Abstract Dr. R. Buchanan
Arousal and Sensory Gating: Single Unit Recordings from PPN Neurons in Awake Rats
In response to an appropriate auditory stimulus neurons of the reticular activating system (RAS) in the pedunculopontine nucleus (PPN) generate an arousal signal that is sent to the cerebral cortex via the thalamus. The cortex responds by sending an inhibitory signal to the RAS that inhibits any further inputs, that is, it “gates” any new information. This sequence of arousal and inhibitory potentials has been identified in several species. For example, in humans the arousal signal has been identified as the P50 potential while in rats it is the P13 potential. These arousal signals share three main characteristics, they are 1) sleep state-dependent (present during waking and REM sleep, but absent during deep sleep), 2) rapidly habituating (attenuated at frequencies over 1 Hz—indicating that they are not mediated by a primary sensory pathway, but rather a ‘reticular’ low synaptic security pathway) and 3) mediated by both muscarinic and nicotinic cholinergic projections. Sensory gating has also been shown to be altered by nicotinic agonists. The research described in this proposal will utilize procedures recently developed by the applicants to use implanted electrode arrays to record single unit responses of PPN neurons in awake, intact animals. The effects of nicotinic and muscarinic agonists and antagonists on these responses will also be investigated. This proposal describes a continuation of a project begun in June 2002 by Drs. Buchanan and Garcia-Rill.
Updated 10/31/2005
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