Changes in the acoustically evoked activity in the inferior colliculus of the XXXX after functional ablation of the auditory cortex.

@entity1022 @entity4524 @entity1372 @entity4763 @entity35
The role of the cortico-tectal pathways in the processing of auditory signals was investigated by recording the click-evoked responses and extracellular multiple unit activity in the inferior colliculus (IC) after functional ablation of the auditory cortex (AC) by local intracortical application of a @entity1372 channel blocker, @entity1022 ( @entity4524 ). Click-evoked IC responses (IC-ER) and multiple unit activity in response to tone bursts were recorded with implanted electrodes in the IC of @entity35 lightly anaesthetized with @entity4763 . Neural activity was recorded before and after the application of @entity4524 into the ipsilateral auditory cortex (AC) through three implanted cannulas in a total dose of 30 ng. The functional status of the AC was monitored by recording click-evoked middle latency responses from a ball electrode implanted on the AC. During inactivation of the AC, IC-ER amplitudes were either increased (48 % of the cases), decreased (32 % of the cases) or not evidently changed (20 % of the cases). Corresponding effects were observed in the firing rate of IC neurons. Functional ablation of the AC also resulted in a significant prolongation of the latencies of individual waves of the IC-ER. However, the discharge pattern of the multiple unit responses, response thresholds and tuning were not altered during AC inactivation. IC neural activity recovered within several hours, and maximally during 2 days. The results reveal principles of the interaction of cortico-tectal pathways with IC neuronal activity.
