Surprising rate at which neuronal networks in the cerebral
cortex delete sensory information
(January 24, 2011) The
dynamics behind signal transmission in the brain are extremely chaotic. This
conclusion has been reached by scientists from the Max Planck Institute for
Dynamics and Self-Organization at the University of Göttingen and the Bernstein
Center for Computational Neuroscience Göttingen. In addition, the
Göttingen-based researchers calculated, for the first time, how quickly
information stored in the activity patterns of the cerebral cortex neurons is
discarded. At one bit per active neuron per second, the speed at which this
information is forgotten is surprisingly high. Physical Review Letters, 105,
268104 (2010)
The brain codes information in the form of electrical
pulses, known as spikes. Each of the brain’s approximately 100 billion
interconnected neurons acts as both a receiver and transmitter: these bundle
all incoming electrical pulses and, under certain circumstances, forward a
pulse of their own to their neighbours. In this way, each piece of information
processed by the brain generates its own activity pattern. This indicates which
neuron sent an impulse to its neighbours: in other words, which neuron was active,
and when. Therefore, the activity pattern is a kind of communication protocol
that records the exchange of information between neurons.