REVIEW | doi:10.20944/preprints201804.0026.v1
Subject: Medicine And Pharmacology, Neuroscience And Neurology Keywords: MS: Multiple sclerosis, TMS: transcranial magnetic stimulation, Evoked Potentials;
Online: 2 April 2018 (16:03:29 CEST)
Multiple sclerosis (MS) is an immune-mediated, chronic inflammatory disease of the central nervous system (CNS), characterized by demyelination, axonal degeneration, and cognitive impairment. It also has an important impact on the quality of life of patients and their family members. An estimated 2,500,000 people in the world have multiple sclerosis. Neurophysiological parameters, like sensitivity to demyelination and the strength of excitatory and inhibitory synaptic interactions in the cerebral cortex, can be identified through transcranial magnetic stimulation (TMS) in patients affected by multiple sclerosis (MS). These parameters can be valid and objective parameters that can be correlated with the progression of MS, and can provide reliable indices for the severity of illness and the efficacy of drugs used to treat it. The discovery of specific and detailed neurophysiological parameters as surrogate end points for disease activity could represent an important step in clinical trials. Changes in cortical connectivity have already been demonstrated in MS, but in clinical practice, other measures are usually used to evaluate disease activity. We speculate that TMS may be more effective in identifying disease progression that leads to long-term disability, compared to standard surrogate markers, due to the fact that it represents a direct measure of synaptic transmission(s) in MS.
ARTICLE | doi:10.20944/preprints202201.0008.v1
Subject: Social Sciences, Behavior Sciences Keywords: functional near-infrared spectroscopy; electroencephalogram; cortico-cerebello-thalamo-cortical loop; transcranial electrical stimulation; transcranial magnetic stimulation
Online: 4 January 2022 (14:47:00 CET)
Background: Maladaptive neuroplasticity related learned response in substance use disorder (SUD) can be ameliorated using non-invasive brain stimulation (NIBS); however, inter-individual variability needs to be addressed for clinical translation. Objective: Our first objective was to develop a hypothesis for NIBS for learned response in SUD based on competing neurobehavioral decision systems model. Next objective was to conduct computational simulation of NIBS of cortico-cerebello-thalamo-cortical (CCTC) loop in cannabis use disorder (CUD) related dysfunctional “cue-reactivity” – a closely related construct of “craving” that is a core symptom. Our third objective was to test the feasibility of our neuroimaging guided rational NIBS approach in healthy humans. Methods: “Cue-reactivity” can be measured using behavioral paradigms and portable neuroimaging, including functional near-infrared spectroscopy (fNIRS) and electroencephalogram (EEG), metrics of sensorimotor gating. Therefore, we conducted computational simulation of NIBS, including transcranial direct current stimulation(tDCS) and transcranial alternating current stimulation(tACS) of the cerebellar cortex and deep cerebellar nuclei(DCN), of the CCTC loop for its postulated effects on fNIRS and EEG metrics. We also developed a rational neuroimaging guided NIBS approach for cerebellar lobule (VII) and prefrontal cortex based on healthy human study. Results: Simulation study of cerebellar tDCS induced gamma oscillations in the cerebral cortex while tTIS induced gamma-to-beta frequency shift. Experimental fNIRS study found that 2mA cerebellar tDCS evoked similar oxyhemoglobin(HbO) response in-the-range of 5x10-6M across cerebellum and PFC brain regions (=0.01); however, infra-slow (0.01–0.10 Hz) prefrontal cortex HbO driven(phase-amplitude-coupling, PAC) 4Hz, ±2mA (max.) cerebellar tACS evoked HbO in-the-range of 10-7M that was statistically different (=0.01) across those brain regions. Conclusion: Our healthy human study showed the feasibility of fNIRS of cerebellum and PFC as well as fNIRS-driven ctACS at 4Hz that may facilitate cerebellar cognitive function via the frontoparietal network. Future work needs to combine fNIRS with EEG for multi-modal imaging.
ARTICLE | doi:10.20944/preprints202106.0584.v1
Subject: Medicine And Pharmacology, Immunology And Allergy Keywords: Transcranial direct current stimulation (tDCS); Realistic volumetric Approach-based Simulator for Transcranial electric stimulation (ROAST); Systematic Approach for tDCS Analysis (SATA); Current dose
Online: 23 June 2021 (12:51:30 CEST)
Background: In Transcranial Direct Current Stimulation (tDCS) the injected current gets distributed across the brain areas. The motive is to stimulate the target region-of-interest (ROI), while minimizing the current in non-target ROIs. For this purpose, determining the appropriate current-dose for an individual is difficult. Aim: To introduce Dose-Target-Determination-Index (DTDI) to quantify the focality of tDCS and examine the dose-focality relationship in three different populations. Method: Here, we extended our previous toolbox i-SATA to the MNI reference space. After a tDCS montage is simulated for a current-dose, the i-SATA(MNI) computes the average (over voxels) current density for every region in the brain. DTDI is the ratio of average current density at target ROI to the ROI with maximum value (peak region). Ideally target ROI should be the peak region, so DTDI shall range from 0 to 1. Higher the value, the better the dose. We estimated the variation of DTDI within and across individuals using T1-weighted brain images of 45 males and females distributed equally across three age groups- (a) Young adults (20 ≥ x ˂ 40 years), (b) Mid adults (40 ≥ x ˂ 60 years), and (c) Older adults (60 ≥ x ˂ 80 years). DTDI’s were evaluated for the frontal montage with electrodes at F3 and right supra-orbital for three current doses 1mA, 2mA, and 3mA with the target ROI at left middle frontal gyrus. Result: As the dose is incremented, DTDI may show (a) increase, (b) decrease, and (c) no change across the individuals. The focality decreases with age and the decline is stronger in males. Higher current dose at older age can enhance the focality of stimulation. Conclusion: DTDI provides information on which tDCS current dose will optimize the focality of stimulation. DTDI recommended dose should be prioritised based on the age (> 40 years) and sex (especially males) of an individual. The toolbox i-SATA(MNI) is freely available.
ARTICLE | doi:10.20944/preprints202006.0338.v1
Subject: Medicine And Pharmacology, Other Keywords: Gait; Stroke; Cerebellum; Transcranial Direct Current Stimulation
Online: 28 June 2020 (10:16:17 CEST)
Stroke often results in impaired gait, which can limit community ambulation and the quality of life. Recent works have shown the feasibility of transcranial Direct Current Stimulation (tDCS) as an adjuvant treatment to facilitate gait rehabilitation. Since the cerebellum plays an essential role in balance and movement coordination, which is crucial for independent overground ambulation, so, we investigated the effects of cerebellar tDCS (ctDCS) on the post-stroke overground gait performance in chronic stroke survivors. Fourteen chronic post-stroke male subjects were recruited based on convenience sampling at the collaborating hospitals where ten subjects finally participated in the ctDCS study. We evaluated the effects of two ctDCS montages with 2mA direct current, a) optimized configuration for dentate stimulation with 3.14cm2 disc anode at PO10h (10/5 EEG system) and 3.14cm2 disc cathode at PO9h (10/5 EEG system), and b) optimized configuration for leg lobules VII-IX stimulation with 3.14cm2 disc anode at Exx8 (electrodes defined by ROAST) and 3.14cm2 disc cathode at Exx7. We found ctDCS to be acceptable by all the exposed subjects. The ctDCS intervention had an effect on the 'Normalised Step length Affected side' (p=0.1) and 'Gait Stability Ratio' (p=0.0569), which was found using Wilcoxon signed-rank test at 10% significance level. Also, ctDCS montage specific effect was found using a two-sided Wilcoxon rank-sum test at a 5% significance level for 'Step Time Affected Leg' (p=0.0257) and '%Stance Time Unaffected Leg' (p=0.0376). Moreover, the changes in the quantitative gait parameters across both the montages were found to be correlated to the mean electric field strength in the lobules based on partial least squares regression analysis (R2 statistic = 0.6574) where the mean electric field strength at the cerebellar lobules, Vermis VIIIb, Ipsilesional IX, Vermis IX, Ipsilesional X, had the most loading. In conclusion, our feasibility study indicated the potential of a single session of ctDCS to contribute to the immediate improvement in the balance and gait performance in terms of gait-related indices and clinical gait measures.
ARTICLE | doi:10.20944/preprints202211.0018.v1
Subject: Medicine And Pharmacology, Orthopedics And Sports Medicine Keywords: stroke; occupational therapy; activities of daily living; goal setting; transcranial magnetic stimulation: upper extremity; motor paralysis
Online: 1 November 2022 (04:46:18 CET)
Repetitive transcranial magnetic stimulation (rTMS) with intensive occupational therapy improves upper limb motor paralysis and activities of daily living after stroke; however, amount of improvement according to paralysis severity remains unverified. Target activities for daily living using patients’ upper limb functions can be established by predicting the amount of change after treatment for each severity level of upper limb motor paralysis and further aid practice planning. This study estimated post-treatment score changes for each severity level of motor paralysis (no, poor, limited, notable, and full) stratified according to Action Research Arm Test (ARAT) scores before combined rTMS and intensive occupational therapy. Severity of motor paralysis was the fixed factor for analysis of covariance, delta (post-pre) of the scores was the dependent variable. Ordinal logistic regression analysis was used to compare changes in ARAT subscores in patients, divided according to paralysis severity before treatment. A multicenter retrospective cohort dataset analyzed 907 patients with stroke hemiplegia. Largest treatment-related changes in scores were observed in the Limited recovery group for upper limb motor paralysis and Full recovery group for quality-of-life activities using paralyzed upper limb. These results will help predict treatment effects and determine exercises and goal movements for occupational therapy after rTMS.
ARTICLE | doi:10.20944/preprints201912.0235.v1
Subject: Medicine And Pharmacology, Neuroscience And Neurology Keywords: cerebellar transcranial direct current stimulation; dentate nucleus; computational modeling
Online: 18 December 2019 (04:20:33 CET)
Objective: Cerebrovascular accidents are the second leading cause of death and the third leading cause of disability worldwide. We hypothesized that cerebellar transcranial direct current stimulation (ctDCS) of the dentate nuclei and the lower-limb representations in the cerebellum can improve standing balance functional reach in chronic (> 6 months’ post-stroke) stroke survivors. Materials and Methods: Magnetic resonance imaging(MRI) based subject-specific electric field was computed across 10 stroke survivors and one healthy MRI template to find an optimal bipolar bilateral ctDCS montage to target dentate nuclei and lower-limb representations (lobules VII-IX). Then, in a repeated-measure crossover study on 5 stroke survivors, we compared 15minutes of 2mA ctDCS based on the effects on successful functional reach(%) during standing balance task. Three-way ANOVA investigated the factors of interest– brain regions, montages, stroke participants, and their interactions.Results: “One-size-fits-all” ctDCS montage for the clinical study was found to be bipolar PO9h – PO10h for dentate nuclei and bipolar Exx7–Exx8 for lobules VII-IX with contalesional anode. Bipolar PO9h–PO10h ctDCS performed significantly (alpha=0.05) better in facilitating successful functional reach (%) when compared to bipolar Exx7–Exx8 ctDCS. Furthermore, a linear relationship between successful functional reach (%) and electric field strength was found where bipolar PO9h–PO10h montage resulted in a significantly (alpha=0.05) higher electric field strength when compared to bipolar Exx7–Exx8 montage for the same 2mA current. Conclusion: We presented a rational neuroimaging based approach to optimize deep ctDCS of the dentate nuclei and lower limb representations in the cerebellum for post-stroke balance rehabilitation.
REVIEW | doi:10.20944/preprints202304.0170.v1
Subject: Medicine And Pharmacology, Psychiatry And Mental Health Keywords: Neuromodulation; Brain Stimulation; Transcranial Direct Current Stimulation; Neurodevelopment Disorder; ADHD; ADD
Online: 10 April 2023 (10:39:24 CEST)
ADHD, a neurodevelopmental condition, is distinguished by a triad of symptoms including inattention, hyperactivity, and impulsivity. It is frequently accompanied by comorbidities such as anxiety, depression, and learning disabilities. As a result, clinicians often face challenges in accurately diagnosing ADHD and differentiating it from other conditions. As a prospective remedy for ADHD, scientists have investigated Transcranial Direct Current Stimulation (tDCS), a non-invasive technique of stimulating the brain. It involves applying low-intensity electrical currents to specific regions of the brain to modulate neural activity. This review paper aims to provide an overview of the comorbidities associated with ADHD and the differential diagnosis of the condition. It also explores the potential of tDCS as a treatment option for ADHD, including its mechanisms of action and efficacy in improving ADHD symptoms. The comorbidities discussed in this review include anxiety disorders, mood disorders, and substance use disorders. These comorbidities are frequently seen in individuals with ADHD and can complicate the diagnosis and treatment of the condition. The paper also highlights the importance of considering comorbidities when assessing ADHD, as well as the potential impact of these conditions on treatment outcomes. The differential diagnosis section of the paper explores conditions that can present with symptoms similar to ADHD, such as anxiety disorders, mood disorders, and learning disabilities. It emphasizes the need for a thorough assessment and differential diagnosis to identify ADHD and differentiate it from other conditions accurately. The final section of the paper discusses the potential of tDCS as a treatment option for ADHD. It examines the mechanisms of action of tDCS and its efficacy in improving ADHD symptoms, including attention, hyperactivity, and impulsivity. It also explores the potential for tDCS to improve comorbid conditions associated with ADHD. Overall, this review provides a comprehensive overview of comorbidities and differential diagnoses in ADHD and the potential of tDCS as a treatment option. The paper highlights the importance of a thorough assessment and personalized treatment plan for individuals with ADHD, particularly those with comorbidities.
REVIEW | doi:10.20944/preprints202310.1301.v1
Subject: Medicine And Pharmacology, Neuroscience And Neurology Keywords: Physiotherapy; neurorehabilitation; gait; transcranial electrical stimulation; stroke; non-invasive stimulation techniques
Online: 19 October 2023 (20:18:19 CEST)
Introduction: The transcranial direct current stimulation (tDCS) is a promising technique for brain modulation after cerebrovascular accident (CVA). This treatment modality has been previously studied in the recovery of patients. The aim of this review is to analyze the evidence in the ap-plication of tDCS in the recovery of gait disturbance in stroke patients. Methods: This review was conducted according to the recommendations of the PRISMA statement. Three different elec-tronic databases were searched for relevant results: PubMed, Scopus, and Cochrane. We included reviews and meta-analyses that only considered randomized controlled trials (RCTs) that inves-tigated the effects of transcranial direct electrical stimulation, in combination or not with other physiotherapy treatment, on gait recovery. Results: Thirteen studies with a total of 195 RCTs were included. Data on population, outcome measures, protocols and outcomes were extracted. The Amstar-2 scale and the GRADE system of certainty of evidence were used. Only one study re-ceived high certainty of evidence, 5 received low certainty of evidence and 7 received critically low certainty of evidence. Conclusions: Although the tDCS produces positive changes in gait recovery in spatio-temporal parameters, mobility, endurance, strength and motor function, there is insuf-ficient evidence to recommend this treatment.
ARTICLE | doi:10.20944/preprints202208.0123.v1
Subject: Medicine And Pharmacology, Neuroscience And Neurology Keywords: systems analysis; model predictive control; transcranial electrical stimulation; functional near infrared spectroscopy; pupillometry
Online: 5 August 2022 (14:26:00 CEST)
Individual differences in the responsiveness of the brain to transcranial electrical stimulation (tES) is increasingly demonstrated in large variability in the tES effects. Anatomically detailed computational brain models have been developed to address this variability; however, static brain models are not ‘realistic’ in accounting for the dynamic state of the brain. Therefore, human-in-the-loop optimization is proposed in this perspective article based on an extensive systems analysis of the tES neurovascular effects. First, modal analysis was conducted using a physiologically detailed neurovascular model that found stable modes in the 0 Hz to 0.05 Hz range for the pathway for vessel response through the smooth muscle cells, measured with functional near-infrared spectroscopy (fNIRS). tES effects in the 0 Hz to 0.05 Hz range can also be measured with functional magnetic resonance imaging (fMRI)-tDCS data with a maximum TR=10sec. Therefore, we investigated an open-source fMRI-tDCS dataset that used a TR=3.36sec. We found that both the anodal tDCS condition and sham tDCS condition had similar Finite Impulse Response at the region of interest underlying the anode and a remote location, which indicated a global hemodynamic effect of sham tDCS beyond the intended transient sensations. Here, transient sensations can have arousal effects on the hemodynamics so we conducted a healthy case series for black box modeling of fNIRS-pupillometry of short-duration tDCS effects. The block exogeneity test rejected the claim that tDCS is not a 1-step Granger-cause of the fNIRS total hemoglobin changes (HbT) and pupil dilation changes (p<0.05). Also, grey-box modeling using fNIRS of the tDCS effects in chronic stroke showed HbT response to be significantly different (paired-sample t-test, p<0.05) between the ipsilesional and the contralesional hemisphere for primary motor cortex tDCS and cerebellar tDCS which was subserved by the smooth muscle cells. Here, our perspective is that various physiological pathways subserving tES effects can lead to state-trait variability that can be challenging for clinical translation. Therefore, we conducted a case study on human-in-the-loop optimization using our reduced dimension model and a stochastic, derivative-free Covariance Matrix Adaptation Evolution Strategy. Future studies need to investigate human-in-the-loop optimization of tES for reducing inter-subject and intra-subject variability in tES effects.
ARTICLE | doi:10.20944/preprints202305.0656.v1
Subject: Medicine And Pharmacology, Neuroscience And Neurology Keywords: transcranial magnetic stimulation; paired associative stimulation; PAS; cortical plasticity; cortical correlates; TMS-EEG; TMS-Evoked potentials; TEPs; sensorimotor integration
Online: 9 May 2023 (12:47:48 CEST)
Paired associative stimulation (PAS) is a non-invasive brain stimulation technique that modulates synaptic plasticity in the human motor cortex (M1). Since previous studies have primarily used motor evoked potentials (MEPs) as outcome measure, cortical correlates of PAS-induced plasticity remain unknown. Therefore, the aim of this observational study was to investigate cortical correlates of a standard PAS induced plasticity in the primary motor cortex by using a combined TMS-EEG approach in a cohort of eighteen healthy subjects. In addition to the expected long-lasting facilitatory modulation of MEPs amplitude, PAS intervention also induced a significant increase in transcranial magnetic stimulation evoked potentials (TEPs) P30 and P60 amplitude. No significant correlation between the magnitude of PAS-induced changes in TEP components and MEP amplitude were observed. However, the linear regression analysis revealed that the combined changes in P30 and P60 component amplitudes significantly predicted the MEP facilitation after PAS. The findings of our study offer novel insight into the neurophysiological changes associated with PAS-induced plasticity at M1 cortical level and suggest a complex relationship between TEPs and MEPs changes following PAS.
CASE REPORT | doi:10.20944/preprints202004.0443.v1
Subject: Medicine And Pharmacology, Neuroscience And Neurology Keywords: traumatic brain injury (TBI); Dysarthria; transcranial direct current stimulation (tDCS); Quantitative Electroencephalography (QEEG); speech therapy
Online: 24 April 2020 (13:56:38 CEST)
Purpose: Dysarthria, a neurological injury of the motor component of the speech circuitry, is of common consequences of traumatic brain injury (TBI). Palilalia is a speech disorder characterized by involuntary repetition of words, phrases, or sentences. Based on the evidence supporting the effectiveness of transcranial direct current stimulation (tDCS) in some speech and language disorders, we hypothesized that using tDCS would enhances the effectiveness of speech therapy in a client with chronic dysarthria following TBI. Method: We applied the constructs of the “Be Clear” protocol, a relatively new approach in speech therapy in dysarthria, together with tDCS on a chronic subject who affected by dysarthria and palilalia after TBI. Since there was no research on the use of tDCS in such cases, regions of interest (ROIs) were identified based on deviant brain electrophysiological patterns in speech tasks and resting state compared with normal expected patterns using the Quantitative Electroencephalography (QEEG) analysis. Results: Measures of perceptual assessments of intelligibility, an important index in the assessment of dysarthria, were superior to the primary protocol results immediately and 4 months after intervention. We did not find any factor other than the use of tDCS to justify this superiority. The percentage of repeated words, an index in palilalia assessment, had a remarkable improvement immediately after intervention but fell somewhat after 4 months. We justified this case with subcortical origins of palilalia. Conclusion: Our present case-based findings suggested that applying tDCS together with speech therapy may improve intelligibility in similar case profiles as compared to traditional speech therapy. To reconfirm the effectiveness of the above approach in cases with dysarthria following TBI, more investigation need to be pursued.
ARTICLE | doi:10.20944/preprints202310.1830.v1
Subject: Medicine And Pharmacology, Neuroscience And Neurology Keywords: Apraxia of speech; Trisomy 21 (Down syndrome); transcranial Direct Current Stimulation (tDCS); Rapid Syllable Transition Training (ReST); Broca’s area; Wernicke’s area; supramarginal gyrus; Sylvian Temporal Parietal Junction
Online: 30 October 2023 (07:16:51 CET)
Apraxia of speech is a persistent speech motor disorder that affects speech intelligibility. Studies on speech motor disorders with transcranial Direct Current Stimulation (tDCS) have been mostly directed to post-stroke aphasia. Only a few tDCS studies have focused on apraxia of speech or childhood apraxia of speech (CAS), and no study has investigated individuals with CAS and people with trisomy 21 (T21, Down Syndrome). This study examined the effects of tDCS combined with a motor learning task in developmental apraxia of speech co-existing with T21 (ReBEC RBR-5435x9). The accuracy of speech sound production of nonsense words (NSWs) during Rapid Syllable Transition Training (ReST) under 10 sessions of anodal tDCS (1.5 mA, 25 cm) over the Broca’s area with cathode over the contralateral region was compared to 10 sessions of sham-tDCS and 4 control sessions in a 20-year-old male individual with T21 presenting moderate-severe childhood apraxia of speech (CAS). The accuracy for NSWs production progressively improved (gain 40%) under tDCS only (sham-tDCS and control sessions showed <20% gain). A decrease in speech severity from moderate-severe to mild-moderate indicated transfer effects in speech production. The speech accuracy under tDCS was correlated with Wernicke’s area activation (P3 current source density), which in turn, was correlated with the activation of the left supramarginal gyrus and the Sylvian Parietal Temporal Junction. Repetitive bihemispheric tDCS paired with ReST may have facilitated the speech sound acquisition in a young adult with T21 and CAS, possibly by recruiting brain regions required for the phonological working memory.
ARTICLE | doi:10.20944/preprints202305.0394.v1
Subject: Biology And Life Sciences, Neuroscience And Neurology Keywords: Cerebellum; Satiation; Transcranial Magnetic Stimulation; TMS
Online: 6 May 2023 (08:45:06 CEST)
Decades of research have indicated that that the hypothalamus is responsible for multiple aspects of appetitive behavior. However, recent neuroimaging studies have led researchers to believe that the cerebellum may also serve a function in the regulation of appetite and satiation. Here we aim to identify, through the use of transcranial magnetic stimulation, or TMS, whether the inhibition of the cerebellum influences appetite in healthy participants. We hypothesized that inhibitory TMS, delivered to the cerebellum, would cause the participants to have an increase in appetite, resulting in overeating and a reduction in satiation. It was found that inhibitory TMS delivered to the cerebellar region increased consumption of high fat and calorie foods. These data support the previous research suggesting a cerebellar role in appetite. We propose that this and related studies may eventuate in a new alternative treatment option for those struggling with obesity and various other genetic disorders that cause overeating.
ARTICLE | doi:10.20944/preprints202310.1585.v1
Subject: Biology And Life Sciences, Neuroscience And Neurology Keywords: depression; predictive biomarkers; electroencephalography; transcranial magnetic stimulation
Online: 25 October 2023 (11:39:04 CEST)
Major depressive disorder (MDD) is a highly prevalent, debilitating disorder with a high rate of treatment resistance. One strategy to improve treatment outcomes is to identify patient-specific, pre-intervention factors that can predict treatment success. Neurophysiological measures such as electroencephalography (EEG), which measures the brain’s electrical activity from sensors on the scalp, offer one promising approach for predicting treatment response for psychiatric illnesses, including MDD. In this study, a secondary data analysis was conducted on the publicly available Two Decades-Brainclinics Research Archive for Insights in Neurophysiology (TDBRAIN) database. Specifically, hierarchical regression modeling was used to predict treatment response from baseline demographics, symptom severity, and resting-state EEG features in 119 MDD patients receiving repetitive transcranial magnetic stimulation (rTMS). Across models, both age and baseline symptom severity, assessed by the Beck’s Depression Inventory, were significant predictors of rTMS treatment response, with older individuals and more severe depression scores associated with decreased odds of a positive treatment response. EEG measures contributed predictive power to these models; however, these improvements in outcome predictability only trended towards statistical significance (p~0.07 in multiple models). These findings provide confirmation of previous demographic and clinical predictors, while pointing to EEG metrics that may provide predictive information in future studies.
ARTICLE | doi:10.20944/preprints202012.0683.v1
Subject: Social Sciences, Psychology Keywords: transcranial direct current stimulation; true recognition; false recognition; aging; experiment.
Online: 28 December 2020 (11:15:38 CET)
Background. False memories tend to increase in healthy and pathological aging, and their reduction could be useful in improving cognitive functioning. The objective was to use an active-placebo method to verify whether the application of tDCS in improving true recognition and reducing false memories in healthy older people. Method. Participants were 29 healthy older adults (65-78 years old) assigned to active or placebo group; active group received anodal stimulation at 2mA for 20 min over F7. An experimental task was used to estimate true and false recognition. The procedure took place in two sessions on two consecutive days. Results. A mixed ANOVA of true recognition showed a significant main effect of session (p = .004), indicating an increase from before treatment to after it. False recognition showed a significant main effect (p = .004), indicating a decrease from before treatment to after it and a significant session x group interaction (p < .0001). Conclusions. Overall, our results show that tDCS is an effective tool for increasing true recognition and reducing false recognition in healthy older people, and suggest that stimulation improves recall by increasing the number of items a participant can recall and reducing the number of memory errors.
ARTICLE | doi:10.20944/preprints201704.0048.v1
Subject: Social Sciences, Behavior Sciences Keywords: stress; transcranial magnetic stimulation; spinal reflex; reaction time; co-contraction
Online: 10 April 2017 (05:59:46 CEST)
The purpose of the present study was to investigate the effects of psychological pressure on corticospinal excitability, the spinal reflex, lower limb muscular activity, and reaction times during a task involving dominant leg movements. Ten healthy participants performed a simple reaction time task by raising the heel of their dominant foot from a switch. After 20 practice trials, participants performed 20 non-pressure and 20 pressure trials in a counterbalanced order. Stress responses were successfully induced, as indexed by significant increases in state anxiety, mental effort, and heart rates under pressure. Significant increases in motor evoked potential (MEP) amplitude of the tibialis anterior muscle (TA) occurred under pressure. In terms of task-related EMG amplitude, the co-contraction rate between the soleus (SOL) and TA muscles significantly increased along with SOL and TA EMG amplitudes under pressure. Hoffmann reflexes for SOL and reaction times did not change under pressure. These results indicate that corticospinal excitability and leg muscle-related EMG activity increase homogeneously during lower limb movements that are performed under psychological pressure.
REVIEW | doi:10.20944/preprints202007.0275.v2
Subject: Medicine And Pharmacology, Neuroscience And Neurology Keywords: Transcranial magnetic stimulation; Corticospinal excitability; Cortical inhibition; Cortical facilitation; Eccentric cycling
Online: 4 August 2020 (07:57:25 CEST)
Corticospinal excitability and particularly the balance between cortical inhibitory and excitatory processes (assessed in a muscle using transcranial magnetic stimulation), are affected by neurodegenerative pathologies or following a stroke. Non-fatiguing conventional locomotor exercise, such as cycling or walking, decreases intracortical inhibition and/or increases intracortical facilitation. These modifications notably seem to be a consequence of neurotrophic factors (e.g., brain-derived neurotrophic factors) resulting from hemodynamic solicitation. Furthermore, it can be inferred from non-invasive brain and peripheral stimulation studies that repeated activation of neural networks can endogenously shape neuroplasticity. Such mechanisms could also occur following eccentric exercises (i.e., active lengthening of the muscle), during which motor-related cortical potential is of greater magnitude and lasts longer (assessed by electroencephalography) than during concentric exercises (i.e., muscle shortening). As single-joint eccentric exercise decreased short- and long-interval intracortical inhibition and increased intracortical facilitation (assessed by paired-pulse transcranial magnetic stimulation immediately after), locomotor eccentric exercise may be even more potent by adding hemodynamic-related neuroplastic processes to endogenous processes. Besides, eccentric exercise is especially useful to develop relatively high force levels at low cardiorespiratory and perceived intensity, which can be a training goal in addition to inducing neuroplastic changes. Further studies are required to understand how neuroplasticity is 1) acutely influenced by locomotor exercise characteristics (e.g., intensity, duration), 2) modulated by an exercise-based rehabilitation program, 3) related to functional cognitive and motor outcomes relevant to pathological population.
ARTICLE | doi:10.20944/preprints202111.0146.v1
Subject: Computer Science And Mathematics, Applied Mathematics Keywords: bipolar fuzzy set; decision making problem; non-classical logic; scholasticism; transcranial magnetic stimulation.
Online: 8 November 2021 (13:38:04 CET)
Instead of the conventional 0 and 1 values, bipolar reasoning uses -1, 0, +1 to describe double-sided judgements in which neutral elements are halfway between positive and negative evaluations (e.g., “uncertain” lies between “impossible” and “totally sure”). We discuss the state-of-the-art in bipolar logics and recall two medieval forerunners, i.e., William of Ockham and Nicholas of Autrecourt, who embodied a bipolar mode of thought that is eminently modern. Starting from the trivial observation that “once a wheat sheaf is sealed and tied up, the packed down straws display the same orientation”, we work up a new theory of the bipolar nature of networks, suggesting that orthodromic (i.e., feedforward, bottom-up) projections might be functionally coupled with antidromic (i.e., feedback, top-down) projections via the mathematical apparatus of presheaves/globular sets. When an entrained oscillation such as a neuronal spike propagates from A to B, changes in B might lead to changes in A, providing unexpected antidromic effects. Our account points towards the methodological feasibility of novel neural networks in which message feedback is guaranteed by backpropagation mechanisms endowed in the same feedforward circuits. Bottom-up/top-down transmission at various coarse-grained network levels provides fresh insights in far-flung scientific fields such as object persistence, memory reinforcement, visual recognition, Bayesian inferential circuits and multidimensional activity of the brain. Implying that axonal stimulation by external sources might backpropagate and modify neuronal electric oscillations, our theory also suggests testable previsions concerning the optimal location of transcranial magnetic stimulation’s coils in patients affected by drug-resistant epilepsy.
BRIEF REPORT | doi:10.20944/preprints202104.0196.v1
Subject: Social Sciences, Psychology Keywords: Perspective Taking; Self-Awareness; Self-Representation; Metarepresentation; Theory of Mind; Transcranial Magnetic Stimulation
Online: 7 April 2021 (11:35:01 CEST)
Only by understanding the ability to take third-person perspective can we begin to elucidate the neural processes responsible for one’s inimitable conscious experience. The current study examined differences in hemispheric laterality during a first-person perspective (1PP) and third-person perspective (3PP) taking task, when using Transcranial Magnetic Stimulation (TMS). Participants were asked to take either the 1PP or 3PP when identifying the number of spheres in a virtual scene. During this task, single-pulse TMS was delivered to the motor cortex of both the left and right hemispheres of 10 healthy volunteers. Measures of TMS-induced motor-evoked potentials (MEPs) of the contralateral abductor pollicis brevis (APB) were employed as an indicator of lateralized cortical activation. The data suggest that the right hemisphere is more important in discriminating between 1PP and 3PP. These data add a novel method for determining perspective taking and add to the literature supporting the role of the right hemisphere in meta representation.
REVIEW | doi:10.20944/preprints201912.0179.v1
Subject: Biology And Life Sciences, Biophysics Keywords: globular set; category theory; multidimensional; visual recognition; drug-resistant epilepsy; transcranial magnetic stimulation.
Online: 13 December 2019 (10:37:03 CET)
Once a wheat sheaf has been sealed and tied up, its packed down straws display the same orientation and zero-divergence. This observation brings us to the mathematical notion of presheaf, i.e., a topological structure in which diverging functions are locally superimposed. We show how the concepts of presheaves and the correlated globular sets, borrowed from category theory and algebraic topology, allow a well-founded mathematical approach to otherwise elusive activities of the brain. The mathematical assessment of brain functions in terms of presheaves: a) explains why spontaneous random spikes synchronize; b) leads to the counterintuitive intuition of antidromic effects in neuronal spikes: when an entrained oscillation propagates from A to B, changes in B lead to changes in A. We provide testable previsions: a) we suggest the proper locations of transcranial magnetic stimulation’s coils to improve the clinical outcomes of drug-resistant epilepsy; b) we advocate that axonal stimulation by external sources backpropagates and alters the neuronal electric oscillatory frequency. Further, we describe how the hierarchical information transmission inside globular sets provides fresh insights concerning different issues at various coarse-grained scales, such as object persistence, memory reinforcement in spite of random noise, Bayesian inferential circuits.
REVIEW | doi:10.20944/preprints202106.0489.v1
Subject: Medicine And Pharmacology, Immunology And Allergy Keywords: Attention Deficit Hyperactivity Disorder (ADHD); functional magnetic resonance imaging (fMRI); Neurofeedback; EEG-Neurofeedback; fMRI-Neurofeedback; brain stimulation; transcranial magnetic stimulation (TMS); transcranial direct current stimulation (tDCS); trigeminal nerve stimulation (TNS).
Online: 18 June 2021 (15:51:34 CEST)
This review focuses on the evidence for neurotherapeutics for Attention Deficit Hyperactivity Disorder (ADHD). EEG-Neurofeedback has been tested for about 45 years with latest meta-analyses of randomised controlled trials (RCT) showing small/medium effects compared to non-active controls only. Three small studies piloted neurofeedback of frontal activations in ADHD using functional magnetic resonance imaging or near-infrared spectroscopy, finding no superior effects over control conditions. Brain stimulation has been applied to ADHD using mostly repetitive transcranial magnetic and direct current stimulation (rTMS/tDCS). rTMS has shown mostly negative findings on improving cognition or symptoms. Meta-analyses of tDCS studies targeting mostly dorsolateral prefrontal cortex show small effects on cognitive improvements with only two out of three studies showing clinical improvements. Trigeminal nerve stimulation has shown to improve ADHD symptoms with medium effect in one RCT. Modern neurotherapeutics are attractive due to their relative safety and potential neuroplastic effects. However, they need to be thoroughly tested for clinical and cognitive efficacy across settings and beyond core symptoms and for their potential for individualised treatment.
CASE REPORT | doi:10.20944/preprints202309.0330.v1
Subject: Public Health And Healthcare, Public Health And Health Services Keywords: Heart; Patent foramen ovale; Right to left shunt; Bubble contrast; Transcranial color coded doppler
Online: 5 September 2023 (14:49:24 CEST)
Traditional diagnosis of patent foramen ovale (PFO) in the heart has involved the use of transcranial doppler (TCD). However, TCD is essentially a blind test that cannot directly visualize the location of blood vessels. Since TCD relies on qualitative assessments by examiners, there is room for errors, such as misalignment of the ultrasound's angle of incidence with the actual blood vessels. This limitation affects the reproducibility and consistency of the examination. In this study, we presented an alternative approach for assessing right-to-left shunt (RLS) associated with PFO using contrast transcranial color-coded doppler (C-TCCD) with bubble contrast. The patient under consideration had been diagnosed with an ischemic stroke through imaging, but the subsequent cardiac work-up failed to determine the cause. Employing C-TCCD for RLS screening revealed a confirmed RLS of Spencer’s three grades. Subsequently, transesophageal echocardiography (TEE) was conducted to evaluate PFO risk factors, confirming an 8 mm PFO size, a 21 mm tunnel length, a hypermobile interatrial septum, and persistent RLS. The calculated high-risk PFO score was 4 points, categorizing it as a very high-risk PFO. This case underscores the importance of C-TCCD screening in detecting RLS associated with PFO, especially in cryptogenic stroke patients when identifying the underlying cause of ischemic stroke becomes challenging.
ARTICLE | doi:10.20944/preprints202307.0795.v1
Subject: Engineering, Bioengineering Keywords: Transcranial photobiomodulation, tPBM, repeated tPBM, light emitting diodes, Psychomotor Vigilance Task, PVT, Electroencephalography, EEG.
Online: 12 July 2023 (08:52:23 CEST)
Transcranial photobiomodulation (tPBM) has been suggested as a non-invasive neuromodulation tool. Repetitive administration of light-emitting diode (LED)-based tPBM for several weeks significantly improved human cognition. To understand the electrophysiological effects of LED-tPBM on the human brain, we investigated alterations by repeated tPBM in vigilance performance and brain networks using electroencephalography (EEG) in healthy participants. Active and sham LED-based tPBM were administered to the right forehead of young participants twice a week for four weeks. The participants performed a psychomotor vigilance task (PVT) during each tPBM/sham experiment. A 64-electrode EEG system recorded electrophysiological signals from each participant during the first and last visits in the 4-week study. Topographical maps of EEG power enhanced by tPBM were statistically compared for the repeated tPBM effect. A new data-processing framework combining the group singular value decompensation (gSVD) with eLORETA was implemented to identify EEG brain networks. The reaction time of PVT in the tPBM-treated group was significantly improved over four weeks compared to that in the sham group. We observed acute increases in EEG delta and alpha powers during 10-min LED-tPBM while the participants performed the PVT task. We also found that theta, beta, and gamma EEG powers significantly increased globally after four weeks of LED-tPBM. Combining gSVD with eLORETA enabled us to identify EEG brain networks and the corresponding network power changes by repeated 4-week tPBM. This study clearly demonstrated that 4-week prefrontal LED-tPBM can neuromodulate several key EEG networks, implying a possible causal effect between modulated brain networks and improved psychomotor vigilance outcomes.
ARTICLE | doi:10.20944/preprints202108.0569.v1
Subject: Social Sciences, Cognitive Science Keywords: visual short-term memory; repetitive transcranial magnetic stimulation; visual memory precision; serial memory effects
Online: 31 August 2021 (11:43:33 CEST)
We investigated the role of the human medio-temporal complex (hMT+) in the memory encoding and storage of a sequence of four coherently moving RDKs by applying repetitive transcranial magnetic stimulation (rTMS) during an early or late phase of the retention interval. Moreover, in a second experiment we also tested whether disrupting the functional integrity of hMT+ during the early phase impaired the precision of the encoded motion directions. Overall, results showed that both recognition accuracy and precision were worse in middle serial positions, suggesting the occurrence of primacy and recency effects. We found that rTMS delivered during the early (but not the late) phase of the retention interval was able to impair not only recognition of RDKs, but also the precision of the retained motion direction. However, such impairment occurred only for RDKs presented in middle positions along the presented sequence, where performance was already closer to chance level. Altogether these findings suggest an involvement of hMT+ in the memory encoding of visual motion direction. Given that both position sequence and rTMS modulated not only recognition but also precision of the stored information, these findings are in support of a model of visual short-term memory with a variable resolution of each stored item, consistent with the assigned amount of memory resources, and that such item-specific memory resolution is supported by the functional integrity of area hMT+.
REVIEW | doi:10.20944/preprints202012.0238.v1
Subject: Social Sciences, Psychology Keywords: Post-stroke aphasia; aphasia rehabilitation; pharmacological approach; virtual reality; transcranial direct current stimulation (tDCS)
Online: 9 December 2020 (18:28:59 CET)
Aphasia is one of the most socially disabling post-stroke deficits. Although traditional therapies have been shown to induce adequate clinical improvement, aphasic symptoms often persist. Therefore, new rehabilitation techniques which act as a substitute or as an adjunct to traditional approaches are urgently needed. The present review provides an overview of the efficacy and safety of the most innovative approaches which have been proposed over the last twenty years. First, we examined the effectiveness of the pharmacological approach, principally used as an adjunct to language therapy, reporting the mechanism of action of each single drug for the recovery of aphasia. Results are conflicting but promising. Secondly, we discussed the application of Virtual Reality (VR) which has been proved to be useful since it potentiates the ecological validity of the language therapy by using virtual contexts which simulate real-life everyday contexts. Finally, we focused on the use of Transcranial Direct Current Stimulation (tDCS), both discussing its applications at the cortical level and highlighting a new perspective, which considers the possibility to extend the use of tDCS over the motor regions. Although the review revels an extraordinary variability among the different studies, substantial agreement has been reached on some general principles, such as the necessity to consider tDCS only as an adjunct to traditional language therapy.
REVIEW | doi:10.20944/preprints201709.0050.v1
Subject: Medicine And Pharmacology, Neuroscience And Neurology Keywords: Alzheimer's-disease; dementia; drug targeting; nanoemulsion; neuroinflammation; oxidative stress; scavenger receptors; sonoporation; transcranial ultrasound
Online: 13 September 2017 (05:44:29 CEST)
Due to the complexity of Alzheimer's disease, multiple cellular types need to be targeted simultaneously in order for a given therapy to demonstrate any major effectiveness. Ultrasound-sensitive coated microbubbles (in a targeted lipid nanoemulsion) are available. Versatile small molecule drug(s) targeting multiple pathways of Alzheimer's disease pathogenesis are known. By incorporating such drug(s) into the targeted LCM/ND lipid nanoemulsion type, one obtains a multitasking combination therapeutic for translational medicine. This multitasking therapeutic targets cell-surface scavenger receptors (mainly SR-BI), making possible for various Alzheimer's-related cell types to be simultaneously searched out for localized drug treatment in vivo. Besides targeting cell-surface SR-BI, the proposed LCM/ND-nanoemulsion combination therapeutic(s) include a characteristic lipid-coated microbubble [LCM] subpopulation (i.e., a stable LCM suspension); such film-stabilized microbubbles are well known to substantially reduce the acoustic power levels needed for accomplishing temporary noninvasive (transcranial) ultrasound treatment, or sonoporation, if additionally desired for the Alzheimer's patient.
REVIEW | doi:10.20944/preprints201709.0166.v1
Subject: Medicine And Pharmacology, Neuroscience And Neurology Keywords: Alzheimer's disease; drug targeting; nanoemulsion; neuroinflammation; neurotrauma; oxidative stress; scavenger receptors; SR-BI; transcranial sonoporation
Online: 30 September 2017 (05:21:37 CEST)
Owing to the complexity of neurodegenerative diseases, multiple cellular types need to be targeted simultaneously in order for a given therapy to demonstrate any major effectiveness. Ultrasound-sensitive coated microbubbles (in a targeted nanoemulsion) are available. Versatile small-molecule drug(s) targeting multiple pathways of Alzheimer's disease pathogenesis are known. By incorporating such drug(s) into the targeted LCM/ND lipid nanoemulsion type, one obtains a multitasking combination therapeutic for translational medicine. This multitasking therapeutic targets cell-surface scavenger receptors (mainly SR-BI), making possible for various Alzheimer's-related cell types to be simultaneously searched out for localized drug treatment in vivo. Besides targeting cell-surface SR-BI, the proposed LCM/ND-nanoemulsion combination therapeutic(s) include a characteristic lipid-coated microbubble [LCM] subpopulation (i.e., a stable LCM suspension); such LCM substantially reduce the acoustic power levels needed for accomplishing temporary noninvasive (transcranial) ultrasound treatment, or sonoporation, if additionally desired for the Alzheimer's patient.
ARTICLE | doi:10.20944/preprints202208.0301.v1
Subject: Medicine And Pharmacology, Oncology And Oncogenics Keywords: corticospinal tract; optic radiations; tractography; transcranial magnetic stimulation; subdural strip electrodes; intra-operative neuro-monitoring; parietal lobe
Online: 17 August 2022 (05:08:09 CEST)
Background: The role played by the non-dominant parietal lobe in motor cognition, attention and spatial awareness networks has potentiated the use of awake surgery. When this is not feasible, asleep monitoring and mapping techniques should be used to achieve an onco-functional balance. Objective: This study aims to assess the feasibility of a dual-strip method to obtain direct cortical stimulation for continuous real-time cortical monitoring and subcortical mapping of motor and visual pathways simultaneously in parietal lobe tumour surgery. Methods: Single-centre prospective study between May’19-November’20 of patients with intrinsic non-dominant parietal-lobe tumours. Two subdural strips were used to simultaneously map and monitor motor and visual pathways. Results: Fifteen patients were included. With regards to motor function, a large proportion of patients had abnormal interhemispheric resting motor threshold ratio (iRMTr) (71.4%), abnormal Cortical Excitability Score (CES) (85.7%), close distance to the corticospinal tract – Lesion-To-Tract Distance (LTD) – 4.2mm, Cavity-To-Tract Distance (CTD) – 7mm and intraoperative subcortical distance - 6.4mm. Concerning visual function, the LTD and CTD for optic radiations (OR) were 0.5mm and 3.4mm, respectively; the mean intensity for positive subcortical stimulation of OR was 12mA±2.3mA and 5/6 patients with deterioration of VEPs>50% had persistent hemianopia and transgression of ORs. 12 patients remained stable, one patient had a de-novo transitory hemiparesis, and two showed improvements in motor symptoms. A higher iRMTr for lower limbs was related with a worse motor outcome (p=0.013) and a longer CTD to OR was directly related with a better visual outcome (p=0.041). At 2 weeks after hospital discharge, all patients were ambulatory at home and all proceeded to have oncological treatment. Conclusion: We propose motor and visual function boundaries for asleep surgery of intrinsic non-dominant parietal tumours. Pre-operative abnormal cortical excitability of the motor cortex, deterioration of the VEP recordings and CTD<2mm from the OR were related to poorer outcomes.
ARTICLE | doi:10.20944/preprints202101.0005.v1
Subject: Medicine And Pharmacology, Immunology And Allergy Keywords: apraxia of speech (AOS); transcranial direct current stimulation (tDCS); primary progressive aphasia (PPA); inferior frontal gyrus (IFG); sound duration; brain stimulation
Online: 4 January 2021 (10:19:48 CET)
Transcranial direct current stimulation (tDCS) over the left Inferior Frontal Gyrus (IFG) was found to improve apraxia of speech (AOS) in post-stroke aphasia, speech fluency in adults who stutter, naming and spelling in primary progressive (PPA). This paper aims to determine whether tDCS over the left IFG coupled with AOS therapy improves speech fluency in patients with PPA more than sham. Eight patients with non-fluent PPA with AOS symptoms received either active or sham tDCS, along with speech therapy for 15 weekday sessions. Speech therapy consisted of repetition of increasing syllable-length words. Evaluations took place before, immediately after, and two months post-intervention. Words were segmented into vowels and consonants and the duration of each vowel and consonant was measured. Segmental duration was significantly shorter after tDCS than sham for both consonants and vowels. tDCS gains generalized to untrained words. The effects of tDCS sustained over two months post-treatment in trained words. Taken together, these results demonstrate that the tDCS over the left IFG facilitates speech production by reducing segmental duration. The results provide preliminary evidence that tDCS can maximize efficacy of speech therapy in non-fluent PPA with AOS.
Subject: Biology And Life Sciences, Biophysics Keywords: consciousness 1; subjective experience 2; will 3; agency 4; self 5; psychopathology 6; treatment 7; transcranial near infrared light 8; biophotomodulation 9
Online: 25 May 2021 (08:44:47 CEST)
In this paper I will address Dr. Sonne’s questions about will, agency, choice, consciousness, relevant brain regions, impacts of disorders and their therapeutics, and I will do this by referring to my theory, Dual-brain Psychology, which posits that within most of us there exist two mental agencies with different experiences, wills, choices, and behaviors. Each of these agencies is associated as a trait with one brain hemisphere (either left or right) and its composite regions. One of these agencies is more adversely affected by past traumas and is more immature and more symptomatic while the other is more mature and healthier. The theory has extensive experimental support through 17 peer-reviewed publications with clinical and non-clinical research. I will discuss how this theory relates to the questions that Dr. Sonne presented and will discuss also my published theory on the physical nature of subjective experience and its relation to the brain and how that theory interacts with DBP, and how the 2 theories relate to subjective experience, will, behavior, psychopathology and its treatment.
REVIEW | doi:10.20944/preprints202207.0439.v1
Subject: Medicine And Pharmacology, Neuroscience And Neurology Keywords: cognition; cognitive functions; localization; lesion studies; body perception; functional magnetic resonance imaging (fMRI); electrical microsimulation; transcranial magnetic stimulation; extrastriate body area; fusiform body area
Online: 28 July 2022 (11:16:04 CEST)
It is one of the central goals of cognitive neuroscience to understand how structure and function relate in the brain. We review how cognitive function characterization has been approached in the past. In addition, we examine the ongoing efforts, as well as the implications for the future. Clinical studies on patients with lesions have provided key insights into the relationship between brain areas and behavior over the past century. We describe cognitive function according to localization considering these early efforts for characterization. We chose a perceptual-cognitive function, namely body perception, to describe our current efforts. Using body perception as an example, we summarize contemporary techniques. Finally, we outline the trajectory of current progress into the future and discuss the implications for clinical and basic neuroscience.