Figure 5.

Proposed cortical circuits underlying an enlarged representation of CS⁺ in barrel cortex. In solid lines, the projections with inputs from a paired whisker (CS⁺) and in dashed lines, the projections with inputs from an unpaired whisker (CS⁻). Stars indicate projections that were strengthened after conditioning. CS⁺ inputs could directly reach the L2/3 of the CS column through transcolumnar circuitries with $\text{L}2/3_{{\text{CS}}^{+}}\to \text{L}2/3_{{\text{CS}}^{-}}$ and ${\text{L4}}_{{\text{CS}}^{+}}\to \text{L}{3}_{{\text{CS}}^{-}}$ projections. They could also reach through the ${\text{(brainstem}\to \text{POm)}}_{{\text{CS}}^{+}}\to {(\text{L5A}\to \text{L2/3)}}_{{\text{CS}}^{-}}$ pathway or through a corticothalamocortical ${\text{(L5B}\to \text{POm)}}_{{\text{CS}}^{+}}\to {(\text{L5A}\to \text{L2/3)}}_{{\text{CS}}^{-}}$ loop.