Inhibitory synaptic interactions between cochlear nuclei: evidence from anin vitro whole brain study

USING guinea-pig isolated whole brain preparation in vitro, synaptic respon ses to electrical stimulation of auditory nerves were examined in intracell ularly recorded and stained neurons of posteroventral and dorsal divisions of the cochlear nucleus. Stimulation of the contralateral auditory nerve ev oked exclusively IPSPs in 70% of neurons, with amplitude of 2.3 +/- 1.2 mV. Neurons of all major cell types were inhibited from the contralateral side . In the majority of responding cells (78%) IPSPs were induced at latencies of 3-9 ms suggesting di- and trisynaptic connections from contralateral au ditory afferents or, respectively, mono- and disynaptic connections from th e contralateral cochlear nucleus. Few cells responded with long-latency IPS Ps (13.5-23 ms), indicating involvement of polysynaptic pathways. These dat a demonstrate the existence of functional, direct and indirect inhibitory c onnections between the cochlear nuclei. NeuroReport 10:1913-1917 (C) 1999 L ippincott Williams & Wilkins.