Neuroscience 2002 Abstract
| Presentation Number: | 12.11 |
|---|---|
| Abstract Title: | Linear systems analysis of functional magnetic resonance imaging in human primary olfactory cortex. |
| Authors: |
Khan, R. M.*1,2
; Johnson, B.1
; Mainland, J. D.1
; Bensafi, M.1,2
; Bremner, E.2
; Anderson, A. K.1
; Sobel, N.1,2
1Helen Wills Neuroscience Institute, UC, Berkeley, Berkeley, CA 2Dept. of Psychology, UC, Berkeley, Berkeley, CA |
| Primary Theme and Topics |
Sensory Systems - Chemical Senses -- Olfaction: CNS pathways and physiology |
| Session: |
12. Chemical senses: olfaction--CNS mechanisms Slide |
| Presentation Time: | Sunday, November 3, 2002 10:30 AM-10:45 AM |
| Location: | Room 206A |
| Keywords: | OLFACTION, FMRI, ODOR |
Functional magnetic resonance imaging (fMRI) of primary olfactory cortex (POC) has yielded inconsistent results. Odorant-induced POC activity is present at times and absent at others even within the same lab using the same task. Most statistical models used in analysis of fMRI data rely on two assumptions: 1. a monotonic transform from quantity of stimulus to quantity of neural activity, and 2. a linear transform from quantity of neural activity to quantity of MR signal. Whereas the latter has been demonstrated for MR (Boynton et al., 1996), the former has not been demonstrated for POC. Models of temporal encoding, unlike rate-encoding models of olfaction, imply no monotonic transform from quantity of stimulus to quantity of neural activity in POC. Thus, fMRI is potentially invalid as a measure of POC activity under temporal encoding models. To address this we set out to quantify the stimulus intensity-dependence in POC. An olfactometer was used to generate high and low concentrations of the odorants citral and valeric acid to 16 subjects (8M/8F) in an event-related design (3T, T2* spiral, TE= 30, TR = 1s, 64x64 FOV, 17 slices, slice thickness = 4mm, stimulus ISI = 20s, stimulus repetition = 30). Activity in POC was significantly greater for the high versus low concentration odorants (F(1, 285) = 48.55, p < .0001). In order to assess the linearity of this transform we will present POC response to 4 different concentrations of two different odorants obtained at 4T (Varian systems).
Supported by SOSI and NIH-NIDCD R03-DC05141-01
Sample Citation:
[Authors]. [Abstract Title]. Program No. XXX.XX. 2002 Neuroscience Meeting Planner. Orlando, FL: Society for Neuroscience, 2002. Online.
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