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movement vision, akinetopsia, cerebral motion blindness, patient LM
Abstract:
The significance of early and sporadic reports in the 19th century of
impairments of motion vision following brain damage was largely
unrecognized. In the absence of satisfactory post-mortem evidence,
impairments were interpreted as the consequence of a more general
disturbance resulting from brain damage, the location and extent of
which was unknown. Moreover, evidence that movement constituted a
special visual perception and may be selectively spared was similarly
dismissed. Such skepticism derived from a reluctance to acknowledge that
the neural substrates of visual perception may not be confined to
primary visual cortex. This view did not persist. First, it was realized
that visual movement perception does not depend simply on the analysis
of spatial displacements and temporal intervals, but represents a
specific visual movement sensation. Second persuasive evidence for
functional specialization in extrastriate cortex, and notably the
discovery of cortical area V5/MT, suggested a separate region
specialized for motion processing. Shortly thereafter the remarkable
case of patient LM was published, providing compelling evidence for a
selective and specific loss of movement vision. The case is reviewed
here, along with an assessment of its contribution to visual
neuroscience.
