Movement‐sensitive and direction and orientation‐selective cutaneous receptive fields in the hand area of the post‐central gyrus in monkeys.

Abstract

SUMMARY1. In the hand area of the post-central gyrus of three alert Macaca apeciosa monkeys neurones related to cutaneous receptors but not activated by simple touch on the receptive field were recorded using the transdural micro-electrode recording technique. Thirty-six cells were found to have complex cutaneous receptive field properties. These neurones were subdivided into the following three groups.2. Nine neurones were not activated by punctate stimuli on the receptive fields but responded well to movement along the skin. The activity of these neurones was not affected by the direction of movement; nor was it sensitive to different textures of the moving surface.3. Eighteen neurones responded to cutaneous movement along the skin surface in a particular direction giving no response to stimulation in the opposite direction and intermediate responses to intermediate directions. Similar responses were evoked from different subparts of the receptive field.4. Nine neurones responded well to an edge placed on the skin in an optimal orientation or moved along the skin in a direction perpendicular to the edge. A maximal response was produced by stimuli of the same optimal orientation in different parts of the receptive field. The significance of the stimuli to the monkey had only a minor influence on the magnitude of the responses of these neurones and no influence on the receptive field properties.5. The occurrence of the complex cutaneous cells increased from anterior to posterior within the post-central gyrus and most of them were found in Brodmann's area 2. Thus we postulate that the complex receptive field properties arise as a consequence of cortical processing in a network in which postsynaptic one-way lateral inhibition generates the directional properties of the neurones.6. The complex cutaneous neurones constituted only 6 % of the neurones studied in the hand area of the post-central gyrus. Thus the prevalence of neurones with elongated and direction-selective receptive fields is low in the primary somatosensory cortex in comparison with the visual cortex. These neurones may, however, serve the stereognostic capacity of the hand by contributing information about stimulus motion, orientation and direction of movement on the skin.

Receptive Field Properties of the Macaque Second Somatosensory Cortex: Nonlinear Mechanisms Underlying the Representation of Orientation Within a Finger Pad

“…Previous studies have shown that many of the RFs in SI show approximately linear response properties and have approximately circular or slightly elongated lobes of excitation or inhibition, like most of the D, C, and DC neurons we report here (DiCarlo et al, 1998;Sripati et al, 2006). Furthermore, Hyvärinen and Poranen (1978) reported that a few neurons in area 2 showed invariant responses to bars placed at different locations on the hand, indicating that some of the invariant properties of SII region neurons may originate from area 2 neurons.…”

“…In the somatosensory system, there are only two reports of position invariant responses. In the first, Hyvärinen and Poranen (1978) found a few area 2 neurons that signaled the orientation of a bar independent of where it was presented on the hand. In the second, Fitzgerald et al (2006a) found many neurons in the second somatosensory (SII) region that had multiple orientation tuned finger pads, and, for those neurons when the bar was indented in the center of their pads, the preferred orientation tended to be highly similar.…”

Visual Responses of Neurons in Somatosensory Cortex of Hamsters with Experimentally Induced Retinal Projections to Somatosensory Thalamus

“…Although neurons in somatosensory cortex of normal animals are selective for the direction and velocity of stimulus movement (34), orientation selectivity is rare (35) and these features may not be abstracted by the same mechanisms as in the visual system. Even if these stimulus parameters are not analyzed similarly in the two systems, the visual and somatosensory cortices may perform a common operation-e.g., selectively filtering their inputs so as to emphasize changes in the spatial or temporal domains.…”

Receptive Field (RF) Properties of the Macaque Second Somatosensory Cortex: RF Size, Shape, and Somatotopic Organization

“…Neurons in area 3b of primary somatosensory cortex (SI) have larger RFs, some of which respond well to simple tactile stimulus features such as oriented bars (Hyvarinen and Poranen, 1978a;Warren et al, 1986;DiCarlo and Johnson, 2000). Like the peripheral neurons, most area 3b neurons have single-digit RFs (Paul et al, 1972;Hyvarinen and Poranen, 1978b;Iwamura et al, 1983a;Chapman and Ageranioti-Belanger, 1991;DiCarlo et al, 1998).…”