Abstract
This study is the first to investigate the neural underpinnings of tactile object familiarity in the blind during both perception and memory. In the sighted, the perirhinal cortex (PRC) of the medial temporal lobe has been implicated in the assessment of visual object familiarity—a crucial everyday task—during both perception and memory (e.g., Murray at al., 2007). This familiarity effect is typically evidenced by reduced activation when an object becomes familiar (Henson et al., 2003). Here, we examined the PRC's role in tactile object familiarity in the absence of vision. To do so, we trained 5 blind subjects on a unique memory-guided drawing technique (Likova, 2012) which has been shown to produce spatiocognitive performance improvements and cortical reorganization in both low-level "visual" regions and high-level regions such as the inferotemporal cortex and hippocampus where perception and memory interact (Likova, 2015). The tasks (20s each) were as follows: tactile perceptual exploration of experimentally novel raised line drawings, tactile memory retrieval via drawing, and a scribble motor control. FMRI before and after a week of training on these tasks revealed a significant decrease in PRC activation from pre- to post-training (i.e., from unfamiliar to familiar) during perceptual exploration as well as memory-guided drawing, but not during the scribble control. This familiarity-based reduction is the first evidence that the PRC represents tactile object familiarity in the blind. Furthermore, the finding of this effect during both tactile perception and tactile memory provides the critical link in establishing the PRC as a structure whose representations are supramodal for both perception and memory.
Meeting abstract presented at VSS 2016