Amm. Vanerp et al., PERIAQUEDUCTAL GRAY LESIONS DO NOT AFFECT GROOMING, INDUCED ELECTRICALLY IN THE HYPOTHALAMIC PARAVENTRICULAR AREA IN THE RAT, Behavioural brain research, 59(1-2), 1993, pp. 95-101
Electrical stimulation inducing behavioral responses from the hypothal
amus seems to activate systems involved in the execution phase of the
behaviour rather than in the introductory or decision-making phase. Ho
wever, the pathways involved are not fully understood. Projections ori
ginating from hypothalamic areas involved in specific behavioral respo
nses are rather complex. The periaqueductal gray (PAG) has been propos
ed to be an essential output station of hypothalamic behavioral mechan
isms. Here we report that lesions of the periaqueductal gray area have
no effect on grooming responses evoked by electrical stimulation of t
he hypothalamic paraventricular area. Neither threshold current intens
ities needed to evoke grooming, nor latencies were affected 7 or 14 da
ys after lesioning. The lesions caused severe behavioural deficits. An
imals did not drink or eat spontaneously, had problems with motor coor
dination and sometimes showed strong defensive reactions upon touch. H
owever, their grooming responses induced by hypothalamic stimulation w
ere not changed. The PAG may have a modulatory role on grooming behavi
our; however, this modulatory effect apparently is overruled during el
ectrical stimulation of the hypothalamus.