The Scientific American Web site describes a conference paper reporting that the angular gyrus may be linked to people’s abitlity to understand metaphors. Vilayanur S. Ramachandran and collegues (University of California at San Diego) have assessed four individuals who have damage to the left angular gyrus but have normal intelligence and can carry on conversation fluently. When Ramachandran tested “them with common proverbs and metaphors such as ‘the grass is always greener on the other side’ and ‘reaching for the stars,’ the subjects interpreted the sayings literally almost all of the time.”
The angular gyrus is a section of the brain that is involved in cross-modal connections—to oversimplify, mapping between visual and verbal stimuli. As Hallahan and Mercer reported, since the late 1800s there has been suspicion about a connection between problems in the left angular gyrus and Learning Disabilities in reading. With the advent of powerful technology for examining brain function (especially fMRIs), the connection between LD in reading and the angular gyrus grew stronger (see S. Shaywitz’s book Overcoming Dyslexia for more).
I found Ramachandran’s report intriguing because the connection between LD in reading and problems in understanding metaphors has been reported previously in LD (see sources). Problems in understanding metaphors may not be diagnostic, but the overlap strengthens the idea that LD in reading is a language problem.
Links for Hallahan & Mercer: HTML (see first two pages) or download PDF
Seidenberg, P. L., & Bernstein, D. K. (1988). Metaphor comprehension and performance on metaphor-related language tasks: A comparison of good and poor readers. Remedial and Special Education, 9(2), 39-45.
Wiig, E. H., Semel, E. M., & Aberle, E. (1981). Perception of ambiguous sentences by learning disabled twelve-year-olds. Learning Disability Quarterly, 4, 3-12.