Fig. 8

Neural circuit diagram based on current functional results, our previous anatomical results in the IC shell, and others’ results in the auditory cortex. a In the IC shell, one group of inhibitory neurons exhibit much higher cross-correlation values with locomotion than the other group of inhibitory neurons and excitatory neurons, which imply that they receive directly excitatory inputs from locomotion-related nuclei, mesencephalic locomotor region (MLR). MLR includes cuneiform nucleus (CnF) and pedunculopontine nucleus (PPN). Excitatory neurons also receive MLR inputs, but their in vivo activities are likely to be excited or inhibited by locomotion indirectly. The SC, PAG, and lateral paragigantocellular nucleus (LPGi) are also related with locomotion control. Compared with the excitatory neurons, the inhibitory neurons are highly inter-connected. Anatomically, the auditory cortex mainly innervates excitatory neurons. b In the auditory cortex, the inhibitory PV neurons receive long-range excitatory inputs from motor cortex, which in turn inhibit the local excitatory neurons. Locomotion-related MLR excites the basal forebrain, which in turn excite the inhibitory VIP neurons of auditory cortex. The VIP neurons will inhibit the inhibitory SOM neurons, which in turn disinhibit the local excitatory neurons. The MLR-related disinhibitory pathway also exist in the visual cortex, but the motor cortex-related inhibitory pathway is unique to the auditory cortex. Importantly, the net effect of locomotion over auditory cortex is inhibitory, since almost excitatory neurons are inhibited during locomotion