Cortical Locus of Coherent Motion Deficits in Deaf Poor Readers

Autor/inn/en	Samar, Vincent J.; Parasnis, Ila
Titel	Cortical Locus of Coherent Motion Deficits in Deaf Poor Readers
Quelle	In: Brain and Cognition, 63 (2007) 3, S.226-239 (14 Seiten) PDF als Volltext Verfügbarkeit
Sprache	englisch
Dokumenttyp	gedruckt; online; Zeitschriftenaufsatz
ISSN	0278-2626
DOI	10.1016/j.bandc.2006.08.004
Schlagwörter	Motion; Deafness; Young Adults; Reading Comprehension; Correlation; Brain; Dyslexia; Reading Difficulties; Brain Hemisphere Functions; Neurological Impairments; Visual Perception; Perceptual Impairments + Suchen Sie Ihr Suchwort? Bewegungsablauf; Gehörlosigkeit; Taubstummheit; Young adult; Junger Erwachsener; Leseverstehen; Korrelation; Gehirn; Dyslexics; Legasthenie; Lese-Rechtschreib-Schwäche; Reading difficulty; Leseschwierigkeit; Neurodegenerative Erkrankung; Visuelle Wahrnehmung; Perceptual handicaps; Wahrnehmungsstörung
Abstract	Samar and Parasnis [Samar, V. J., & Parasnis, I. (2005). Dorsal stream deficits suggest hidden dyslexia among deaf poor readers: correlated evidence from reduced perceptual speed and elevated coherent motion detection thresholds. "Brain and Cognition, 58," 300-311.] reported that correlated measures of coherent motion detection and perceptual speed predicted reading comprehension in deaf young adults. Because deficits in coherent motion detection have been associated with dyslexia in the hearing population, and because coherent motion detection is strongly dependent on extrastriate cortical area MT, these results are consistent with the claim that hidden dyslexia occurs within the deaf population and is associated with deficits in MT. However, coherent motion detection can also be influenced by subcortical deficits in both magnocellular and parvocellular pathways. To confirm the putative cortical locus of coherent motion perception deficits, we measured contrast thresholds for detecting the direction of movement of drifting sine wave gratings in the same participant group as [Samar, V. J., & Parasnis, I. (2005). Dorsal stream deficits suggest hidden dyslexia among deaf poor readers: correlated evidence from reduced perceptual speed and elevated coherent motion detection thresholds. "Brain and Cognition," 58, 300-311.], under stimulus conditions that selectively biased for input from the subcortical magnocellular and parvocellular pathways, respectively. Contrast thresholds were not related to reading comprehension performance under either the magnocellular or parvocellular conditions. Furthermore, the previously reported correlations among reading comprehension, coherent motion thresholds, and perceptual speed remained significant even after contrast thresholds and non-verbal IQ were controlled in partial correlation analyses. In addition, coherent motion detection thresholds were found to correlate specifically with a reading-IQ discrepancy score, one commonly used indicator of dyslexia. These results provide direct psychophysical evidence that the previously reported deficit in coherent motion detection in deaf poor readers does not involve subcortical pathway deficits, but rather is associated with a cortical deficit likely involving area MT. They also strengthen the argument for the existence of hidden dyslexia in the deaf adult population. (Author).
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Erfasst von	ERIC (Education Resources Information Center), Washington, DC
Update	2017/4/10