What Does a Barrel Do?
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Thalamic barreloid neurons typically respond to several neighboring whiskers. For example, in the C2 barreloid, corresponding to the C2 whisker, thalamic neurons (in gray) are excited strongly by the C2 whisker and less strongly by the C3 and/or C1 whisker. Adjacent whiskers only weakly suppress responses to deflections of the C2 whisker. Excitatory neurons (in green) in the C2 barrel are excited strongly only by the C2 whisker and are inhibited by the adjacent ones. |
Inhibitory barrel neurons (in red) are similar to the thalamic input neurons, though they fire more robustly and have even larger receptive fields.
Thus, barrel circuitry transforms multi-whisker receptive fields having weak adjacent-whisker inhibition into single-whisker receptive fields (of excitatory neurons) having strong adjacent-whisker inhibition.