title: Hemodynamic responses in neural circuitries for detection of visual target and novelty: An event-related fMRI study.
abstract: The oddball paradigm examines attentional processes by establishing neural substrates for target detection and novelty. Event-related functional imaging enables characterization of hemodynamic changes associated with these processes. We studied 36 healthy participants (17 men) applying a visual oddball event-related design at 4 Tesla, and performed an unbiased determination of the hemodynamic response function (HRF). Targets were associated with bilateral, albeit leftward predominant changes in frontal-parietal temporal and occipital cortices, and limbic and basal ganglia regions. Activation to novelty was more posteriorly distributed, and frontal activation occurred only on the right, while robust activation was seen in occipital regions bilaterally. Overlapping regions were left thalamus, caudate and cuneus and right parietal precuneus. While robust HRFs characterized most regions, target detection was associated with a negative HRF in the right parietal precuneus and a biphasic HRF in thalamus, basal ganglia, and all occipital regions. Both height of the HRF and longer time to peak in the right cingulate were associated with slower response time. Sex differences were observed, with higher HRF peaks for novelty in men in right occipital regions, and longer time to peak in the left hemisphere. Age was associated with reduced peak HRF in left frontal region. Thus, indices of the HRF can be used to better understand the relationship between hemodynamic changes and performance and can be sensitive to individual differences.
authors.affiliation: Department of Psychiatry, University of Pennsylvania Medical Center, Philadelphia, PA 19104, USA. gyr@bbl.med.upenn.edu
authors.forename: Ruben C
authors.initials: RC
authors.lastname: Gur
authors.forename: Bruce I
authors.initials: BI
authors.lastname: Turetsky
authors.forename: James
authors.initials: J
authors.lastname: Loughead
authors.forename: Jonathan
authors.initials: J
authors.lastname: Waxman
authors.forename: Wendy
authors.initials: W
authors.lastname: Snyder
authors.forename: J Daniel
authors.initials: JD
authors.lastname: Ragland
authors.forename: Mark A
authors.initials: MA
authors.lastname: Elliott
authors.forename: Warren B
authors.initials: WB
authors.lastname: Bilker
authors.forename: Steven E
authors.initials: SE
authors.lastname: Arnold
authors.forename: Raquel E
authors.initials: RE
authors.lastname: Gur
mesh_terms: D000293:Adolescent; D000328:Adult; D000367:Age Factors; D001288:Attention / Q000502:physiology; D001921:Brain / Q000098:blood supply / Q000502:physiology; D001931:Brain Mapping; D002560:Cerebrovascular Circulation; D005074:Evoked Potentials, Visual / Q000502:physiology*; D005106:Exploratory Behavior / Q000502:physiology*; D005260:Female; D006801:Humans; D008279:Magnetic Resonance Imaging; D008297:Male; D008875:Middle Aged; D008959:Models, Neurological; D010364:Pattern Recognition, Visual / Q000502:physiology*; D012727:Sex Characteristics