Olfactory system activation from sniffing: Effects in piriform and orbitofrontal cortex

David A. Kareken, Merav Sabri, Alexander J. Radnovich, Eric Claus, Brian Foresman, Dwight Hector, Gary D. Hutchins

Research output: Contribution to journalArticlepeer-review

73 Scopus citations


Neuroimaging studies suggest that piriform cortex is activated at least in part by sniffing. We used H215O positron emission tomography (PET) to study 15 healthy volunteers while they participated in four conditions, two of which were sniffing odorants and odorless air. The remaining two conditions involved a constant, very low flow of either odorized or odorless air during velopharyngeal closure (VPC), a technique that prevents subject-induced airflow through the nasal passages. Contrary to expectation, sniffing under odorless conditions did not induce significant piriform and surrounding cortical (PC+) activity when compared to odorless VPC, even at a liberal statistical threshold. However, a small correlation emerged in PC+ between the difference signal of [odorless sniffing - odorless VPC] and peak rate of nasal pressure change. PC+ activity was, however, strongly evoked by odorant exposure during sniffing and VPC, with neither technique showing greater activation. Activity in orbitofrontal (olfactory association) cortex was absent during odorant stimulation (OS) with VPC, but present during odorant sniffing. Sniffing may therefore play an important role in facilitating the higher-order analysis of odors. A right orbitofrontal region was also activated with odorless sniffing, which suggests a possible orbitofrontal role in guided olfactory exploration.

Original languageEnglish (US)
Pages (from-to)456-465
Number of pages10
Issue number1
StatePublished - May 2004

All Science Journal Classification (ASJC) codes

  • Neurology
  • Cognitive Neuroscience


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