Abstract:
An ascending cholinergic projection, which originates in the laterodorsal tegmental
nucleus (LDT), was implicated in the initiation of ultrasonic vocalization. The goal of this study
was to histochemically examine the activity the LDT following ultrasonic calls induced by two
methods. It was hypothesized that cholinergic LDT cells would be more active during air puffinduced
vocalization than carbachol-induced one.
Choline acetyltransferase (ChAT), and cFos protein were visualized histochemically as
markers of cholinergic calls and cellular activity, respectively. Results indicated that animals
vocalizing after carbachol, but not after air puff, had a significantly higher number of Fos labeled
nuclei within the LDT than non vocalizing controls. A significantly higher number of doublelabeled
neurons were discovered in the LDT of vocalizing animals (in both groups) as compared
to control conditions. Thus, there were significantly more active cholinergic cells in the LDT of
vocalizing than non-vocalizing rats for both methods of call induction.
