title: Frontal lobe hypoactivation in medication-free adults with bipolar II depression during response inhibition.
abstract: In executive function, specifically in response inhibition, numerous studies support the essential role for the inferior frontal cortex (IFC). Hypoactivation of the IFC during response-inhibition tasks has been found consistently in subjects with bipolar disorder during manic and euthymic states. The aim of this study was to examine whether reduced IFC activation also exists in unmedicated subjects with bipolar disorder during the depressed phase of the disorder. Participants comprised 19 medication-free bipolar II (BP II) depressed patients and 20 healthy control subjects who underwent functional magnetic resonance imaging (fMRI) while performing a Go/NoGo response-inhibition task. Whole-brain analyses were conducted to assess activation differences within and between groups. The BP II depressed group, compared with the control group, showed significantly reduced activation in right frontal regions, including the IFC (Brodmann's area (BA) 47), middle frontal gyrus (BA 10), as well as other frontal and temporal regions. IFC hypoactivation may be a persistent deficit in subjects with bipolar disorder in both acute mood states as well as euthymia, thus representing a trait feature of bipolar disorder.
authors.affiliation: Department of Psychiatry & Biobehavioral Sciences, UCLA Semel Institute for Neuroscience & Human Behavior, Los Angeles, CA 90095, United States.
authors.forename: Conor
authors.initials: C
authors.lastname: Penfold
authors.affiliation: Department of Psychiatry & Biobehavioral Sciences, UCLA Semel Institute for Neuroscience & Human Behavior, Los Angeles, CA 90095, United States.
authors.forename: Nathalie
authors.initials: N
authors.lastname: Vizueta
authors.affiliation: Department of Psychiatry & Biobehavioral Sciences, UCLA Semel Institute for Neuroscience & Human Behavior, Los Angeles, CA 90095, United States.
authors.forename: Jennifer D
authors.initials: JD
authors.lastname: Townsend
authors.affiliation: Department of Psychiatry & Biobehavioral Sciences, UCLA Semel Institute for Neuroscience & Human Behavior, Los Angeles, CA 90095, United States; Center for Cognitive Neuroscience, UCLA, Los Angeles, CA 90095, United States.
authors.forename: Susan Y
authors.initials: SY
authors.lastname: Bookheimer
authors.affiliation: Department of Psychiatry & Biobehavioral Sciences, UCLA Semel Institute for Neuroscience & Human Behavior, Los Angeles, CA 90095, United States. Electronic address: laltshuler@mednet.ucla.edu.
authors.forename: Lori L
authors.initials: LL
authors.lastname: Altshuler
mesh_terms: D000328:Adult; D000339:Affect / Q000502:physiology; D001714:Bipolar Disorder / Q000175:diagnosis / Q000378:metabolism*; D001931:Brain Mapping / Q000379:methods; D056344:Executive Function / Q000502:physiology; D005260:Female; D005625:Frontal Lobe / Q000378:metabolism*; D006801:Humans; D007266:Inhibition, Psychological; D008279:Magnetic Resonance Imaging / Q000379:methods; D008297:Male; D008875:Middle Aged; D010775:Photic Stimulation / Q000379:methods; D011597:Psychomotor Performance / Q000502:physiology; D011930:Reaction Time / Q000502:physiology*
keywords: Bipolar II disorder; Bipolar depression; FMRI; Go/NoGo task; Inferior frontal gyrus; Inhibitory control