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Effects of Harmaline on the acoustic startle pattern
264 I t is also suggested that the responses of the lemniscal type in awake cats ca~ reach the red nucleus through t h i s pathway. The somesthetic information transmitted through t h i s fast feed-back loop ~,;~ rubrospinal c e l l s could be of main importance in exploratory behaviour.
EFFECTS OF HARMALINE ON THE ACOUSTIC STARTLE PATTERN PELLET, J, GOURDON, M . - J . , WEISS, M. Psychophysiology Laboratory, U n i v e r s i t y of Provence, 13397 Marseille Cedex 13, (France) The effects of Harmaline, an indolamine hallucinogen and a MAOI, were t e s t ed on the acoustic s t a r t l e pattern. EMG measures of the s t a r t l e r e f l e x (nuchal muscles) and the pinna r e f l e x ( a u r i c u l a r muscles), as well as the corticographic characters of the vertex evoked responses to high i n t e n s i t y auditory s t i m u l i ( I I 0 dB, 60 msec pulses, 8000 Hz) were simultaneously studied in four a l e r t Guinea-pigs. The basic experimental design was a 4 x 4 l a t i n square, with the treatments being given at two day i n t e r v a l s . The four doses were isotonic sal i n e , 0.25, 5.0, and I0.0 mg/Kg IM of Harmaline-HCl. Compared with saline baselines, a l l the drug doses resulted, throughout the 60 min session, in overall high s i g n i f i c a n t depressions of the s t a r t l e r e f l e x , the pinna r e f l e x and the i n i t i a l
wave of the vertex evoked p o t e n t i a l . In con-
t r a s t , Harmaline in the doses used had paradoxically l i t t l e
or no influence on
amplitude and latency of the late wave of the vertex s t a r t l e - r e l a t e d response. These r e s u l t s may support an involvement of serotonergic systems in the modulation of the sensori-motor r e a c t i v i t y at the brainstem l e v e l . Nevertheless, the more complex c o r t i c a l processes involved in s t a r t l e r e s p o n s i v i t y do not appear univocaly affected by Harmaline. Comparisons with the effects of other indolamine hallucinogens, l i k e LSD, on the s t a r t l e pattern are discussed.
HABITUATION OF EXPLORATORYACTIVITY IN MICE AS A MODELOF MEMORY: PHARMACOLOGICAL EVIDENCE PLATEL, A. AND PORSOLT, R.D. Centre de Recherche DELALANDE, Unit~ de Neuropharmacologie, I0 rue des Carri~res, 92500 Rueil-Malmaison, (France)
EFFECTS OF HARMALINE ON THE ACOUSTIC STARTLE PATTERN PELLET, J, GOURDON, M . - J . , WEISS, M. Psychophysiology Laboratory, U n i v e r s i t y of Provence, 13397 Marseille Cedex 13, (France) The effects of Harmaline, an indolamine hallucinogen and a MAOI, were t e s t ed on the acoustic s t a r t l e pattern. EMG measures of the s t a r t l e r e f l e x (nuchal muscles) and the pinna r e f l e x ( a u r i c u l a r muscles), as well as the corticographic characters of the vertex evoked responses to high i n t e n s i t y auditory s t i m u l i ( I I 0 dB, 60 msec pulses, 8000 Hz) were simultaneously studied in four a l e r t Guinea-pigs. The basic experimental design was a 4 x 4 l a t i n square, with the treatments being given at two day i n t e r v a l s . The four doses were isotonic sal i n e , 0.25, 5.0, and I0.0 mg/Kg IM of Harmaline-HCl. Compared with saline baselines, a l l the drug doses resulted, throughout the 60 min session, in overall high s i g n i f i c a n t depressions of the s t a r t l e r e f l e x , the pinna r e f l e x and the i n i t i a l
wave of the vertex evoked p o t e n t i a l . In con-
t r a s t , Harmaline in the doses used had paradoxically l i t t l e
or no influence on
amplitude and latency of the late wave of the vertex s t a r t l e - r e l a t e d response. These r e s u l t s may support an involvement of serotonergic systems in the modulation of the sensori-motor r e a c t i v i t y at the brainstem l e v e l . Nevertheless, the more complex c o r t i c a l processes involved in s t a r t l e r e s p o n s i v i t y do not appear univocaly affected by Harmaline. Comparisons with the effects of other indolamine hallucinogens, l i k e LSD, on the s t a r t l e pattern are discussed.
HABITUATION OF EXPLORATORYACTIVITY IN MICE AS A MODELOF MEMORY: PHARMACOLOGICAL EVIDENCE PLATEL, A. AND PORSOLT, R.D. Centre de Recherche DELALANDE, Unit~ de Neuropharmacologie, I0 rue des Carri~res, 92500 Rueil-Malmaison, (France)