Thus, the data in the study by Dr. Buchanan and colleagues include measurements of substantial portions of the unimodal association cortex (premotor region and superior temporal gyrus) and do not take into account the heteromodal cortex in the middle temporal gyrus and superior parietal lobule. This affects some of the study’s findings, since the distinction between the heteromodal and unimodal association cortices are not purely semantic. For example, in single-unit recording experiments in primates, the neurons in the unimodal (auditory) association cortex respond primarily to auditory stimuli (2). By contrast, single-unit recordings in the heteromodal association cortex identify a broad array of cells. Some respond to only one type of sensory stimulus (auditory, visual, or somatosensory), others respond to two, and still others respond in all three sensory channels (2).