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Granule cells make up the input layer of the cerebellum and receive sensory information from the body, for example when a finger touches a surface. The cerebellum is thought to act as a link between the body's senses and its movements, such as guiding the finger across a surface smoothly and efficiently.
Paul Chadderton and colleagues at UCL's Wolfson Institute for Biomedical Research used a method called patch-clamping to measure the activity of a single granule cell in an intact brain. By applying the patch-clamp technique, where a cell membrane is gently sucked onto a glass pipette which records small electrical signals coming from the cell, UCL researchers were able to see the granule cell layer at work, confirming predictions made over 30 years ago by the English theoretical neuroscientist David Marr.
Marr suggested that the layer uses a sparse coding scheme to represent sensory input, where the firing rate of the cells is low in order to maximise the number of different patterns of sensory input that can be represented by the cerebellum. In other words, the cells keep their activity low to ensure that they remain sensitive to every type of sensation that is being picked up.
The group's findings could ultimately help researchers understand more about movement disorders and potentially help in the development of drug treatments targeting the cerebellum, for example for sufferers of ataxia and dysmetria. The group also found that the activity of granule cells is kept in check by a ‘tonic inhibition' mechanism. There is growing evidence that alcohol can boost this inhibition and thus affect cerebellar function, possibly accounting for the drunken swaying and unsteadiness often associated with inebriation.
MEDICA.de, Source: Nature