Content area
Full Text
NEUROSCIENCE
The combined neuronal activity of two seemingly opposite types of Purkinje cell in the brain's cerebellum has been found to be required to control the jerky eye movements known as saccades in monkeys. See Letter p.439
The brain has tremendous informationprocessing power and computational capacity. Neuroscientists have made great efforts to unravel how the brain encodes, decodes and processes information, but deconstructing these computations is a difficult task. On page 439 of this issue, Herzfeld et al.1 use monkeys to masterfully unearth how one of the brain's most intriguing structures, the cerebellum, efficiently encodes - and perhaps subsequently decodes - the information needed to control the quick, jerky eye movements known as saccades, which occur as the eye explores a scene.
Deciphering how the brain computes is exceptionally difficult, because it requires a reverse-engineering approach. Without any prior knowledge of how the brain's circuits are designed, neuroscientists need to dissect these circuits to understand their function and computational principles. Consider the heroic efforts needed to reverse-engineer the Enigma machine, which was used during the Second World War to encrypt and decrypt military messages. By analogy, each of the brain's different computational units (neurons or neuronal circuits that process the information contained in their inputs to determine appropriate outputs) can be considered to be like an Enigma machine, with its own algorithm and code. Although Enigma's purpose was to encrypt and subsequently decrypt the same message, brain circuits process the information that they receive and often completely transform it to generate a new message. Furthermore, we do not fully understand the different types of information processing that occur in different brain regions.
However, this problem can be made more manageable by the thoughtful selection of specific brain regions to study. The more information there is about the inputs and outputs of a brain region, the...