Functional disconnection in pure alexia and color naming deficit demonstrated by facilitation methods.

The authors suggest that the possible combinations of pure alexia with concomitant neuropsychological symptoms form a continuum determined by the extent and severity of the brain lesion. The disconnection mechanism underlying these syndromes is demonstrated by the facilitating effect of unblocking methods (in the tactile, somesthetic, auditory, and visual modality) on the reading performance of a pertinent case. In the unblocking situation, other pathways than the one impaired by the brain lesion are used. It is proposed that the color naming deficit is associated with defective verbal identification of graphemic stimuli because of their common linguistic features. The delineation from aphasic color naming and reading deficit is discussed.