Previous evidence from this Laboratory showed that after chronic lesions of the dorsal columns, single-shock stimulation of the VPL nucleus of one side elicits evoked potentials in the contralateral cortex also after complete callosal transection, whereas in acute preparations identical lesions are ineffective in promoting such an effect. The evidence presented in this report shows that in curarized cats clear-cut extracallosal activation can consistently be obtained after acute interruption of the medial lemniscal bundle supplying the VPL nucleus contralateral to the one stimulated. Comparable effects can also be obtained, in a reversible way, by cooling the dorsal-column nuclei (gracile and cuneate). The results are related to previous data concerning the possibility of reciprocal activation between VPL nuclei through subcortical linkages. Some interpretative hypotheses are put forward.