Ultra-fast speech comprehension in blind subjects engages primary visual cortex, fusiform gyrus, and pulvinar – a functional magnetic resonance imaging (fMRI) study

• Published in: BMC neuroscience Vol. 14; no. 1; p. 74
• Main Authors: Dietrich, Susanne, Hertrich, Ingo, Ackermann, Hermann
• Format: Journal Article
• Language: English
• Published: England BioMed Central Ltd 23.07.2013; BioMed Central
• Subjects: Adult; Age; Behavior; Blind; Blindness; Brain; Brain Mapping; Brain research; Cerebral Cortex - physiology; Cognition & reasoning; Comprehension - physiology; Computational linguistics; Consent; Female; Humans; Image Interpretation, Computer-Assisted; Language; Language processing; Linguistics; Magnetic Resonance Imaging; Male; Natural language interfaces; NMR; Nuclear magnetic resonance; Physiological aspects; Pulvinar - physiology; Speech Perception - physiology; Studies; Time Factors; Visual Cortex - physiology; Visually Impaired Persons; Germany
• ISSN: 1471-2202; 1471-2202
• DOI: 10.1186/1471-2202-14-74

Individuals suffering from vision loss of a peripheral origin may learn to understand spoken language at a rate of up to about 22 syllables (syl) per second - exceeding by far the maximum performance level of normal-sighted listeners (ca. 8 syl/s). To further elucidate the brain mechanisms underlying this extraordinary skill, functional magnetic resonance imaging (fMRI) was performed in blind subjects of varying ultra-fast speech comprehension capabilities and sighted individuals while listening to sentence utterances of a moderately fast (8 syl/s) or ultra-fast (16 syl/s) syllabic rate. Besides left inferior frontal gyrus (IFG), bilateral posterior superior temporal sulcus (pSTS) and left supplementary motor area (SMA), blind people highly proficient in ultra-fast speech perception showed significant hemodynamic activation of right-hemispheric primary visual cortex (V1), contralateral fusiform gyrus (FG), and bilateral pulvinar (Pv). Presumably, FG supports the left-hemispheric perisylvian "language network", i.e., IFG and superior temporal lobe, during the (segmental) sequencing of verbal utterances whereas the collaboration of bilateral pulvinar, right auditory cortex, and ipsilateral V1 implements a signal-driven timing mechanism related to syllabic (suprasegmental) modulation of the speech signal. These data structures, conveyed via left SMA to the perisylvian "language zones", might facilitate - under time-critical conditions - the consolidation of linguistic information at the level of verbal working memory.