Intratrial cue observations and delayed response performance in normal and prefrontal monkeys

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Intratrial cue observations and delayed response performance in normal and prefrontal monkeys
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Delayed response performance in normal and prefrontal monkeys
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Table of Contents
    Title Page
        Page i
    Acknowledgement
        Page ii
    Table of Contents
        Page iii
        Page iv
    List of Tables
        Page v
    List of Figures
        Page vi
    Abstract
        Page vii
    Introduction
        Page 1
        Page 2
        Page 3
    Method
        Page 4
        Page 5
        Page 6
        Page 7
        Page 8
        Page 9
        Page 10
        Page 11
        Page 12
        Page 13
        Page 14
        Page 15
    Results
        Page 16
        Page 17
        Page 18
        Page 19
        Page 20
        Page 21
        Page 22
        Page 23
        Page 24
        Page 25
        Page 26
        Page 27
        Page 28
    Discussion
        Page 29
        Page 30
        Page 31
        Page 32
        Page 33
        Page 34
        Page 35
        Page 36
        Page 37
        Page 38
        Page 39
        Page 40
        Page 41
    Appendix
        Page 42
        Page 43
        Page 44
        Page 45
    Bibliography
        Page 46
    Biographical sketch
        Page 47
        Page 48
        Page 49
        Page 50
Full Text










Intratrial Cue Observations and Delayed Response
Performance In Normal and Prefrontal Monkeys











By

ROGER WINTON BUDDINGTON


A DISSERTATION PRESENTED TO THE GRADUATE
COUNCIL OF THE UNIVERSITY OF FLORIDA
IN PARTIAL FULFILLMENT OF THE REQUIREMENTS
FOR THE DEGREE OF DOCTOR OF PHILOSOPHY










UNIVERSITY OF FLORIDA
1971













ACKNOWLEDGEMENTS


The author wishes to express his gratitude to his

chairman, Dr. Frederick A. King, for his valuable suggestions

and support. The services of members of the author's Super-

visory Committee are also gratefully acknowledged.

He also wishes to express his appreciation to his wife,

Sharon, who worked so diligently in the realization of this

project.














TABLE OF CONTENTS

Page
A CK N OW L E D G EM E N T S . . . . . . . .... . .. . it

LIST OF TABLES.......................................... v

LIST OF FIGUES..............................0*0.0.0*** Vi

ABSTRACT . . . . . 0 0 0 0 . . . . . vi








Srgcedr. . . . . . a * * * * * * * * 0 * * 6 4


Habi tuat Ion. . . . c 0 0 e c 0 c 0 0 0 0 0 e 0 c 0 6
Shaping. 0 0 . 0. 0 c 0 0 * e 0 9 e e c 0 c 0 e 0 0 9 0 # 0 e 7
Discrimination training.......... ..eo.* 10
Stimulus s.11p...tion.. .......c......c... 11
Delayed response .... ........ ....... .... 12
Food deprivation ................... 12
Histology...on training ....... .. .... 13



Behavior., e r...es. e... ...a .. .....aa ..... 16
Recovery period............................. 16
Trials to criterion........................... 16
Cue observation ... ....a....c..e........ 19

Histology...... ....... .......... c e a cc c.c a23







iii








DISCUSSION................................................ 29
Trials to Criterion ......................... *..... 29

Intratrial Cue Observation.......................... 32
General oonsiderations..................... 32
Observation period. .................... ..... 32
Cue period........... ....... .. .......... 33
Delay period.. . . .. . . . . . .. ... ..... *..... 37

Summar9.............................................. 4
APPENDIX......................... oo....................... 42

BIBLIOGRAPHY.............................................. 46
BIOGRAPHICAL SKETCH....................................... 47












LIST OF TABLES


Table Page
1. Cue Period: Average Number of Motion Picture
Frames Showing Cube Observation.................... 20
2. Delay Period: Average Number of Motion Picture
Frames Showing Cue Observation..................... 22
3. Cue Period: Individual Averages for the Number
of Motion Picture Frames Showing Cube Obser-
vation............................................ 43
4* Delay Period: Individual Averages for the
Number of Motion Picture Frames Showing Cube
Observation........................ 45













LIST OF FIGURES


Figure Page

1. A schematized representation of the fully
restrained animal as he would have appeared
in the camera viewfinder when he was observing
the rewarded cube.................................. 9
2. Trials to the 90 percent criterion............... 18

3. Average latency of the initial rewarded cube
observation...............................* ..... *25

4. A dorsal view of the brain from each prefrontal
operate...............,.............*.*..***.*.***. 27










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


INTRATRIAL CUE OBSERVATIONS AND DELAYED RESPONSE
PERFORMANCE IN NORMAL AND PREFRONTAL MONKEYS


By

Roger Winton Buddington

June, 1971

Chairman: Dr. Frederick A. King
Major Department: Psychology

When they were restrained during testing prefrontal

squirrel monkeys were found to be deficient with respect to

normal controls in their performance on two variations of an

indirect delayed response test. Three measures of the intra-

trial cue observations of prefrontal and normal monkeys were

studied. The latency for the first rewarded cube observation

was the same for prefrontal and normal monkeys throughout DR

testing. Stimulus observation during the cueing period of DR

testing was also similar for normal controls and prefrontal

operates. Furthermore, stimulus observation during the delay

period of DR testing did not vary as a function of lesion.

Prefrontal and normal monkeys were comparable in their Intra-

trial cue observations on DR even when their overall performance

levels differed greatly. It was concluded that intratrial

cue-observation was not related to DR test performance.













INTRODUCTION


Buddington et al. (1969) studied the performance of

normal and prefrontal squirrel monkeys on discrimination and

indirect delayed response (DR) tests. It was found that the

introduction of an intratrial delay, into a testing procedure

that was otherwise unchanged from previous discrimination

tasks, resulted in decreased levels of both prefrontal and

normal performance. Furthermore, the efficiency with which

criterion performance was reattained during initial DR test-

ing was dependent upon the cueing situation for prefrontal

operates, but not for normal controls. A further analysis

of" their data revealed that neither the cueing situation

presented during DR testing nor the effect of introducing

the delay could, in themselves, sufficiently account for the

DR performance of prefrontal operates. Rather, it was the

interaction of the cue situation with the effect of intro-

ducing the intratrial delay which determined whether pre-

frontal DR performance would be comparable or inferior to

that of normal controls.

Considering the decreased level of performance for all

animals during initial DR testing Buddington et al. (1969)

hypothesized that, with the introduction of an intratrial

delay, modification of the response patterns previously

established during discrimination training was necessary.
1








This hypothesis was investigated in the present report

by comparing the average behavioral pattern during individual

discrimination and DR test-trials with the overall level of

performance. By obtaining these two measures during selected

portions of the testing sequence, variations of performance-

level across tasks could be related to concomitant altera-

tions of within-trial behavior. With this approach, and by

employing the testing sequence described by Buddington et al.

(1969), it would be possible to identify the hypothesized

modification of within-trial behavior during initial DR

testing, as well as to compare prefrontal and normal within-

and between-trial behaviors, when adaptation to the intro-

duction of an intratrial delay was occurring.

For the purposes of thepresent investigation, within-

trial behavior was limited to a single response variable.

The animals were restrained during testing with the permitted
intratrial behaviors being related primarily to cue observa-

tion (head movement) or reward attainment (hand, arm, and

some torso movement). Because previous investigations (Miles

and Blomquist, 1960; Buddington et al., 1969) have reported
that prefrontal damage does not alter the motor behavior of

squirrel monkeys, it was expected that the motor aots

involved in reward attainment would be similar for the pre-

frontal and normal squirrel monkeys in the present study.

The pattern of within-trial behavior was therefore expressed

in terms of a single intratrial behavior (i.e., amount of

cue observation).








The second objective of this study was a further inves-
tigation of the relationship between cue situation and delay

introduction. As was mentioned above, the interaction of

these two factors was found to determine whether prefrontal

performance during DR testing was comparable, or inferior,

to that of normals (Buddington, et al., 1969). On the basis

of this result these same authors hypothesized that dorsolat-

eral prefrontal damage in the squirrel monkey resulted in an

increased dependence upon external cues for the guidance of

behavior when modification of response patterns (the hypothe-

sized effect of delay introduction) was required. This

hypothesis was studied in the present investigation by com-

paring prefrontal and normal intratrial cue-observations

during the initial DR tests for the training sequence.














METHOD


Subjects

Twelve naive adult male squirrel monkeys (Saimiri

sclureus) served as subjects. All animals were housed

throughout the experiment in individual cages permitting some

degree of communication with neighbors. Six monkeys were ran-

domly assigned to the normal control group and six animals

received damage to the dorsolateral prefrontal cortex.


Surgery

All operations were performed under aseptic conditions as

described elsewhere (Buddington et al., 1969). The intention

was to ablate the region of the sulcus principalis of the pre-

frontal cortex. Animals in the operated group were allowed

either a one-month or a two-year recovery period between oper-

ation and the commencement of any experimental procedures.


Apparatus

A modification of the Wisconsin General Test Apparatus

(Harlow, 1959) was utilized, The compartment containing the

monkey was 43 cm. deep, 56 cm. wide and 87 om. high. A Plex-

iglas monkey perch extended from one side of the animal compart-

ment to the other and could be adjusted in the vertical plane

from 8 to 20 cm. below the surface of the stimulus tray. An








eyehook was located on the animal compartment floor 30 cm.

behind, and 30 cm. below, the monkey perch.

The stimulus tray which remained stationary in a position

forward and towards the monkey compartment contained two

foodwells 1.6 cm. in diameter and spaced 31.8 cm. apart.

Each foodwell was covered by a 3.8 om. cube constructed with

translucent Plexiglas. The cubes were each attached to the

stimulus tray by two lightweight chains, one chain fastened

to the back lower edge of the cube and the other fastened to

the lower edge of the cube-side facing away from the monkey.

Inside each cube was a miniature 6 volt light bulb (Westing-

house number 47-radio) which was controlled by a swirohbox

outside of the apparatus. The bulbs were held by sockets

mounted in the rear wall of each cube with all external

wiring concealed from the animal's view.

An opaque screen and a transparent Plexiglas screen, both

of which could be raised or lowered, separated the monkey from

the stimulus cubes. These screens were constructed so that

when they were lowered a center area of the stimulus tray

25 cm. wide, 22 cm. high, and 18 cm. deep was left open to

the animal compartment. A snaphook was fastened to a metal

post in the center of this area. Located 20 cm. from this

post, within the stimulus tray compartment, was an Arriflex

16-8 16 mm. motion picture camera. The camera was equipped

with a 10 mm. wide-angle lens which protruded through a

closely fitted opening in an opaque barrier directly in front

of the camera. A black curtain on either side of the camera








barrier allowed the experimenter to bait the foodwells during
the intratrial interval without being observed when he subse-

quently raised the opaque screen separating the monkey from

the stimulus tray compartment. Located 10 cm. in front of the

camera was a timer-light which flashed once each second. The

camera which was set at a speed of eight to ten frames per

second was controlled by a microswitch that was activated

when the opaque screen separating the animal from the stimulus

tray compartment was raised. The apparatus was illuminated

by a 25 watt floursoent ceiling light in the stimulus tray

compartment, and by a 25 watt incgdesoent bulb in a photoflood

reflector at the rear of the animal compartment. The test-

trials were recorded on 100-foot rolls of Kodak Tri-X, black

and white reversal film.

Each animal wore loosely fitting, lightweight, neck and

waist chains (American Chain and Cable Company number 16,

single brass Jack chain) 95 cm. and 56 cm. respectively, in

length. A snaphook was fastened tightly to the end of each

chain. An 85 cm. section of wooden pole with an eyehook on

either end allowed for handling of the animals between home

cage and test apparatus.

Procedure
Habituation.--Each monkey was gradually habituated to
being handled and restricted by his neck and waist chains.

During the first habituation day the monkey was transfered

from his home cage to the apparatus cubicle by attaching his

neck chain to the handling pole. The monkey was then offered








as many currants as he would eat before being returned to his

home cage. During the second and third habituation days the

monkey was placed in the apparatus and began eating currants

while sitting on the Plexiglas perch. The waist chain was

attached to the eyehook on the animal compartment floor

during this period but the neck chain remained on the

handling pole. After attaching the waist chain, during the

final habituation day, the monkey's neck chain was threaded

through the snaphook in the center of the stimulus tray, then

removed from the handling pole and brought down under the

perch to be snapped onto the eyehook in the animal compart-

ment floor. Restrained in this manner (see Figure 1), the

monkey was given currants on the stimulus tray until satiated.

No subsequent procedure was begun for any animal until he had

completed this habituation sequence.

Shaping.--Prior to testing, each animal was given a

minimum of five days'training in displacing one or another

of the unlit stimulus cubes for a currant placed in the

foodwell beneath the cube. On successive trials, one of the

cubes was placed over the baited foodwell while the other was

positioned at the rear of the tray behind the unbaited food-

well. Currant placement was determined by a restricted

Gellerman (1933) series. There were 40 trials a day until

the last two days of shaping when there were 60 trials. In

no case was testing begun until the subject responded without

hesitation to cube presentation for 120 trials during two

consecutive days. The last 60 shaping trials of every




















Figure 1. A schematized representation of the fully restrained

animal as he would have appeared in the camera viewfinder when

he was observing the rewarded cube. The monkey is separated

from the stimuli by two translucent Plexiglas doors, and is

attached to the center post by a neck chain.
























































































































































































............
. . . . . .



...........





............






. . . . . .. . . .





............. .



............ ........
.............
............ ......
............. .....
............ ....



. .. . . . . . .
.............

............. ...





..........
.............
..............









animal were filmed. Each animal was restrained in the

apparatus just prior to the daily test-session in this and

all subsequent procedures.

Discrimination training.--When an animal reached the

shaping criterion, discrimination training (DT) was begun.

A currant was placed in one foodwell and both stimulus cubes
were positioned covering their respective wells. Location

of the baited well was determined by the same Gellerman

series used in shaping. Each DT trial commenced by raising

the opaque screen separating the animal and the stimulus

cubes. A two-second observation period was subsequently

allowed during which the transparent Plexiglas screen

remained in place allowing the animal to view, but not

manipulate, the cubes. At the end of the observation period

the baited cube was immediately illuminated to begin a two-

second cue period. During the cue period, the Plexiglas

screen remained in place preventing manipulation of the

stimulus cubes. At the end of the cue period the trans-

parent screen was immediately removed and, with one cube lit

and the other darkened, the animal was allowed to respond.

A trial was begun every 45 seconds and the non-correction

technique was employed. The lit cube was positive for all

animals (i.e. a currant was placed in the foodwell beneath

it). Each animal was tested daily for as many trials as

could be recorded on a single 100-foot roll of film. On

a single day during DT there were never fewer than 45, nor

more than 60, test-trials for any animal. All animals were








trained to the criterion of 36 correct responses in any

block of 40 trials. On the day criterion performance was

achieved the next test in the sequence was immediately begun.

Stimulus manipulation.--Prior to the beginning of the

experiment the normal and operated animals were randomly

assigned to either an A or a B subgroup (three normal con-

trols and three prefrontal operates per subgroup). When an

animal in Group A reached criterion on DT it was tested on

two successive stimulus manipulations (STM). The procedure

during STM training was identical to DT for the observation

and cue periods. Therefore, when the transparent screen was

about to be raised at the beginning of the response period

during STM, one cube was lighted and the other was unlit.

However, as the screen was raised during STM (zero delay)

the unlighted cube was illuminated and the monkey was present-

ed with two lit cubes. When criterion had been reached on

this first STM, training on the second began. Testing

conditions were identical to those present during the first

STM, except that the illuminated cube went out as the trans-

parent screen was removed. The animals in Group A were

therefore faced with two darkened cubes at the time of

response execution during the second STM.

Group B, after reaching criterion on DT, was presented
with the same two STMs as Group A, but in reverse order.

Throughout all STM procedures, the cube which was

illuminated during the two-second cue period was rewarded.

The performance criterion and number of daily test-trials








were the same as described for DT.

Delayed response.--Delayed response (DR) testing was

begun for each animal as soon as it had reached criterion on

the second STM. The procedure for DR testing was the same
as that for the STM tasks except that the transparent screen

remained in place for an additional two seconds when the

stimulus manipulation occurred at the end of the cue period..

On the first DR test both cubes were darkened during this

two-second delay period and at the time of response execution

for Group A animals. For their second DR task Group A ani-

mals were presented with two illuminated cubes during the

delay period. Group B animals received the same two DR tasks,

but in reverse order. As in all previous tests, criterion

performance was 36 correct responses in any block of 40

trials, and the cube illuminated during the cue period was

positive. Training on the second DR task began for each

monkey as soon as it had achieved criterion performance on

the first DR test. If an animal had not attained criterion

within 500 trials on the first DR test, training on the

second DR task began immediately.

Food deprivation.--For approximately one hour following

daily testing, all animals were provided with a diet of
standard, small monkey, lab chow supplemented twice weekly

with portions of apples and oranges. Subjects were conse-

quently 22-23 hours food deprivedat the beginning of each

daily training session. In addition to this deprivation

schedule the amount of food provided at the daily feeding









hour was adjusted for each animal so that, by the time he

started discrimination training, he readily accepted 60

currants during each daily test-session.

Histology.--At the end of the experiment each operated

monkey was sacrificed and perfused with saline followed by

10 percent formalin. The brains were subsequently removed

and photographed from the dorsal view to verify the locus of

damage within the prefrontal areas.

Data analysis.--Since DT testing conditions were the
same for all animals, these data were withheld from the over-

all trials-to-criterion analysis and the combined A and B

normal subgroups compared with the A and B prefrontals in a

separate DT analysis. The remaining data were analyzed by

means of a four-way repeated-measures analysis of variance.

The factors were designated as (a) task, i.e., STM versus

DR; (b) stimuli, i.e., cubes-on versus cubes off; (c) order,

i.e., both cubes on for the first test of a task followed

by both cubes off Versus cubes off and then cubes on; and

(d) lesion, i.e., normals versus prefrontals.

Discriminanda observations were analyzed for the cue

period during DT and STM and for both the cue and delay

periods during DR. The observation data for the cue period

during STM and DR were analyzed by means of a six-way repeated-

measures model. Four of the factors (task, stimuli, order,

and lesion) were the same as described for the trials-to-

criterion analysis. The remaining factors were designated









as (a) trials, i.e., the first versus the last twenty trials

of each STM or DR test; and (b) cue contingency; i.e., the

rewarded versus non-rewarded cube.

The observation data for the cue period during DT were

analyzed with a three-way repeated-measures model. Because

the DT testing conditions were the same for all animals the

combined A and B normal subgroups could be compared with the

combined A and B prefrontals. The factors were therefore

designated as (a) lesion; (b) trials; and (c) cue contingency,

with the same definitions as their counterparts in the above -

described analyses.

Cue observation during the delay period on DR testing

was analyzed as a five-way repeated-measures design. The

factors, which were designated as (a) order; (b) lesion;

(c) stimuli; (d) trials; and (e) cue contingency, were defined

as in the previously described data analyses.

The latency of the first rewarded cube observation

during the cue period was analyzed with a three-way repeated-

measures model. The factors were designated as (a) order,

i.e., Group A prefrontal and normal monkeys versus Group B;

(b) lesion, i.e., prefrontal operates versus normal controls;

and (o) latency; i.e., for the entire test sequence the total

average latency of the first rewarded cube observation based

upon selected 20 trial blocks from each task.

A second analysis of the DR latency data was conducted

employing a four-way repeated-measures design. The factors

were designated as (a) order, i.e., Group A prefrontal








and normal monkeys versus Group B; (b) lesion, i.e., prefront-

al operates versus normal controls; (c) stimuli, i.e., both

cubes illuminated during the delay versus both cubes darkened;

(d) trials, i.e., the first versus the last twenty trials of

each DR test.













RESULTS


Behavior

Recovery period.--The prefrontal operates provided with

the twelve-month recovery period (SM 374, 376, and 379) and

those with the one-month recovery period were randomly

assigned to Subgroups A and B. Although the twelve-month

group was inferior to the one-month group on DT, the overall

performance of the two groups was not consistently different

and did not affect the statistics or interpretation of the

study.

Trials to criterion.--The number of trials each monkey

required to reach criterion is presented for each of the

testing conditions in Figure 2.

The combined A and B prefrontal subgroups were not

significantly different from the combined normal subgroups

on DT (t=l.30, p> 0.20). For the analysis of variance con-

ducted on the STM and DR trials-to-criterion data there were

four main effects, six two-way interactions, four three-way

interactions, and one four-way interaction. The lesion (L)

and task (T) main effects were both significant at the 0.01

level of confidence (F=17.27 and 51.66, df=1/8 for each test).

The L X T interaction was significant at the 0.02 confidence

level (F--9.35, drf=1/8). All other main effects and inter-

actions for this analysis were not significant.
16


















Figure 2. Trials to the 90 percent criterion. (The stimulus

cues present when the manipulanda were presented to the animal

are indicated schematically at the top of each column for

Groups A and B. Lines drawn around a cube indicate that it

was illuminated, while a + above a cube indicates that the re-

ward was located in the foodwell beneath it. The task abbrevia-

tions at the top of each column are the same as in the text.

Following a trials-to-criterion score, + indicates that testing

was discontinued after the number of trials indicated. All

scores include the criterion trials).






GROUP A
TASK DT STM DR
STIMULUS [/,t + t -- \ /
SITUATION D -LIF F .. n -- -

NORM.
SM366 113 40 40 40 167
SM402 194 X= 188 38 X = 42 41 X=40 148 X=76 90 X = 01
SM 413 254 47 38 40 45
FRONT.
SM 379 344 41 52 481 500+
SM412 143 X=220 40 X=58 36 42 500- 397 500+X=400
SM 414 173 93 39 211 201

GROUP B
TASK DT STM DR

STIMULUS _D Dj- DjL
SITUATION \ 'I \ /1 \/ / \

NORM.
SM384 190 III 37 263- 38-
SM399 159 X= 161 38 X=62 40 X 38 412 X=286 43 X=99
SM445 134 36 37 184 217
FRONT.
SM 374 208- 55 63 263_ 500+
SM410 189 X=224 40 X=11 47 X 60 307 X 237 38 X=346
SM 376 274 239 71 142 500+








Cue observation.--The data for discriminanda observation

during the cue period of each task are presented in Table 1.

For DT, the analysis of observations during the cue period
had three main effects, three two-way interactions and one
three-way interaction. The cue contingency (C) main effect

(F=59.62, df=1/10) and the C X trials (TR) interaction

(F=35.35, df_=1/10) were both significant beyond the 0.01

level. All other main effects and interactions for this DT

analysis were not significant. The statistical analysis of

observations during the cue period for STM and DR testing had

six main effects, fifteen two-way interactions, twenty three-

way interactions, fifteen four-way interactions, six five-way

interactions, and one six-way interaction. The task (T),

stimuli (S), and cue contingency (C) main effects were all

significant beyond the 0.01 level while the trials (TR) main

effect was significant at the 0.025 confidence level (FT=39.55,

FS=12.06, FC=230.09, FTR=7.57, df=l/8 for each test). The

significant two-way interactions were T X TR (F=11.84,

df=l/8, p=0.01) and T X C (F=9.23, !K=1/89 0.01
Of the significant three-way interactions, lesion (L) X S X

TR and T X TR X C were both significant at the 0.05 confi-

dence level (F=5.39 and 5.69, respectively, and df=l/8 for

each test), while order (0) X S X C was significant at the

0.025 level (F=l0.79, d f=1/8). All other main effects and

interactions for this analysis were not significant.

The data for cue observations during the delay period

of DR testing are presented in Table 2. The statistical










Table 1. Cue Period: Average Number of
Motion Picture Frames Showing Cube Observation@


GROUP A


Task

Stimulus
Cubes

Trials
Sampled

Cue
Observed

Normals

Frontals


Discrimination

One Cube
Illuminated

First 20 Last 20


R* N**


7.3

5.1


6.3

5.6


R N


10.8 4.0

9.6 4.0


Stimulus Manipulation

Both Cubes
Illuminated

First 20 Last 20


R N


10.1 5.1

8.5 3.8


a N


9.5

10.6


4.0

2.6


GROUP B


Task Discrimination Stimulus Manipulatio

Stimulus One Cube Both Cubes
Cubes Illuminated Unlit

Trials First 20 Last 20 First 20 Last 20
Sampled
Cue R N R N H N R N
Observed

Normals 5.2 4.6 8.3 4.4 8.6 3.3 8.3 3.

Frontals 6.5 7.8 8.8 3.4 8.5 4.7 9.8 3.
*R=Rewarded stimulus cube

**N=Unrewarded stimulus cube

@The raw scores for these data are presented In the Appendix


n1


0

2














Table 1. continued


Stimulus Manipulation
Both Cubes
Unlit

First 20 Last 20


Delayed Response

Both Cubes
Unlit

First 20 Last 20


Delayed Response

Both Cubes
Illuminated

First 20 Last 20


R N R N


R N R N


8.8 4.5

10.9 3,1


9.8 4.1

10.7 3.1


9.9 3.2

9.3 3.7


8.4 4.6

8.9 2.5


7.2 4.1

8.4 3.0


6.7 2.9

6.8 3.7


Stimulus Manipulation

Both Cubes
Illuminated

First 20 Last 20


Delayed Response

Both Cubes
Illuminated

First 20 Last 20


Delayed Response

Both Cubes
Unlit

First 20 Last 20


R N R N


R N R N


7.7 2.5

9.1 3.2


8.5 2.3

9.6 3.0


8.2

8.2


3.3

3.1


7.0 2.5

7.3 2.8


6.8 3.0

8.7 5.0


7.4 2.7

5.4 3.8


R N


R N


R N


R N











Table 2. Delay Period: Average Number of
Motion Picture Frames Showing Cue Observation


GROUP A


Task

Stimulus
Cubes

Trials
Sampled

Cue
Observed

Normals

Frontals


Delayed Response

Both Cubes
Unlit

First 20 Last 20


R* N**


8.7 2.6

6.6 4.0


R N


7.3

7.0


2.5
2.1


Delayed Response

Both Cubes
Illuminated

First 20 Last 20


R N


6.5 3.7

6.9 3.5


R N


6.4 2.0

5.4 3.5


GROUP B


Task Delayed Response Delayed Response

Stimulus Both cubes Both Cubes
Cubes Illuminated Unlit

Trials First 20 Last 20 First 20 Last 2
Sampled

Cue R N R N R N R
Observed

Normals 6.8 4.6 6.0 3.1 5.9 2.4 6.4 1

Frontals 7.7 3.3 7.2 2.6 7.5 3.4 5.7 2

*R=Rewarded Stimulus Cube

**N=Unrewarded Stimulus Cube

*The raw scores for these data are presented in the Appendix


0


N


.9

.4








analysis for tkese data had five main effects (order, lesion,

stimuli, trials, and cue contingency) and a total of 26

interactions. The cue contingency and the trials main effect

were each significant beyond the 0.01 confidence level (F=18.66

and 57.62 respectively, df=1/8 for each test). The five-way

interaction of the factors designated as main effects was

also significant (F=9.04, df=I/8, 0.01 p 0.025). All other

main effects and interactions for ttese analyses were not

significant.

The average latency of the initial rewarded cube obser-

vation during the first and/or last twenty trials of each

task is presented in Figure 3. None of the main effects or

interactions were statistically significant for either of the

variance analyses conducted on these data.


Histology

A dorsal view of the brain from each prefrontal operate

is presented in Figure 4. From the gross brain specimens,
bilateral damage to the prefrontal areas of SMs 374, 376,

379, and 412 appeared to be similar in extent and located

within the area of the sulcus principals as intended.

Damage to the prefrontal area in the right hemisphere of

SMs 410 and 414 was as intended and was similar in extent

and locus to the damage sustained by the other operates.

Damage to left prefrontal areas however was less extensive

than intended for these latter two animals. In the case of

SM 410 damage appearedto be located in a medial and anterior

position within the dorsal prefrontal cortex of the left




















Figure 3. Average Latency of the Initial Rewarded Cube Observation.

(The column and row headings are the same as for Figure 2 except that

the individual animals are not listed. The number given for the first

and/or last twenty trials of each test is the group average for the

number of motion picture frames, counting from the beginning of the

cue period, until the initial positive cube orientation. The scores

in parentheses present the range for each mean).





GROUP A
TASK DT STM DR

STIMULUS +
SITUATION DF DT Fl/ -I EI -I Ml -/- E

FIRST20 LAST20 LAST20 LAST 20 FIRST2O LAST20 FIRST2O LAST20
NORMALS 73 6.9 7.0 7.3 5.5 6.2 5.6 7.1
(6.7-8.3) (6.6-74) (6.3-8.3) (6.9-8.0) (3.9 -8.6) (5.6 -78) (4.0-7.4) (4.7-103)
FIRST 20 LAST 20 LAST20 LAST20 FIRST20 LAST 20 FIRST20 LAST20
FRONTALS 10.3 74 5.9 5.4 7.6 6.9 8.3 11.6
(72-13.6) (4.5-9.8) (53-70) (4.2-6.9) (4.4-12.0)(5.6-8.4) (6.7-11.0) (72-15.0)

GROUP B
TASK DT STM DR


SITUATION / I\ / \ / I\/i\ / \

FIRST20LAST20 LAST20 LAST 20 FIRST 20 LAST 20 FIRST20 LAST20
NORMALS 8.4 6.5 4.9 5.3 6.2 6.5 7.7 8.5
(6.2- 10.6) (5.5-72) (4.1-5.9) (35-72) (3.7-8.9) (4.5-8.0) (6.2-9.9) (6.8-10.7
FIRST20 LAST20 LAST20 LAST20 FIRST 20LAST20 FIRST20LAST20
FRONTALS 8.4 8.6 7.7 6.4 8,0 8.0 9.2 78
(6.5-10.3)(4.2-12.6) (5.8-11.6) (3.7-9.1) (3.9-13.3) (6.2-10.5) (6.4-11.7) (6.6-87)






























Figure 4. A dorsal view of the brain from
each prefrontal operate.

















410


412


414








hemisphere leaving the major portion of the sulcus prncipalIs

intact. Injury to the left prefrontal cortex of SM 414 was

more correctly located, but removal of the sulcus principals

was less than total. As can be seen by reference to the

trials-to-criterion data (Figure 2), these variations in

lesion locus and size were correlated with test performance.

In particular, the DR performance for SM 410, with an essen-

tially unilateral sulcus principalis removal, was comparable

to the DR performance of the normal controls in Group B. The

DR performance of the remaining Group B operates, however, was

deficient in comparison to normal controls. The DR perfor-

mance of SM 414 was impaired in comparison to Group A normal-

control performance. This animal was, however, less impaired

on DR than the remaining Group A prefrontals with more complete

bilateral sulous principals removals. These lesion varia-

tions had the effect of increasing between-subjects variability

on the DR tests (e.g., see Figure 2, Group B prefrontal

operates on their second DR test), but did not otherwise alter

the results or interpretation of the study.













DISCUSSION


Trials to Criterion

As indicated by the significant lesion main effect,

prefrontals were poorer in their overall STM and DR pefor-

mance than normals. This same tendency was also present on

DT, although prefrontals were not statistically different

from normals. These results are in agreement with a previous

investigation (Buddington et al., 1969) where unrestrained

monkeys were observed in an identical testing situation.

The task main effect indicates that the DR tests were
significantly more difficult than STM for both normal and

prefrontal monkeys. As shown by the significant L X T

interaction, however, this increase in difficulty between

STM and DR was greater for prefrontal operates than normal

controls.

It is concluded on the basis of these results that there

is a general, debilitating effect of the lesion resulting in

the overall inferiority of prefrontal operates on disorimi-

nation and discrimination-based tasks. It Is further

concluded that there is a second, task-specific effect of
the lesion resulting in especially deficient prefrontal DR
performance. Whether these effects are related or separate

could not be decided on the basis of the present investigation.
29









The DR performance for prefrontal monkeys restrained

during testing is not the same as the performance of monkeys

free to roam an animal compartment. Buddington et al. (1969)

reported that unrestricted prefrontal operates were impaired

in comparison to normal controls when their first DR test was

with the cubes off stimulus situation. When subsequently

tested with both cubes illuminated during the delay prefron-

tal monkeys were observed to perform as well as normal

controls. In the present study, prefrontal operates tested

with this same stimulus sequence (see Figure 2, Group A

prefrontals) were impaired throughout DR training. Further-

more, Buddington et al. (1969) reported that non-restrained

prefrontal operates were unimpaired when tested on DR with

the both cubes on followed by the cubes off stimulus

situations. When prefrontal operates were tested with this

same cue sequence in the present investigation they were com-

parable to normal controls on their first DR test (cubes "on")

but were deficient when subsequently tested with two darkened

cubes (see Figure 2, Group B prefrontals). It is concluded

on the basis of these comparisons that eliminating locomotor

behavior during testing increases the severity of prefrontal

impairment on DR tasks.

The DR performance of restrained normal monkeys, tested

with both cubes darkened during the delay, did not appear to

be different from the performance reported by Buddington

et al. (1969) for unrestricted normal animals during cubes off

DR testing. Restraining the monkeys did, however, appear






31
to increase the number of trials normal animals took to reach

criterion on DR training when both cubes were illuminated dur-
ing the delay. This increase in the number of trials to cri-

terion was not as large for the normal subjects as it was for

the prefrontal monkeys that were tested on DR with two illumi-

nated cubes. The debilitating effects of eliminating locomotor

behavior during DR testing were therefore much less severe and

pervasive for normal controls than prefrontal operates. It is
therefore concluded that the DR performance of prefrontal

squirrel monkeys is more dependent upon locomotor behavior than

is the DR performance of normal squirrel monkeys.
The interaction of the cue situation with the effect of
delay introduction was less effective in determining DR per-

formance level when prefrontal monkeys were restrained during

testing. Buddington et al. (1969) reported that when monkeys
were unrestricted during testing, prefrontal performance was

comparable to that of normals on the first DR test if both

cubes were illuminated during the delay, but was deficient if
both cubes were darkened. In the present investigation for

monkeys restrained during testing, prefrontal performance also

appears to be more comparable to that of normals on the first

DR test when both cubes were illuminated rather than unlit dur-
ing the delay (see Figure 2). This tendency was not verified

by the statistics however. The lack of a significant four-way
interaction, in conjunction with the significant L X T inter-
action, necessitates the conclusion that prefrontal performance
did not vary as a function of either the cue situation or

sequence of DR tests in the present study.








Intratrial Cue Observation

General considerations.--A test-trial was comprised of

distinct but contiguous time periods. Each trial began with

a two-second observation time during which both of the stim-

ulus cubes were unlit. Immediately following this was a two-

second cue period when one of the cubes was illuminated while

the other remained darkened. At the end of the cue period,

for the DT and STM tests, a transparent door separating the

monkey from the stimulus cubes was removed and the monkey

could respond. For DR testing, however, the cue period was

immediately followed by a two-second delay period with both

cubes either illuminated or unlit. A response was permitted

at the end of the delay period during DR testing.

Observation period.--During the observation period that

began each trial, all animals viewed the stimulus cubes.

Typically, discriminanda observations were rapidly alternated

from one cube to the other during this period. There were,

however, frequent observations of the test environment which

were not directed towards either stimulus cube. On the

average therefore, only 40 to 60 percent of the two-second

observation period was spent actually viewing the stimulus

cubes. The alternate observation of the two stimulus cubes

continued into the cue period until the illuminated (rewarded)

stimulus cube was first observed. Behavior during the

observation period was therefore conceived of as being

directed towards a search for the rewarded cube. The

efficiency of prefrontal and normal search behavior was









assessed in terms of the latency for the first rewarded cube

observation during the cue period (see Figure 3). Cube

observations in this, and all subsequent analyses, were

defined on the basis of frame by frame inspection of the

motion picture records from testing. When a monkey viewed

the stimulus cube he typically appeared as is indicated,

semi-schematically, in Figure 1. The absence of significant

effects from either of the statistical analyses for this

latency measure indicates that search behavior did not vary

as a function of lesion or testing conditions. It is there-

fore concluded that this aspect of intratrial behavior is

not related to either the DR, or the overall performance

deficit of prefrontal monkeys.

Cue period.--After the initial rewarded cube inspection,

the monkeys typically made subsequent alternating observa-

tions of the negative (unrewarded) and positive (rewarded)

cubes throughout the remainder of the cue period. Cue

observations were quantified for each trial in terms of the

number of motion picture frames in which the monkey observed

the rewarded and unrewarded cue.

The significant cue-contingency main effect for the

analysis of discriminanda observation during the cue period

on DT indicates that the rewarded cube was observed more

than the negative stimulus on both the first and last twenty

trials of this test. The significant C X TR interaction,

however, shows that the preference for positive cube obser-

vation increased greatly from the first to the last twenty








trial block. The lack of a significant TR main effect,

however, indicates that the total amount of cue observation

was the same for the first and last twenty trials of DT.

It is therefore concluded that as DT is mastered the amount

of rewarded cube inspection increases while there is a con-

comitant decrease in the amount of negative cube observation.

Considering that all animals were trained with two darkened

cubes during the shaping procedure, it is suggested that the

slight preference for positive cube observation during the

first twenty DT trials resulted from the novelty of the

illuminated cube in its debut as an environmental stimulus.

Finally, prefrontal operates were not statistically differ-

entiable from normal controls in their intratrial cue obser-

vations on DT. This result agrees with the trials-to-

criterion data where prefrontal performance was also statis-

tically undifferentiable from that of normal controls.

The average total amount of discriminanda observation

during STM (12.7 frames per trial) was less than during the

last twenty trials of DT (13.3 frames per trial). As indi-

cated by the significant task main effect for the analysis

of discriminanda observation during the cue period of STM

and DR, the average total amount of cube observation for DR

(11.1 frames per trial) was less than that for STM. Finally,

the significant trials main effect indicates that the amount

of cue observation also decreased from the first to the last

twenty trials for all tests. It is suggested that the

decreased amount of stimulus observation, from DT to STM









to DR, reflects habituation to the general conditions of the

test procedure. It is not unlikely, considering the basic

similarity of the individual test procedures, that a

learning-set for cue observations was developed as the ani-

mals progressed through the testing sequence. That the

amount of disoriminanda observation also decreased from the

first to the last twenty trials is interpreted as indicating

that "habituation" to the conditions of each test also

occurred during acquisition. The significant task by trials

interaction indicates that decrease in amount of cue obser-

vation from the first to the last twenty trials was greater

for the DR tasks than for the STM tests. Considering that

a much greater period of time (in terms of the number of

trials to criterion) was spent on DR testing than on STM,

it is concluded that habituation to the test conditions was

greater during DR than during STM testing.

Approximately 70 percent of the total cue observation

during the last twenty DT trials was directed towards the

rewarded cube. The significant reward main effect for the

analysis of observations during the cue period of STM and

DR indicates that there was an overall preference for

positive cue orientations on these tasks. More precisely,

an average of 71 percent of the total observations were

directed towards the positive cue during STM and DR testing.

The significant task reward interaction shows that the per-

centage of positive cue orientations was greater for STM

(73 percent) than DR (70 percent). Furthermore, the








significant task-trials reward interaction indicates that the

percentage of rewarded cube observations increased from the

first (70 percent) to the last (75 percent) twenty trials on

STM, but decreased slightly from the first (70 percent) to the

last (69 percent) twenty DR test-trials. These results

support the conclusion that the preference for positive cue

observation that was established during DT was maintained

with little variation throughout STM and DR testing.

As indicated by the significant stimulus main effect,

there was a greater total amount of observation on STM and

DR when both cubes were darkened at the end of the cue period.

The significant order stimulus cue-contingency interaction

shows that there was a greater difference between positive

versus negative cue orientations when both cubes were darken-

ed for Group A monkeys, Group B monkeys, however, showed

the greatest difference between positive and negative cube

orientations when both cubes were illuminated at the end of

the cue period. Finally, the significant lesion stimulus

trials interaction revealed that there was a slight decrease

from the first to last twenty trials in the total amount of

cue orientations for prefrontal monkeys when they were tested

on 8TM and DR with the both cubes darkened stimulus situation.

For normal monkeys, however, there was a slight increase in

total observation from the first to the last twenty test

trials for the both cubes darkened STM and DR tasks. These

results were not paralleled in the trials-to-criterion data.

In particular, there was no significant stimulus main effect








and the performance of the monkeys was therefore similar for

both of the cue situations during STM and DR testing. Also,

there was no significant main effect or interaction involving

the order factor, and the trials-to-criterion performance did

not differ between Groups A and B during the STM and DR tasks.

Finally, there was no significant difference between prefron-

tal and normal monkeys in the overall trials to criterion

performance for the both cubes darkened stimulus situation.

It is concluded therefore that the variations of Intratrial

observation indicated by the significant S, 0 X S X C, and

L X S X TR effects reflect minor adaptations to the changes

in overall performance level that were described for the

trials-to-criterion data.

Delay period.--The significant cue-oontingency main

effect for the analysis of cue observations during the delay

period, indicates that the rewarded cube was observed more

than the negative cube throughout DR testing. More specific-

ally, an overall average of 69.5 percent of the total cue

observation during the delay period was directed toward the

rewarded stimulus, and it should be noted that this figure

is virtually identical to the percentage of positive cube

observation during the cue period. While the significant

trials main effect shows that the total amount of cue obser-

vation decreased from the first to the last twenty trials,

the absence of a significant TR X C interaction indicates

that the preference for positive cue observation was present

during the first twenty DR test trials. It must be concluded,








therefore, that a preference for positive cube orientation

during the delay does not develop as a result of DR training

but is fully present at the first introduction of the delay

into the testing procedure.

An inspection of the cell means for the significant

five-way interaction revealed an overall pattern for oue

observation during the delay period. There was an overall

decrease in the total amount of discriminanda observation,

from the first to last twenty test-trials, as was previously

indicated in considering the T main effect. The relative

proportion of rewarded and unrewarded cue observation,

however, tended to be constant on the first and last twenty

trials. The most notable exception to this general trend was

for the Group A prefrontal operates on their first DR test

with the darkened cube stimulus configuration. During the

first twenty trials the proportion of positive cube observations

for this group of prefrontals was decreased to 62 percent

from the overall average of 70 percent. By the last twenty

trials however the proportion of observations for the reward-

ed stimulus was increased to 75 percent. This result is in

accord with the deficient trials-to-criterion performance of

this prefrontal group on their first DR test (see Figure 2,

Group A prefrontals for the both cubes darkened stimulus

situation).
I It is suggested on the basis of these results that, when

their first DR test is with the cubes "off" situation, pre-

frontal squirrel monkeys have difficulty In maintaining








an orientation toward the rewarded cube during the delay

period. This effect does not explain the overall DR impair-

ment of prefrontal monkeys in that it is transitory and only

appears for the first twenty test-trials. Furthermore, the

pattern of cue observation for prefrontals under all other

test conditions was similar to the overall pattern and did

not match the variations in trials-to-criterion performance

for the operated or normal groups. It is concluded therefore

that the amount of rewarded and unrewarded cue observation

is not related to the level of performance during DR testing.


Summary

It was not expected that the DR performance for monkeys

restrained during testing would be different from the perfor-

mance of prefrontal operates free to move about. Because

the increased impairment of restricted prefrontal operates

resulted in deficient performance throughout DR training,

one of the original goals of this study was frustrated. It

was originally intended that intratrial cue observations

would be compared for operated and normal monkeys when

prefrontal performance during initial DR testing was impaired

for one of the cue situations but not the other. Cue situa-

tion interacted in this way with the effect of delay intro-

duction for monkeys that were unrestrained during testing

(Buddington et al., 1969). On the basis of this interaction

those authors hypothesized that, in comparison to normal

controls, prefrontal squirrel monkeys were more dependent








upon external cues for the guidance of their behavior when

modification of response patterns was required during initial

DR testing. Cue situation did not interact with the effect

of delay introduction in the present investigation.for re-

strained prefrontal monkeys and further study of this

hypothesis was therefore abandoned.

If response modification occurred during initial DR

testing, it was not reflected in the pattern of discriminanda

observations during either the cue or delay periods. A

preference for positive cube observations was established

during DT and was subsequently maintained at a constant

level throughout testing by both prefrontal and normal

monkeys. There was, in fact, no @onsistant correlation

between trials-to-criterion behavior and cube observation

during either the cue or delay period for the DR tests, and

it was therefore concluded that this measure was not related

to DR test performance. The efficiency of search behavior

during the observation period was also constant throughout

DR testing for both normal and prefrontal monkeys.

Considering the drastic impairment of prefrontal perfor-

mance during DR testing, it was surprising that no evident

differences were found when the intratrial behavior of .pre-

frontal and normal monkeys was compared. If prefrontal DR

impairment derived from an increased perseverative tendency

(e.g. Mishkin, 1964) or increased distractibility (e.g.

Malmo, 1942), etc., it would be expected that one or another








aspect of the within-trial behavior for frontal monkeys would

be greatly different from normal. This investigation shows,

however, that prefrontal lesions have a much more subtle

effect upon intratrial behavior than would have been expected

on the basis of current hypotheses concerning the nature of

prefrontal DR impairment.

The DR performance of prefrontal squirrel monkeys was

shown to be more dependent upon locomotor behavior than was

the performance of normal squirrel monkeys. This suggests

that locomotor behavior is employed by the prefrontal monkey

during DR testing to substitute for the lost function of his

prefrontal cortices. Further experimentation is needed,

however, to elucidate the functional role of locomotor.

behavior in the DR performance of prefrontal squirrel monkeys.


































APPENDIX







Table 3. Cue Period: Individual Averages for the Number of
Motion Picture Frames Showing Cube Observation


GROUP A


Discrimination


Stimulus Manipulation


Stimulus
Cubes
Trials
Sampled

Cue
Observed*
Normals
SM 366
SM 402
SM 413
Frontals
SM 379
SM 412
SM 414

GROUP B


One Cube
Illuminated


First 20


R N


7.0
6.9
8.0

5.3
5.5
4.5


7.8
7.6
3.6

7.0
5.4
4.4


Both Cubes
Illuminated


Last 20

R N


12.5
10.7
9.0

10.0
10.0
8.7


2.8
4.2
5.1

4.6
3.9
3.4


First 20


R N


12.4
9.7
8.3

8.2
9.1
8.1


5.0
4.9
5.5

5.0
3.4
3.0


13.0
7.8
7.4

11.7
8.9
11.1


Di scrimination


Stimulus Manipulation


Stimulus
Cube s
Trials
Sampled

Cue
Observed
Normals
SM 384
SM 399
SM 445
Frontals
SM 374
SM 410
SM 376


One Cube
Illuminated


First 20


R N


3.5
5.9
6.3

6.7
5.4
7.2


3.7
3.7


7.6
7.1
8.7


Both Cubes
Unlit


Last 20

R N


7.1
8.0
9.7

9.0
10.9
6.5


6.1
3.6
3.3

3.0
3.4
3.7


First 20


R N


6.8
8.2
10.6

7.3
8.8
9.2


5.4
2.3
2.2

7.0
3.5
3.4


*Cue Observed: R=Rewarded Cube; N=Unrewarded Cube


Task


Last 20

R N


Task


1.6
6.3
4.4

2.2
3.0
2.5


Last 20

R N


8.8
6.8
9.3

9.0
10.0
10.3


4.2
1.7
8.9

3.1
3.5
3.1










Table 3. oontinued

GROUP A
Stimulus Manipulation
Both Cubes
Unlit


First 20

R N


10.8 5.1
8.1 3.6
7.4 4.9

9.9 4.3
10.4 3.4
12.2 1.6

GROUP B


Last 20


Delayed Response
Both Cubes
Unlit


First 20


R N R N


10.7
8.9
9.7

10.6
11.3
10.4


4.0
4.
3.

2.6
3.6
3.3


9.1
11.3
8.9

8.1
7.7
11.8


3.8
2.7
2.8

4.1
4.2
2.7


Last 20


Delayed Response
Both Cubes
Illuminated


First 20


a N R N


10.3
7.4
7.4

10.7
5.9
9.9


5.6
4.1
3.9

3.6
1.6
1.3


9.8
5.7
6.1


10.9
6.1
8.0


3.3
5.4
3.5

2.8
3.3
2.7


Last 20

R N


6.4
7.1
6.6

6.1
5.6
8.6


Stimulus Manipulation
Both Cubes
Unlit


First 20


R N


7.9 3.
5.7 1.6
9.4 2.7

10.7 4.3
7.3 3.0
9.3 2.4


Last 20


Delayed Response
Both Cubes
Unlit


First 20


R N a N


9.0
7.7
8.9


10.8
8.8
9.0


2.5
2.6
1.8

2.9
2.6
3.5


7.7 3.5
8.0 2.0
8.9 4.3


6.6
8.3
9.6


4.3
3.2
1.7


Last 20


Delayed Response
Both Cubes
Illuminated


First 20


R N R N


6.4
5.6
8.9

7.6
5.0
9.1


3.5
1.8
2.0

1.4
3.6
3.3


7.6 3.6
5.4 1.9
7.3 3.3


9.3
6.4
10.4


6.7
4.4
3.8


Last 20

R N


9.5
6.5
6.4

6.4
5.3
4.5


4.2
2.4
2.2

5.2
3.2
2.5


3.1
2. 3
2.2

2.8
5.6
3.0







Table 4. Delay Period: Individual Averages for the Number of
Motion Picture Frames Showing Cube Observation




GROUP A


Delayed Response


Delayed Response


Stimulus
Cubes

Trials
Sampled

Cue
Observed*

Normals
SM 366
SM 402
SM 413

Frontals
SM 379
SM 412
SM 414

GROUP B


Both Cubes
Unlit


First 20


R N


9.0
9.8
7.4

7.0
5.8
7.0


2.2
2.4
3.0

2.4
4.8
4.8


Last 20

R N


8.9
6.2
6.8

8.3
4.0
8.5


2.2
2.3
2.8

1.1
3.2
2.0


Both Cubes
Illuminated


First 20


R N


8.4
4.8
6.3

7.6
4.5
8.5


3.0
3.9
4.0

4.3
3.5
2.6


Delayed Respons


Delayed Response


Stimulus
Cubes

Trials
Sampled

Cue
Observed

Normals
SM 384
SM 399
SM 445

Frontals

SM 37
SM 376


Both Cubes
Illuminated


First 20


R N


7.6
5.0
7.8

8.6
6.8
7.4


4.5
4.1
5.1

2.0
3.8
3.9


Both Cubes
Unlit


Last 20
R N


6.8
4.3
6.8.

7.5
6.0
8.0


3.1
2.9
3.2

0.8
2.5
4.4


First 20


R N


6.9
4.9
5.9

6.4
7.8
8.3


3.1
1.7
2.4

4.2
2.0
4.0


R=Rewarded Cube; N=Unrewarded Cube


Task


Last 20

R N


8.7
3.5
6.6

6.2
1.9
7.9


Task


1.0
1.5
3.6

5.7
3.6
i.


Last 20
R N


8.6
6.2
4.6

6.2
6.7
4.4


1.7
1.2
2.2

1.0
3.0
3.3


*Ce Observeds














BIBLIOGRAPHY


Buddington, R. W., King, F. A., Roberts, L. Analysis of
changes in indirect delayed response performance in
monkeys with prefrontal lesions. J. comp. physiol.
Psych., 1969, 68, 147-154.

Malmo, R. B. Interference factors in delayed response in
monkeys after removal of frontal lobes. J. Neurophysiol.,
1942, 1, 295-308.

Miles, R. C., and Blomquist, A. J. Frontal lesions and
behavioral deficits in monkeys. J. Neurophysiol.,
1960, 23, 471-484.

Mishkin, M. Perseveration of central sets after frontal
lesions in monkeys. In Warren, J. M., and Akert, K.
(Eds.) The frontal granular cortex and behavior.
New York: McGraw-Hill, Inc. 1964, 219-241.














BIOGRAPHICAL SKETCH


Roger Winton Buddington was born on June 13, 1943, in
Bridgeport, Connecticut. His parents moved to Stratford,

Connecticut in 1947 where he attended public school until

he was graduated from Bunnell High School in 1961. He

attended Fairfield University in Fairfield, Connecticut

from 1961 until 1965 when he received his Bachelor of Arts

degree with a major in Experimental Psychology. In September,

1965, he entered the University of Florida Graduate School in

the Department of Psychology. He worked as a research assis-

tant in the Division of Neurosurgery from 1965 to 1967, when

he received the degree of Master of Arts with a major in

Experimental Psychology. From 1967, until the present time

he has held a Predoctoral Fellowship in the Center for

Neurobiological Sciences of the University of Florida and

has pursued his work toward the degree of Doctor of Philosophy.

Roger Buddington is married to the former Sharon Marie

Cunha, and has two sons.














I certify that I have read this study and that in my
opinion it conforms to acceptable standards of scholarly
presentation and is fully adequate, in scope and quality,
as a dissertation for the degree of Doctor of Philosophy.



Frederick A. King, ChAirman
Professor of Neurosolence


I certify that I have read this study and that in my
opinion it conforms to acceptable standards of scholarly
presentation and is fully adequate, in scope and quality,
as a dissertation for the degree of Doctor of Philosophy.



Charles J,,, lerok T 7 TM
Assoclate-Professor of Neurosolence


I certify that I have read this study and that in my
opinion it conforms to acceptable standards of scholarly
presentation and Is fully adequate, in scope and quality,
as a dissertation for the degree of Doctor of Philosophy.



HRo"rt M. saaeson
Co-Director of Center for
Neurobiological Sciences
Professor of Psychology








I certify that I have read this study and that in my
opinion it conforms to acceptable standards of scholarly
presentation and is fully adequate, in scope and quality,
as a dissertation for the degree of Doctor of Philosophy.



Wilse B. Webb,,n ,
Graduate Research Professor



I certify that I have read this study and that in my
opinion it conforms to acceptable standards of scholarly
presentation and is fully adequate, in scope and quality,
as a dissertation for the degree of Doctor of Philosophy.



Henry S. Penopacker
Professor of Psychology



This dissertation was submitted to the Dean of the College
of Arts and Sciences and to the Graduate Council, and was
accepted as partial fulfillment of the requirements for the
degree of Doctor of Philosophy.

February, 1971


ran. Collge o rOabSciences


Dean, Graduate School