Abstract
It was reported that a surface-negative, depth-positive (s-N, d-P) cortical field potential (no-go potential) appeared in the dorsal bank of the principal sulcus with suppression of movements in the monkey [1]. The s-N, d-P potential is due to the activation of superficial thalamo-cortical (T-C) projections. In the monkey, we identified thalamic nuclei which sent superficial T-C projections to the prefrontal cortex by recording cortical field potentials induced by thalamic stimulation under pentobarbital anesthesia with electrodes implanted on the surface and at a 2.5–3.0 mm depth of the cortex. The stimulation of the ventral anterior nucleus (VA) or mediodorsal nucleus (MD) evoked superficial T-C responses in dorsal parts of areas 8 and 46, which included the dorsal bank of the principal sulcus. The distribution of superficial T-C responses by the VA stimulation in the dorsal bank of the principal sulcus was restricted within the caudal part. These results suggest that the no-go potential was generated by superficial T-C projections from the VA or MD. In addition, the stimulation of the cingulate cortex (area 23, 24) also induced an s-N, d-P potential in much the same cortical area as that in which superficial T-C responses by the stimulation of the VA or MD distributed. This indicates that the VA, MD-prefrontal projection, a putative circuit responsible for the no-go potential was possible to be activated by the cingulate-thalamic projection. [1] Sasaki K, Gemba H, Exp Brain Res 64: 603-606, 1986 [Jpn J Physiol 55 Suppl:S179 (2005)]
