201 research outputs found

    Direct current stimulation of right anterior superior temporal gyrus during solution of compound remote associates problems

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    Background: Research has implicated the right temporal lobe in verbal insight problems. Gamma frequency activity is coincident with insight, and fMRI showed there was greater hemodynamic activity when first seeing problems eventually solved with insight. fMRI research localized the activity to the rASTG. Direct current stimulation (DCS) can be used to modulate neuronal activity and has both enhanced and disrupted cognition via temporal lobe targets.Objectives: To determine if rASTG activity drives insight processes or is epiphenomenal.Main Hypotheses: Depolarizing anodal stimulation would enhance insight solutions; while hyperpolarizing cathodal stimulation would impede insight solutions.Methods: 28 normal participants solved CRA) problems during 3 sessions while receiving 3 types of DCS. Participants were asked if they solved each problem with insight or analytic processes. Rate, speed, accuracy, and proportion of insight solution were compared to see if rASTG stimulation affected insight processes.Results: Anodal stimulation was associated with fewer analytic solutions, decreased time to insight solution and decreased insight error rate. Cathodal stimulation increased time to insight solution and increased insight error rate.Conclusions: Direct current stimulation alters solution strategies for compound remote associates problems, perhaps via effects on left-hemisphere-mediated impasse or coarse semantic integration at rASTG.Ph.D., Clinical Psychology -- Drexel University, 201

    Network-state dependent effects in naming and learning

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    NIBS as a research tool in studying and enhancing episodic memory in the left prefrontal cortex

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    In the absence of effective treatments for memory disorders including dementia, NIBS methods are being tested for studying and enhancing memory. Anodal transcranial direct-current stimulation (atDCS) is a safe, non-invasive method of stimulating the brain and modulating neural activity through electrodes placed on the scalp. Controversy has surrounded the implementation of atDCS as a research and clinical tool because of inconsistency in effects and a limited understanding of atDCS parameters and mechanisms. Heterogeneity in atDCS parameters across studies could contribute to the inconsistency in effects. Thus, the current research included a systematic ethodological investigation of atDCS as a potential research and clinical tool. Two meta-analyses and a set of five methodological experiments analysed the efficacy of atDCS given a consistent set of parameters. In younger adults, atDCS led to a weak and volatile effect under certain conditions that fluctuated with modifications to verbal stimuli and sample size. While there was a robust improvement in memory following atDCS over the left PFC in Experiment 1, this effect did not remain consistent in direct and conceptual replications. The metaanalyses provided support to this investigation by demonstrating that when effect sizes were pooled together across all eligible published studies, the average effect size was close to zero. When only the studies in the current investigation were pooled together, the effect size was larger but also non-significant. Thus, the results inform future considerations of atDCS as a research and clinical tool and provide recommendations for the limited applications of atDCS with a framework for applying effective parameters that take into account individual differences. Furthermore, through the course of the investigation of atDCS, novel findings about episodic memory processes and neural correlates were revealed, confirming the importance of activity in the ventrolateral prefrontal cortex (VLPFC) to episodic memory formation. These findings on VLPFC function were further extended with an investigation of the cognitive mechanisms of atDCS effects on VLPFC 3 function in Chapter 6 and an examination of the time window and process in the VLPFC that was most crucial to memory formation with repetitive transcranial magnetic stimulation (rTMS) in Chapter 7. Together, the findings contributed to developing a clearer understanding of atDCS effects on episodic memory and the episodic processes that occur in the VLPFC. This understanding can inform future research in NIBS with other cognitive functions and the development of memory nterventions that can target the VLPFC

    New techniques for neuro-rehabilitation: Transcranial Electric Stimulation and Virtual Reality

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    Recovery of motor and cognitive performances after a neurological illness remains a significant challenge for rehabilitation specialists. The traditional rehabilitative interventions are usually delivered using a multidisciplinary approach, whose results are not always satisfactory. These limitations in functional recovery have led researchers to consider alternative approaches. The hypothesis of providing new therapeutic possibilities in the different patients treated is, as a rehabilitator, very rewarding and represents a challenge for the future. The application of simple and low-cost techniques, defined by the literature as "unconventional" or “novel”, can provide new ideas not only in the field of research but above all of application in clinical reality.A suitable approach to improve the rehabilitation outcome is to utilize these novel rehabilitation techniques that act as a substitute or an addition to the traditional ones. In this context, some recent approaches have been proposed that might increase the effectiveness of a traditional treatment. Among them, two techniques have been demonstrated to be very promising, namely non-invasive brain stimulation (NIBS) and Virtual Reality (VR).In light of the foregoing, my thesis has been divided into two main lines of research, namely: a) the study of the effects of transcranial direct current stimulation (tDCS) in different neurological conditions; b) the application of VR (used alone or combined with tDCS) in the treatment of some neurocognitive disorders. A semi-immersive VR tool (ReMOVES system) has been used as a user-friendly platform providing activities based on exergames
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