State-dependent functional connectivity of rat olfactory system assessed by fMRI

• Published in: Neuroscience letters Vol. 497; no. 2; pp. 69 - 73
• Main Authors: Wilson, D.A., Hoptman, M.J., Gerum, S.V., Guilfoyle, D.N.
• Format: Journal Article
• Language: English
• Published: Shannon Elsevier Ireland Ltd 22-06-2011; Elsevier
• Subjects: Amygdala; Animals; Biological and medical sciences; Functional magnetic resonance imaging; Fundamental and applied biological sciences. Psychology; Hippocampus; Magnetic Resonance Imaging - methods; Male; Memory consolidation; Olfactory Pathways - physiology; Olfactory system and olfaction. Gustatory system and gustation; Piriform cortex; Rats; Rats, Long-Evans; Respiratory Physiological Phenomena - drug effects; Resting state; Sleep - drug effects; Sleep - physiology; Sleep. Vigilance; Slow-wave sleep; Urethane - pharmacology; Vertebrates: nervous system and sense organs; Memory consolidation; Slow-wave sleep; Resting state; Amygdala; Piriform cortex; Functional magnetic resonance imaging; Hippocampus; Rat; Memory; Rodentia; Central nervous system; Basal ganglion; Nuclear magnetic resonance imaging; Slow wave sleep; Olfactory system; Encephalon; Vertebrata; Mammalia; Animal; Functional imaging
• ISSN: 0304-3940; 1872-7972
• DOI: 10.1016/j.neulet.2011.04.031

► Respiration can be used to monitor fast- and slow-wave states during rat fMRI. ► fMRI-based functional connectivity of the olfactory cortex changes with state. ► Such state-dependent changes may contribute to odor memory consolidation.
Functional connectivity between the piriform cortex and limbic and neocortical areas was assessed using functional magnetic resonance imaging (fMRI) of urethane anesthetized rats that spontaneously cycled between slow-wave and fast-wave states. Slow-wave and fast-wave states were determined indirectly through monitoring of respiration rate, which was confirmed to co-vary with state as determined by electrophysiological recordings. Previous electrophysiological data have suggested that the piriform cortex shifts between responsiveness to afferent odor input during fast-wave states and enhanced functional connectivity with limbic areas during slow-wave state. The present results demonstrate that fMRI-based resting state functional connectivity between the piriform cortex and both limbic and neocortical areas is enhanced during slow-wave state compared to fast-wave state using respiration as an indirect measure of state in urethane anesthetized rats. This state-dependent shift in functional connectivity may be important for sleep-dependent odor memory consolidation.