DISTRIBUTION of NADPH-diaphorase (NADPH-d) positive neurones was inves
tigated in the central auditory structures of the rat. NADPH-d positiv
e perikarya were found in the dorsal and external cortices of the infe
rior colliculus and in the intercollicular commissure. Within the medi
al geniculate body (MGB), stained cell bodies were observed in the dor
sal part of the suprageniculate nucleus and in the basal part of the m
edial division of the MGB. Occurrence of the NADPH-d positive perikary
a in the MGB is limited to its caudal third. NADPH-d positive cells ar
e dispersed in the auditory temporal cortex within layers II-VI, with
a slight prevalence in the infragranular layers. NADPH-d positive neur
ones have smooth dendrites without stained dendritic spines.