The dorsal cochlear nucleus contributes to a high intensity component of the acoustic startle reflex in rats.

The dorsal cochlear nucleus (DCN) has been shown to project to a region of the nucleus reticularis pontis caudalis (PnC) critical for the evocation of startle in rats, suggesting a possible modulatory influence of the DCN on startle. This study examined the involvement of the DCN in the acoustic startle reflex and various other forms of behavioral plasticity seen with this response. Animals received bilateral electrolytic lesions of the DCN and were tested for acoustic startle responses, background noise facilitation, short-term habituation, prepulse inhibition and facilitation, and fear conditioning. Compared to sham lesioned rats, DCN lesioned rats showed a significant reduction in startle amplitude at the two highest startle-eliciting intensities (110 and 115 dB SPL) and normal responses on all other measures. Hence, the DCN appears to contribute to a high intensity component of the acoustic startle response in rats.