Reduction of neophobic responses in mice following lesions of basal ganglia

218 perceptual stages in visual information processing. The presence of a R.H. advantage in Exp. I I is in agreement with the above view in that i t underlines the importance of higher-order cognitive operations in determining l a t e r a l i t y

e f f e c t s . F i n a l l y , the lack of hemispheric asymmetries in Exp.

I I I might be interpreted as related to the mixed requirements of the task that c a l l s f o r the l i n g u i s t i c a b i l i t y of the L.H. in addition to the s p e c i f i c physiognomic competance of the R.H.

REDUCTION OF NEOPHOBIC RESPONSES IN MICE FOLLOWING LESIONS OF BASAL GANGLIA MISSLIN, R., ClGRANG, M. AND VOGEL, E. Laboratoire de Psychophysiologie, 7 rue de l ' U n i v e r s i t ~ , 67000 Strasbourg, France In preliminary work, we showed that male mice exposed to novel places displayed a novelty preference, while they avoided a novel object introduced in t h e i r f a m i l i a r environment and frequently buried i t .

This l a t t e r behaviour can be considered as a species-typical response.

There has been considerable i n t e r e s t in recent years in the mechanisms of limbic-motor integrat i o n . The caudate-putamen, globus p a l l i d u s complex is t r a d i t i o n a l l y regarded as p r i m a r i l y motor in function. However, i t has been suggested that signals from the limbic system contribute to the i n i t i a t i o n of adaptive behaviors such as exploratory responses or defensive reactions to nonpainful stimuli. Our results indicate that e l e c t r o l y t i c lesions of the caudate nucleus and of the putamen reduce neophobic behavior in mice: lesioned animals frequently contacted the novel object, did not show the i n i t i a l

neophobic reactions toward novel places and shifted from exploration to eating or s e l f -

grooming. These findings provide an i n t e r e s t i n g p a r a l l e l f o r t h i s syndrome a r i s i n g from damage to area of the basal ganglia and the well-known "amygdala-lesionsyndrome". Basal ganglia appeared to be positioned s t r a t e g i c a l l y f o r limbic-motor i n t e g r a t i o n and i n i t i a t i o n

of adaptive behaviors and not only

for motor regulation.

DEVELOPMENT OF THE MONOCULAR VISUAL FIELD IN THE FIRST POSTNATAL YEAR MOHN, G. AND VAN HOF-VAN DUIN, d. Dept. of Physiology I , Erasmus U n i v e r s i t e i t Rotterdam, P.O.Box 1738, 3000 DR Rotterdam, The Netherlands The binocular visual f i e l d has been reported to be severely r e s t r i c t e d during the f i r s t and months of l i f e

weeks

( I , 2). Monocularly, the nasal visual f i e l d is smaller than the temporal f i e l d in

newborn infants (3), but no l o n g i t u d i n a l data are a v a i l a b l e . Using a simple behavioural t e s t , the monocular visual f i e l d was tested in 15 f u l l t e r m infants aged I to 12 months. While the i n f a n t was