Rostrocaudal gradients in the neuronal receptive field complexity in the finger region of the alert monkey's postcentral gyrus

Abstract

In the primate postcentral gyrus, the cytoarchitectonic characteristics gradually shift from those of koniocortex to more homotypical parakoniocortex along its rostrocaudal axis. To find the physiological correlates of these changes we examined a large body of data accumulated during a series of our experiments with alert monkeys. Along the rostrocaudal axis of the postcentral gyrus, we found a gradual and continuous increase in the number of neurons with converging receptive fields and those in which receptive field positions or submodalities were not determined. Deep or skin submodality neurons were dominant in area 3a or 3b respectively. The proportion of skin submodality neurons decreased gradually from area 3b to the more caudal part of the gyrus. The proportion of deep submodality neurons was almost constant from area 3b to area 2 inclusive; they were not the majority in area 2. The data are consistent with the hierarchical scheme, i.e., within the postcentral gyrus sensory information is processed from the primary sensory receiving stage to the more associative, integrative stages.

Intraparietal Bimodal Neurones Delineating Extrinsic Space Through Intrinsic Actions

“…to install 5 screws against the skull to fix their heads to the monkey chair in an upright position. Chronic recordings of single neuron activities were made from the hand-arm region of the anterior bank of the intraparietal sulcus (a posterior extension of the first somatosensory cortex, SI) in twelve hemispheres, using a microelectrode technique described previously (Iwamura et al, 1993). These monkeys were the same animals we had used for our previous reports (Iriki et al, 1996b;Iriki et al, 2001;Obayashi et al, 2000).…”

“…At the end of the experiments, electrode tracks and neuronal recording sites were reconstructed from serial histological sections. Detailed techniques for histological reconstruction have been described elsewhere (Iwamura et al, 1993).…”

“…The brain area investigated in the present study was laterally adjacent to the MIP (more or less overlapping boundaries) and superficially adjacent to the VIP within the medial bank of the IPS, vis-à-vis AIP. Unexpectedly, this area has not been studied extensively for visual properties, probably because it has been believed to be somatosensory-dominant, with relatively inconspicuous visual properties (Iwamura et al, 1993). Therefore, the present article is the first attempt to systematically describe the receptive field properties of IPS bimodal neurons driven by both joint displacements of the forearm and visual stimuli moving in particularly correlative directions.…”

“…This most likely takes place in the intraparietal cortices where the hierarchically processed somatosensory information (Iwamura, 1998;Iwamura & Tanaka, 1996;Iwamura, Tanaka, & Hikosaka, 1980;Iwamura, Tanaka, & Iriki, 1994;Iwamura, Tanaka, Sakamoto, & Hikosaka, 1993;Taoka, Toda, & Iwamura, 1998;Toda & Taoka, 2002) adjoins the information on spatial vision processed along the dorsal stream (Seltzer & Pandya, 1980;Ungerleider & Mishkin, 1982). Indeed, in human patients, lesions in this brain area are known to cause impairment of the body schema (Head & Holmes, 1911), which makes it difficult for the patient to achieve purposeful hand movements in the dark or without seeing, i.e., without visual guidance.…”

Lighter or Heavier Than Predicted: Neural Correlates of Corrective Mechanisms during Erroneously Programmed Lifts

“…1, grip force rate profile). In man, the S1 and M1 are activated by muscle spindle responses from the muscles of the contralateral hand (Naito et al, 1999(Naito et al, , 2002, and in monkeys, neurons in both M1 (Lemon et al, 1976;Fetz et al, 1980;Soso and Fetz, 1980;Lemon, 1981) and S1 (Iwamura et al, 1983(Iwamura et al, , 1993 respond to muscle stretch. Thus, the activation of these areas could reflect increased sensory feedback arising from the pulsatile force increase, as well as the generation of the corrective force responses.…”