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The inlfuence of the early visual deprivation on phonological processing.

Poster D13 in Poster Session D with Social Hour, Friday, October 7, 5:30 - 7:15 pm EDT, Millennium Hall

Gabriela Dzięgiel-Fivet¹, Joanna Beck¹, Katarzyna Jednoróg¹; ¹Nencki Institute of Experimental Biology

Reading is a cognitive process in which graphic symbols are mapped onto the spoken language to convey meaning. Phonological awareness is a capacity to understand and manipulate the sound structure of spoken words and is strongly connected to reading efficiency in sighted readers. This relationship was also demonstrated in the blind Braille readers in several small sample studies. The neural correlates of phonological processing were also found to be similar between the blind and the sighted. However, recently we have shown that temporal areas typically involved in phonological processing are disengaged during Braille reading by blind subjects, who additionally engage the left ventral occipitotemporal cortex (vOT) in both spoken and written language processing. Therefore, in the current study, we tested the relationship between phonological processing and reading in a large sample of blind Braille readers. Additionally, we tested the left vOT involvement in phonological processing in the blind. Fifty-three blind and 53 sighted subjects (age: 6-60) completed a battery of behavioral tests measuring their reading and reading-related skills and were subjected to a phonological task on spoken language stimuli during fMRI. We tested the association between phonological awareness and reading efficiency on the behavioral level. On the neural level, we used whole-brain and region-of-interest fMRI analyses. Contrary to the results of previous studies on small samples we have found that the relationship between phonological awareness and reading is different between the blind and the sighted. The blind subjects were more proficient in phonological processing than the sighted subjects. In contrast to the sighted participants, phonological awareness was not significantly related to reading efficiency in the blind. In this group, it was rapid automatized naming, along with working memory span and tactile acuity that explained the largest proportion of variance in word reading. At the same time, blind subjects engaged the left vOT to a larger extent than the sighted subjects during both phonological and control spoken language tasks. However, our results did not indicate that phonological processing is the sole function of the vOT in the blind. The left vOT presented similar activation to other language-network nodes and was related to the reading level only in the blind group. Visual deprivation and tactile literacy seem to alter behavioral and cognitive correlates of reading. It is possible that due to the sequential nature of tactile Braille reading blind subjects become much more proficient in phonological awareness as they are confronted with the inner sound structure of words more often than sighted readers who rely on whole-word processing. Visual deprivation changes the neural correlates of phonological processing to some extent, probably due to the reorganization of the language network. We hypothesize that in the sighted the sensitivity to spoken language in the left vOT is secondary to its involvement in reading whereas in the blind the sensitivity to speech in this region comes first, although it is further refined by reading. The results show that the blinds’ vOT is capable of assuming various cognitive functions, in line with the pluripotent cortex hypothesis.

Topic Areas: Phonology and Phonological Working Memory, Reading