The human brain representation of odor identification 1
نویسندگان
چکیده
28 Odor identification (OI) tests are increasingly used clinically as biomarkers for 29 Alzheimer's disease and schizophrenia. The aim of this study was to directly 30 compare the neuronal correlates to identified odors versus non-identified odors. 31 Seventeen females with normal olfactory function underwent an fMRI 32 experiment with post-scanning assessment of spontaneous un-cued OI. An event-33 related analysis was performed to compare within subject activity to spontaneously 34 identified versus non-identified odors at the whole brain level, and in anatomical and 35 functional regions of interest (ROI) in the medial temporal lobe (MTL). Parameter 36 estimate values and BOLD signal curves for correctly identified and non-identified 37 odors were derived from functional ROIs in hippocampus, entorhinal, piriform and 38 orbitofrontal cortices. Number of activated voxles and max parameter estimate values 39 were obtained from anatomical ROIs in the hippocampus and the entorhinal cortex. 40 At the whole brain level correct OI gave rise to increased activity in left 41 entorhinal cortex, and secondary olfactory structures including orbitofrontal cortex. 42 Increased activation was also observed in fusiform, primary visual and auditory 43 cortices, inferior frontal plus inferior temporal gyri. The anatomical MTL ROI analysis 44 showed increased activation in left entorhinal cortex, right hippocampus, and 45 posterior parahippocampal gyri in correct OI. In entorhinal cortex and hippocampus 46 the BOLD signal increased specifically in response to identified odors and decreased 47 for non-identified odors. In orbitofrontal and piriform cortices both identified and non-48 identified odors gave rise to increased BOLD signal, but the repose to identified 49 odors was significantly greater than for non-identified odors. These results support a 50 specific role for entorhinal cortex and hippocampus in OI, while piriform and 51 3 orbitofrontal cortices are active in both smelling and OI. Moreover, episodic as well as 52 semantic memory systems appeared to support OI.
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