Intraparietal Bimodal Neurones Delineating Extrinsic Space Through Intrinsic Actions

Abstract

We can mentally calibrate the directions of our bodily movements into visual coordinate systems to achieve purposeful actions in space. Alternatively, we can apprehend characteristics of the peri-personal space through actions performed by our own body parts. Such interactions between representations of our body motions and extrinsic space should occur in the intraparietal cortices, where the hierarchically processed somatosensory information adjoins the information on spatial vision processed along the dorsal stream. In this brain area of monkeys, we analyzed the response properties of "bimodal joint neurones", which responded simultaneously to forearm joint displacements and visual stimuli moving in one direction in space. For the majority of these neurones, the directions of hand movements in space as a result of adequate joint displacements were congruent with the preferred directions of the moving visual stimuli. When the arm position was rotated, the preferred direction of the joint displacement became inverted so as to match the induced hand movement in space with the preferred visual stimulus direction. On the other hand, in some neurones the visual preferred direction became inverted when the joint was rotated, becoming to match the preferred direction of joint displacement. Hence, intraparietal neurones appear not only to represent mental recalibration of intrinsic movements into extrinsic coordinates, but also render delineation of extrinsic space through intrinsic actions.

Visual Responsiveness of Neurons in the Secondary Somatosensory Area and its Surrounding Parietal Operculum Regions in Awake Macaque Monkeys

“…Two of the 6 animals were used only in the present experiments. The other 4 animals were used in our previous studies ( Tanaka et al 2004 ; Taoka et al 2013 ). All experimental procedures were approved by the RIKEN Animal Experimental Committee and were in accordance with the National Institutes of Health Guide for the Care and Use of Laboratory Animals.…”

“…To cover the SII, a skull opening (20 mm in diameter) was made stereotaxically, 8–10 mm anteriorly and 20–25 mm laterally (ear bar zero), and the chamber was fixed to the skull with dental acrylic. A more detailed surgical procedure is described elsewhere ( Tanaka et al 2004 ; Taoka et al 2013 ).…”

Somatosensory Processing in the Postcentral, Intraparietal and Parietal Opercular Cortical Regions

“…We also found bimodal neurons of the proprioceptive types [38] (Fig.4). They were intermingled with somatosensory neurons that responded to the movement of bilateral arms or shoulders or with those responding to stimulation of bilateral arms or trunk skin [8].…”