Smelling sounds: olfactory-auditory sensory convergence in the olfactory tubercle.
Historical and psychophysical literature has demonstrated a perceptual interplay between olfactory and auditory stimuli-the neural mechanisms of which are not understood. Here, we report novel findings revealing that the early olfactory code is subjected to auditory cross-modal influences. In vivo extracellular recordings from the olfactory tubercle, a trilaminar structure within the basal forebrain, of anesthetized mice revealed that olfactory tubercle single units selectively respond to odors-with 65% of units showing significant odor-evoked activity. Remarkably, 19% of olfactory tubercle single units also showed robust responses to an auditory tone. Furthermore, 29% of single units tested displayed supraadditive or suppressive responses to the simultaneous presentation of odor and tone, suggesting cross-modal modulation. In contrast, olfactory bulb units did not show significant responses to tone presentation nor modulation of odor-evoked activity by tone-suggesting a lack of olfactory-auditory convergence upstream from the olfactory tubercle. Thus, the tubercle presents itself as a source for direct multimodal convergence within an early stage of odor processing and may serve as a seat for psychophysical interactions between smells and sounds.
Wesson
Daniel W
DW
Emotional Brain Institute, Nathan S. Kline Institute for Psychiatric Research, Orangeburg, New York 10962, USA. dwesson@nki.rfmh.org
Wilson
Donald A
DA
D000161:Acoustic Stimulation; D000200:Action Potentials / Q000502:physiology; D000818:Animals; D001244:Association; D001306:Auditory Pathways / Q000033:anatomy & histology / Q000502:physiology*; D001307:Auditory Perception / Q000502:physiology; D001309:Auditory Threshold; D004594:Electrophysiology; D006309:Hearing / Q000502:physiology*; D008297:Male; D051379:Mice; D009812:Odorants; D009833:Olfactory Pathways / Q000033:anatomy & histology / Q000502:physiology*; D055696:Olfactory Perception / Q000502:physiology; D011601:Psychophysics / Q000379:methods; D011984:Sensory Receptor Cells / Q000502:physiology; D012903:Smell / Q000502:physiology*; D013329:Structure-Activity Relationship