Faculty Bibliography

Synaptic transmission produced by artificially generated presynaptic depolarizations, having the same waveform as normal presynaptic action potentials, was studied in the squid giant synapse. These stimulated spikes produced synaptic transmission virtually indistinguishable from that obtained with the original presynaptic spike activation. The technique allows a direct determination of the onset and amplitude of the Ca current, ICa, triggered by the presynaptic action potential and the relationship between ICa and postsynaptic response. The results closely resemble theoretical predictions by a previously published model for synaptic transmission in this synapse and demonstrate that ICa occurs at the falling phase of the presynaptic spike.

The concept of space-time representation in the brain is redefined using tensor network theory. We make the following suggestions. (a) In order to deal with the external world, the brain embeds the external space-time continuum into a high dimensional internal space. External space-time events are represented within the CNS in overcomplete, inherently oblique, reference frames where space and time information is detected as a continuum over each coordinate axis. (b) The central nervous system may be seen as imposing a geometry on this internal hyperspace in such manner that neuronal networks transform inputs in a metric tensor-like manner. (c) In order to coordinate movements the cerebellum acts as a predictive motor space-time metric which allows the establishment of coincidences of goal-directed movements of limbs in space-time with external targets.