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Somatotopic organization of motor thalamus in the macaque monkey
228 the f i r s t week the Ss were punished, once within the dark chamber, by an inescapable shock (2 sec); a f t e r this the connecting door was opened and 10 sec l a t e r the Ss could escape a second shock ( 5 sec). During the second week no shocks were administered. Step-through l a t e n c i e s , from the l i g h t into the dark chamber (passive avoidance) were timed up to 180 sec. Exits from the dark chamber within 10 sec were counted as active avoidance responses. Also, duration of the f i r s t
freezing in
the l i g h t chamber was timed. Passive avoidance. No s i g n i f i c a n t differences were found between HODI and HEDI Ss during acquls i t i o n a n d e x t i n c t i o n f o r both stimulus i n t e n s i t i e s . Active avoidance. In general HODI Ss performed b e t t e r than HEDI Ss: in fact s i g n i f i c a n t d i f f e r ences between the two groups were found during both weeks f o r 0.6 mA shocks, and during the f i r s t week f o r 2 mA shocks. HODI Ss performed s i g n i f i c a n t l y better f o r 0.6 mA shocks than f o r 2 mA shocks during the f i r s t week. On the contrary HEDI Ss performed s i g n i f i c a n t l y better f o r 2 mA shocks than fo r 0.6 mA shocks during the second week. Freezing. Freezing duration was longer f o r 2 mA than f o r 0.6 mA shocks: in p a r t i c u l a r HEDI Ss exhibited longer freezing than HODI Ss. In fact s i g n i f i c a n t differences were found during the f i r s t week f o r 0.6 mASs and during the second week f o r 2 mASs. Concluding, f o r e i t h e r shock i n t e n s i t y s i g n i f i c a n t differences between HODI and HEDI Ss were found only f o r active avoidance responses. Both f o r HODI and HEDI Ss avoidance learning was better f o r 0.6 mA shocks. I t may be surmised that the time course of active avoidance responses can be somehow related to freezing duration, which follows a complementary trend.
SOMATOTOPIC ORGANIZATION OF MOTORTHALAMUS IN THE MACAQUEMONKEY LUPPINO, G., SOLA, P., MATELLI, M., FOGASSI, L. AND RIZZOLATTI, G. I s t i t u t o di F i s i o l o g i a Umana, Universit~ di Parma, via Gramsci 14, 43100 Parma, I t a l y On the basis of i t s cytochrome oxidase a c t i v i t y the agranular f r o n t a l cortex (area 4-6 complex) can be subdivided into f i v e d i s t i n c t areas (FI-F5). FI lays on the a n t e r i o r bank of the central sulcus and the cortex immediately r o s t r a l to i t . This area b a s i c a l l y corresponds to area 4. F4 and F5 are located l a t e r a l to the spur of the arcuate sulcus and form together the i n f e r i o r area 6. F5 constitutes the r o s tr a l part of i t ,
F4 the caudal part. The purpose of the present study was to de-
scribe the thalamic afferents to areas FI and F5 as revealed by small i n j e c t i o n s of tracers in spec i f i c functional f i e l d s of these two areas. The experiments were carried out on nine monkeys (8 Macaca f a s c i c u l a r i s and I Macaca nemestrina). Each animal received one i n j e c t i o n (0.08-0.1 ~I) of 4% WGA-HRP e i t h e r in F1 or in F5. Six injections were made in F1 (3 in the mouth f i e l d ,
2 in the hand f i e l d and I in the leg f i e l d ) ,
three injections
were made in F5 along the p o s t e r i o r bank of the i n f e r i o r arcuate sulcus. Following FI i n j e c t i o n s retrograde transport was observed mainly in VPLo. Labelled c e l l s however, were found also in VLo and VLc. The connections betwene VPLo and F1 were somatotopically organized. In t h i s thalamic nucleus the leg representation was located l a t e r a l l y , the hand representation cent r a l l y and the mouth representation medially. 1 In agreement with previous data f o l l o w i n g F5 injections many l a b e l l e d c e l l s were observed in area X of Olzewski and, to a lesser degree, in VA, VLo and VLc. Additional label was found in MD, CL and CM. The l a b e l l e d c e l l s formed elongated stripes extending over several thalamic f r o n t a l
229 sections. As well as VPLo area X also appeared to be somatotopically organized with the mouth f i e l d located l a t e r a l l y and the hand f i e l d more m e dially , a f in d in g in agreement with a previous degenera2 tion study Taken together, these data indicate th a t : in the motor thalamus there are at leas t two somatotopic representations, one in
VPLo and one in area X, and that these two representations correspond
respectively to those in the c o r t i c a l area FI and F5. REFERENCES I.
Shell and S t r i c k , J. Neuroscience, 4 (1984) 539-560.
2.
R i z z o l a t t i , G. et a l . Brain 106 (1983) 655-673.
THE ABSENCE OF CEREBELLUM INFLUENCES AND ASSOCIATIVE CONDITIONING IN NORMALAND MUTANTMICE MARCHETTI-GAUTHIER, E. AND SOUMIREU-MOURAT,B. Laboratoire de Neurobiologie des Comportements, Universit~ A i x - M a r s e i l l e I , Centre St. Jer6me, 13397 Marseille Cedex 13, France Recent studies have demonstrated that the cerebellum is involved in associative c o n d i t i o n i n g . These studies have shown that in the r a b b i t the dentate-interpositus nuclei seem to be involved in the production of classical conditioning of the eyelid or the n i c t i t a t i n g membrane. With respect to this problem, we tested the extent of associative conditioning in normal hemicerebellectomized, and staggerer mice.
The present study examines whether the absence of the cerebellum in staggerer mice
(mutant mice), and the hemicerebellectomy in the normal mice modify lear ning, retention and e x t i n c tion of the one-way active avoidance conditioning task. The results show that l e a r n i n g , retention and e x t i n c t i o n in the normal and sham-operated mice are s i m i l a r . However, learning is much slower in the mutant and lesioned mice. After 9 days of t r a i n ing ( 20 t r i a l s per day), t h e i r average performance was only h a l f of that observed in the normal and sham-operated mice. Extinction takes place from the 10th to the 17th day. I t is faster in staggerer and hemicerebellectomized mice than in normal mice. Therefore the cerebellum seems to be involved in associative learning during active avoidance condit ioning.
SPONTANEOUS DARK OR LIGHT PREFERENCE IN ALBINO MICE ? MELAN, C. AND UNGERER, A. Laboratoire de Psychophysiologie, 7 rue de l ' U n i v e r s i t # , 67000 Strasbourg, France I t is commonly stated that nocturnal rodents, i f they have the choice between an illuminated and an
i d e n t i c a l , but darkened environment,
prefer the l a t t e r one. However, this g e n e r a l i z a t i o n was
recently challenged by work on laboratory rodents. In order to review the t o p i c , we studied spontaneous l i g h t / d a r k preferences of albino mice in a Y-maze. On four consecutive t r i a l s ,
the animals
could f r e e l y enter e i t h e r a l i g h t e d arm (16 lux) or a darkened arm of the maze; the position of the l i g h t arm ( r i g h t or l e f t ) was randomized across the t r i a l s .
Half of the mice ( = 36) were tested
during the l i g h t period of the day (group L) and the rest during the dark period (group D). The mice
freezing in
the l i g h t chamber was timed. Passive avoidance. No s i g n i f i c a n t differences were found between HODI and HEDI Ss during acquls i t i o n a n d e x t i n c t i o n f o r both stimulus i n t e n s i t i e s . Active avoidance. In general HODI Ss performed b e t t e r than HEDI Ss: in fact s i g n i f i c a n t d i f f e r ences between the two groups were found during both weeks f o r 0.6 mA shocks, and during the f i r s t week f o r 2 mA shocks. HODI Ss performed s i g n i f i c a n t l y better f o r 0.6 mA shocks than f o r 2 mA shocks during the f i r s t week. On the contrary HEDI Ss performed s i g n i f i c a n t l y better f o r 2 mA shocks than fo r 0.6 mA shocks during the second week. Freezing. Freezing duration was longer f o r 2 mA than f o r 0.6 mA shocks: in p a r t i c u l a r HEDI Ss exhibited longer freezing than HODI Ss. In fact s i g n i f i c a n t differences were found during the f i r s t week f o r 0.6 mASs and during the second week f o r 2 mASs. Concluding, f o r e i t h e r shock i n t e n s i t y s i g n i f i c a n t differences between HODI and HEDI Ss were found only f o r active avoidance responses. Both f o r HODI and HEDI Ss avoidance learning was better f o r 0.6 mA shocks. I t may be surmised that the time course of active avoidance responses can be somehow related to freezing duration, which follows a complementary trend.
SOMATOTOPIC ORGANIZATION OF MOTORTHALAMUS IN THE MACAQUEMONKEY LUPPINO, G., SOLA, P., MATELLI, M., FOGASSI, L. AND RIZZOLATTI, G. I s t i t u t o di F i s i o l o g i a Umana, Universit~ di Parma, via Gramsci 14, 43100 Parma, I t a l y On the basis of i t s cytochrome oxidase a c t i v i t y the agranular f r o n t a l cortex (area 4-6 complex) can be subdivided into f i v e d i s t i n c t areas (FI-F5). FI lays on the a n t e r i o r bank of the central sulcus and the cortex immediately r o s t r a l to i t . This area b a s i c a l l y corresponds to area 4. F4 and F5 are located l a t e r a l to the spur of the arcuate sulcus and form together the i n f e r i o r area 6. F5 constitutes the r o s tr a l part of i t ,
F4 the caudal part. The purpose of the present study was to de-
scribe the thalamic afferents to areas FI and F5 as revealed by small i n j e c t i o n s of tracers in spec i f i c functional f i e l d s of these two areas. The experiments were carried out on nine monkeys (8 Macaca f a s c i c u l a r i s and I Macaca nemestrina). Each animal received one i n j e c t i o n (0.08-0.1 ~I) of 4% WGA-HRP e i t h e r in F1 or in F5. Six injections were made in F1 (3 in the mouth f i e l d ,
2 in the hand f i e l d and I in the leg f i e l d ) ,
three injections
were made in F5 along the p o s t e r i o r bank of the i n f e r i o r arcuate sulcus. Following FI i n j e c t i o n s retrograde transport was observed mainly in VPLo. Labelled c e l l s however, were found also in VLo and VLc. The connections betwene VPLo and F1 were somatotopically organized. In t h i s thalamic nucleus the leg representation was located l a t e r a l l y , the hand representation cent r a l l y and the mouth representation medially. 1 In agreement with previous data f o l l o w i n g F5 injections many l a b e l l e d c e l l s were observed in area X of Olzewski and, to a lesser degree, in VA, VLo and VLc. Additional label was found in MD, CL and CM. The l a b e l l e d c e l l s formed elongated stripes extending over several thalamic f r o n t a l
229 sections. As well as VPLo area X also appeared to be somatotopically organized with the mouth f i e l d located l a t e r a l l y and the hand f i e l d more m e dially , a f in d in g in agreement with a previous degenera2 tion study Taken together, these data indicate th a t : in the motor thalamus there are at leas t two somatotopic representations, one in
VPLo and one in area X, and that these two representations correspond
respectively to those in the c o r t i c a l area FI and F5. REFERENCES I.
Shell and S t r i c k , J. Neuroscience, 4 (1984) 539-560.
2.
R i z z o l a t t i , G. et a l . Brain 106 (1983) 655-673.
THE ABSENCE OF CEREBELLUM INFLUENCES AND ASSOCIATIVE CONDITIONING IN NORMALAND MUTANTMICE MARCHETTI-GAUTHIER, E. AND SOUMIREU-MOURAT,B. Laboratoire de Neurobiologie des Comportements, Universit~ A i x - M a r s e i l l e I , Centre St. Jer6me, 13397 Marseille Cedex 13, France Recent studies have demonstrated that the cerebellum is involved in associative c o n d i t i o n i n g . These studies have shown that in the r a b b i t the dentate-interpositus nuclei seem to be involved in the production of classical conditioning of the eyelid or the n i c t i t a t i n g membrane. With respect to this problem, we tested the extent of associative conditioning in normal hemicerebellectomized, and staggerer mice.
The present study examines whether the absence of the cerebellum in staggerer mice
(mutant mice), and the hemicerebellectomy in the normal mice modify lear ning, retention and e x t i n c tion of the one-way active avoidance conditioning task. The results show that l e a r n i n g , retention and e x t i n c t i o n in the normal and sham-operated mice are s i m i l a r . However, learning is much slower in the mutant and lesioned mice. After 9 days of t r a i n ing ( 20 t r i a l s per day), t h e i r average performance was only h a l f of that observed in the normal and sham-operated mice. Extinction takes place from the 10th to the 17th day. I t is faster in staggerer and hemicerebellectomized mice than in normal mice. Therefore the cerebellum seems to be involved in associative learning during active avoidance condit ioning.
SPONTANEOUS DARK OR LIGHT PREFERENCE IN ALBINO MICE ? MELAN, C. AND UNGERER, A. Laboratoire de Psychophysiologie, 7 rue de l ' U n i v e r s i t # , 67000 Strasbourg, France I t is commonly stated that nocturnal rodents, i f they have the choice between an illuminated and an
i d e n t i c a l , but darkened environment,
prefer the l a t t e r one. However, this g e n e r a l i z a t i o n was
recently challenged by work on laboratory rodents. In order to review the t o p i c , we studied spontaneous l i g h t / d a r k preferences of albino mice in a Y-maze. On four consecutive t r i a l s ,
the animals
could f r e e l y enter e i t h e r a l i g h t e d arm (16 lux) or a darkened arm of the maze; the position of the l i g h t arm ( r i g h t or l e f t ) was randomized across the t r i a l s .
Half of the mice ( = 36) were tested
during the l i g h t period of the day (group L) and the rest during the dark period (group D). The mice