title: A widely distributed spectral signature of task-negative electrocorticography responses revealed during a visuomotor task in the human cortex.
abstract: While research of human cortical function has typically focused on task-related increases in neuronal activity, there is a growing interest in the complementary phenomenon-namely, task-induced reductions. Recent human BOLD fMRI studies have associated such reductions with a specific network termed the default mode network (DMN). However, detailed understanding of the spatiotemporal patterns of task-negative responses and particularly how they compare across different cortical networks is lacking. Here we examined this issue in a large-scale electrocorticography study in patients performing a demanding backward masking task. Our results uncovered rapid (<1 s) task-induced reductions in gamma power, often concomitant with power increase in alpha/beta bands. Importantly, these responses were found both in the DMN and sensory-motor networks. Comparing the task-negative responses across these different networks revealed similar spectral signatures and dynamics. We hypothesize that the task-negative responses may reflect a cortical switching mechanism whose role is to steer activity away from cortical networks, which are inappropriate for the task at hand.
authors.affiliation: Interdisciplinary Center for Neural Computation, The Hebrew University of Jerusalem, Jerusalem 91904, Israel. Rafi.Malach@weizmann.ac.il
authors.forename: Michal
authors.initials: M
authors.lastname: Ramot
authors.forename: Lior
authors.initials: L
authors.lastname: Fisch
authors.forename: Michal
authors.initials: M
authors.lastname: Harel
authors.forename: Svetlana
authors.initials: S
authors.lastname: Kipervasser
authors.forename: Fani
authors.initials: F
authors.lastname: Andelman
authors.forename: Miri Y
authors.initials: MY
authors.lastname: Neufeld
authors.forename: Uri
authors.initials: U
authors.lastname: Kramer
authors.forename: Itzhak
authors.initials: I
authors.lastname: Fried
authors.forename: Rafael
authors.initials: R
authors.lastname: Malach
mesh_terms: D000328:Adult; D001931:Brain Mapping; D002540:Cerebral Cortex / Q000503:physiopathology*; D016000:Cluster Analysis; D004566:Electrodes; D004569:Electroencephalography; D004827:Epilepsy / Q000473:pathology; D005260:Female; D005583:Fourier Analysis; D006801:Humans; D008297:Male; D010775:Photic Stimulation / Q000379:methods; D011597:Psychomotor Performance / Q000502:physiology*; D013057:Spectrum Analysis; D015898:Tomography Scanners, X-Ray Computed; D014796:Visual Perception / Q000502:physiology*; D055815:Young Adult