3 Clinical Trials for Various Conditions
The overall objective is to validate the methodology of a metaplasticity experimental design by assessing change in motor excitability after administration of priming transcranial direct current stimulation (tDCS) followed by repetitive transcranial magnetic stimulation (rTMS) in healthy human participants.
This study will determine if applying electrical stimulation of the brain can influence training to perform finger movements. The study may provide information that can be used to design rehabilitation therapies for people who have lost the ability to move a part of their body, such as an arm, leg, or hand following a stroke. Healthy volunteers 18-50 years of age may be eligible for this study. Candidates are screened with a medical history, physical examination, MRI (if one has not been done within the last year), questionnaire to evaluate memory and attention and a pregnancy test for women who can become pregnant. Participants have the following tests and procedures in seven sessions over about 8 weeks: * Questionnaires to test attention, fatigue and mood before, during and after each session * Surface electromyography: Electrodes are filed with a conductive gel and taped to the skin over one small hand muscle to measure the electrical activity of muscles. * Transcranial magnetic stimulation: A wire coil is held on the scalp. A brief electrical current passes through the coil to stimulate the brain. During the stimulation, the subject may be asked to tense certain muscles slightly or perform other simple actions. The stimulation may cause a twitch in muscles of the face, arm, or leg, and the subject may hear a click and feel a pulling sensation on the skin under the coil. * Transcranial direct stimulation (tDCS) before and during motor training: Small, wet sponge electrodes are applied to the head - one above the eye and the other on the back of the head. A small electrical current is passed between them. The subject may feel an itching or tingling sensation under the electrodes or see light flashes. * Motor learning under tDCS: tDCS is repeated while the subject performs the training task. The training task consists of performing voluntary brisk thumb movements in a direction opposite to TMS-induced movement directions, during 30 minutes. Training blocks are in 10-minute segments and tDCS is applied during the first 20 minutes. * Behavioral measurements: Evaluation of learned movement tasks.
OBJECTIVES: The current protocol seeks to develop brain-based intermediate phenotypes of response to transcranial magnetic stimulation (TMS) in chronic substance use disorder (SUD). To date the field has relied on subjective reports, behavioral performance, and long-term clinical outcomes as primary measures of TMS efficacy. While certainly ecologically valid, these observable behaviors lack the sensitivity necessary to fully quantify the effects (or lack thereof) across both individual participants and TMS intervention protocols. This proposed within-subjects design seeks to leverage differences in metaplasticity that is, the context in which stimulation occurs-by studying the response to stimulation in both sated and abstinent states. It is predicted these state manipulations will potentiate response to TMS. When a disruptive allostatic load like chronic nicotine exposure or acute abstinence is placed on the brain, the underlying network becomes less stable and thus more susceptible to TMS intervention. For SUD in general and tobacco use disorder (TUD) in particular, this state dependence of TMS response is a potentially valuable tool to improve a given intervention s clinical efficacy. STUDY POPULATION: Physically and psychiatrically healthy smokers will be recruited. A comparison group of non-smokers will be concurrently enrolled. We estimate we will require n=51/group of completers to have sufficient power to develop the intermediate phenotypes of TMS. DESIGN: The protocol is a two group, between/within subject, fully counterbalanced design. The between-subjects factor is GROUP (smoker/non-smoker) and the within-subjects factor for each GROUP is TMS CONDITION (active/sham). Additionally, and for the smoker group, nicotine STATE (sated/abstinent) is a nested within-subjects factor. Each group will receive single sessions of active and sham intermittent theta burst stimulation to left dorsal lateral prefrontal cortex, followed immediately by an MRI scan to characterize the acute neurobiological response to stimulation. Smokers will repeat these procedures both during smoking satiety and following an \~48-hour period nicotine abstinence. OUTCOMES PARAMETERS: In addition to subjective and behavioral task performance changes associated with TMS intervention, changes in MRI BOLD signal will be used to characterize the neurobiological response to TMS intervention across groups and states. Taken together, the development of brain-based markers of TMS response may thus improve both our mechanistic understanding of the causal dysfunctions of TUD as well as the potential efficacy of these interventions longer term to address the relevant clinical characteristics of the disease and ultimately improve treatment outcomes.