Auditory Stimulation Dishabituates Olfactory Responses via Noradrenergic Cortical Modulation

Abstract EN

Dishabituation is a return of a habituated response if context or contingency changes.

In the mammalian olfactory system, metabotropic glutamate receptor mediated synaptic depression of cortical afferents underlies short-term habituation to odors.

It was hypothesized that a known antagonistic interaction between these receptors and norepinephrine ß-receptors provides a mechanism for dishabituation.

The results demonstrate that a 108 dB siren induces a two-fold increase in norepinephrine content in the piriform cortex.

The same auditory stimulus induces dishabituation of odor-evoked heart rate orienting bradycardia responses in awake rats.

Finally, blockade of piriform cortical norepinephrine ß-receptors with bilateral intracortical infusions of propranolol (100 μM) disrupts auditory-induced dishabituation of odor-evoked bradycardia responses.

These results provide a cortical mechanism for a return of habituated sensory responses following a cross-modal alerting stimulus.