For the past half century, neuroscientists have seen the visual cortex as the part of the brain that processes imagery. Visual information enters the brain via the retina and is processed one stage at a time by dedicated neural circuits, much like a car is assembled out of discrete components on an assembly line. Such experiments have typically been performed by presenting visual stimuli to restrained or anesthetized animals. As such, vision is understood to be a passive sense in which information is absorbed by stationary animals.
However, animals are rarely passive observers of the world: instead, they make myriads of movements to sample their environments, from sniffing to smell, whisking to feel, or licking to taste. Vision too is an active sense: animals and insects make eye, head, and body movements to direct their gaze or follow moving objects. How such movements affect the activity of cortical visual circuits is mostly unknown.
To investigate this questions, researches set up a simple experiment and they found that 3D head-orienting movements (HOMs) modulate primary visual cortex (V1) activity in a direction-specific manner that also depends on light.