Role of the Visual Cortex in Spontaneous Eye Movement

Neuroscientists usually study the visual cortex area of the brain, to try to learn more about other parts of the neocortex- the largest part of the human brain which is responsible for much of our cognitive function.  Now a new study, published in Nature magazine has shown that signals from the visual cortex of mice can promote the flexibility of innate motor reflexes in the eyes of mice being studied.

The research, led by scientists at the University of California, San Diego, will shed more light on brain flexibility- the ability of the brain to adapt and change.

The new study was led by Massimo Scanziani, Ph.D, former Professor of Neurobiology at the University of California, San Diego, now working at UCSF in collaboration with Andrew Huberman, Associate Professor at Stanford University and Bao-hua Liu Ph.D of UCSD.

Two automatic eye reflexes are involved in enabling mammals to see objects clearly when our heads or the object we are looking at are moving.  One of these is the optokinetic reflex, which causes our eyes to move, without our being aware of it, for example, when we are driving past a stationary road sign. The second reflex, the vestibule-ocular reflex, adjusts the position of our eyes when the head moves.  These two reflexes need to work together and are known to compensate for each other when one is impaired.

The researchers found that when they used light to reduce the activity of cells in the visual cortex area of the brain, there was a measurable reduction in the optokinetic reflex.  This might mean that the visual cortex has a role in mediating the flexibility of the two reflexes.

Scanziani was quoted as explaining “Most of our reflexes are encoded in the brainstem, but from an evolutionary standpoint, the ability for one’s cortex to modify those reflexes expands one’s behavioural repertoire as the circumstances require”.

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