
days. The following day bilateral lesions of the septal area were

produced and emotionality ratings carried out for two days postoperative-

ly; these animals constitute Group I (N=41). Then thalamic lesions

were produced in those animals which displayed the full amplitude of

all aspects of septal rage, as measured by the emotionality scale.

These animals constitute Group II (N=21). The subjects were again

rated for at least three days, beginning 18 hours postoperatively.

Emotionality ratings can be made quite accurately and have been found
15, 35, 17
to be very reliable. 35, 17

Surgical procedure.-- Subjects were administered 0.1cc of atro-

pine sulfate, 0.8mg/ml, and anesthetized with intraperitioned sodium

pentobarbital, 50mg/ml. Bilateral, sometimes multiple, radio-frequency

lesions were produced in the septal region by stereotaxic insertion of

a stainless steel electrode 0.5mm in diameter, insulated with epoxy

except for 0.5mm at the tip. The circuit was completed by a rectal

electrode. Lesions were varied in three planes in order to damage

selectively the various septal nuclei. The anterior-posterior extent

was 0.5mm to 2.5mm anterior to bregma, the dorsal-ventral extent was

from 5.5mm to 7.5mm ventral to the outer layer of neocortex, and the

lateral extent was from the margins of the midsaggittal sinus to 1.5mm

lateral to the sinus. Lesions were varied in size by controlling the

time of the electric current. Thalamic lesions were also varied in

size and location in order to damage selectively structures in and

around the thalamus. All injury was bilateral, and in many instances

two lesions were produced on each side.

Rating scale.-- Once a day the animals were removed from their

cages, placed in the testing area (a table), and rated for emotionality.

The animals were scored on twelve different behaviors, which could be

categorized as reaction to threat, attack, and handling: (1) reaction

to visual presentation of a pencil or gloved hand; (2) reaction to a

tactile stimulus produced by a tap on the back; (3) resistance to

capture; (4) resistance to handling; (5) amount and kind of vocaliza-

tion during testing; (6) response to a discrete air puff delivered

through a syringe to the side of the subject's body (Puff-l); (7)

response to an air puff delivered over the entire dorsal surface of

the body (Puff-2); (8) response to an auditory stimulus consisting

of a sharp rap on the side of the cage; (9) amount of urination and

defecation during testing; (10) degree of cataplexy (a sleep-like

atonic state seen when septal rats are placed on their backs); (11)

amount of aggressive or defensive posturing; (12) gross motor activity

measured by number of squares traversed in one minute in a defined

area. For the first five categories the rat received a score from

0-5, and from 0-3 for categories 6-11. A final category, 13, was

the sum of scores received on 1-11 (see Appendix I).

Histology.-- The animals were given a lethal dose of sodium

pentobarbital and perfused with 10 percent saline followed by 10

percent formalin. The brains were embedded in celloidin, cut serially

at 30p through the lesion, and every second section stained with

thionine. One nonlesioned animal (normal control) within the age

range of the experimental was perfused and prepared histologically.

Statistical method.-- The five main components of the septal

area were chosen for examination of their contribution to the septal

syndrome (Group I): (1) nucleus accumbens and anterior commissure;

(2) medial septal nucleus and nucleus and tract of the diagonal

band; (3) lateral septal nucleus; (4) medial preoptic area; (5) pre-

and postcommisural fornix, including nucleus triangularis septi and

nucleus septalis fimbrialis. A sixth category, the summation of 1


through 5, represented the total area involved in Group I. Five

thalamic areas which receive somesthetic information were chosen for

examination of their possible role in attenuating septal rage (Group

II); (1) the thalamic reticular nucleus; (2) the thalamic radiations

and the internal capsule; (3) ventrobasal thalamus and medial lemniscus;

(4) zona incerta and Forel's Field; (5) other thalamic nuclei, includ-

ing the anterior and lateral thalamic nuclei and nucleus medialis

dorsalis,parafascicularis, reunions, and rhomboideus. A sixth cate-

gory, the summation of 1 through 5, represented the total area in-

volved in Group II. The nuclear areas are outlined in Fig. 1, A

through F.

Each section of the brain of the intact animal (normal control)

was projected onto a white background through a tabletop microprojector.

The bilateral area of each of the above nuclear categories was measured

in arbitrary units with a planimeter as it appeared serially. These

areas were summed cumulatively for their entire rostrocaudal extent

to determine the volume of each structure. The percentage of a struc-

ture as represented on each section was then determined, and each

section was photographed. In addition, all five components of the

septal area were summed for a total volume of the tissue involved, and

the same was done for the areas involved in the thalamic lesion. The

information derived from the normal control was used as a standard

in computing the volume of the various areas destroyed in the experi-

mental animals in the following manner. Slides from each experimental

animal were projected until the section was found where the lesion

first began. The rostrocaudal extent of the lesion was determined

by comparing sections from experimental animals with photographs of

the normal control. The percent of each nucleus already traversed

up to that point was recorded from the normal control. Thon for each

slide through the lesion the intact area remaining for each nucleus

was measured with a planimeter, summed through the lesion, and the

intact percentage determined and added to that recorded earlier. The

total percent of nucleus remaining intact after the lesion was sub-

tracted from unity to obtain percent of nucleus destroyed. Percent

destruction of each of the twelve nuclear categories made up the inde-

pendent variables.

The data were analyzed by means of the step-wise multiple re-
gression method. The percent of nuclear destruction was the inde-

pendent variable and the difference between preoperative and post-

operative emotionality ratings was the dependent variable. Difference

in the emotionality scores between the last preoperative and first

postoperative ratings (Group I data) of the twelve behavioral cate-

gories was obtained for all animals. Following septal lesions, the

process was repeated for animals receiving the second lesion (Group

II data).

The step-wise multiple regression relates the emotionality score

(the dependent variable) to a single nuclear area of lesion (the inde-

pendent variable) which most affects the response. Then in the second

step of the regression the next most effective independent variable in

determining the dependent variable is added to the first. This results

in a new correlation of effective lesion sites and emotionality behavior.

The rest of the independent variables are added in order of their

contribution to the dependent variable.

In summary, a method was employed to determine which one or

two of a number of simultaneously lesioned nuclei contributed most

to particular behavioral patterns. This method involved determining

what percent of each nucleus was destroyed, and correlating change in

behavior with amount of destruction of a nuclear area.

Control for experimenter bias.-- Individual variability in

brain size and shape, coupled with inherent error in electrode place-

ment, insure that the actual locus and extent of lesions can be de-

termined only by histological analysis. This provides a degree of

control for any rater bias which might occur. There were also con-

trols for the effects of surgical trauma alone: unknown to the ex-

perimenter, no septal lesion was produced in two animals because of

a faulty electrode, and no change in emotionality was detected; in

several animals the lesion intended for the ventrobasal thalamus was

discovered at histological examination to have been outside the in-

tended area (Fig. 2, B), and the expected behavioral effect did not

occur; in four of the 21 Group II animals a sham operation was per-

formed in which holes were drilled in the cranium but no lesion made,

and again there was no effect on postoperative behavior; finally, the

experimenter arranged the data sheets so that he was unaware of each

animal's previous ratings and, whenever possible, of the type of

lesion sustained. These precautions were taken in order to lower

variability in the data, since inaccuracy of lesion placement, errors

of measurement, and differences in brain size would distribute experi-

mental effects among the dependent variables and result in no significant


difference between them.


Group I.-- The anatomico-behavioral results of the first lesion

are given in Table I. All values are significant at least at the .05

level. Two subscales, Puff-1 and Auditory, were not affected by lesion

of the various nuclear areas. Of the remaining eleven, eight were af-

fected solely by damage to nucleus accumbens. For each of the sub-

scales Urination/Defecation and Object Presentation, the behavior is

affected by damage to any of three nuclear areas; and finally, the

Activity measure is influenced by lesion of the lateral septum alone.

The regression coefficients are constants by which one would multiply

percent nuclear damage to predict a behavioral score. The correla-

tions between destruction of the most relevant nucleus (e. g., accumbens)

and the resulting behavior are given in column R; they are all high,

indicating that change in eight behavioral measures is highly asso-

ciated with amount of injury to nucleus accumbens. Multiple corre-

lation coefficients have no sign. However, a positive regression

coefficient implies a positive correlation, while a negative regres-

sion coefficient, as in the case of the Activity measure, implies a

negative correlation. Column 5R shows the increase in correlation if

the effect of all five nuclei are added to the effect of the first.

Except for the Urination/Defecation response, the increase in corre-

lation is small, underlining the importance of the accumbens nucleus

in determining the response. An estimate of the percent variance of

the response accounted for by lesion of a nuclear area can be obtained

by squaring the correlation coefficient (R). It should also be noted

that total mass of tissue destroyed, which includes that of nucleus

accumbens, is always less highly correlated with the behavioral re-

sult than damage to the accumbens alone. Such a finding indicates

that the behaviors resulting from the forebrain lesions studied in

this experiment are less an effect of destruction of mass of tissue per

se in this forebrain region than of destruction of specific nuclei.

Group II.-- The results of the second lesion, intended to atten-

uate septal emotionality, are presented in Table II. The level of

significance and meaning of the numbers is the same as in Table I.

In every case, except for the Activity and Urination/Defecation meas-

ures, it is either the ventrobasal thalamus or zona incerta-Forel's

Field which is most involved in the attenuation of behavior. All

correlations (R) are high, and are increased only moderately by add-

ing the effects of destruction of other nuclear areas (5R). In four

cases the category comprising all other thalamic nuclei contributed

significantly to the behavior, but it should be noted that in three

of these the regression coefficient is positive, implying that lesion

in these areas would increase, rather than decrease, emotionality.

Illustrations of six lesions, along with pre- and postoperative

emotionality ratings, are given in Fig. 2. The lesions in sections A

through C were ineffective in lowering emotionality. Of particular

interest are sections C and D; they are similar except for the

slightly more ventral placement in D, but differ greatly in behavioral

effect. The lesions in sections E and F attenuated emotionality, but

differed in their medio-lateral extent. These data thus strongly


implicate both the ventrobasal complex of the dorsal thalamus and the

zona incerta-Forel's Field (ventral thalamus) in the attenuation of



Group I.-- The advantage of the histological-statistical pro-

cedure employed in this experiment is that it yields a quantitative

correlation between a behavior and an anatomical locus, and eliminates

noncontributing or minimally contributing anatomical loci. Thus, it

was found that a number of the behaviors associated with septall"

rage result specifically from lesion of the nucleus accumbens rather

than the septal nuclei. The resulting rage behaviors were found to

be attenuated by a second lesion in the ventrobasal thalamus-zona

incerta area. Another advantage of this method is that it permits

neurological analysis of different individual behaviors instead of

treating them together as a sum of scale points. Summing all behav-

iors would tend to mask differences among the individual components,

making it difficult to determine whether they are correlated with in-

jury to specific anatomical structures. One of the assumptions neces-

sary for this type of analysis is that the behavior studied results

from damage to nuclear masses. Interruption of tracts can occur,

however, with so little tissue damage as to be unmeasurable by this

technique. Therefore, it is possible that it is injury to fibers of

passage within or nearby the nuclear areas studied that may be re-

sponsible for the resulting behavior. Interpretation of the results,

therefore, should take into consideration fiber tracts of passage

within or around the area surrounding the significant nucleus. All

brains were re-examined in order to confirm the statistical finding

that high emotionality ratings are associated with injury to nucleus

accumbens. Two animals were found that had high scores, but no gross

damage to the accumbens had been observable. A study of the cells in

nucleus accumbens revealed a number of chromalytic neurons in one

brain, and large clusters of reactive neuroglia in the other. This

evidence suggests that the nucleus accumbens of both these brains had

suffered traumatic injury. The lateral width of all brains was

measured in order to determine whether gross brain size correlated with

amount of damage to the nucleus accumbens, thus accounting for the

statistical results. The correlation was not significantly differ-

ent from zero.

Group II.-- The animals used in the second part of the experi-

ment had exhibited a maximal increase in total scale score following

forebrain lesion. Their preoperative average was ten points, their

postoperative average was 31. In a number of these animals, scores

fell to five subsequent to the second lesion. It was not clear, how-

ever, which of two areas which had been determined statistically--

ventrobasal thalamus and zona incerta-Forels Field--was critical,

since half of the rated behaviors were correlated with one area, and

half with the other (Table II). Therefore, animals were grouped

into those showing the least, and those showing the most attenuation,

and the site of lesion was re-examined to determine whether a differ-

ence in lesion placement could be discerned. These data (e. g., Fig.

2, C and D) show that lesions which invaded the ventral thalamus


bilaterally were extremely effective. Lesions confined to the medial

lemniscus and ventrobasal thalamus were less effective, or not effec-

tive at all (Fig. 2, B and C). Fig. 2, D and E, indicates that lesions

that extend into medial and lateral ventral thalamus are equally
1 2 25
potent. Lesions of the ventral thalamus in cat and man2' produce

the same extreme sluggishness and loss of interest in the environ-

ment seen in the rats in the present experiment.

What structures in this area are important in attenuating rage?

Several lines of evidence permit elimination of the classical somes-

thetic afferents. A wide variety of stimuli can elicit rage in de-
cerebrate preparations, including Group I muscle afferents, affer-
ents mediating the chemoceptive aortic reflexes, stimulation of the

vestibular nuclei and the spinal tract of the trigeminal nerve,5 and

the light touch, auditory and visual stimuli used in the present

experiment. However, interruption of structures which carry somes-

thetic information (medial lemniscus and lateral spinothalamic tracts)

superimposed upon destruction of the thalamus does not affect elici-
station of sham rage. The fact that many stimulus modalities do

elicit the response, and yet the rage continues to appear after tran-

section of sensory afferents, suggests that they are effective through
their influence on the reticular activating system (RAS). This is

supported by experiments showing the effectiveness of electrical

stimulation in lateral and medial reticular formation of medulla and

pons in eliciting sham rage in decerebrates, and sham rage attenua-

tion by RAS blockade following thiopental sodium anesthesia.5 Rage

in such animals can also be eliminated by large lesions of the medial


and lateral reticular formation at the midcollicular level.20 These

data strongly indicate rage is mediated and sustained through the RAS

of the brain stem and tegmentum.

It is noteworthy that the Activity measure in both Group I and

Group II was correlated with nuclei which had very little effect on

the other behavioral measures. Activity differs from all the other

measures in that the animal is left alone and is not forced to respond

to stimuli presented by the experimenter. Thus the distinction be-

tween spontaneous and elicited behavior may result from involvement

of different anatomical structures. The reduction in activity fol-

lowing septal lesions replicates the results of Corman, Meyer, and

Anatomical systems and affective behaviors.-- The search for

the structures critical for rage has been long and perplexing. Early

experiments indicated that decortication produced undirected ("sham")
26 28
rage, while other studies reported placidity after decortication.
4, 28
The same contradictory results pertain to the amygdala, fornix,
24,34 6, 10 4, 24 10
24,3 septum, 10 cingulate cortex, 24 and nucleus accumbens,10

This situation can be clarified by comparing the various lesions and

their behavioral results. Only individual components of the rage

response, elicited with difficulty, can be observed in an animal after

transaction at the mesodiencephalic junction. A decerebrate animal

with caudal hypothalamus intact, however, is hyperirritable and gives
a complete but undirected rage behavior pattern. Animals with greatly

restricted forebrain lesions, as in the present case, while still

hyperirritable, direct their attack toward relevant stimuli. In


addition, there are lesions which produce the motor patterns of rage,

as in chorea and hemiballism, but none of the affect. These consid-

erations indicate that there are structures particularly involved in

integrating the motor patterns of the behavior in question, others

with directing behavior toward relevant stimuli, still others with

the amplitude of behavior, with affect, and so on. The form rage

takes will vary depending on which of these systems remain intact

and which ones are disconnected.

The rage seen in "the septal syndrome" appears to result from

an inability to regulate the amplitude of behavior. Rats with de-

struction of the nucleus accumbens are hyperreactive to threat and

handling, on the one hand, and cataplectic, and hyporeactive in an

exploratory situation, on the other. In addition, the abnormalities

of the sleeping and waking electroencephalograms of rats lesioned

in this area suggest disruption of a mechanism which regulates
arousal. In contrast, rats with lesions in the ventral thalamus

seem impaired in their ability to achieve even a moderate level of

arousal. Thus, animals from Groups I and II exhibit behaviors which

could result from injury to different parts of the RAS. It appears

possible that rage and hyporeactivity, or more generally amplitude of

behavior, are controlled and modulated by a reticular system of

fibers whose ascending limb is excitatory and extends from the RAS

of the tegmentum to the forebrain, and whose descending limb feeds

back on the RAS, ventral thalamus, or hypothalamus to inhibit or

modulate the input. A lesion in the ascending, excitatory link would

produce depressed behavior, while destruction of the descending


inhibitory part of the circuit would disinhibit or disturb the regu-

lation of certain behaviors. This hypothesis is based on the follow-

ing anatomical data, and indirectly supported by further chemo- and

electrophysiological studies.

Nauta has shown that the main ascending fibers of the RAS are
in Forel's tractus fasciculorum tegmenti. When this diffuse bundle

reaches the diencephalon it bifurcates into a main component which

traverses the ventral thalamus, and a smaller component which sends

collaterals to the intralaminar nuclei of the thalamus. More recently,

Shute and Lewis have described specific pathways of cholinergic fibers

linking the reticular formation of the midbrain with certain limbic
structures. Of particular interest is a ventral tegmental pathway

which arises from the pars compact of the substantial nigra and from

cells in the ventral tegmental area in the anterior mesencephalon.

This tract enters the zona incerta, supramammillary and lateral

hypothalamic regions, and traverses the lateral preoptic area, prob-

ably via the medial forebrain bundle, to terminate in the medial septal-

diagonal band region. These afferents may constitute the ascending,

excitatory link of the circuit. From the medial septum the path

leads to the hippocampus by way of the stria: of Lancisi, dorsal

fornix, alveus, and fimbria, and then to the nucleus accumbens, either
directly or by way of a synapse in the nucleus of the anterior
commissure. The principal efferents of the nucleus accumbens are

to the lateral preoptic and lateral hypothalamic areas via the medial

forebrain bundle, with significant collaterals to the paratenial and

dorsomedial nuclei of the thalamus.18 These efferents may constitute


the descending, inhibitory or modulatory link of the circuit. Other

possible circuits, although not as convincing because of a lack of a

common chemical substrate, include reticular projections to the basal
ganglia by way of Forel's Field, and to nucleus accumbens and
orbitofrontal cortex by way of the rostral intralaminar nuclei.

Feedback may come from the basal ganglia to the ventral thalamus via
ansa and fasciculus lenticularis.

Evidence that the midbrain-limbic reticular system described by

Nauta and by Shute and Lewis involves sleep and arousal is seen in

the work of Sterman, who obtains electrophysiological and behavioral

sleep with electrical stimulation in the accumbens-diagonal band
area, and in the work of Hernandez-Peon, et al., who with cholinergic stim-

ulation produces sleep from the anterior commissural area, and directed

rage from the anterior commissural, septal, medial preoptic, and
accumbens areas. Rage is also produced by electrical stimulation

of the lateral hypothalamus,33 through which both afferents and ef-

ferents of this system travel, and is produced by stimulation of the
nucleus accumbens-ventral diagonal band area. Further investigation

is needed, however, to clarify the anatomical and behavioral relation

between the RAS and the forebrain.


An investigation was made of the anatomical localization of

"the septal rage" syndrome and its attenuation by a thalamic lesion.

Destruction of the nucleus accumbens correlated with change in eight

of thirteen measures of emotionality (correlations ranged from +0.43

to +0.77). The medial and lateral septal nuclei and the medial

preoptic area were correlated with three of the remaining measures,

and in no nucleus did amount of damage correlate with the final two

measures. Lesions in the ventrobasal thalamus and zona incerta were

effective (correlations -0.47 to -0.70) in lowering all measures of



Regression and Multiple Correlation Coefficients
Between Damage to Nuclei in the
Septal Region and Emotionality Ratings

Regression coefficients are constants which predict a behavioral

score when they are multiplied by percent nuclear damage. These con-

stants are specific as to nucleus and to behavioral measure. Correla-

tion coefficients denote the degree of relationship between damage to

a particular nucleus and the resulting change in behavior. Positive

values of the regression coefficients denote increased rating score

with increased nuclear damage, while negative values denote a decrease

in behavioral ratings with an increase in nuclear damage. Multiple

correlation coefficients have no sign. However, a negative regression

coefficient, for example, implies that the amount of nuclear damage

and change in the behavioral score are negatively correlated. Numbers

in parentheses denote the order in which the nuclei contribute to the

behavior in question. Only values significant at P < .05 or beyond

are shown. Abbreviations: Acc, nucleus accumbens; Ms, medial septal

nucleus and diagonal band; Ls, lateral septal nucleus; Med Preop,

medial preoptic area; Fx, fornix; R, correlation coefficient; 5R, com-

bined correlations of the five nuclear areas and behavioral ratings;

Total Tissue, total amount of tissue damage of the five nuclear areas.



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Regression and Multiple Correlation Coefficients
Between Damage to Diencephalic
Structures and Emotionality Ratings

Refer to Table I for explanation of the meaning of the numbers.

Only values significant at P .05 or beyond are shown. Abbreviations:

Rt, thalamic reticular nucleus; Gen thai, a general category of thalamic

nuclei, including the anterior, lateral, medialis dorsalis, parafas-

cicularis, reunions, and rhomboideus nuclei; Ventrobasal, ventrobasal

complex of the dorsal thalamus; Zi, zona incerta and Forel's Field;

Ic/rti, internal capsule and thalamic radiations; Total Tissue, total

amount of tissue damage of the five nuclear categories; R, correlation

coefficient of the nucleus which most affects the behavior in question;

5R, combined correlations of the five nuclear areas and behavioral



o o~ o r


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Lr -t D 00 o *

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Nuclear Categories Used for Statistical Analysis

Abbreviation: a, nucleus accumbens; db/ms, diagonal band/medial

septal nucleus; Is, lateral septal nucleus; F, fornix; rt, thalamic

reticular nucleus; vb, ventrobasal complex of dorsal thalamus; zi,

zona incerta/Forels Field. The medial preoptic area is directly below

the columns of the fornix. The last section, F, represents the most

caudal extent of the anatomical analysis.






v b z
1. r^ \ U

Figure 1.

Nuclear Categories Used for Statistical Analysis


Representative Lesions and Their Effect
On Hyperirritability Which had been Previously
Induced by a Forebrain Lesion

Pre- and postoperative emotionality ratings are given for each



B p fop c:

4 '2:r ) '

pre: 36.5 post: 35.5 pre: 29 pos

pre: 24 post: 5.5 pre: 24 post

Figure 2.

Representative Lesions and Their Effect
On Hyperirritability Which had been Previously
Induced by a Forebrain Lesion

t: 5.5

: 11.5



Rating Scale

1. Object Presentation:

Pencil is presented close to animal's snout.

0 Rat ignores pencil; sniffs pencil; vibrissae twitch;
1 Rat alert and attentive, some body tenseness.
2 Legs and body tense and immobile, vibrissae point
forward, ears cocked.
3 Scurries away or makes occasional mild biting
attack on pencil; magnet reflex; nibbles on pencil.
4 Intermediate.
5 Very aggressive attack, disorganized panic, or
violent flight.

2. Auditory:

A sharp rap is given to the side of the cage.

0 No response.
1 Orientation to the stimulus; slight startle;
restless moving.
2 Greater startle; no vocalization; jumps up on two
3 Exaggerated startle; leaps in air.

3. Puff-1:

A quick, discrete puff of air is given to the side of the animal.

0 No response.
1 Orientation to the stimulus; slight startle.
2 Startle response; jumps up on two feet.
3 Leaps in air.



4. Puff-2:

A quick puff of air is delivered to the entire dorsal surface
of the animal.

O No response.
1 Orientation to the stimulus; slight startle.
2 Startle responses; jumps up on two feet.
3 Leaps in air.

5. Response to Tap on Back:

0 No reaction.
0.5 Slight muscular reflex to tap.
1 Twitching or restlessness and slight reflex.
1.5 Startle reflex of entire body, but not exagger-
2 Twitching or scurrying away, and startle reflex
and feet in air.
3 Jumps or hops up in the air, but then settles
down; exaggerated reflex.
4 Leaps in air and runs about in fright; big hop
and movement after.
5 Leaps violently, runs off in panic, frantic
rebounding in cage.

6. Resistance to Capture:

Glove is extended forward to animal slowly and rat is grasped,
firmly but not roughly.

0 Remains calm, does not move when approached or
struggle when grasped.
1 Remains calm when approached but runs away and
tugs when grasped.
2 Avoids on approach, struggles.
2.5 Slips out of hand very easily.
3 Retreats when approached, struggles vigorously
when grasped.
4 Strong attempts to escape when approached,
struggles strongly and is disorganized, some biting.
5 Leaps violently when grasped, bites frantically,
very hard to catch.


7. Resistance to Handling:

0 Relaxes in hand, does not attempt to escape.
1 Restless with some feeble squirming, turns over
in hand.
2 Sporadic attempts to pull out of hand, energetic
2.5 Slips out of hand very easily.
3 Struggles pretty continuously and quite vigorous
in attempt to escape.
4 Bites also.
5 Frantic biting, powerful tugging, and disorgan-
ized twisting.

8. Cataplexy:

Rat is held in one hand by hindquarters, and with other is
restrained in a supine position for 5-10 secs., then released.

0 Rat sits or struggles as soon as released.
1 Rights or struggles after release, but with a
brief latency.
2 Longer latency, head and neck tonus variable,
heavy respiration.
3 Remains supine indefinitely (over 10 secs.) and
shows a marked tendency toward heavy respiration;
head and neck atony.

9. Vocalization During Testing:

0 None.
1 Few squeaks.
2 Frequent squeaking, a few squawks.
3 Frequent squealing-squawking.
4 Squealing-squawking continuous.
5 Frantic and loud screeching continued.

10. Urination and Defecation During Testing:

0 None.
1 Slight urination and/or one stool.
2 Few stools.
3 Loose stools.

11. Posture During Testing:

0 No definite posture or alertness; rat is on all
1 Alert and tense, on all fours.
2 Stands on two feet.
2.5 Also hisses or cries.
3 Assumes aggressive or defensive posture, then
attacks or retreats.

12. Activity:

Rat is placed in a standard, confined area marked off into
squares. Number of squares entered in one minute are re-

13. Total Score:

Total points obtained on Scales 1 11 are summed.


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Experiment Two

Electroencephalographic Correlates
of the Septal Syndrome


Rats with lesions of the septal area (septals) exhibit several

seizure-like behaviors. Most notable are vicious biting attacks or

frantic flight, and loud and sustained screeching when attempts are

made to capture and handle lesioned animals. A peculiar hop, and a

sleep-like atonic state cataplexyy) when lesioned animals are placed

on their backs are also observed. In contrast to normal rats, when

left alone septals are remarkably inactive and show little explora-

tory behavior. The explosiveness of attack or flight may be caused

by irritative seizures, whereas cataplexy is similar to sleep attacks

(narcolepsy). In addition, the hypoactivity is often similar to

sleep. Such a syndrome might well be reflected in electroencephalo-

graphic (EEG) abnormalities. The present experiment describes some

EEG correlates of these behaviors.


Surgical procedure.-- Subjects were Long-Evans male hooded rats

(N=22) 90-150 days of age. The experimental animals (N=19) were ad-

ministered 0.1cc of atropine sulfate, 0.8mg/ml, and anesthetized with



intraperitoneal sodium pentobarbital, 50mg/ml. Bilateral, sometimes

multiple, radio-frequency lesions were produced in the septal region

by stereotaxic insertion of a stainless-steel electrode, 0.5mm diam.,

insulated with spox except for 0.5mm at the tip. The circuit was

completed by a rectal electrode. During the operation, stainless-

steel screws were inserted into the skulls of the rats in order to

record the cortical EEG. In addition, in ten of these rats teflon-

insulated bipolar depth electrodes were stereotaxically placed for

recording from subcortical structures. Normal animals (N=3) were used

for control recordings. Two of these had cortical dural electrodes

only, and one had dural as well as depth electrodes. Controls were

maintained, housed, and underwent the same surgical procedure (ex-

cept for the lesion) as the experimental animals. All animals were

maintained postoperatively on ampicillin trihydrate in order to con-

trol infection.

The electrode configuration for cortical recordings was chosen

from those described by Dillon so that slow wave sleep (HVS),

paradoxical sleep (PS), and the waking EEG could be easily discrim-

inated from each other using a two-channel recording. Two of the dural

electrodes were bilaterally and symmetrically inserted over posterior

cortex. The other two dural electrodes were placed anteriorly, one

over motor cortex and one over frontal cortex. Recordings could be

obtained between the anterior and posterior cortical electrodes, or

between the anterior ones and between the posterior ones. In rats

which also had depth electrodes, recordings could be obtained between


the depth electrodes, or between depth and dural electrodes. Stain-

less-steel wires were led from the screws used for the cortical re-

cording to a miniature socket. The entire electrode pedestal was

cemented to the screws with dental acrylic.

Behavioral and electrophysiological procedure.-- All animals

were rated preoperatively for emotionality with a modification of the

scale described by King. The animals were also rated postoperatively

for as long as they continued in the experiment. Emotionality ratings

were taken to measure the septal syndrome and to determine whether

changes in the behaviors were related to EEG patterns.

The experiments were begun within 24-48 hours after lesion and

electrode implantation. EEG recordings were obtained in two differ-

ent behavioral settings. In Setting I (response to threat, attack,

and handling), the rat was placed on a table and allowed to explore

for one minute. Then the experimenter placed the animal in differ-

ent stimulus situations: (1) visual presentation of a pencil or

gloved hand, and flashing a xenon lamp or flashlight in the animal's

eyes; (2) firing a popgun near the animal; (3) tapping the rat on the

back, puffing air suddenly over the dorsal surface of his back, and

stroking his side with a pencil; (4) catching and handling the animal;

(5) holding the animal supine on his back in order to induce cataplexy.

All rats were given this behavioral battery.

For seventeen animals, EEGs were recorded during sleeping and

waking (Setting II). In five septals and one control, EEGs of sleep-

ing and waking were recorded for 30 continuous hours, beginning 24

hours after surgery. After this experiment had been terminated, it


was discovered that the sleep-wake record was abnormal and could not

be evaluated by conventional criteria. In order to observe whether the

EEG abnormalities resulting from the lesion were transitory, electrodes

were implanted in an additional eleven animals and recordings lasting

up to four hours made daily for a period of up to eight days. Behav-

ioral observations were made during the sleep of one control and three

septals in order to ascertain the presence of the behavioral indica-

tions of PS. All EEGs were recorded on a 12-channel, Grass Model 3,

electroencephalograph. Two channels were recorded from each subject.

Histology.-- At the end of the experiment, all animals were

given a lethal dose of sodium pentobarbital and perfused with 10 per-

cent saline followed by 10 percent formalin. The brains were embedded

in celloidin, cut serially at 30P through the lesion, and every

second section stained with thionine. All experimental animals were

found to have total or extensive damage to the lateral and medial

septum, diagonal band, nucleus accumbens, and fornix. Placement of

the depth electrodes was determined by microscopic examination.


Setting I (response to threat, attack, and handling).-- A very

prominent 4-5/sec burst of electrical activity (Fig. 1, A through D)

was observed in 13 of 17 rats with damage to the septal area. This

activity, hereafter referred to as the septal-injury rhythm (sigma),

was never recorded in the three control animals, and only rarely dur-

ing exploration on the table in lesioned rats. It was easily evoked,

however, by a variety of applied stimuli. An object, such as a


gloved hand, presented suddenly in front of the rat and then quickly

withdrawn, was a potent stimulus in evoking the sigma rhythm (Fig.

1, B). Similarly, a flickering lamp, a flashlight beam, a tap on the

back, or a stroke along the side of the body were all capable of

eliciting the sigma response (Fig. 1, A through D). Stimuli were

deliberately presented in such a way that the rat could not attack the

stimulus source. Large movements, but not small ones, overloaded the

amplifier system and an interpretable EEG could not be obtained for

5-10 seconds afterwards. Since the latencies of sigma activity were

within this period, it is not possible to say whether this burst

occurs during attack. Typically, the animal was quite immobile in

the period between the presentation and withdrawal of the stimulus,

on the one hand, and the occurrence of the sigma burst on the other.

In normal implanted control rats, the battery of stimuli uniformly

failed to elicit this activity.

The frequency of the sigma rhythm was 4-5/sec for all rats ex-

cept three; in two it was recorded at 5.5/sec, and in another it

varied from 3.5-4.3/sec. The burst typically had a duration between

1-2 sec. Latency to the sigma response was from 1.8-7.5 sec after

onset of the stimulus. The amplitude of the response varied from

125-250 V, although in a given rat it was constant. An enlargement

of the wave is given in Fig. 2, A, and a sample of the sleeping theta

rhythm from a normal control in B for comparison.

Recordings were obtained from sites verified by histology. Either

no sigma activity or only a low amplitude form of it was recorded from


the caudate (Fig. 1, A through C), lateral nucleus of the thalamus

(Fig. 1, A and B), pretectal area, and neocortex just above the dorsal

hippocampus at the level of the rostral habenula. Therefore, these

sites can probably be ruled out as sources of the sigma activity.

Recordings taken from posterior cortex to any other reference showed

the full amplitude of the sigma pattern. Recordings from anterior

cortex to other subcorticall) points showed a greatly diminished

pattern or none at all (Fig. 1, A through D).

The sigma burst could usually be elicited within 24 hours of

surgery, but in some animals it did not develop until 48 hours after-

wards. In most cases the rhythm was elicited only during behavioral

testing (Setting I), although occasionally it occurred "spontaneous-

ly." Success in eliciting sigma activity varied among animals. In

most cases it was obtained with almost every stimulus presentation,

while in a few it was seen only once or twice a session. In all rats

the frequency of the appearance of sigma bursts decreased with time,

disappearing at its earliest by the fourth postoperative day. The

activity remained as long as seven days in some animals, and seemed

to parallel the decline of emotionality, as measured by the emotion-

ality scale. However, there were insufficient data to demonstrate a

statistical correlation between the decline in emotionality and the

disappearance of the sigma bursts.

Setting I was a situation which evoked alertness and a great

deal of persistent exploratory behavior in normal controls. In con-

trast, septals not only did not explore, but tended to remain in one

place and fall asleep, as shown by the EEG. Recordings were taken


from all animals during cataplexy. During this state the EEG could

not be distinguished from the low voltage fast (LVF) activity of

alert animals.

Setting II (sleeping and waking).-- A comparison of the EEG of

five septals and one control demonstrated striking abnormalities in

the sleeping EEG of the lesioned animals and prevented the quantita-

tive scoring of the records for the amount and distribution of the
stages of sleep. This finding was replicated in a further group of

eleven animals. Recordings lasting up to four hours daily were ob-

tained from each animal for a maximum period of eight days. EEG ob-

servations are combined for both groups. All recording was begun 24

hours after surgery. EEG records were judged independently by two

experimenters for each animal, each day, on seven categories. A

description and the results of each category follow.

(1) Waking EEG

A comparison was made of the LVF waking EEG of normal

controls and septals. Normal animals showed normal waking LVF on the

first postoperative day. Three of the twelve septals showed only

short spurts of LVF on the first postoperative day. Thus their

records could not be considered normal. Longer periods of the usual

waking pattern had returned by day three. For the most part, there-

fore, the septal rat was capable of showing some periods of waking

EEG that were normal in amplitude, frequency, and pattern. However,

a large proportion of the time in which the animal was behaviorally

awake, LVF activity alternated with the HVF pattern, or the LVF pat-

tern was slower than normal.


(2) Sleeping EEG.

The sleep patterns of eight of twelve septals were

judged abnormal with regard to normal controls in that the usual

stages of sleep could not be discerned.7 High frequencies were super-

imposed upon low frequencies, there was frequent alternation of fast

and slow activity, and abnormal slowing during sleep (Fig. 3, A and B).

In half of these animals the normal sleep pattern had returned after

four days, in the other half it remained abnormal for the eight days of

testing. The wave patterns typical of the septal EEG will be dis-

cussed in the following categories.

(a) Mixed frequencies. In ten of the experi-

mental animals rapid alternation of HVS and LVF, or their

simultaneous occurrence, resulted in a blurring of the

normal sleep stages and thus made conventional scoring

impractical (Fig. 3, B). This was especially true for

the first and second postoperative days. Although in

several rats this characteristic disappeared after two or

three days, in others it recurred sporadically through-

out the experiment.

(b) Septal HVS. The most obvious sleep ab-

normality in the septal rat was the appearance of a rhythm

which, in comparison to HVS in controls was: (1) slower,

(2) more regular, (3) had less superimposed fast activity,

and (4) had a much longer duration. Normal sleep occas-

sionally contains similar brief periods of activity (some-

times only a few individual waves), which occur usually

just prior to PS onset (Fig. 3, C). Septal sleep, how-

ever, may consist predominantly of this slower HVS activ-

ity. Two variations of this abnormality, recorded from the

same animal at different times, are shown in the top and

bottom tracings of Fig. 3, A. This rhythm was observed

in eight of twelve septals. In half of the animals this

rhythm disappeared in three or four days, and in the other

half it continued for the eight days of the experiment.

The usual amplitude was 225 iV. Normal HVS was seen in

all animals, although in several it was not evident until

the second or third postoperative day.

(c) Spindle bursts. Spindle bursts of 10/sec

in frequency were almost totally absent from the sleep of

septals throughout the eight-day period. In one animal

they were noted only occasionally.

(d) Theta. Theta rhythm (a sign of both PS and

exploratory behavior) was never observed in lesioned animals.

Nevertheless, the sleep of septals sometimes shifts suddenly

from HVS to LVF, as if PS had been initiated. The behavior

of three septals and one control was observed during a number

of such shifts, and the characteristic irregular breathing,

twitching, loss of tonus, and eye closure of PS were recorded

in all instances.


Setting I (response to threat, attack, and handling)-- Sigma


bursts (Fig. 2, A) occur within or near the frequency range of theta

activity. However, these EEG patterns are distinguishable. Two types

of theta are seen in the normal animal: (1) sleeping theta appears to

be analyzable into a smooth 7-8/sec. wave, of variable amplitude, with

what appears to be additional spikes at the peaks and troughs of this

smooth wave, thus giving theta a spike-like appearance. Sleeping

theta is an indication of the initiation of PS, and is always preceded

by HVS sleep. Typically, 10/sec. spindlesintermix with the HVS sleep

which precedes PS onset, and the initial half minute of PS also tends

to have a few spindle bursts. (2) Exploratory theta, typically seen

in a moving and exploring animal in a new environment, appears

analyzable into a smooth 7-8/sec. wave with a low amplitude high

frequency pattern superimposed. In contrast to sleeping theta, sigma

bursts are slower and have fewer and smaller spikes. Furthermore,

they are not preceded by HVS sleep nor associated with spindles. In

contrast to exploratory theta, sigma bursts are slower, have little

superimposed fast activity, and occur in a relatively immobile and

incurious animal.

The appearance of the sigma rhythm presents two paradoxes. The

first is that it occurs only after presentation of a novel or threat-

ening stimulus, yet its long latency does not suggest a primary

sensory discharge, or reticular arousal resulting from the stimulus.

Secondly, this activity appears related over a period of days to the

gross level of hyperirritability, although in any one test session

it could only be noticed (due to recording problems) during behavioral

immobility. Therefore, this burst appears in the period following the

nonspecific orienting response and before onset of a specific behavior


Several authors have examined the relationship of different be-

haviors with rhythmical electrical activity. Radulovacki and Adey

have correlated hippocampal theta with three behavior states:

(1) immobile alertness (a variable 4-7/sec. rhythm); (2) the orient-

ing response (5/sec.); and (3) activity during performance of a dis-
crimination task (6/sec.). None of these, however, is strictly

related to a defined stimulus event, and they differ only subtly

from the ongoing electrical activity. Pickenhain and Klingberg show

6-9/sec. cortical activity appearing after orientation to the condi-
tioned stimulus in an avoidance task. The 6-9/sec. activity con-

tinues during the performance of the early avoidance responses, but

disappears entirely with further training. Sigma bursts do not re-

quire a conditioning stimulus for their appearance, but do require

an unconditioned stimulus. These authors also report 5-6/sec. photic

after-discharges after presentation of a repetitive flash. An

attempt to replicate these findings in this experiment was unsuccess-

ful. Another series of experiments has defined a 4-12/sec. pattern

occurring after positive reinforcement, and a 12-20/sec. pattern
occurring after negative reinforcement. These electrical rhythms

(4-12/sec. and 12-20/sec.) disappear following diagonal band lesion;

the sigma rhythm is therefore unrelated to these activities since it

is activated only after destruction of this area. Finally, sigma

activity does not appear to be a seizure discharge, since no behavior

signs of seizure were noticed. However, a review by Kaada of evidence


linking seizure discharges with increased aggression does not yet per-
mit elimination of this alternative.

In review, the sigma burst differs from other electrophysiolog-

ical rhythms in frequency, duration, behavioral context, and occur-

rence of lesion. It may represent the result of nonspecific arousal

or the inhibition of nonspecific arousal, reflect recruitment of an

incipient behavior sequence, represent inhibition of a goal-directed

response, or be a manifestation of cerebral injury, or reorganization

after injury. At present, it would seem important to define the source

of sigma activity, establish what stimuli and pathways are effective

in driving it, determine if it is lesion-specific, define its rela-

tion to other EEG patterns, and specify further the behavior occurring

during the rhythm.

Setting II. (sleeping and waking).-- A problem in recording the

EEG 24 hours postoperatively is that any abnormal effects might be

due to drugs administered during surgery. For example, atropine, an

anticholinergic drug, has been shown to produce an HVS activity that

is strikingly similar to that observed in the sleep of the present

experimental animals.8 9 his HVS activity is not due to drug effect

because the effect of atropine is short in duration (2-3 hours after
administration). Furthermore, the pattern did not occur in non-

lesioned controls tested at similar postoperative periods, and the

abnormal HVS was seen in some septals as long as eight days post-


The changes in this experiment in HVS, theta, and sleep spindles

--major electrical signs of sleep--demonstrate the involvement of the


septal area in the sleep cycle, and confirms in the rat some effects
10 4
observed in the septal cat by Parmeggiani and Zanocco, and Jouvet.

The former investigators observed no theta, and found a 75 percent

decrease in the occurrence of PS, which normally follows the HVS

stage. However, when PS did occur, the behavioral signs were present

despite absence of theta. Jouvet found no evidence at all of PS in

the septal cat, and the waking EEG was normal. He did not, however,

notice any change in HVS sleep. Finally, Brugge discovered no change

at all in the sleeping EEG of septal rats, with the exception of the

disappearance of theta waves.1 A finer anatomical analysis is needed

to explain this discrepancy in the HVS sleep stage with the present


Stimulation experiments have demonstrated limbic involvement

in all of the sleep stages. Hernandez-Peon obtained both HVS and PS

with drug-induced cholinergic stimulation in the areas adjacent to

the anterior commissure. Sterman and Clemente produced spindles,

slow waves, and PS in freely moving cats with electrical stimulation

of the ventral diagonal band and nucleus accumbens, an area which

also has been implicated in the septal rage syndrome.3' 18

Thus the evidence obtained from several methodological approaches

implicates the forebrain in the electrophysiological manifestations

of sleep. A central problem concerns the nature of this participa-

tion, and its relationship to the reticular activating system (RAS).

There is now increasing evidence that the sleep-wake cycle is mediated

by cholinergic nerve fibers extending from the RAS of the tegmentum
to the diagonal band-medial septal area, projecting from there to


the hippocampus, and then to the nucleus accumbens. It may be possible

that the forebrain areas of the reticular system are involved with the

relative balance of HVS sleep, PS, and waking. The septal region, for

example, might selectively drive, coordinate, or modulate potentials

arising in other structures that relate to the production of the two

patterns of sleep. For example, the medial septal nucleus is

essential for the appearance of the hippocampal theta,1 and possibly

for the appearance of spindles (which probably arise in the thalamic

recruiting system). Sleep spindles were not observed in the septal

animals in this experiment. The frequency mixing seen in the present

experiment may reflect the destruction of such a coordinating mechanism

in the septal region.

This concept of the septal region as a modulator of sleeping

and waking is supported by behavioral evidence. Septal rats are

hypoactive when left alone, yet hyperreactive when handled. These

behavioral extremes indicate that the effect of the lesion is not due

to simple elimination, inhibition, or facilitation of pre-existing be-

haviors, but rather is a disruption of a system regulating the ampli-

tude of behavior. Further evidence for the involvement of the septal

region in sleep and arousal (behavior amplitude) is the finding by

Turner that lesions in diencephalic reticular areas abolish the
hyperemotionality of rats with the septal syndrome. The region

that attenuates the behavior is the diencephalic extension of the

RAS, whose involvement in arousal is now a classical observation.


EEGs were obtained from cortical dural and depth electrodes in


rats following lesions of the septal area. A high amplitude (200 V)

burst of 4-5/sec. waves (sigma rhythm) was elicited upon presentation

of a threatening or novel stimulus. Latency of the sigma rhythm var-

ied from 1.8-7.5 sees. after stimulus presentation, and was of short

duration (1-2 sees.). Sigma rhythm appeared 1-2 days after surgery,

and disappeared in 4-7 days. The greatest amplitude of response was

recorded over posterior cortex. EEGs were also taken during sleep and

found to be abnormal in that at no time was theta activity or sleep

spindles observed. High voltage slow and low voltage fast components

were highly intermixed, and the signal was often extremely slow.


Electroencephalograms of Normal and Septal
Animals in Different Stimulus Situations

Record A., flickering strobe; B., tap on the back and visual

presentation of a gloved hand; C., stroke to flank; D., flashlight

shined in the eyes; and E., tap and air puff to a normal control.

Records A through D were obtained from rats with lesions in the septal

area. Sigma bursts (4-5/sec.) were elicited in all cases, but not in

the normal control (E). Electrode leads are indicated to the left of

each tracing. Each EEG tracing lasts 26 secs. Abbreviations: caud.,

caudate nucleus; AC, PC, anterior and posterior cortex; LT, lateral

nucleus of the thalamus; HIPP, electrode intended for hippocampus,

but histology lost; and L, R, left, right.



z t fi ? I c t ? ;1 f

I ~ ~ ~ C v .i :. n t I

CI ^ S i ^?I{ .

c( I

^/)~~CC -HU ^^
u-\d ii -1

- a- a 0a- 0
fl D 0 -J 0 0 C
< < < < < a- -A
u L)c -j 44 41

0 -
S1 44 i

0 0
a- L L a_ |^
s~~~~ Y f i'

D a- Z) I
< M(
L) L)i rJ d r


Electroencephalograms of Lesioned and Normal
Rats in a Novel Environment

Record A., sigma activity (4-5/secs.) elicited by a tap on the

back in a rat with septal damage; B., sample of continuous theta

activity in a normal rat exploring a novel environment.



A M.AkI 1,N

-I I

Figure 2.
Electroencephalograms of Lesioned and Normal
Rats in a Novel Environment

I vI

1 !1

r Y


Sleep Records from Animals
with Septal Lesions and Normal Controls

Record A., top and bottom tracings are taken from the same

animal at different times during sleep. The animal has a lesion in

the septal area. The low voltage fast (LVF) activity in the second

half of the bottom tracing indicates the rat has entered paradoxical

sleep (PS) or awakened. Record B., high voltage slow (HVS) activity

intermixed with LVF in a septal animal. Record C., normal animal.

HVS sleep on top two channels, changing into PS sleep on bottom two

channels. Top and bottom tracings are continuous. The first third

of the bottom channel is HVS sleep, the second third is PS, and the

last third is PS at a higher paper speed. Electrode leads are indi-

cated to the left of each tracing. Each EEG tracing lasts 26 secs.

Abbreviations: AC, PC, anterior and posterior cortex; HIPP, hippo-




AC-PC '-- ' A'.' y '* t ;''.' "'" '';
H IPP 4,,..) '. .' '
AC-PC (t, .j ', ,

c- PC

AC-PC 1(1a

Hi i I PP

A C- P C ':', ,' ,";' ,',.. ,

HIPP ,,' '

Figure 3.
Sleep Records from Animals
with Septal Lesions and Normal Controls


1. Brugge, J. F. An electrographic study of the hippocampus
and neocortex in unrestrained rats following septal lesions. Electro-
enceph. clin. Neurophysiol., 18(1965) 36-44.

2. Dillon, R. F. The relationship between sleep and activity
in the rat. Master's thesis (unpublished), University of Florida,
Gainesville, Florida, 1963.

3. Hernandez-Peon, R., Chavez-Ibarra, G., Morgane, P. J., and
Timo-Iaria, C. Limbic cholinergic pathways involved in sleep and
emotional behavior. Exp. Neurol., 8(1963) 93-111.

4. Jouvet, M. Recherches sur les structures nerveuses et les
mecanismes responsables des differences phases du commeil physiolog-
ique. Arch. ital. Biol., 100(1962) 125-206.

5. Kaada, B. Brain mechanisms related to aggressive behavior.
In Clemente, C. D., and Lindsley, D. B. (eds.), Aggression & Defense,
University of California Press, Berkeley and Los Angeles, 1967, p. 95.

6. King, F. A. Effects of septal and amygdaloid lesions on
emotional behavior and conditioned avoidance responses in the rat.
J. nerv. ment. Dis., 126(1958) 57-63.

7. Lewis, P. R., and Shute, C. C. D. The cholinergic limbic
system: projections to hippocampal formation, medial cortex, nuclei
of the ascending cholinergic reticular system, and the subfornical
organ and supraoptic crest. Brain, 90(1967) 521-540.

8. Loeb, C., Magni, F., and Rossi, G. F. Electrophysiological
analysis of the action of atropine on the central nervous system.
Arch. ital. Biol., 98(1960) 293-307.

9. Longo, V. G. Effects of scopolamine and atropine on electro-
encephalographic and behavioral reactions due to hypothalamic stimu-
lation. J. Pharmacol., 116(1956) 198-208.

10. Parmeggiani, P. L., and Zanocco, G. A study on the bio-
electrical rhythms of cortical and subcortical structures during
activated sleep. Arch. ital. Biol., 101(1963) 385-412.


11. Petsche, H., Stumpf, Ch., and Gogolak, G. The signifi-
cance of the rabbits' septum as a relay station between the midbrain
and the hippocampus. I. The control of hippocampus arousal activity
by the septum cells. Eletroenceph. clin. Neurophysiol., 14(1962)
202 211.

12. Pickenhain, L., and Klingberg, F. Behavioural and electro-
physiological changes during avoidance conditioning to light flashes
in the rat. Electroenceph. clin. Neurophysiol., 18(1965) 464-476.

13. Radulovacki, M., and Adey, W. R. The hippocampus and the
orienting reflex. Exp. Neurol., 12(1965) 68-83.

14. Shute, C. C. D., and Lewis, P. R. The ascending cholin-
ergic reticular system: neocortical, olfactory, and subcortical
projections. Brain, 90(1967) 497-520.

15. Sterman, M. B., and Clemente, C. D. Forebrain inhibitory
mechanisms: sleep patterns induced by basal forebrain stimulation
in the behaving cat. Exp. Neurol., 6(1962) 103-117.

16. Sterman, M. B., and Wyrwicka, W. EEG correlates of sleep:
evidence for separate forebrain substrates. Brain Research, 6(1967)

17. Swisher, J. Manifestations of "activated" sleep in the
rat. Science, 138(1962) 1110.

18. Turner, B. N. Localization of the septal syndrome and
its attenuation by thalamic lesions. (Submitted for publication.)


Mr. Turner was born January 25, 1938, in Evanston, Illinois.

He attended high school and grammar school there. He graduated

from Amherst College in 1960 with a Bachelor of Arts degree in Amer-

ican Studies and Classics. Upon graduation he then entered the U. S.

Army and served for three years as a linguist in Romanian. Mr. Turner

received his Master of Arts from the University of Florida in 1966

in Psychology and his Doctor of Philosophy in Physiological Psychol-

ogy in 1968.


This dissertation was prepared under the direction of the

chairman of the candidate's supervisory committee and has been ap-

proved by all members of that committee. It was submitted to the

Dean of the College of Arts and Sciences and to the Graduate Council,

and was approved as partial fulfillment of the requirements of the

degree of Doctor of Philosophy.

December, 1968

Dean, Colge af 1Ats and Sciences

Dean, Graduate School

Supervisory Committee:

Ch man

00< I

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