Akademik

   Also referred to as cerebral akinetopsia and visual motion blindness. The term akinetopsia comes from the Greek words akinesia (absence of motion) and opsis (seeing). It was introduced in or shortly before 1991 by the British neurobiologist Semir Zeki to denote a selective deficit in the ability to perceive motion. Akinetopsia is an extremely rare condition attributed to bilateral cortical lesions in the vicinity of striate cortex. The first full description of visual motion blindness was formulated by the German neurologist Josef Zihl and colleagues, who in 1983 reported a case in which the individual affected was unable to see motion. As rendered by Zihl et al., streaming fluids were described as frozen, and people who were moving about as popping up here and there. Akinetopsia is generally classified as a * sensory distortion. Pathophysiolog-ically, it is associated with bilateral damage to the occipito-temporal area V5, the so-called specialized motion area of the visual cortex. Transient forms of akinetopsia can be induced by the use of psychotomimetic substances such as LSD and mescaline. When occurring as an *aura in the context of a paroxysmal neurological disorder such as migraine, transient forms of akinetopsia are referred to as * cinematographic vision. Conceptually as well as phenomenologically, akine-topsia constitutes the counterpart of *Riddoch's phenomenon (i.e. the inability to see stationary light stimuli, whereas the conscious perception of moving light stimuli remains intact). The term akinetopsia is used in opposition to the term kinetopsia. It should not be confused with the slide show format characteristic of some types of visual hallucinations or with the *quick-motion phenomenon, in which time appears to pass too quickly.

   References

   Zihl, J., Cramon, D., Mai, N. (1983). Selective disturbance of movement vision after bilateral brain damage. Brain, 106, 313-340.

   Zeki, S. (1991). Cerebral akinetopsia (visual motion blindness). Brain, 114, 811-824.