Neural timing, inhibition and the nature of stellate cell interaction in the ventral cochlear nucleus.
The ventral cochlear nucleus (VCN) stellate cell population comprises two clusters: narrowly-tuned, excitatory T stellate neurons, and D stellate neurons, a broadly-tuned population of inhibitory cells. These neurons respond to best frequency (BF) tone bursts in a chopper or onset manner, respectively. Through extensive local and commissural projections the D stellate population provides a source of fast inhibitory input to both intrinsic and contralateral T stellate neurons. Whilst the nature of interactions between intrinsic stellate populations is difficult to examine, our previous intracellular investigations of the commissural pathway have provided a means by which to study this relationship in the in vivo preparation. It is the aim of this paper to both review and extend our understanding of the link between stellate populations and their involvement in the commissural pathway by presenting an overview of the results attained in our recently expanded study. The sample of 17 intracellular and 34 extracellular onset chopper (O(C)) and late/ideal (On(L)/On(I)) neurons revealed antidromic activity in 31.4% of neurons following contralateral stimulation, providing physiological evidence that On(L)/On(I) neurons also contribute projections to the commissural connection. Alternatively, 64.7% of the 34 intracellularly-recorded chopper neurons displayed fast, monosynaptic inhibitory potentials. This commissural input was found to influence the timing of neural activity in chopper neurons, providing insight into the relationship that exists between T and D stellate neurons.
Department of Otolaryngology, The University of Melbourne, 32 Gisborne Street, East Melbourne, Vic. 3002, Australia. kneedam@bionicear.org
Karina
K
Needham
Antonio G
AG
Paolini
D000818:Animals; D001306:Auditory Pathways; D002450:Cell Communication / Q000502:physiology*; D017626:Cochlear Nucleus / Q000166:cytology* / Q000502:physiology*; D004558:Electric Stimulation; D004594:Electrophysiology; D008564:Membrane Potentials; D009433:Neural Inhibition / Q000502:physiology; D009474:Neurons / Q000166:cytology* / Q000502:physiology*; D051381:Rats; D017208:Rats, Wistar; D011930:Reaction Time; D009435:Synaptic Transmission / Q000502:physiology