Acoustic trauma induced the alteration of the activity balance of excitatory and inhibitory neurons in the inferior colliculus of mice.

We examined the effect of acoustic trauma on the spontaneous activities of the glutamatergic and GABAergic neurons in the inferior colliculus (IC) of mice. Optogenetics was used to identify the neuron type. In control animals, the spontaneous firing rate was higher in GABAergic neurons than in glutamatergic neurons. However, in the animals with acoustic trauma, the balance of spontaneous activities between glutamatergic and GABAergic neurons was inverted. The spontaneous firing rate was enhanced in glutamatergic neurons only, with bursting episodes occurring frequently. Moreover, the spike shapes of GABAergic and glutamatergic neurons were modified differently in both cell types. These results suggested that the acoustic trauma induced plastic changes in the neuronal circuits in the IC and altered the balance of the activities of excitatory and inhibitory neurons. This aberrant excitatory-inhibitory balance in the IC might underpin tinnitus perception.