The roles of local inhibition mediated by γ-aminobutyric acid (GABA)-A receptor in duration tuning in the inferior colliculus of guinea pigs

Abstract

Conclusion. GABA-mediated inhibition is responsible for the duration tuning in the inferior colliculus (IC) of guinea pigs, a non-echo-locating mammal. Duration tuning in this species is better demonstrated in an appropriate short time window. Objectives. To investigate the role of GABA-mediated inhibition in duration tuning of neurons in the IC of guinea pigs. Materials and methods. Duration tuning pattern was recorded by measuring the spikes of single neurons in response to broadband noise of different durations. The effect of GABA-mediated inhibition was verified by comparing the responses with and without the use of the GABA-A receptor blocker bicuculline (BIC), which was applied using micro-iontophoresis. Results. In addition to overall increase in responsiveness, the application of BIC was found to significantly reduce or eliminate the duration selectivity in 44 of the 67 neurons that showed clear duration tuning from a sample of total 340 neurons.

• Duration tuning
• inferior colliculus
• local inhibition