Dynamics of cortical activation in a hemianopic patient

Although residual vision in patients with cortical blindness is common, its brain mechanisms are poorly known. To study these mechanisms we measured n euromagnetic responses to visual stimuli in a patient with right posterior cerebral lesion and left visual field hemianopia. His vision had partially recovered with intensive training before our measurements. Compared with th e processing in the healthy side, early occipital responses were attenuated for both passive viewing of checkerboard reversal patterns and a letter id entification task. In both conditions there were prominent longer-latency r esponses at the right superior temporal cortex. We suggest that the activat ion in the superior temporal cortex can partially compensate for the failur e to produce synchronized population responses at the early stages of visua l cortical processing. NeuroReport 12:861-865 (C) 2001 Lippincott Williams & Wilkins.