ABSTRACT
Lashley also recognized the importance of understanding the relative functional roles of cortico-cortical and cortiço-subcortical connections, and this problem—as it was singled out by Lashley in the forties—remains at the forefront of brain research in the eighties. Given the fact that signals relayed by the dorsal column nuclei can reach MI by cortico-cortical connections but not by direct thalamo-cortical connections, it becomes critical to determine the extent to which dorsal column signals are necessary for transmission of sensory feedback to ML. Thus, current evidence is consistent with the hypothesis that cortico-cortical pathways have a significant role in transmitting short-latency kinesthetic inputs to motor cortex. The pathways from postcentral gyrus to motor cortex provide inputs that can continuously control motor cortex output in the closed-loop mode. Cerebellar nuclear cooling produced no change in the early component of motor cortex response, demonstrating that a transcerebellar route was not necessary for the early feedback-dependent phase.
