Nous ne pouvons tout voir. L'attention, notre capacité à filtrer et moduler les informations, nous permet d'interagir de façon efficace avec le monde. Nous avons utilisé une technique non-invasive de modulation de l'activité cérébrale, la Stimulation Magnétique Transcrânienne (SMT) pour manipuler l'activité d'une région clé du réseau de l'attention spatiale, le champ oculomoteur frontal (FEF) droit. L'accent est mis sur les connexions anatomiques observées en IRM de diffusion sous-tendant la modulation de la perception visuelle. Après avoir présenté nos connaissances tirées de données comportementales, physiologiques et anatomiques ainsi que les techniques utilisées, nous présentons nos études qui montrent une amélioration des performances visuelles après des impulsions simples ou des trains d'impulsions de SMT à une fréquence spécifique (30Hz) appliqués sur le FEF droit juste avant l'apparition d'une cible visuelle. Nous examinons ensuite si des différences interindividuelles de connectivité anatomique influencent la modulation perceptive induite par SMT. Nous décrivons un faisceau fronto-tectal qui connecte le FEF avec le colliculus supérieurs et montrons que la probabilité de connexion entre ces deux régions dans l'hémisphère droit influence la contribution du FEF sur la détection visuelle. Nous décrivons aussi les trois branches du faisceau longitudinal supérieur et démontrons l'influence de la 1ère branche dans l'hémisphère droit sur la modulation visuelle induite par des trains de SMT à 30 Hz. Ces résultats suggèrent un rôle important de la connectivité anatomique dans la possibilité de synchroniser les aires d'un réseau à une fréquence spécifique. / We are unable to see everything. Attention, our ability to filter, select and modulate information, allows us to interact efficiently with the world. We employed a non-invasive brain stimulation technique, the Transcranial Magnetic Stimulation (TMS), to manipulate in humans the activity of a key area of the attentional network, the right Frontal Eye Field (FEF). Our work focuses on the characterization with diffusion MRI of anatomical connections and their role underlying the modulation of visual perception. We first introduce previous behavioral, physiological and anatomical findings and the techniques used in our work. We then present evidence showing an improvement of visual performances tied to activity patterns consisting in either single pulses or frequency-specific rhythmic TMS bursts (30Hz) applied over the right FEF, prior to the onset of a visual target. We also examine whether inter-individual differences in white matter connectivity could influence the modulatory role that the FEF exerts on visual perception. We describe a fronto-tectal pathway connecting the FEF with the superior colliculus and show that the probability of connection between these two sites in the right hemisphere influences the FEF contributions to visual detection. We also characterize the three branches of the superior longitudinal fasciculus connecting frontal and parietal lobes and demonstrate an influence of its first branch in the right hemisphere on visual modulation induced by frequency-specific TMS bursts. Our results suggest a crucial role in the modulation of visual perception of the anatomical connectivity to synchronize areas of a network at a specific frequency.

This thesis describes a series of experiments in human observers using neurophysiological and behavioural approaches to investigate the effects of varying haptic stimuli, attentional demand and age on motor control and perception during haptic sensing (i.e., using the hand to seek sensory information by touch). In Experiments I-IV, transcranial magnetic stimulation (TMS) was used to explore changes in corticomotor excitability when participants were actively engaged in haptic sensing tasks. These studies showed that corticospinal excitability, as reflected in motor evoked potential (MEP) amplitude, was greatly enhanced when participants were engaged in different forms of haptic sensing. Interestingly, this extra corticomotor facilitation was absent when participants performed finger movements without haptic sensing or when attention was diverted away from haptic input by a concurrent cognitive task (Exp I). This provided strong evidence that the observed corticomotor facilitation was likely central in origin and related to haptic attention. Neuroimaging has shown activation of the parieto-frontal network likely subserves this aspect of haptic perception. Further, this haptic-specific corticomotor facilitation was finely modulated depending on whether participants focused attention on identifying material (texture) as opposed to geometric properties of scanned surfaces (Exp II). With regards to aging effects, haptic-related corticomotor facilitation was associated with higher recognition accuracy in seniors (Exp III). In line with this, seniors exhibited similar levels of haptic-related corticomotor facilitation to young adults when task demands were adjusted for age (Exp IV). Interestingly, both young and senior adults also showed substantial corticomotor facilitation in the ‘resting’ hand when the ipsilateral hand was engaged in haptic sensing (Exp IV). Simply touching the stimulus without being required to identify its properties (no attentional task demands) produced no extra corticomotor facilitation in either hand or age group, attesting again to the specificity of the effects with regards to haptic attention. In Experiments V-VI, the ability to recognise 2-D letters by touch was investigated using kinematic and psychophysical measures. In Experiment V, we characterized how age affected contact forces deployed at the fingertip. This investigation showed that older adults exhibited lower normal force and increased letter-to-letter variability in normal force when compared to young adults. This difference in contact force likely contributed to longer contact times and lower recognition accuracy in older adults, suggesting a central contribution to age-related declines in haptic perception. Consistent with this interpretation, Experiment VI showed that haptic letter recognition in older adults was characterized not only by lower recognition accuracy but also by substantial increases in response times and specific patterns of confusion between letters. All in all, these investigations highlight the critical interaction of central factors such as attentional demand with aging effects on motor and perceptual aspects of haptic sensing. Of particular significance is the clear demonstration that corticomotor excitability is greatly enhanced when a haptic sensing component (i.e., attending to specific haptic features) is added to simple finger movements performed at minimal voluntary effort levels (typically <15 % of the maximal effort). These observations underline the therapeutic potential of active sensory training strategies based on haptic sensing tasks for the re-education of motor and perceptual deficits in hand function (e.g., subsequent to a stroke). The importance of adjusting attentional demands and stimuli is highlighted, particularly with regards to special considerations in the aging population.

The effects of cranial electrotherapy stimulation (CES) on human EEG and brain current density were evaluated by quantitative electroencephalography (qEEG) and low resolution brain electromagnetic tomography (LORETA). A total of 72 research subjects were provided with a single session of CES, 38 were provided with 0.5 Hz CES while 34 were provided with 100 Hz CES. The qEEG paired t-tests revealed that in both frequencies of CES there was a significant (.05) increase in alpha relative power with concomitant decreases in delta and beta relative power. The 0.5 Hz CES decreased a wider frequency range of delta activity, while the 100 Hz CES decreased a wider frequency range of beta activity; suggesting some difference may exist in the EEG response to different frequencies of CES. The changes found in qEEG relative power were consistent with the affective and cognitive effects of CES reported in the literature, such as increased relaxation and decreased anxiety. Statistically significant changes for qEEG values other than relative power, such as coherence, amplitude asymmetry, phase lag and power ratios were also found. The LORETA paired t-tests found statistically significant (.05) increases in cortical and subcortical theta and alpha frequency current density with concomitant decreases in delta and beta current density. The effects of CES on current density varied by frequency, but did not show a differential in response based on proximity to the contacts, or structures within the brain. Statistically significant changes in current density were found in all 2394 gray matter voxels represented by LORETA, indicating a whole brain response to the CES stimulus. The qEEG and LORETA findings revealed that a single 20-minute session of CES does have a significant effect on the cortical and subcortical activity of the human brain resulting in activity consistent with decreased anxiety and increased relaxation.

Deficits in executive functions, specifically in response inhibition (RI), have been reported in antisocial behavior, conduct disorder, attention-deficit/hyperactivity disorder (ADHD), etc. Individuals with deficits in RI have a high probability to show non-adapted social behavior that can lead to crime. Many studies have shown that transcranial direct current stimulation (tDCS), a noninvasive brain stimulation (NIBS) technique, modulate the activity of the prefrontal cortex and the functions involved in executive control and RI. This article aims to review the literature on the effect of tDCS on RI and executive control and to highlight research avenues to develop therapeutic alternatives to prevent onset and recidivism of crime. A systematic review of the literature was performed in the Libsearch database following PRISMA method. Ten studies were selected showing tDCS modulation of RI measured with the Stop Signal and the Go-NoGo task. Eight of the studies showed gains on RI with tDCS versus sham. The data led to consideration of tDCS as a new therapeutic alternative to improve RI and hence prevention of onset and recidivism on crime. Individual differences, targeted brain areas, the polarity of electrodes and long-term learning effects are further discussed as crucial considerations for future studies.

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Previous studies suggest that non-invasive transcranial direct current stimulation (tDCS) applied to the prefrontal cortex modulates food choices and calorie intake in obese humans. In a fully randomized, placebo-controlled, within-subject and double-blinded study, we applied single sessions of anodal, cathodal, and sham tDCS to the left dorsolateral prefrontal cortex (DLPFC) and contralateral frontal operculum in 25 hungry obese women and investigated possible influences on food reappraisal abilities as well as calorie intake. We hypothesized that tDCS, (i) improves the ability to regulate the desire for visually presented foods and, (ii) reduces their consumption. We could not confirm an effect of anodal or cathodal tDCS, neither on the ability to modulate the desire for visually presented foods, nor on calorie consumption. The present findings do not support the notion of prefrontal/frontal tDCS as a promising treatment option for obesity.:1. Introduction 1.1 Obejective of investigation 1.1.1 Obesity 1.1.2 Homeostasis versus hedonism? 1.1.3 Regulating the desire to eat 1.1.4 Obesity and the brain 1.2 Previous studies 1.2.1 EEG study 1.2.2 Buffet study 1.3 Transcranial direct current stimulation (TDCS) 1.4 TDCS study 2 Publication 3 Summary of work 3.1 Data Acquisition ans analysis 3.2 Results and discussion 3.2.1 Absence of evidence is not evidence of absence 3.2.2 Multifactorial influence on behavior 3.2.3 Limitations of study design 3.2.4 Limitations of method 3.3 Outlook 4 References 5 Attachments 5.1 Academic contribution 5.2 Erklärung über die eigenständige Abfassung der Arbeit 5.3 Einreichungserklärung 5.4 Curriculum vitae 5.5 Publications 5.6 Acknowledgements

Transcranial magnetic stimulation (TMS) is a 37-year-old non-invasive tool and can be used for diagnostic, therapeutics, and research purposes. In research, TMS is mostly used to stimulate the motor cortex, resulting in a neuroelectric excitatory response called a motor evoked potential (MEP). The resulting nerve signal leads to muscle movement, which can be measured by electromyography (EMG). Majority of previous research has targeted muscles of the upper limbs, due to the relative inaccessibility of the cortical leg area. Thus, the aim of this study is to investigate whether asymmetry occurs during lower limb stimulation and if there is a difference in stimulated muscles between dominant and non-dominant leg. Nine healthy adults conducted cortical stimulation over the motor cortex using double cone coil. EMG was recorded from the rectus femoris, tibialis anterior and abductor hallucis on both left and right leg. Depending on the subject's tolerance, data was collected by delivering 30 or 35 pulses. For each intensity, five MEPs were recorded, starting at 30% of the intensity and increasing in steps of 10%. Results showed no significant difference (p&gt;0,05) between the dominant and non-dominant leg in all three muscles. In conclusion, the study no stimulus response asymmetry between the dominant and non-dominant leg in the respective muscle.

Prediction of the therapeutic response in the treatment of affective disorders using repetitive transcranial magnetic stimulation MUDr. Jakub Albrecht Summary Background: Transcranial magnetic stimulation (TMS) is an effective and safe neuromodulatory treatment of several neuropsychiatric conditions. Treatment resistant depression (TRD) is becoming the leading cause of morbidity and mortality. The design was narutallistic and observational. Methods: The cohort (2016-2018) contains 39 depressed patients (STAR*D grade ≥3). The parameters of TMS were: 10 days of 10 Hz stimulation with an energy of 100 % of motor evoked potential (MEP), 1500 pulses in 15 trains over the left dorsolateral prefrontal cortex. Self-reporting scales were administered prior to and after the final stimulation: Zung's Self-Rating Depression Scale (SDS), Perceived Stress Scale (PSS), Beck's Anxiety Inventory (BAI) and Quick Inventory of Depressive Symptomatology (QIDS-SR). Co-medication was not altered. Results: The subjective effect was significant and widespread with a median decrease: in SDS of 10 points (from 75 ±8.16 to 65 ±9.56), 59 % of patients improved ≥10 % from the baseline; in PSS of 4 points (29 ±5.34 to 25 ±5.90), 62 % improved ≥10 %; in BAI of 4 points (46 ±13.72 to 42 ±11.51), 54 % improved ≥10 %; in QIDS-SR 6 points (17...

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京都大学 / 0048 / 新制・課程博士 / 博士(教育学) / 甲第20127号 / 教博第204号 / 新制||教||167(附属図書館) / 京都大学大学院教育学研究科教育科学専攻 / (主査)准教授 野村 理朗, 教授 齊藤 智, 教授 Emmanuel MANALO / 学位規則第4条第1項該当 / Doctor of Philosophy (Education) / Kyoto University / DGAM