INTERSYNAPTIC DIFFUSION OF NEUROTRANSMITTER

According to many theories of brain function, the computational power of the brain depends upon the number of independent synapses it contai ns. A synapse will not be independent if its receptors are activated o r modified by neurotransmitter released at neighbouring synapses, Rece ntly, there have been several reports suggesting the occurrence of 'cr osstalk' or 'spillover', and a large number of results consistent with crosstalk. However, the quantitative importance of this phenomenon re mains uncertain. We estimate the significance of crosstalk using a sim ple model which predicts that, during concentrated synaptic activity, crosstalk between distinct synapses is likely to activate high-affinit y receptors and may also desensitize certain receptors, Comparison of these predictions with the experimental data highlights the informatio n that is required for a more detailed model of crosstalk.