NERVE GROWTH FACTOR (NGF) AFFECTS TEMPORAL INFORMATION PROCESSING

The sequence of neuronal spikes, referred to as "spike trains", and their spatio-temporal organization within discrete populations of neurons have been postulated to carry the information processed by the brain and thus underlie cognitive functions and the associated behaviors.

In several species, including man, several cognitive impairments have been associated with loss of integrity of basal forebrain cholinergic neuron (BFCN) functions. Nerve growth factor (NGF), which is known to exert a trophic action on BFCN, can induce a partial reversal of these alterations. On the contrary, in subjects with preserved BFCN functions, NGF administration may induce detrimental effects. The overall outcome of NGF action may relate to its ability to modulate firing properties in brain regions whose activity is, directly or indirectly, regulated by BFCN.

We have tested this hypothesis in the rat auditory thalamus by recording single unit activity in the reticular thalamic nucleus (RE), which is densely innervated by BFCN, and in the medial geniculate body, a nucleus tightly connected with RE, after an intracerebroventricular administration of NGF. Recordings are achieved during both spontaneous as well as acoustically driven firing activity; time domain analyses and cross renewal density histograms are commonly computed.

The trophic action exerted by NGF on BFCN is associated with important modifications of temporal information processing in auditory thalamus. The ability of NGF to change firing patterns in discrete brain regions offers new vistas for investigating and interpreting its effects in cognitive function paradigms and further address its therapeutic potential for the treatment of neurodegenerative diseases.