Abstract
To diagnose the onset of subtle forms of visual pathology in the elderly, it is critical to develop an understanding of performance during healthy visual aging. In the ventral or form vision pathway, our research and that of others shows that healthy elderly performance remains roughly equivalent to the young in V1 (orientation discrimination) and V4 (curvature processing in radial frequency patterns). However, we have recently documented a significant deficit in face discrimination across view changes in healthy aging. Further work using adaptation shows that this results from broadened bandwidths for representing different face views. Neural modeling can explain this on the assumption of weakened lateral inhibition between adjacent face views along with increased neural noise. Subsequent fMRI studies show differences between young and elderly on face identification tasks consistent with psychophysics. These results are consonant with electrophysiology in higher visual areas of senescent monkeys, where bandwidths for motion direction increase dramatically. Finally, this reduction in inhibition higher in the ventral pathway in aging is consistent with the increase in first, unprovoked epileptic seizures around age 70.