The Journal of Neurophysiology Vol. 84 No. 3 September 2000, pp. 1656-1666
Copyright ©2000 by the American Physiological Society
Functional Mapping of Human Brain in Olfactory Processing: A
PET Study
Ahmad
Qureshy,1
Ryuta
Kawashima,1,3
Muhammad Babar
Imran,1
Motoaki
Sugiura,1
Ryoi
Goto,1
Ken
Okada,1
Kentaro
Inoue,1
Masatoshi
Itoh,2
Thorsten
Schormann,6
Karl
Zilles,4,5 and
Hiroshi
Fukuda1,3
1Department of Nuclear Medicine and
Radiology, Institute of Development, Aging and Cancer, Tohoku
University, Sendai 980-8575; 2Cyclotron and
Radioisotope Center, Tohoku University, Sendai 980-8578;
3Aoba Brain Imaging Research Center,
Telecommunications Advancement Organization, Sendai 980-8575, Japan; 4C. and O. Vogt-Institute of Brain
Research, Heinerich-Heine University, D-40001 Dusseldorf;
5Institute of Medicine, Research Center, D-52425
Julich; and 6Institute for Neuroanatomy,
Heinerich-Heine University, D-40001 Dusseldorf, Germany
Qureshy, Ahmad,
Ryuta Kawashima,
Muhammad Babar Imran,
Motoaki Sugiura,
Ryoi Goto,
Ken Okada,
Kentaro Inoue,
Masatoshi Itoh,
Thorsten Schormann,
Karl Zilles, and
Hiroshi Fukuda.
Functional Mapping of Human Brain in Olfactory Processing: A
PET Study. J. Neurophysiol. 84: 1656-1666, 2000. This study describes the functional anatomy of olfactory and
visual naming and matching in humans, using positron emission tomography (PET). One baseline control task without olfactory or visual
stimulation, one control task with simple olfactory and visual
stimulation without cognition, one set of olfactory and visual naming
tasks, and one set of olfactory and visual matching tasks were
administered to eight normal volunteers. In the olfactory naming task
(ON), odors from familiar items, associated with some verbal label,
were to be named. Hence, it required long-term olfactory memory
retrieval for stimulus recognition. The olfactory matching task (OM)
involved differentiating a recently encoded unfamiliar odor from a
sequentially presented group of unfamiliar odors. This required
short-term olfactory memory retrieval for stimulus differentiation. The
simple olfactory and visual stimulation resulted in activation of the
left orbitofrontal region, the right piriform cortex, and the bilateral
occipital cortex. During olfactory naming, activation was detected in
the left cuneus, the right anterior cingulate gyrus, the left insula,
and the cerebellum bilaterally. It appears that the effort to identify
the origin of an odor involved semantic analysis and some degree of
mental imagery. During olfactory matching, activation was observed in
the left cuneus and the cerebellum bilaterally. This identified the
brain areas activated during differentiation of one unlabeled odor from
the others. In cross-task analysis, the region found to be specific for
olfactory naming was the left cuneus. Our results show definite
recruitment of the visual cortex in ON and OM tasks, most likely
related to imagery component of these tasks. The cerebellar role in
cognitive tasks has been recognized, but this is the first PET study
that suggests that the human cerebellum may have a role in cognitive
olfactory processing as well.
