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Olfactory fMRI : Implications of Stimulation Length and Repetition Time

Georgiopoulos, Charalampos LU ; Witt, Suzanne T ; Haller, Sven ; Dizdar, Nil ; Zachrisson, Helene ; Engström, Maria and Larsson, Elna-Marie LU (2018) In Chemical Senses 43(6). p.389-398
Abstract

Studying olfaction with functional magnetic resonance imaging (fMRI) poses various methodological challenges. This study aimed to investigate the effects of stimulation length and repetition time (TR) on the activation pattern of 4 olfactory brain regions: the anterior and the posterior piriform cortex, the orbitofrontal cortex, and the insula. Twenty-two healthy participants with normal olfaction were examined with fMRI, with 2 stimulation lengths (6 s and 15 s) and 2 TRs (0.901 s and 1.34 s). Data were analyzed using General Linear Model (GLM), Tensorial Independent Component Analysis (TICA), and by plotting the event-related time course of brain activation in the 4 olfactory regions of interest. The statistical analysis of the time... (More)

Studying olfaction with functional magnetic resonance imaging (fMRI) poses various methodological challenges. This study aimed to investigate the effects of stimulation length and repetition time (TR) on the activation pattern of 4 olfactory brain regions: the anterior and the posterior piriform cortex, the orbitofrontal cortex, and the insula. Twenty-two healthy participants with normal olfaction were examined with fMRI, with 2 stimulation lengths (6 s and 15 s) and 2 TRs (0.901 s and 1.34 s). Data were analyzed using General Linear Model (GLM), Tensorial Independent Component Analysis (TICA), and by plotting the event-related time course of brain activation in the 4 olfactory regions of interest. The statistical analysis of the time courses revealed that short TR was associated with more pronounced signal increase and short stimulation was associated with shorter time to peak signal. Additionally, both long stimulation and short TR were associated with oscillatory time courses, whereas both short stimulation and short TR resulted in more typical time courses. GLM analysis showed that the combination of short stimulation and short TR could result in visually larger activation within these olfactory areas. TICA validated that the tested paradigm was spatially and temporally associated with a functionally connected network that included all 4 olfactory regions. In conclusion, the combination of short stimulation and short TR is associated with higher signal increase and shorter time to peak, making it more amenable to standard GLM-type analyses than long stimulation and long TR, and it should, thus, be preferable for olfactory fMRI.

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author
; ; ; ; ; and
publishing date
type
Contribution to journal
publication status
published
keywords
Adult, Brain Mapping, Humans, Magnetic Resonance Imaging, Male, Odorants, Olfactory Pathways/pathology, Smell/physiology, Time Factors
in
Chemical Senses
volume
43
issue
6
pages
389 - 398
publisher
Oxford University Press
external identifiers
  • scopus:85050809042
  • pmid:29726890
ISSN
1464-3553
DOI
10.1093/chemse/bjy025
language
English
LU publication?
no
id
b2825a8e-62b1-4963-842b-2c73d7264caa
date added to LUP
2023-02-09 11:20:56
date last changed
2024-04-03 10:20:04
@article{b2825a8e-62b1-4963-842b-2c73d7264caa,
  abstract     = {{<p>Studying olfaction with functional magnetic resonance imaging (fMRI) poses various methodological challenges. This study aimed to investigate the effects of stimulation length and repetition time (TR) on the activation pattern of 4 olfactory brain regions: the anterior and the posterior piriform cortex, the orbitofrontal cortex, and the insula. Twenty-two healthy participants with normal olfaction were examined with fMRI, with 2 stimulation lengths (6 s and 15 s) and 2 TRs (0.901 s and 1.34 s). Data were analyzed using General Linear Model (GLM), Tensorial Independent Component Analysis (TICA), and by plotting the event-related time course of brain activation in the 4 olfactory regions of interest. The statistical analysis of the time courses revealed that short TR was associated with more pronounced signal increase and short stimulation was associated with shorter time to peak signal. Additionally, both long stimulation and short TR were associated with oscillatory time courses, whereas both short stimulation and short TR resulted in more typical time courses. GLM analysis showed that the combination of short stimulation and short TR could result in visually larger activation within these olfactory areas. TICA validated that the tested paradigm was spatially and temporally associated with a functionally connected network that included all 4 olfactory regions. In conclusion, the combination of short stimulation and short TR is associated with higher signal increase and shorter time to peak, making it more amenable to standard GLM-type analyses than long stimulation and long TR, and it should, thus, be preferable for olfactory fMRI.</p>}},
  author       = {{Georgiopoulos, Charalampos and Witt, Suzanne T and Haller, Sven and Dizdar, Nil and Zachrisson, Helene and Engström, Maria and Larsson, Elna-Marie}},
  issn         = {{1464-3553}},
  keywords     = {{Adult; Brain Mapping; Humans; Magnetic Resonance Imaging; Male; Odorants; Olfactory Pathways/pathology; Smell/physiology; Time Factors}},
  language     = {{eng}},
  month        = {{07}},
  number       = {{6}},
  pages        = {{389--398}},
  publisher    = {{Oxford University Press}},
  series       = {{Chemical Senses}},
  title        = {{Olfactory fMRI : Implications of Stimulation Length and Repetition Time}},
  url          = {{http://dx.doi.org/10.1093/chemse/bjy025}},
  doi          = {{10.1093/chemse/bjy025}},
  volume       = {{43}},
  year         = {{2018}},
}