Visual cortical activity during tactile perception in the sighted and the visually deprived

Abstract

This article reviews studies demonstrating activity in visual cortex during tactile perception in sighted participants as well as in those who have experienced visual deprivation of varying duration. This field has been very active over the last few years, with the result that a number of exciting findings have emerged, but a unifying framework is still lacking. The first section of this article deals with investigations revealing that visual cortical activity is regularly associated with the neural processing of tactile inputs in normally sighted individuals. Next, the possible reasons underlying such visual cortical recruitment are considered. The focus then shifts to the effects of visual deprivation, examining the involvement of visual cortex in sensory and language processing in the early and late blind. The final section gives an account of studies suggesting that a remarkable degree of plasticity can be observed even after quite short-lasting visual deprivation. Overall, it appears that the nature of visual cortical activity during nonvisual tasks in the sighted can be influenced by late-onset blindness and even by brief interruptions of visual input; however, the relevant neural plasticity seems to considerably more exuberant if vision is lost very early in life or was never present, which suggests that there is a critical period for the maximal expression of such plasticity.

Passive tactile feedback facilitates mental rotation of handheld objects

“…These findings suggest a tight coupling between the continuous tactile information specifying a rotating object and the corresponding dynamic representation of the rotating object. This correspondence between haptic and visual modalities is in line with Sathian and colleagues' proposed account of haptic-visual translation for mental rotation (Prather & Sathian, 2002;Prather et al, 2004;Sathian, 2005). Research explicating the neural mechanisms underlying this relationship is in an incipient stage.…”

“…Recent support for this claim has come from functional neuroimaging studies, which have shown activation in visual-processing regions during visual mental rotation tasks (e.g., Cohen et al, 1996;Kosslyn et al, 1998;Wraga, Shephard, Church, Inati, & Kosslyn, 2005). Sathian and colleagues have hypothesized that the tactile feedback participants receive during active and passive haptic mental rotation tasks may be translated into visual format for mental rotation (Prather & Sathian, 2002;Prather et al, 2004;Sathian, 2005). In the present study, we explored this issue using a behavioral paradigm.…”

Combined Activation and Deactivation of Visual Cortex During Tactile Sensory Processing

“…Increasing evidence suggests that occipital cortex, in addition to its visual functions, is implicated in processing information from other sensory modalities (Sathian 2005;Schroeder and Foxe 2005;Sur and Leamey 2001). For example, after prolonged visual deprivation, visual cortex is recruited in a compensatory manner to process both tactile and auditory information (Burton et al 2002;Gougoux et al 2004;Kujala et al 1995;Roder et al 2002;Sadato et al 1996).…”

Aura-like features and photophobia in sightless migraine patients

“…Blind individuals may compensate for the lack of sight by developing hypereffective nonvisual senses. Although tactile input activates the visual cortex in sighted individuals 20 , blinds activate their primary visual areas V1 and V2 during Braille reading as a compensatory cross-modal strategy. 4 Blind subjects develop auditory abilities beyond controls 21 , and the absolute pitch is more prevalent in blind musicians 22 .…”