EEG recording studies in humans have revealed the presence of oscillatory rhythms in brain activity, and D oscillations in different frequency bands have been associated with cognitive processes such as working D memory. Additionally, alterations of oscillatory activity are found in psychiatric illnesses such as D schizophrenia. Despite their apparent relevance, however, the role of neural oscillations in cognitive D processes are as yet poorly understood. The proposed project explores these issues using simultaneous D transcranial magnetic stimulation (TMS) and EEG recording. Specifically, the present proposal assesses D two proposals regarding the mechanisms by which TMS influences ongoing neural activity and hence D behavior. The first proposal holds that TMS achieves it effects by injecting electrical noise into task-related D neural areas, producing characteristic declines in performance. However, this proposal is inconsistent with D findings of TMS-related improvements in performance, which have been reported in several studies. Thus, C an alternative account holds that TMS interacts in subtle ways with ongoing neural activity related to the D performance of specific tasks, producing disruptions or improvements in performance depending on the D nature of the interaction. This issue is explored in an experiment comparing the effects of 10-Hz repetitive D (r)TMS on neural activity, to the effects of 10-Hz visual flicker, which is known to produce widespread D entrainment (i.e. disruption) of neural activity to the flicker frequency. Two additional experiments explore 7 task-related changes in neural oscillations, and how TMS can be used to alter such oscillations, producing u improvements or disruptions in performance at the individual subject level. D D The proposed project will help to clarify how neurostimulation methods such as transcranial magnetic D stimulation (TMS) influence ongoing neural activity, and will contribute decisively to our understanding of D the role of neural oscillations in cognitive processes such as working memory. Moreover, the methods D developed here will point the way towards the use of TMS in the exploration and treatment of abnormal D oscillations found in psychiatric illnesses such as schizophrenia.

National Institute of Health (NIH)
National Institute of Mental Health (NIMH)
Postdoctoral Individual National Research Service Award (F32)
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Special Emphasis Panel (ZRG1-F02A-J (20))
Program Officer
Vogel, Michael W
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University of Wisconsin Madison
Schools of Medicine
United States
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Kundu, Bornali; Johnson, Jeffrey S; Postle, Bradley R (2014) Trait-like differences in underlying oscillatory state predict individual differences in the TMS-evoked response. Brain Stimul 7:234-42
Kundu, Bornali; Johnson, Jeffrey S; Postle, Bradley R (2014) Prestimulation phase predicts the TMS-evoked response. J Neurophysiol 112:1885-93
Johnson, Jeffrey S; Kundu, Bornali; Casali, Adenauer G et al. (2012) Task-dependent changes in cortical excitability and effective connectivity: a combined TMS-EEG study. J Neurophysiol 107:2383-92
Hamidi, Massihullah; Johson, Jeffrey S; Feredoes, Eva et al. (2011) Does high-frequency repetitive transcranial magnetic stimulation produce residual and/or cumulative effects within an experimental session? Brain Topogr 23:355-67
Johnson, Jeffrey S; Sutterer, David W; Acheson, Daniel J et al. (2011) Increased Alpha-Band Power during the Retention of Shapes and Shape-Location Associations in Visual Short-Term Memory. Front Psychol 2:128
Johnson, Jeffrey S; Hamidi, Massihullah; Postle, Bradley R (2010) Using EEG to explore how rTMS produces its effects on behavior. Brain Topogr 22:281-93