title: Oscillatory activity in neocortical networks during tactile discrimination near the limit of spatial acuity.
abstract: Oscillatory interactions within functionally specialized but distributed brain regions are believed to be central to perceptual and cognitive functions. Here, using human scalp electroencephalography (EEG) recordings combined with source reconstruction techniques, we study how oscillatory activity functionally organizes different neocortical regions during a tactile discrimination task near the limit of spatial acuity. While undergoing EEG recordings, blindfolded participants felt a linear three-dot array presented electromechanically, under computer control, and reported whether the central dot was offset to the left or right. The average brain response differed significantly for trials with correct and incorrect perceptual responses in the timeframe approximately between 130 and 175ms. During trials with correct responses, source-level peak activity appeared in the left primary somatosensory cortex (SI) at around 45ms, in the right lateral occipital complex (LOC) at 130ms, in the right posterior intraparietal sulcus (pIPS) at 160ms, and finally in the left dorsolateral prefrontal cortex (dlPFC) at 175ms. Spectral interdependency analysis of activity in these nodes showed two distinct distributed networks, a dominantly feedforward network in the beta band (12-30Hz) that included all four nodes and a recurrent network in the gamma band (30-100Hz) that linked SI, pIPS and dlPFC. Measures of network activity in both bands were correlated with the accuracy of task performance. These findings suggest that beta and gamma band oscillatory networks coordinate activity between neocortical regions mediating sensory and cognitive processing to arrive at tactile perceptual decisions.
authors.affiliation: Department of Physics and Astronomy, Georgia State University, Atlanta, GA, USA.
authors.forename: Bhim M
authors.initials: BM
authors.lastname: Adhikari
authors.affiliation: Department of Neurology, Emory University School of Medicine, Atlanta, GA, USA; Department of Rehabilitation Medicine, Emory University, Atlanta, GA, USA; Department of Psychology, Emory University, Atlanta, GA, USA; Rehabilitation R&D Center of Excellence, Atlanta VAMC, Decatur, GA, USA.
authors.forename: K
authors.initials: K
authors.lastname: Sathian
authors.affiliation: Department of Neurology, Emory University School of Medicine, Atlanta, GA, USA.
authors.forename: Charles M
authors.initials: CM
authors.lastname: Epstein
authors.affiliation: Department of Physics and Astronomy, Georgia State University, Atlanta, GA, USA.
authors.forename: Bidhan
authors.initials: B
authors.lastname: Lamichhane
authors.affiliation: Department of Physics and Astronomy, Georgia State University, Atlanta, GA, USA; Neuroscience Institute, Center for Behavioral Neuroscience, Georgia State University, Atlanta, GA, USA. Electronic address: mdhamala@gsu.edu.
authors.forename: Mukesh
authors.initials: M
authors.lastname: Dhamala
mesh_terms: D000293:Adolescent; D000328:Adult; D001611:Beta Rhythm / Q000502:physiology; D015984:Causality; D003657:Decision Making; D004192:Discrimination, Psychological / Q000502:physiology*; D004569:Electroencephalography; D005071:Evoked Potentials / Q000502:physiology; D005260:Female; D006801:Humans; D007091:Image Processing, Computer-Assisted; D008297:Male; D019579:Neocortex / Q000502:physiology*; D009415:Nerve Net / Q000502:physiology*; D059906:Neuroimaging; D010296:Parietal Lobe / Q000502:physiology; D017397:Prefrontal Cortex / Q000502:physiology; D011597:Psychomotor Performance / Q000502:physiology; D013003:Somatosensory Cortex / Q000502:physiology; D013028:Space Perception / Q000502:physiology*; D014110:Touch / Q000502:physiology*; D055815:Young Adult
keywords: Brain rhythms; Connectivity; EEG; ERP; Granger causality; Oscillations; Perceptual decision-making; Somatosensory; Touch