Figure 7.

Schematic illustration of convergent deep layer inputs from sensory thalamus and VTA. VTA projections mainly target upper and infragranular layers of the gerbil auditory cortex (see also Fig. 1B). Stimulating the VTA projections led to a frequency-specific gain amplification of early sensory-evoked responses in thalamocortical recipient layers Vb/VIa. This gain increase effectuated an enhanced spectral tuning representation in supragranular layers I/II. The supragranular gain modulation might hence be inherited via intratelencephalic neurons targeting upper layers and bypassing granular input circuits⁴⁴, may originate from a direct influence of dopamine released in upper layers or a combination of both. MGB, medial geniculate body.