Spatiotemporal patterns of language-specific brain activity in patients with chronic aphasia after stroke using magnetoencephalography

Abstract

Six participants with chronic aphasia secondary to first-ever ischemic stroke within the middle cerebral artery (MCA) distribution of the left hemisphere and six neurologically intact controls of similar age were given a running recognition memory task for words while the magnetic flux normal to the scalp surface was measured with a whole-head neuromagnetometer. This task had been previously shown to be valid for the localization and lateralization of brain activity specific to receptive language function. As expected, patients exhibited relatively decreased activation in areas known to be involved in receptive language function, including superior temporal gyrus (STG) in the left hemisphere, as well as increased activation of areas outside of the left STG that might potentially support language function. Decreased activation within left STG was associated with a reduction in receptive language in patients, as was increased activation outside of left STG. Results support hypotheses suggesting that peri-lesional areas outside premorbid language areas may assume receptive language function after aphasia secondary to stroke, but that better recovery occurs when putative premorbid language areas are able to normalize.