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Is food reward necessary for radial arm maze patrolling by rats?
209
Mammals with l a t e r a l eyes and global v i s i o n show an asymmetric o p t o k i n e t i c nystagmus (OKN) when tested monocularly. Only temporal to nasal movement of the o p t o k i n e t i c stimulus e l i c i t s response. No OKN can be e l i c i t e d
in the naso-temporal d i r e c t i o n , i . e .
a vigorous
in the pigmented r a t .
In the
a l b i n o r a t OKN is also absent in temporo-nasal d i r e c t i o n . Neurophysiological experiments have shown t h a t in pigmented rats as in other animals the nucleus of the o p t i c t r a c t (NOT) in the pretectum is critically
involved in mediating OKN. In a l b i n o rats the NOT was found to be p h y s i o l o g i c a l l y abnormal
(1). Our i n v e s t i g a t i o n addresses the question whether there are morpho]ogica] changes in the NOT corresponding to the behavioural d e f i c i t s . Horseradish-Peroxidase was i n j e c t e d i o n t o p h o r e t i c a l l y i n t o the i n f e r i o r o l i v e which has been shown to receive a p r o j e c t i o n from the NOT. D e n d r i t i c morphology, soma size and frequency of labeled c e l l s w i l l
be compared f o r pigmented and a l b i n o r a t s . So f a r no
s i g n i f i c a n t d i f f e r e n c e s have been found. REFERENCES I . Precht and Cazin 1979; Lannou, Cazin, Precht and Toupet, 1982.
IS FOOD REWARD NECESSARY FOR RADIAL ARM MAZE PATROLLING BY RATS? ISLER, R.B., OETTINGER, R., FITZGERALD, R. AND BATTIG, K. Swiss Federal I n s t i t u t e of Technology, Dept. of Behavioural Science, Turnerstrasse I , CH-8092 Z~rich, Switzerland A well established procedure f o r examining working memory in rats uses a s p a t i a l maze in which eightarms radiate from a central platform ( I ) . Animals are required to patrol a l l the arms f o r food reward w i t h o u t repeating previous choices. The present experiment employed an automated maze which provides a complete space-time record of the animal's movement - i . e . not only p a t r o l l i n g e f f i c i e n c y variables (number of r e p e t i t i o n s , s e r i a l p o s i t i o n of the f i r s t ted maze d i f f e r s
r e p e t i t i o n ) but also time variables (e.g. time to v i s i t
in three other important ways from the usual maze (2):
a l l arms). The automa-
I) the maze is completely enclo-
sed r a t h e r than elevated, the top c o n s i s t i n g of transparent p l e x i g l a s s . 2 ) t h e arm are not s t r a i g h t and 3) there is
achoice point leading to a s h o r t b l i n d - a l l e y j u s t a f t e r
the e n t r y point of each arm.
Two groups of food deprived Roman High Avoidance (RHA/Verh) male rats (85% body weight) were tested f o r ten days w i t h a d a i l y 4~ min t r i a l .
One group was provided with one 45 mg Noyes food pel-
l e t at the end of each arm. Behavior during the f i r s t
"sequence" of choices was examined i . e . u n t i l
a l l arms had been v i s i t e d . Food reward influenced only the time to v i s i t
a l l arms but not the number of b l i n d - a l l e y e n t r i e s
or the e f f i c i e n c y of p a t r o l l i n g , which even tended to be lower in the food rewarded group. This group also showed more stereotyped sequence of choices ( i . e . the nonrewarded group. For the food rewarded
group
repeating the same turn d i r e c t i o n ) than
a second sequence of choices w i t h i n each t r i a l ,
i . e . r e v i s i t i n g a l l arms a f t e r a l l food had been c o l l e c t e d , was also a v a i l a b l e f o r analysis and was compared with the f i r s t sequence.
210
The p a t r o l l i n g e f f i c i e n c y remained high in the second (nonrewarded) sequence of choices a]though the degree of stereotypy in arm choice was much lower than in the f i r s t
sequence.
In summary, food reward increased the speed of movement and the stereotypy of the rewarded choice sequence, and tended to decrease e f f i c i e n c y of p a t r o l l i n g r e l a t i v e to nonrewarded animals. These results indicate that food reward is not necessary for radial arm maze p a t r o l l i n g by rats, and may even i n t e r f e r e with i t . REFERENCES I. Olton, D.S., Amer. Psychologist., 34 (1979) 583-596. 2. Olton, D.S. and Samuelson, R.J., J. Exp. Psychol.: Anim. Behav. Processes, 2 (1976) 97-116.
EFFECTS OF INTRANIGRAL INJECTIONS OF DOPAMINE, DOPAMINERGIC AGONISTS AND ANTAGONISTS ON CIRCLING BEHAVIOUR AND LOCOMOTORACTIVITY JACKSON, E.A. AND KELLY, P.H. Preclinical research, Sandoz Ltd., Basle, Switzerland Evidence has accumulated in recent yearsto indicate thatdopamineis released fromdendritesin the substantia nigra ( I ) . However, a functional role for dopamine at nigral dopaminergic receptors has not yet been convincingly demonstrated. We have shown here that dopaminergic mechanisms in the substantia nigra can influence both c i r c l i n g behaviour and locomotor a c t i v i t y . In rats pretreated with a monoamine oxidase i n h i b i t o r , contralateral c i r c l i n g was e l i c i t e d by unilateral intranigral injections of dopamine or amphetamine. The c i r c l i n g caused by intranigral dopamine lasted more than 4 hours and was s i m i l a r in i n t e n s i t y to that seen a f t e r an equivalent amount injected i n t r a s t r i a t a l l y . Contralateral c i r c l i n g was also e l i c i t e d by unilateral intranigral injections of the dopaminergic agon sts ergometrine and SKF 38393. In rats with unilateral 6-hydroxydopamine-induced n i g r o s t r i a t a l lesions, amphetamine-induced c i r c l i n g was greatly reduced by b i l a t e r a l intranigral haloperidol injections. Bilateral intranigral injections of dopamine or epinine (N-methyldopamine) in rats pretreated with monoamine oxidase i n h i b i t o r resulted in long-lasting stimulation of locomotor a c t i v i t y . B i l a t e ral intranigral injections of the dopaminergicagonists ergometrine, (±)-2-amino-6, 7-dihydroxy-1, 2, 3, 4-tetrahydronapthalene hydrobromide (ADTN) and 1,2,3,4-tetrahydro-6,7-dihydroxyisoquinoline hydrochloride (THIQ) also elicted locomotor a c t i v i t y . Ergometrine was much less e f f e c t i v e when injected into the r e t i c u l a r formation immediately above the substantia nigra. Locomotor a c t i v i t y e l i c i t e d by b i l a t e r a l ergometrine was blocked by systemic haloperidol, but was not affected by intranigral haloperidol. Locomotor a c t i v i t y e l i c i t e d by systemic amphetamine was blocked by intranigral injections of haloperidol or ~ - f l u p e n t h i x o l , but that e l i c i t e d by b i l a t e r a l intra-accumbens ergometrine was not altered by either of these neuroleptics injected i n t r a n i g r a l l y . The results support a functional role of nigral dopamine receptors in c i r c l i n g behaviour and locomotor a c t i v i t y .
Mammals with l a t e r a l eyes and global v i s i o n show an asymmetric o p t o k i n e t i c nystagmus (OKN) when tested monocularly. Only temporal to nasal movement of the o p t o k i n e t i c stimulus e l i c i t s response. No OKN can be e l i c i t e d
in the naso-temporal d i r e c t i o n , i . e .
a vigorous
in the pigmented r a t .
In the
a l b i n o r a t OKN is also absent in temporo-nasal d i r e c t i o n . Neurophysiological experiments have shown t h a t in pigmented rats as in other animals the nucleus of the o p t i c t r a c t (NOT) in the pretectum is critically
involved in mediating OKN. In a l b i n o rats the NOT was found to be p h y s i o l o g i c a l l y abnormal
(1). Our i n v e s t i g a t i o n addresses the question whether there are morpho]ogica] changes in the NOT corresponding to the behavioural d e f i c i t s . Horseradish-Peroxidase was i n j e c t e d i o n t o p h o r e t i c a l l y i n t o the i n f e r i o r o l i v e which has been shown to receive a p r o j e c t i o n from the NOT. D e n d r i t i c morphology, soma size and frequency of labeled c e l l s w i l l
be compared f o r pigmented and a l b i n o r a t s . So f a r no
s i g n i f i c a n t d i f f e r e n c e s have been found. REFERENCES I . Precht and Cazin 1979; Lannou, Cazin, Precht and Toupet, 1982.
IS FOOD REWARD NECESSARY FOR RADIAL ARM MAZE PATROLLING BY RATS? ISLER, R.B., OETTINGER, R., FITZGERALD, R. AND BATTIG, K. Swiss Federal I n s t i t u t e of Technology, Dept. of Behavioural Science, Turnerstrasse I , CH-8092 Z~rich, Switzerland A well established procedure f o r examining working memory in rats uses a s p a t i a l maze in which eightarms radiate from a central platform ( I ) . Animals are required to patrol a l l the arms f o r food reward w i t h o u t repeating previous choices. The present experiment employed an automated maze which provides a complete space-time record of the animal's movement - i . e . not only p a t r o l l i n g e f f i c i e n c y variables (number of r e p e t i t i o n s , s e r i a l p o s i t i o n of the f i r s t ted maze d i f f e r s
r e p e t i t i o n ) but also time variables (e.g. time to v i s i t
in three other important ways from the usual maze (2):
a l l arms). The automa-
I) the maze is completely enclo-
sed r a t h e r than elevated, the top c o n s i s t i n g of transparent p l e x i g l a s s . 2 ) t h e arm are not s t r a i g h t and 3) there is
achoice point leading to a s h o r t b l i n d - a l l e y j u s t a f t e r
the e n t r y point of each arm.
Two groups of food deprived Roman High Avoidance (RHA/Verh) male rats (85% body weight) were tested f o r ten days w i t h a d a i l y 4~ min t r i a l .
One group was provided with one 45 mg Noyes food pel-
l e t at the end of each arm. Behavior during the f i r s t
"sequence" of choices was examined i . e . u n t i l
a l l arms had been v i s i t e d . Food reward influenced only the time to v i s i t
a l l arms but not the number of b l i n d - a l l e y e n t r i e s
or the e f f i c i e n c y of p a t r o l l i n g , which even tended to be lower in the food rewarded group. This group also showed more stereotyped sequence of choices ( i . e . the nonrewarded group. For the food rewarded
group
repeating the same turn d i r e c t i o n ) than
a second sequence of choices w i t h i n each t r i a l ,
i . e . r e v i s i t i n g a l l arms a f t e r a l l food had been c o l l e c t e d , was also a v a i l a b l e f o r analysis and was compared with the f i r s t sequence.
210
The p a t r o l l i n g e f f i c i e n c y remained high in the second (nonrewarded) sequence of choices a]though the degree of stereotypy in arm choice was much lower than in the f i r s t
sequence.
In summary, food reward increased the speed of movement and the stereotypy of the rewarded choice sequence, and tended to decrease e f f i c i e n c y of p a t r o l l i n g r e l a t i v e to nonrewarded animals. These results indicate that food reward is not necessary for radial arm maze p a t r o l l i n g by rats, and may even i n t e r f e r e with i t . REFERENCES I. Olton, D.S., Amer. Psychologist., 34 (1979) 583-596. 2. Olton, D.S. and Samuelson, R.J., J. Exp. Psychol.: Anim. Behav. Processes, 2 (1976) 97-116.
EFFECTS OF INTRANIGRAL INJECTIONS OF DOPAMINE, DOPAMINERGIC AGONISTS AND ANTAGONISTS ON CIRCLING BEHAVIOUR AND LOCOMOTORACTIVITY JACKSON, E.A. AND KELLY, P.H. Preclinical research, Sandoz Ltd., Basle, Switzerland Evidence has accumulated in recent yearsto indicate thatdopamineis released fromdendritesin the substantia nigra ( I ) . However, a functional role for dopamine at nigral dopaminergic receptors has not yet been convincingly demonstrated. We have shown here that dopaminergic mechanisms in the substantia nigra can influence both c i r c l i n g behaviour and locomotor a c t i v i t y . In rats pretreated with a monoamine oxidase i n h i b i t o r , contralateral c i r c l i n g was e l i c i t e d by unilateral intranigral injections of dopamine or amphetamine. The c i r c l i n g caused by intranigral dopamine lasted more than 4 hours and was s i m i l a r in i n t e n s i t y to that seen a f t e r an equivalent amount injected i n t r a s t r i a t a l l y . Contralateral c i r c l i n g was also e l i c i t e d by unilateral intranigral injections of the dopaminergic agon sts ergometrine and SKF 38393. In rats with unilateral 6-hydroxydopamine-induced n i g r o s t r i a t a l lesions, amphetamine-induced c i r c l i n g was greatly reduced by b i l a t e r a l intranigral haloperidol injections. Bilateral intranigral injections of dopamine or epinine (N-methyldopamine) in rats pretreated with monoamine oxidase i n h i b i t o r resulted in long-lasting stimulation of locomotor a c t i v i t y . B i l a t e ral intranigral injections of the dopaminergicagonists ergometrine, (±)-2-amino-6, 7-dihydroxy-1, 2, 3, 4-tetrahydronapthalene hydrobromide (ADTN) and 1,2,3,4-tetrahydro-6,7-dihydroxyisoquinoline hydrochloride (THIQ) also elicted locomotor a c t i v i t y . Ergometrine was much less e f f e c t i v e when injected into the r e t i c u l a r formation immediately above the substantia nigra. Locomotor a c t i v i t y e l i c i t e d by b i l a t e r a l ergometrine was blocked by systemic haloperidol, but was not affected by intranigral haloperidol. Locomotor a c t i v i t y e l i c i t e d by systemic amphetamine was blocked by intranigral injections of haloperidol or ~ - f l u p e n t h i x o l , but that e l i c i t e d by b i l a t e r a l intra-accumbens ergometrine was not altered by either of these neuroleptics injected i n t r a n i g r a l l y . The results support a functional role of nigral dopamine receptors in c i r c l i n g behaviour and locomotor a c t i v i t y .