Table 1.
Pathways in the whisker-to-barrel cortex system.
| Pathway | Brainstem (trigeminal nuclei) | Thalamus (contralateral) | Neocortex (main target regions are italicized and bold) | Response type |
|---|---|---|---|---|
| Lemniscal (1) | N. principalis | VPMdm core barreloid | S1 Layer 3 | Single whisker |
| S1 Layer 4 barrels | ||||
| S1 Layer 5B | ||||
| S1 Layer 6A | ||||
| Lemniscal (2) | N. principalis | VPMdm head barreloid | S1 Layer 4 septa | Single whisker |
| Multiple whisker | ||||
| Extralemniscal | N. interpolaris (caudal) | VPMvl No clear barreloid detectable | S1 Layer 3 dysgranular | Multiple whisker |
| S1 Layer 4 dysgranular | ||||
| S1 Layer 6A dysgranular | ||||
| S2 Layer 4 | ||||
| S2 Layer 6 | ||||
| Paralemniscal | N. interpolaris (rostral) | POm | S1 Layer 1 barrels and septa | Multiple whisker |
| S1 Layer 4 septa | ||||
| S1 Layer 5A barrels and septa | ||||
| S2 |
Pathways from the brain stem to the barrel cortex indicating the name of the pathway, the brainstem relay, the thalamic relay station, the target regions in the primary and secondary somatosensory cortices and whether the neuronal response is elicited only by a single or by several (multiple) whiskers.