The role of scopolamine on complex spatial learning: Link with aging

230 THE ROLE OF SCOPOLAMINE ON COMPLEX SPATIAL LEARNING: LINK WITH AGING SOFFIE, M., LEBAILLY, B. AND SWANET, E. Biologie du comportement, Louvain-la-Neuve, Belgium Behavioural impairments caused by a n t i c h o l i n e r g i c drugs, such as scopolamine have often been considered to be s i m i l a r to those r e s u l t i n g from normal as well as pathological aging processes ( i . e. s e n i l e dementia). In t h i s perspective, a d u l t rats treated with scopolamine and aged rats ( > 26 months) were submitted to a complex s p a t i a l learning task. The p r i n c i p l e of s p a t i a l learning consists in r e q u i r i n g an animal placed in a four arm maze, to o r i e n t i t s e l f with f l i c k e r i n g

to the r i g h t of a visual cue ( s t r i p e d panel

l i g h t ) whose p o s i t i o n is changed at random. During the f i r s t

t r a i n i n g session an-

other cue (box) is placed above the baited arm. A. Cholinergic approach The role of the c h o l i n e r g i c system in memory and c o g n i t i o n has often been mentioned. Recently, the hypothesis has been put forward that related impairments caused by a n t i c h o l i n e r g i c drugs would only be the consequence of m o d i f i c a t i o n s in e m o t i v i t y , perception and a t t e n t i o n . Our r e s u l t s show that scopolamine does not impair the a c q u i s i t i o n of a complex response. However, the learning strategy is different,

treated animal using a cue

strategy and not an abstract s p a t i a l one. Scopolamine has l i t

t l e e f f e c t when the spatial response has already been learned and seems to i n t e r f e r e more with a c q u i s i t i o n of the s p a t i a l response than with i t s r e t e n t i o n . Neither an impairment in stimulus d i s c r i m i n a t i o n nor a state dependent e f f e c t can explain the observed d i f f e r e n c e s . B. Aging approach Aged rats show a d e f i n i t e impairment in the f i r s t

t r a i n i n g session. The r e l a t i v e importance of the

task complexity, of the i n t e r f e r e n c e of the visual cue and of the visual capacity is discussed.

PERMANENT CHANGES IN EYE-HEAD COORDINATION AFTER BOTH UNILATERAL FRONTAL EYE FIELD LESIONS IN MONKEYS AND FUNCTIONAL RECOVERY VAN DER STEEN, J.*,RUSSELL, I . S . * * AND JAMES. G.O.** *Dept. of Physiology I , Erasmus U n i v e r s i t e i t Rotterdam, P.O.Box 1738, Rotterdam, The Netherlands ** MRC Unit on Neural Mechanisms of Behaviour, U n i v e r s i t y Colleae London. United Kinadom Since F e r r i e r ' s discovery (1886) that s t i m u l a t i o n of the FEF in monkeys e l i c i t s

saccades to the

c o n t r a l a t e r a l side, f u r t h e r evidence has emerged from behavioural, e l e c t r o p h y s i o l o g i c a l and eye movement studies that the FEF is involved in v i s u a l l y guided behaviour. Yet the precise f u n c t i o n of the FEF s t i l l

has to be established: i . e . the ways monkeys recover from the temporary neglect of the

c o n t r a l a t e r a l visual f i e l d a f t e r u n i l a t e r a l FEF lesions is s t i l l

unclear.

For t h i s reason we studied the e f f e c t s of such lesions upon eye-head coordination in 3 monkeys. The animals were t r a i n e d in a computerized apparatus to perform a visual search task, while eye and