title: Modulation of response patterns in human auditory cortex during a target detection task: an intracranial electrophysiology study.
abstract: Selective attention enhances cortical activity representing an attended sound stream in human posterolateral superior temporal gyrus (PLST). It is unclear, however, what mechanisms are associated with a target detection task that necessitates sustained attention (vigilance) to a sound stream. We compared responses elicited by target and non-target sounds, and to sounds presented in a passive-listening paradigm. Subjects were neurosurgical patients undergoing invasive monitoring for medically refractory epilepsy. Stimuli were complex tones, band-limited noise bursts and speech syllables. High gamma cortical activity (70-150 Hz) was examined in all subjects using subdural grid electrodes implanted over PLST. Additionally, responses were measured from depth electrodes implanted within Heschl's gyrus (HG) in one subject. Responses to target sounds recorded from PLST were increased when compared to responses elicited by the same sounds when they were not-targets, and when they were presented during passive listening. Increases in high gamma activity to target sounds occurred during later portions (after 250 ms) of the response. These increases were related to the task and not to detailed stimulus characteristics. In contrast, earlier activity that did not vary across conditions did represent stimulus acoustic characteristics. Effects observed on PLST were not noted in HG. No consistent effects were noted in the averaged evoked potentials in either cortical region. We conclude that task dependence modulates later activity in PLST during vigilance. Later activity may represent feedback from higher cortical areas. Study of concurrently recorded activity from frontoparietal areas is necessary to further clarify task-related modulation of activity on PLST.
authors.affiliation: Department of Neurosurgery, The University of Iowa, Iowa City, IA 52242, USA. Electronic address: kirill-nourski@uiowa.edu.
authors.forename: Kirill V
authors.initials: KV
authors.lastname: Nourski
authors.affiliation: Department of Neurology, Albert Einstein College of Medicine, New York, NY 10461, USA.
authors.forename: Mitchell
authors.initials: M
authors.lastname: Steinschneider
authors.affiliation: Department of Neurosurgery, The University of Iowa, Iowa City, IA 52242, USA.
authors.forename: Hiroyuki
authors.initials: H
authors.lastname: Oya
authors.affiliation: Department of Neurosurgery, The University of Iowa, Iowa City, IA 52242, USA.
authors.forename: Hiroto
authors.initials: H
authors.lastname: Kawasaki
authors.affiliation: Department of Neurosurgery, The University of Iowa, Iowa City, IA 52242, USA.
authors.forename: Matthew A
authors.initials: MA
authors.lastname: Howard
mesh_terms: D000161:Acoustic Stimulation; D000328:Adult; D001303:Auditory Cortex / Q000503:physiopathology*; D001307:Auditory Perception / Q000502:physiology*; D001931:Brain Mapping; D004569:Electroencephalography; D004827:Epilepsy / Q000473:pathology*; D005072:Evoked Potentials, Auditory / Q000502:physiology*; D006801:Humans; D008279:Magnetic Resonance Imaging; D008297:Male; D011571:Psychoacoustics; D011930:Reaction Time / Q000502:physiology; D017603:Signal Detection, Psychological / Q000502:physiology*; D013016:Sound; D013997:Time Factors; D055815:Young Adult
keywords: Attention; Averaged evoked potential; Electrocorticography; Heschl's gyrus; High gamma; Superior temporal gyrus