Neuroscience and Neurobiology Commons^™

Network-Level Mechanisms Underlying Effects Of Transcranial Direct Current Stimulation (Tdcs) On Visuomotor Learning, Pejman Sehatpour, Clément Dondé, Matthew J. Hoptman, Johanna Kreither, Devin Adair, Elisa Dias, Blair Vail, Stephanie Rohrig, Gail Silipo, Javier Lopez-Calderon, Antigona Martinez, Daniel C. Javitt

Publications and Research

Transcranial direct current stimulation (tDCS) is a non-invasive brain stimulation approach in which low level currents are administered over the scalp to influence underlying brain function. Prevailing theories of tDCS focus on modulation of excitation-inhibition balance at the local stimulation location. However, network level effects are reported as well, and appear to depend upon differential underlying mechanisms. Here, we evaluated potential network-level effects of tDCS during the Serial Reaction Time Task (SRTT) using convergent EEG- and fMRI-based connectivity approaches. Motor learning manifested as a significant (p <.0001) shift from slow to fast responses and corresponded to a significant increase in beta-coherence (p <.0001) and fMRI connectivity (p <.01) particularly within the visual-motor pathway. Differential patterns of tDCS effect were observed within different parametric task versions, consistent with network models. Overall, these findings demonstrate objective physiological effects of tDCS at the network level that result in effective behavioral modulation when tDCS parameters are matched to network-level requirements of the underlying task.

Encoding Of Saltatory Tactile Velocity In The Adult Orofacial Somatosensory System, Rebecca Custead

College of Education and Human Sciences: Dissertations, Theses, and Student Research

Processing dynamic tactile inputs is a key function of somatosensory systems. Spatial velocity encoding mechanisms by the nervous system are important for skilled movement production and may play a role in recovery of motor function following neurological insult. Little is known about tactile velocity encoding in trigeminal networks associated with mechanosensory inputs to the face, or the consequences of movement.

High resolution functional magnetic resonance imaging (fMRI) was used to investigate the neural substrates of velocity encoding in the human orofacial somatosensory system during unilateral saltatory pneumotactile inputs to perioral hairy skin in 20 healthy adults. A custom multichannel, scalable …

Dissociation Of Automatic And Strategic Lexical-Semantics: Functional Magnetic Resonance Imaging Evidence For Differing Roles Of Multiple Frontotemporal Regions, Brian T. Gold, David A. Balota, Sara J. Jones, David K. Powell, Charles D. Smith, Anders H. Andersen

Neuroscience Faculty Publications

Behavioral research has demonstrated three major components of the lexical-semantic processing system: automatic activation of semantic representations, strategic retrieval of semantic representations, and inhibition of competitors. However, these component processes are inherently conflated in explicit lexical-semantic decision tasks typically used in functional magnetic resonance imaging (fMRI) research. Here, we combine the logic of behavioral priming studies and the neurophysiological phenomenon of fMRI priming to dissociate the neural bases of automatic and strategic lexical-semantic processes across a series of three studies. A single lexical decision task was used in all studies, with stimulus onset asynchrony or linguistic relationship between prime and …