Hearing Shapes Our Perception of Time: Temporal Discrimination of Tactile Stimuli in Deaf People

Abstract

Confronted with the loss of one type of sensory input, we compensate using information conveyed by other senses. However, losing one type of sensory information at specific developmental times may lead to deficits across all sensory modalities. We addressed the effect of auditory deprivation on the development of tactile abilities, taking into account changes occurring at the behavioral and cortical level. Congenitally deaf and hearing individuals performed two tactile tasks, the first requiring the discrimination of the temporal duration of touches and the second requiring the discrimination of their spatial length. Compared with hearing individuals, deaf individuals were impaired only in tactile temporal processing. To explore the neural substrate of this difference, we ran a TMS experiment. In deaf individuals, the auditory association cortex was involved in temporal and spatial tactile processing, with the same chronometry as the primary somatosensory cortex. In hearing participants, the involvement of auditory association cortex occurred at a later stage and selectively for temporal discrimination. The different chronometry in the recruitment of the auditory cortex in deaf individuals correlated with the tactile temporal impairment. Thus, early hearing experience seems to be crucial to develop an efficient temporal processing across modalities, suggesting that plasticity does not necessarily result in behavioral compensation.

Synchronization to auditory and visual rhythms in hearing and deaf individuals

“…This result is somewhat surprising in light of a range of findings suggesting temporal processing impairments in deaf individuals (e.g., Bolognini et al, 2012; Conway et al, 2009; Kowalska & Szelag, 2006). However, these other studies dealt with temporal sequencing or the perception of the duration of single time intervals, suggesting that the timing processes involved in synchronization with repetitive visual stimuli are not similarly impaired by the lack of auditory experience.…”

Audiotactile interaction can change over time in cochlear implant users

“…Indeed, imaging data suggests that vibrotactile stimuli can activate auditory regions in the deaf (Levänen et al, 1998; Schürmann et al, 2006; Sharma et al, 2007) and cortical over-representation of somatosensory evoked potentials in the left temporal region was found in deaf children using a CI (Charroó-Ruíz et al, 2013). Several data demonstrate that brain reorganization induced by deafness leads to behavioral changes for numerous perceptual tasks (Hanson, 1982; Neville and Lawson, 1987; Loke and Song, 1991; Bavelier et al, 2000, 2001, 2006; Bosworth and Dobkins, 2002; Heming and Brown, 2005; Turgeon et al, 2012), although it is unsure whether behaviorally advantageous (e.g., Bolognini et al, 2012). The effect of cross-modal reorganization raises important questions on the importance of hearing experience in shaping perceptual processing, but also in regards to cochlear implantation.…”

Dissecting neural circuits for multisensory integration and crossmodal processing

“…Indeed, anodal tDCS over auditory cortex, which modulates auditory frequency sensitivity [59], improves performance on a tactile frequency discrimination task by enhancing frequency sensitivity or perceptual learning in the frequency domain [45] (figure 3b). Additionally, spTMS targeting the superior temporal gyrus (STG) impairs performance on a tactile duration discrimination task [60,61]. In individuals with normal hearing, TMS targeting STG impairs tactile performance only when TMS pulses are presented 180 ms after touch; however, TMS delivered to STG 60 ms after touch impairs tactile performance in congenitally deaf individuals [61].…”

“…Additionally, spTMS targeting the superior temporal gyrus (STG) impairs performance on a tactile duration discrimination task [60,61]. In individuals with normal hearing, TMS targeting STG impairs tactile performance only when TMS pulses are presented 180 ms after touch; however, TMS delivered to STG 60 ms after touch impairs tactile performance in congenitally deaf individuals [61]. These studies reveal that tactile recruitment of auditory cortex may be ubiquitous in hearing and deaf individuals, and the degree and nature of crossmodal processing is shaped by auditory experience.…”