Increased sensitivity after repeated stimulation of residual spatial channels in blindsight

• DOI: 10.1073/pnas.0607073103
• Publication Date: 2006-09-26T01:03:54Z
• Authors: Arash Sahraie; Ceri T. Trevethan; Mary Joan MacLeod; Alison D. Murray; John A. Olson; Lawrence Weiskrantz
• Keywords: Blindsight; Cortical blindness

Lesions of the occipital cortex result in areas cortical blindness affecting corresponding regions patient's visual field. The traditional view is that, aside from some spontaneous recovery first few months after damage, when acute effects have subsided are absolute and permanent. It has been found, however, that within such field defects residual capacities may persist absence acknowledged awareness by subject (blindsight type 1) or impaired (type 2). Neuronal pathways mediating blindsight a specific narrow spatial temporal bandwidth. A group cortically blind patients (n = 12) carried out daily detection "training" task over 3-month period, discriminating grating stimuli optimally configured for homogeneous luminance-matched stimuli. No feedback was given during training. Assessment training psychophysical measurements before included range frequencies (0.5-7 cycles per degree), contrast at 1 cycle degree, clinical perimetry, subjective estimates defect. results show repeated stimulation appropriate can improvements sensitivities very depths