Our Research

The major goals of our research are to understand how people learn to read and what goes wrong in developmental dyslexia. In order to learn to read, the brain must integrate systems that originally evolved for other purposes, such as linguistic communication and visual perception. In most individuals, the reading network in the brain is quite extensive, and includes the classic left hemisphere language regions where meanings and pronunciations appear to be computed (Wernicke's and Broca's areas) as well as regions that connect visual processing of print to the language network, such as the occipito-temporal junction, also known as the visual word form area (VWFA). Dyslexic individuals struggle to learn to read, and even as adults, show reduced activation in the reading network, including the VWFA, as well as compensatory activation in other regions of the brain.

Crosshairs show the location of activation in the VWFA
during the reading of words and pseudowords

Our research group is conducting studies in both children and adults to explore why dyslexic people have so much trouble learning to read, and what their problems can tell us about the normal process of reading. One line of work focuses on VWFA activation in adults with and without dyslexia. In previous work, faculty members Frank Manis and Zhong-Lin Lu, along with graduate students Allison Zumberge (Neuroscience), Jennifer Bruno (Psychology), and Jason Goldman (Psychology), used a novel fMRI methodology to isolate activation to printed words in the VWFA and analyze the properties of printed words that affect VWFA activation in dyslexic and non-dyslexic adults, as well as activation across the entire reading network.

Current research is examining the structural development of the various brain regions throughout the reading network in both skilled readers and in dyslexic individuals. We hypothesize that differences in reading experience (i.e. the cumulative amount of printed text that one has read) may be related to differences in the structural development of the brain.

Diagrams showing some of the sections of the brain, many of which are important for reading. Some of these regions are: visual cortex (yellow), auditory cortex (blue),
Broca's area (dark red), motor cortex (lighter red), and cerebellum (peach).
Image modified by Christine Vidal, from “Human Brain Anatomy in Computerized Images” (2005), 2nd edition, Oxford University Press, New York, by Dr. Hanna Damasio.

The most salient reading problem for dyslexic children involves sounding out unfamiliar words (phonological decoding deficit). One of the critical areas for the development of phonological processing ability is the left inferior frontal gyrus (Broca's area). This deficit is thought to lead to problems in building up representations of words in the VWFA, and hence is developmentally primary. However, it is unclear what causes the phonological decoding problem. Two seemingly unrelated deficits occur in dyslexic children and adults who have phonological decoding deficits. The first involves visual magnocellular processing, as for example, in pattern recognition under conditions of low visual contrast, or perception of visual motion. The second involves the categorical perception of speech sounds. We think that these two areas of deficiency may be related.

Image modified by Christine Vidal, from "Human Brain Anatomy in Computerized Images" (2005), 2nd edition, Oxford University Press, New York, by Dr. Hanna Damasio.

In experiments conducted by Frank Manis, Anne Sperling (Neuroscience Ph.D., 2004) and Zhong-Lin Lu, we showed that the visual magnocellular deficit only occurred under noisy visual conditions, and furthermore that it was more salient among dyslexic children with oral language delays. In previous work with Patricia Keating (UCLA Phonetics Lab), our research group had demonstrated that the speech perception deficit was more severe among dyslexics with language deficits. We now hypothesize that a problem in forming perceptual categories in a noisy environment might underlie both the visual and auditory perception problems. In an ongoing study with Lu and Keating, Frank Manis, graduate student Rachel Beattie (Psychology), and undergraduate student Jason Batten are investigating whether dyslexic children show deficits in noise exclusion with both auditory and visual stimuli, and whether the noise perception problems are associated with poor phonological decoding and word recognition.