MAPPING BRAIN LESIONS IN INDIVIDUALS WITH APHASIA

picture of George Hariri presenting his/her poster: MAPPING BRAIN LESIONS IN INDIVIDUALS WITH APHASIA

George Hariri , Andrew DeMarco, M.S., Steven Rapcsak, M.D., and Pelagie M. Beeson, PhD.

MAPPING BRAIN LESIONS IN INDIVIDUALS WITH APHASIA

Aphasia, or difficulties using or understanding language, is a result of damage to the left hemisphere of the brain. Because language is supported by a network of regions in the left hemisphere, different aphasia profiles reflect impairment to different components of language. One goal of aphasia research today is to better understand how language is supported in the brain by understanding the relation between the location of brain damage and specific behavioral deficits.

High resolution brain images obtained through magnetic resonance imaging (MRI) allow relatively precise determination of the regions of brain damage (referred to as lesions). When brain damage and behavioral performance are examined in multiple individuals, patterns emerge that suggest functional specialization of specific brain regions. The study of lesion-deficit relations is the foundation of one important approach to studying the brain.

However, there is no simple method to identify the location of damaged tissue in an individual’s brain. Some researchers use computerized labelling/segmentation of lesioned tissue, but these approaches are prone to error leading to under- or over-estimation of the lesion extent. The most precise method of lesion analysis relies on careful tracing of the lesions by hand. The approach is made easier with the use of the computer mouse or drawing tablet to paint the lesions in three dimensions. Accurately demarcating the extent and borders of lesions is a complex and considerably difficult task which has been described with only modest detail in the literature.

Here we provide an introductory tutorial in brain mapping using the developed procedure, which employs a Wacom tablet and brain imaging software, with examples of brains showing specific issues and how they are addressed. With the consultation of a neurologist, rules for delimiting ambiguous lesion borders were developed. In cases where multiple image types were available, procedures for optimizing the presence of these images were developed. Finally, we provide a brief description of how a collection of mapped brains can be combined to localize a specialized neural function. This work is supported by UA Provost and R01 DC007646 from the National Institute of Deafness and Other Communication Disorders.

 

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