Relations between stimulus-bound eating and intracranial reinforcing strength

Beholvoural 3 Elsevler

Proce>ses, 1 (1976) Sclentltlc

RELATIONS

165 Amsterdam

BETWEEN STIMULUS-BOUND

REINFORCING

hl

165-175 Company

Publlshmg

- Prlnted

111The

EATING

Netherlands

-AND INTRACRANIAL

STRENGTH

BEYRA*

Laboratorre de lv’europhyslologle C’nrverwte de Louuo~r~. Cl C L venue Hlppocrate 54 B 1200 Brurelles (Belgum) (Received

18 March

5139

1976)

ABSTRACT Beyra

hl , 1976

strength

Behau

Relations

Processes,

between

1

stimulus-bound

eating

and

Intracranial

reInforcIng

165-175

Rats ~lth monopolar electrodes Implanted In the lateral h> pothalamus were trained to self stimulate. each under 38 different electrical stimulus values Stimulus-bound drlnhlng and eating (SBB) were ellclted b> strmulatlng the rats through the same electrode with the same parameters and the same rate at which the) self-admmlstered the stlmulatlon It was observed that the frequency of SBB depended on the parameters of the electrlcal stimulus The Spearman ranh order correlation was computed between strength of SBB and the strength of the reinforcing effect ellclted bq bram stimulation 4 factor analysis showed that the relnforcmg process elicited by brain stlmulatlon m this area IS composed of several factors and that SBB IS not loaded In all the factors composmg reinforcement

INTRODUCTION

It 1s well known that electrical stlmulatlon of several hypothalamic IOCI through the same electrode yields self-stlmulatlon behavior (ICSS) as well as stimulus-bound behavlour (SBB), 1 e eatmg, drinking, copulation, etc (see reference m Vale&em, 1969. Valenstem et al , 1970, Hoebel, 1971) It was generally considered that electrical stlmulatlon ehcltmg SBB excites the phys101og~al system controllmg specific motlvatlonal state and that the evoked behavlours were the expression of the activation of speclflc drives However. this generally accepted mterpretatlon of the behavloural effects of hypothalamic stlmulatlon, as well as of the neural substrates of this behavlour, became a matter of controversy (Valenstem et al , 1970) when several studies showed that the type of consummatory behavlour elicited by hypothalamic stlmulatlon may change mth time and that the same stimulation may elicit different consummatory behavlours (Cox and Valenstem. 1969, Valenstem et al , 1970, Valenstem, 1971, Mogenson, 1971) *The author passed away on August article was revised and then submitted colleague and friend

4, 1975 A rough manuscript forming the by his collaborators In memory of their

basis of this deceased

166

Because the same electrode j lelcls self-stlmulntlon as well as feeclmg 01 drinking. it has been questIoned why an animal would work to obtain a stimulus that made It hungry or thwstg Several solutIona have been proposed to this parado\ One solution l Valensteln 1969) is to assume that stimulation evoking eating or drlnklng behavlours does not e\ oke speclflc cleaves, but creates conclltions which are referred to by the author 85 moocl states’ which excite the neural substrate underlyIng flkecl nctlon patterns A second solution 1s Hoehel’s I 1971 I clrlve Induction hypothesis. that hypothalamic stunulatlon 1s rewarcllng (as are many natural btimuli w+ ‘1s food OCIOLI~S I ant1 thus induces eating A thn-cl solution 1s to assume with Ball ( 1969) and Huston I 1971 I that the drive ancl the reuarrl effects of hypothalamic stlmulatlon represent different degrees of actlvdtion of two neural systems These contloversles show how the nature of the relation between remforctng and drive effects ellcltecl II>, h>lpoth,alamlc stmlulation 1s far from clear The present work wab pelformecl to study the relation between the strength of the lelnforcmg effect and the strength of the stimulus-bound behavlour elicitelI by hypothalamic stiniulatlon Specifically. this stucly investigates whether the more reinforcing braIn stiniulatlons are thobe ehcitlng a stronger alimentar) consummatov behaviour RIETHOD Subjects,

tralnirlg

nnd hlstologv

The suhJects were male allxno rats of the \Vlstar strain. welghmg approxlmate11 300 g at the time of operation Each rat was Implanted wth one monopolar nickel-chrome electrode (0 25 mm dlnmeter I Insulated except for the cross set tlon of the tip The regon aimed for wxs the lateA posterior hypotblamus The Indifferent electrode was placed 1 mm dnterlor to the bregrna The electrodes were implanted stereota\lcally accordmg to the followmg coorcllnates A 3 5 mm posterior to bregma. L 1 2 mm H 8 3 mm helow the skull surface After the operation. the animals were ,allowecl to recover one week before training for self-stlmulatlon started X relnfolcecl lever press produced n 0 5 second train of negative rectangulx pulses of 0 1 msec duration, at d frequency of 100 Hz Current threshold for self-stlmulatlon ranged from 150-280 PA and was monitored at all times by means of ‘an oscilloscope Rats were sub mltted to trammg sessions until the bar pressing rate became steady Rats which chd not e\hlblt self- stlmulatlon behavlour were ehmmated Followng termlnatlon of the experiment the subjects were sncnflced The brains were removed from the skull and put m formalln solution for 10 clays The brains were then frozen, sectioned at 100 p and staned with cresyl-wolet

167

.4ppara tus Lever pressmg for self-stlmulatlon was tested In plexiglass enclosures 45 cm long, 30 cm wide and 60 cm high A reinforced lever press produced a tram of brain stlmulatlon and an electrical pulse that was recorded on a magnetic tape The parameters of the braln stimulus were monltored by the e\penmenter A bottle of water and a small clash contammg food purma pellets were placed m opposite corners of the experImental box during testmg for elicited behavlours Procedure Thirty-eight electrical brain stirnull were composed by Larymg the electrical parameters, I e pulse width, frequency and train duration The electrical parameters of sttmulatlon are represented m Table I For purposes of habltuatlon. the subJects were allowed to self-stimulate for several days under the various stimulus condltlons. after the habltuatlon sessions each stimulus condltlon was presented in a random order to each SubJect Each presentation lasted eight minutes, dunng which subJects were remforced for bar pressing under a contmuous remforcement schedule The bar pressmg rate was recorded on magnetic tape The subjects were then tested for stlmulatlon-induced eatmg and drmklng wth the same parameters used during self-stlmulatlon The stimulator was trlggered by the magnetic tape The rate at which an animal was stimulated under each stimulus condition was the same rate at which It had previously self-stimulated The SubJects were allowed to habituate to the experimental condltlons before starting the expenmental senes The stimulus-bound eating or drmkmg ehclted by the brain stimulus was measured as follows Each subject was stimulated under the 38 different condltlons of the brain stimulus Each stimulus conclltlon was presented 4 times to each rat, I e 24 times for the sample of 6 rats Smce there were 38 stimulus condltlons, the results were computed on the basis of 912 presentations Each presentation lasted 5 minutes and was dlvlded Into sets of 15 seconds It was noted if SUbJeCtS ate or drank durmg each 15-set set The number of times that eating or drinking behavlours were recorded m these condltlons ~111 be called the frequency of stimulus-bound behavlour Durmg a 5-mm session the maximum frequency of SBB was 20 As each stimulus condltlon was presented 3 times to each SubJect, the maximum frequency for a SUbJect and for a brain stimulus condltlon was 80, and thus 480 for the 6 rats After each stimulus presentation, the amount of food and water consumed was also recorded Data analysrs We attempted to estimate the relation between mg effect and the strength of the stunulus-bound electrical stlmulatlon of this bram area, computmg

the strength of the remforcbehavlour ehclted by the the Spearman rank order

correlation The stu-null were ranhed accordmg to the strength mg effect and according to the strength of the stm~ulus-bound IJraln stimulation ellclts The strength of the relnforclng effect. these parameters of electrical stimulation in this bram area, has studied (Beyra. 197lal Finally. a factor analysis was performed

of the relnforcbehavlour this ellclteci b> tJeen previousl>

RESULTS

Table I shows the values of the electrical parameters of bran stlmulatlon used to test for ICSS and SBB This t,lble aho lntlwates for each subJect the freqiiency at mhlch stimulus-bound eating and dnnhlng were elicited the amount of food consumed 111grams, and the amount of water consumed in mlllihtres These data clearly show that the electrical stlmuhtlon of this h-aln area, at the same rate self-stlmulatlon occurs. excites a neural substrate supporting feeding and dnnkmg behabqour It appears also that. m this brain area, stlmUhIs-bound eating IS evohed at a higher frequency than IS stlmulusbound dnnkmg FInall). the level of excltatlon of these neural systems. as evaluated LJ~ SBB. depends on the parameters of the electrIcal stimulus XII the sublects tended to react Iclentlcalllg at this level of stlmulatlon Fig 1 represents the frequent> at Mhlch. under each stimulus rats e\hlblt a SBB. I e e,atmg Note that the Intenslt> of the stimulus-bound behavlour increases monotonically with the stimulus duration HoNever for L\ brain stlmulub of a constant duration. the Intensity of SBB depends on the other parameters of the electrical stimulus pulse width, pulse .requenc> nncl intenslt> (see different panels. Fig 1 I A quantitative estlmatlon of the relation between the reinforcmg effect and the drive effect elicited by rewarding hypothalamic stu-nulatlon was made by computing the Spearman rank order correlation between these two be havlours For this purpose, brain stunulatlons were ranked according to the strength of the remforclng effect and the strength of SBB they elicit The strength of the relnforcmg effect of these brain stlmulatlons has been previously studied (Beyra, 19Sla). with rats submltted to ICSS 111ldentlcal condltlons to those described m this paper It 1s assumed that the samples of rats used to measure the reinforcmg effect and the SBB effect of hypothalamic stimulation Here homogeneous. on the basis of two arguments First. durmg ICSS trammg. self-strmulatlon behavlour uas slmllar for the different SubJects and these subjects were randomly asslkmed to the different esperimental groups Second. the hlstolo@cal analysis showed that electrode tips of the SubJects from the different samples were randomly dlstnbuted m the same brain area Consequently, the vanatlons observed on the dependent variables, I e SBB and reinforcing strength, are mainly due to differences m the parameters of electrIcal stlmulatlon. I e the Independent variable The strength of the relnforcmg effect of the stimulus was evaluated by a rate method (measurmg bar pressing). by a consummatory method (measunng the amount of electrical charge the SubJects self-admmlster dunng a penod of work, as well as the duration of self-administered stimulation), try a choose method (measunng the frequency at which a stimulus IS chosen m a

169

Fig 1 The frequency of stimulus-bound eating elIcited by bram stlmulatlon IS represented on the ordinate (F S B maxlmal frequency 480 J The values of the electrlcal parameters of the brarn stimulus are represented In each panel I e DP = pulse width, F = pulse frequency, and DT = stimulus duration on the abscissa The current Intensity remalned constant at the ICSS threshold

pared comparison procedure), by a cost method (measurmg the voltage of a foot shock necessary to suppress self-stlmulatlon behavlour), by regulation of the tram duration, and fmally by different flxed ratlo procedures (ratio of bar pressing to obtam one bram stimulation) The correlation coefficients obtamed are represented in Table II The correlation between the frequency of SBB and the strength of the remforcmg effect elicited by hypothalamic stimulation is zero when the remforcmg effect

1’0

z z 0

6’1

i

S’O 1

90’0 90’0

OOT 001

001

0

1 0 9'0 P

0 1

0

8

z 1 1

00 1’0

1’0 L’O

00 9’0

E-0

VI

9.0 9’Z

9

1

z 9

S

8

91

0

0 0

0 0

0 0

0 z 0 0

0 0 0 0

0 0 0 1 0 1

0

1 0

0 8 0

9’0

90’0 SZT’O SZ’O

0

Z’O 0

0

8 0

1

Z P

PO’0

0

6’0 0

6’0 E’Z

0 or

9’0

1

Z'O Z'O Z'O Z'O Z'O Z'O z.0 Z'O

Z'O Z'O Z'O Z'O Z'O Z'O 2'0 Z'O

Z'O Z'O 2'0 Z'O Z'O Z'O Z'O

Z'O Z'O Z'O Z'O Z'O Z'O

OOP OOP 00) OOP OOP OOP OOP OOP

ooc 008 OOE OOE OO& OOE 008 008

002 002 ooz ooz ooz ooz ooz

OOT OOI 001 001 001 001

001

001 001 001 001

OOT

6’:

90’0 90’0

Z

s

Z P

00

8 I

0

0

0

0

P’l

sz.0 S’O 1

1’0 I’0 1’0 5.0 1’0

0

P

9’0

0 zz ST

2 P

0 0

z 1

9’0

x

9’0 0

z T

9’0 9’0 0 00 00

0

Z

9’Z 8’0

sz Zl

921’0 sz ‘0

0

1’0

1

0

0

0

1

B

0

0 00 1’0 1’0

0

Z

8 0 1 1’0

E’O Z 1

P 1 P 1’0 T’O 0 Z 1

1 9’0 Z z 0 6 L 81 Pl

g8 BP

1 0

9.8

0

6 I 0 9’0 I.0 1’1 8’1 SZ OZ

L-29

8P Z9 1P

0

0 6’0 P’l 8’0

9.z 8’0

0 Zl

S’O

0 0

L 0 P & ZI P.Z 8‘0

0 0 Z

0 Z’O 0 0 E 8

6&Z

P’P 67 L‘6

0 0 0

Pl

0

0

0 0

8 Z

P’l

0

P

Z

0

0 0 01 9 I

6 9

9‘0

8T

P oz

0

01 8

0

0

9’2

1 1

LI P 6 1 Z

00 8’0

01 01 1’0 L’l 8 11 9

91 6 LZ

0 0 P 6 0

0

Z

1’1

0

0 Ll

0 z

1

0 0

0 & 2’0 p’o 2’0

Z 0 : 0 9 L 18 LP

0 E’O 1’0 91

0 9’1

92

I

0

0 0 z E’O 8’Z 1’S

L

0 0 9

1

6.1

8 PF:

0

0

:1 PZ 91 9’0 9 Z 8 81

PT 8

E'O

0 0

9’1 P’1 Z’O 0 8 01

P 0

O g’” El

0

z z

0 01

L

L z-11

0 0 0

0

8 8 S 0 1’S 8

00 2 0

8 1 9’P S’P P 81 T’O

OE 9’Z 8’0 11

9’1 L’O E’O 92

I

0 P 1 01 S LP 9’9

8P 88

0 8 1’0 S.1 L9

17 9.9

Z& 88

L

8’1 81 Ll

6 ! Z 61: PT.

0 1 91 Zl zz

0 0 0’0 9’0 9’1

0 1 9

‘2.6 96 0 0 S

P

99 69

VI P’B

P’l L.Z

z 1

8 v1

9’0

L’:

z

OP

L 1

S’Z Z

S’S

0 E

1’0

PI

E S’O

1 11

‘2.6

ZP

I’0

0 T

0

9

P’Z

z 0 ZZ 08

I L

11 8P

9’0 9’1 6S IP

0

0 0

0 0

P

Z

ZI 9

8 81 P

80’0 91’0 ZB’O 99’0

P

0 8 :

P’O

0 6’0 8’: 00 00 P‘O 00

E’O

0 L 0

L

S.8 0

1

0 0 0

01 08 OS

I z

z z

; Zl

z

9’0 0 0 0

0 8’0 0’1

00 I.0 1’0 BP 08 6P EZ

9.: I‘1

I

0 Zl 81 ‘21

0 1

ZE

T’O

0 P’T 8’0 8’0

0

L‘zv PX 9’Z

1 0 0 + 0 1 0

0 0

P Z 9

Z‘Z

z PT 81 oz 88

02

1 P PT

8’0 E‘P

6’Z Z’T

Et

SE 92 0

P’O 0 -2’0

0 8

Z 81

6’0 6’0 0

z 0

01 0

11

9’0 P 01 El

8’0 P 0

0 Z

9’9 ZZ PE ZI

S’O 0

0 6

Z

I

OS

0 9’0 6Z SP

S t S’L 1

99 9S

LZ

61 P 91 SE

Z8

9

0 0 0 z 0 1 0

P P

S.S 8 6I S ZI

Z’O 9’1 L’I 8‘8 87

LB

S 1

61

9'8

9

827 9s ‘2 Z’S

S 9 61

Z. 8 Z

Z E S 91 81 PZ

L’O

8%

S P Z8

Zl 11

91

0

Z’I

8’0 9’0 S’Z

S 0

01

SE

0

LI

0

L

9’0 P’O 0

00 S’O 0

E

WI

0 1 Z

0 0

01 0 T

SZ

ZI

9

S& 6E

00 0 0

8’0

1 P

P’Z 9’1

9 01

Z 0 ST

0 0

zz OZ 00 1’0 9’0

00 1 0

8

z S’L

S’S 0

0 0 Z

5; ZB

z

z vz t”l 9’0

0

z

l’&

ES 1 1 t L

0

K

P 0 1’0

S’O

L 8’1 8’0

69

0

L L E’I P’Z

z

t9 Z

E P 6’1

Z 1 0

0 L’O

8 2

E1 roS’O Z’Z Z’l S’Z 9 8

0 1 81

I 2

9 I & L 9 E’Z P’Z

0 0 Z E 0 0 0 1

oz

B 1

1’1 6’0 Z’l

OE

1.; P 9 9

6’0

9'0

80’0 90’0 SZI’O SZ ‘0

11

GI d

3

9 s

P

1 1 8

ml

0 L’O 9’0 S‘l

B’P L’Z 6T

‘9

ILB

w

6

0

S

ST L

S’l

0

0 i I 0 z 6

2.7

T’O 0

1

z9

0 0 1 Z ZS

w a

171

IS evaluated by a rate method However. the strength of SBB IS partially correlated w:lth the strength of the relnforcmg effect. when the latter 1s evaluated by a consummatov method. I e the time subJect.s are stimulated and the amount of electrical charge they self-admInIster N’e ha[e previously pointed out that the frequency of SBB tends to Increase monotonlcally with the stemulus duration, It thus makes sense that the frequency of SBB IS strongly correlated to the time subJects self-stimulate

TABLE

11

Spearman rank order correlation coettlcrents between the strength of the relntotcrng eftect and the strength of the stimulus-bound behavloul ehclted b\, hraln stlmulntlon The btrength OI the stimulus bound beha\lour 1s evaluated b) the ttequenq (DF) and amount of food Intake (DQ) The relnfotclng eftrct 01 the strmulus IS evaluated b) J rate method (CRF) A conaummator~ method ( pC and TSJ a choice method ICY) J co-st method IC, d >elt regulntlon of train duration method (SR) and the tl\ed ratio methods (FR, FR FR, ,

F-R,,)

DQ DF

CRF

UC

TS

03 003

73 81

70 76

Ch S-1 61

c b5 b3

SR

FR

FR

FR,

FR,

54 -il

s9 b6

70 77

57 61

47 53 ~~__

The cllfferent values of the correlation coefflclents show how dlfflcult It is to establish an empu-ical relationship between the reinforcmg effect and the dnve effect elicited by hypothalamic stimulation The complexity of the relatlonshlp observed between the different behavlours ehclted by electrical stlmulatlon m this bram area 15 also shown by the follo~r~ng observation since It IS commonly supposed that a dnire state IS unpleasant and smce rewarding hypothalamic stimulation is supposed to attenuate aversive states, the relatlonshlp between these two effects of hypothalamic stimulation was studied The Spearman rank order correlation w(as computed between the strength of SBB and the elevation of the escape threshold to a foot shock elicited by the rewarding stimulation The data concerning the attenuation of aversive state dunng ICSS have been reported elsewhere I Beyra. 1974b1 Thus correlation coefflclent IS vel?, low, I e 0 20, which means that the brain stlmulatlons ehcltmg a higher drive state are not those stlmulatlons which produce a higher elevation of escape threshold In order to slmphfy this comples set of correlations, a factor analysts was performed The loading of these behaviours In the factcrs, after orthogonal rotation of the axis. IS represented in Fig 2 It appears that SBB IS highly loaded in factors +I and -11, when the attenuation of aversive state ehclted by ICSS IS highly loaded In factors +I and +II, whtle SBB and averslbe state are poorly loaded m factor III As the behavlours used to assess the strength of relnforcers

are loaded III the first two factors. we ~111 assume that the relnforclng effect eliclted by txaln stnnulatlon 111this locus IS composed of at least two factors ConsequentI>. the relation between relnforclng effect and drive effect ehcltecl by hypothalamic stlmulatlon ml1 depend on the method considered to establish this relation

II

III 6 3 =‘/.=,

15 OfC

0

011

.-

l

1 CKF

7

Ch

2 FR3

8

c

9

PC

3 FR

.I_ ..

. . .

FIN 2 Spdtlal

-II

_ .r

15?0

4 FRIO

81

5 I=R

.0’

6

representation

of the

5

three

factors

15

SR

obtained

by factor

10

TS

11

Esc

12

Drive

Q

13

Drive

F

analysis

Numbers

1 to

10 represent the methods used to evaluate the strength of relnforcers In the continuous reenforcement schedule (l), the flxed ratlo methods (2 to 5), the self regulation method (6) the choice method (7). the cost method (8) and the consummatory methods (9 ,~nd 10 J Number latlon

11 lndlcates Numbers

cy of the eating palred

the attenuation

12 and

13 represent

behavlour

(13)

and

(I vs II, Ivs III and II vs III)

the relations

observed

(77

of aversive

state

elrclted

the stlmulatlon-bound by the amount The

8 ? In factor

percentages

of food lndlcate

I, 15 c”r In factor

b> rewarding eating consumed how

II and

brarn

evaluated much

(12) the

strmu

by the The factors

6 3 % In factor

frequen

factors III)

are

explain

173

DISCUSSION

This study shows that the hypothalamic stlmulatlon dehvered through the same electrode, employmg the srune electrical parameters and stnnulatmg at the same rates at which self-stlmulatlon occurs, evokes stimulus-bound eatmg and dlmkmg On the basts of the results, It appears plausible to assume that during ICSS a neural system underlymg feeding and drinking behavlour 1s also excited However it IS very dlfflcult to estimate the relation between these two effects of hypothalamic stimulation due to the multlfactonal structure Of the reinforcing effect elicited by hypothalamic stlmulatlon m this bram area, as assessed by the factor analysis Apart from this mathematical relatlonshlp, it 1s a more complex problem to arnve at a theoretlcal Interpretation concernmg the relatlon between remforcmg and drive state ehclted by hypothalamic stlmulatlon If we assume. hlth Valenstem (1969), that brain stlmulatlon evoking SBB does not ehclt a speclflc state but a general ’ mood state”, it appears then that this mood state, or at least the behavloural expression of this mood state. IS related to the fn-st factor composlng the relnforclng effect elicited by hypothalamic stimulation On the other hand. Hoebel’s (1971) hypothesis seems confirmed by the present data, If the strength of the remforclng effect IS evaluated by methods highly loaded in factors +I and --II The more the method used to evaluate the remforcers IS loaded 111factor +II. the smaller 1s the correlation between the reinforcing effect and the drive effect eltclted by hypothalamic stlmulatlon Nevertheless. a different conclusion can be drawn from these data lf they are analysed flom the methods only loaded m factor I, I e the cost, the choice, the self-regulation and the fused ratio methods Accordmg to these methods, It appears that the strength of the remforclng effect tends to Increase with the strength of the drive up to a mazlmum Ilmlt, after which the strength of the remforclng effect tends to decrease iwth further Increase in drive (Fig 3 1 From this observation, it appears that two relations exist one concerning low level, the second high level of excltatlon of the dnve Under low level of excltatlon of the drive the hypothalamic stlmulatlon 1s rewarding and Induces eating. as assumed by Hoebel’s drive mductlon hypothesis But. the higher the level of excltatlon of the drive. the less remforclng 1s the hypothalamic stlmulatlon. as if hypothalamic stlmulatlon, at high levels of excitation of the drive, tnggers an aversive process The data demand two supplementary comments One concerns their rehablhty, for examnle, the posslblllty remains that different relations between the drive-Inducing and remforcmg effects of hypothalamic stlmulatlon might be obtained when the elicited behavlours are studied during self-stlmulatlon and during expenmenter-controlled stlmulatlon A second comment IS related to the theoretical interpretation of these data If the remforcmg effect ehclted by hypothalamic stimulation IS really composed of several factors by which It mfluences self-stimulation behavlour as well as other goal-oriented behavlours (SBB and Blthdrawal behavlours), the theoretlcal mterpretatlon of the relatlon-

FIN 3

The

havtour

strength

ellctted

evaluated strength

by the

ot the

by hratn trequenck

ot the retnforctng

measuttng

the voltage

by a choice

retntorctng sttmulatton

method

and strength

ot thts hehavtour effect

ot the (ftrst

ettect The

foot

column

15 evaluated

and

the strength ts represented

h> d cost

shock

necessx\

1. t e

measurtng

ot the \ttmulus-bound

ot stimulus method

to suppress the

percentage

hound

on the ordtnate

1fourth ot ttme

line)

ISBE)

column

self ~ttmul~tlon

be

I tull

behavlour

13

The

I, I e hehdblour

a braln

I VI

btlmulus

IS

chosen tn a patred compartson procedure (‘; 1, by a self-regulation ot the tratn duration (SRI and finally the escape threshold ( EW ). I e attenuatton ot the foot shock voltage I Vb during electrtcal

sttmulatton

ot the braln

ulus are represented tn each panel stimulus duration on the absctssn

The

values

of the electrical

parameters

of the hraln

DP = pulse width F = pulse frequency, and DT = The tntensttv rematns constant at the ICSS threlhold

5ttt-n

175

ship between these behavlours iv111depend on the ablllt) to mterprete these factors The present dlscusslon shows how, If these factors are not esplarned. a contradictory set of emplrlcal relations can result depending on the method used to establish the relation REFERENCES Ball,

G C

1969

the hypothalamus Be>r,l, bl , 197la

Separation

of electrIcal

self stlmulatlon

and

electrrcall>

Commun Behav BIOI , A, 3 (1) S-10 The measurement of reInforcIng brain stlmulatlon

ellclted Brain

Res

eating 70

In 467-

479 Beyr.1 hl 1974b Eflects 01 lntracranlal rewarcr strength on escape threshold Phvs~ol Behav 13 507-511 COY, V C and Vdlensteln, E S , 1969 Dlstrlbutron of hypothalamic sites yielding stimulus bound behavior Br.iln Behav Evol , 2 359-376 Hoebel, B G , 1971 FeedIng neural control of Intake Ann Rev Physlol , 33 533-568 Huston, J P , 19i’l RelatIonshIp between motlvatlng and rewarding stlmulatlon of the lateral hypothalamus Phlslol Behav, 6 ‘ill-716 hlogenson, G J 1971 Stabllrty and modlflcatlon 01 consummator> behaviors elIcIted b) etectrlcal stlmulatlon of the h) pothalamus Physlol Behav 6 255-260 Valensteln, E S , 1969 Behavior elicited by h\ pothalamrc stlmulatron Brain Behav Ebol 2 295-316 Ialenstern E S , 1971 Channeling of responses elicited b\ h>pothalamlc stlmulatlon J Pqchlatr Res, 8 33.5-344 Valensteln E S , Cou c’ C and Kakolewskl, J K , 1970 Reexamlnatlon of the role of the hypothalamus III motlvatlon Psychol Rev 77 16-31

,