Dominant Hemisphere Research Articles

The Sidney Sperry/Heber Snell Debates: Critical Biblical Scholarship and Mormon Tradition

The Sidney Sperry/Heber Snell Debates: Critical Biblical Scholarship and Mormon Tradition

RIGHT BRAINER, LEFT BRAINER OR WHOLE BRAINER? UNDERSTANDING THE BRAIN HEMISPHERIC DOMINANCE THEORY AND ITS IMPLICATIONS IN EDUCATION

This paper provides an insight into the neurologic phenomenon of Brain hemispheric dominance in which one hemisphere tends to be dominant over the other, leading to a greater consistency in utilising certain functions. The right and left hemispheres of the brain are structurally similar but significantly unlike in their functions. Based on the dominant hemisphere, a person can be right brained or left brained; and whole brained if both the hemispheres work about equally. This paper delineates the functional differences between the two brain hemispheres based on evidences from brain research. It also provides an understanding of the emergence of the Nobel Prize winning Brain dominance theory, the various models that bring about further distinctions between the brain hemispheres and the implications of the theory in Education.

Acil Servise Başvuran İzole El Yaralanmalı İş Kazalarının Serebral Lateralizasyon İle İlişkisi

Aim: This study aimed to determine the distribution of hand dominance and to evaluate the relationship between the dominant hand and injury site among patients who presented to emergency service with occupational accident and had isolated hand injury. Material and Methods: This single-center prospective descriptive study included 528 patients who administered to the emergency department due to work accident and were found to have isolated hand injuries between 01.12.2019-01.06.2020. Results: 369 (69.9%) patients had isolated skin cuts while the rest of the patients had more severe accompanying injuries such as neurovascular and tendon injury, fracture, or amputation. The most common mechanism of injury was hand cuts while using a tool (163 cases, 30.9%). The most commonly affected regions in hand were the first and second fingers. In patients with right hemisphere dominant, the dominant use of the hand that is not suitable for the dominant hemisphere was found to be statistically significantly higher than in patients with left hemisphere dominant (38.1% vs 1.7%, p<0.0001). Conclusion: The risk of isolated hand injury due to occupational accidents appears to be greater in left-handed individuals, and hand injury more commonly involves non-dominant hand in left-handed individuals than the right-handed ones.

Особливості клінічного дослідження причин затримки мовленнєвого розвитку.

The article contains a study of the causes of speech delay in young children. The symptoms of this disorder, clinical and hardware methods of studying the manifestations of this disorder in children from birth to three years are described. The description of pedagogical manifestations of speech development delay and features of reflection of pathological changes in the structure and functioning of the brain and its trunks is given. Examples of clinical description of pathological symptoms on echoencephalogram, neurosonographic and Doppler examination are given. The causes of speech developmental delay, which include cerebral hypoxia / ischemia, CNS birth trauma, CNS infections, systemic dysmetabolic and toxic-metabolic disorders, are highlighted. The connection between the manifestations of speech developmental delay and the data of X-ray examination of disorders of the integrity and functionality of the cervical spine has been studied. Neurosonographic data confirm problems with harmonious blood supply and maintenance of typical cerebrospinal fluid dynamics in the vessels and ventricles of the brain. The study presents the results of deciphering the results of echoencephalography in relation to the passage of waves of different frequencies through the structures of the brain, identified pathological conditions accompanied by non-normative indicators of frequency and changes in the amplitude of the waves. The reactions of children to auditory stimuli that accompanied the study with the help of audiometry and echoencephalography were studied, and the features of subcortical evoked potentials in the dominant and nondominant hemispheres were determined

Task-State Cortical Motor Network Characteristics by Functional Near-Infrared Spectroscopy in Subacute Stroke Show Hemispheric Dominance.

BackgroundThere was a reorganization of the brain network after stroke. Some studies have compared the characteristics of activation or functional connectivity (FC) of cortical and subcortical regions between the dominant and non-dominant hemisphere stroke.ObjectivesTo analyze hemispheric dominance differences in task-state motor network properties in subacute stroke by functional near-infrared spectroscopy (fNIRS).Materials and MethodsPatients with first ischemic stroke in the basal ganglia within 1–3 months after onset and age- and sex-matched right-handed healthy subjects (HS) were enrolled. fNIRS with 29 channels was used to detect the oxyhemoglobin concentration changes when performing the hand grasping task. Activation patterns of motor cortex and two macroscale and two mesoscale brain network indicators based on graph theory were compared between dominant and non-dominant hemisphere stroke.ResultsWe enrolled 17 subjects in each of left hemisphere stroke (LHS), right hemisphere stroke (RHS), and HS groups. Both patient groups showed bilateral activation. The average weighted clustering coefficient and global efficiency of patients were lower than those of healthy people, and the inter-density was higher than that of the HS group, but the significance was different between LHS and RHS groups. The intra-density changes in the RHS group were opposite to those in the LHS group. The correlation between mesoscale indicators and motor function differed between dominant and non-dominant hemisphere stroke.ConclusionThe changes in macroscale cortical network indicators were similar between the two patient groups, while those of the mesoscale indicators were different. The mesoscale brain network characteristics were affected by the severity of dysfunction to varying degrees in the LHS and RHS patients.

Choosing Sides: Impact of Prismatic Adaptation on the Lateralization of the Attentional System.

Seminal studies revealed differences between the effect of adaptation to left- vs. right-deviating prisms (L-PA, R-PA) in normal subjects. Whereas L-PA leads to neglect-like shift in attention, demonstrated in numerous visuo-spatial and cognitive tasks, R-PA has only minor effects in specific aspects of a few tasks. The paucity of R-PA effects in normal subjects contrasts with the striking alleviation of neglect symptoms in patients with right hemispheric lesions. Current evidence from activation studies in normal subjects highlights the contribution of regions involved in visuo-motor control during prism exposure and a reorganization of spatial representations within the ventral attentional network (VAN) after the adaptation. The latter depends on the orientation of prisms used. R-PA leads to enhancement of the ipsilateral visual and auditory space within the left inferior parietal lobule (IPL), switching thus the dominance of VAN from the right to the left hemisphere. L-PA leads to enhancement of the ipsilateral space in right IPL, emphasizing thus the right hemispheric dominance of VAN. Similar reshaping has been demonstrated in patients. We propose here a model, which offers a parsimonious explanation of the effect of L-PA and R-PA both in normal subjects and in patients with hemispheric lesions. The model posits that prismatic adaptation induces instability in the synaptic organization of the visuo-motor system, which spreads to the VAN. The effect is lateralized, depending on the side of prism deviation. Successful pointing with prisms implies reaching into the space contralateral, and not ipsilateral, to the direction of prism deviation. Thus, in the hemisphere contralateral to prism deviation, reach-related neural activity decreases, leading to instability of the synaptic organization, which induces a reshuffling of spatial representations in IPL. Although reshuffled spatial representations in IPL may be functionally relevant, they are most likely less efficient than regular representations and may thus cause partial dysfunction. The former explains, e.g., the alleviation of neglect symptoms after R-PA in patients with right hemispheric lesions, the latter the occurrence of neglect-like symptoms in normal subjects after L-PA. Thus, opting for R- vs. L-PA means choosing the side of major IPL reshuffling, which leads to its partial dysfunction in normal subjects and to recruitment of alternative or enhanced spatial representations in patients with hemispheric lesions.

Modulation of sensory cortical activity by deep brain stimulation in advanced Parkinson's disease.

Despite optimal oral drug treatment, about 90% of patients with Parkinson's disease develop motor fluctuation and dyskinesia within 5–10 years from the diagnosis. Moreover, the patients show non‐motor symptoms in different sensory domains. Bilateral deep brain stimulation (DBS) applied to the subthalamic nucleus is considered the most effective treatment in advanced Parkinson's disease, and it has been suggested to affect sensorimotor modulation and relate to motor improvement in patients. However, observations on the relationship between sensorimotor activity and clinical improvement have remained sparse. Here, we studied the somatosensory evoked magnetic fields in 13 right‐handed patients with advanced Parkinson's disease before and 7 months after stimulator implantation. Somatosensory processing was addressed with magnetoencephalography during alternated median nerve stimulation at both wrists. The strengths and the latencies of the ~60‐ms responses at the contralateral primary somatosensory cortices were highly variable but detectable and reliably localized in all patients. The response strengths did not differ between preoperative and postoperative DBSON measurements. The change in the response strength between preoperative and postoperative condition in the dominant left hemisphere of our right‐handed patients correlated with the alleviation of their motor symptoms (p = .04). However, the result did not survive correction for multiple comparisons. Magnetoencephalography appears an effective tool to explore non‐motor effects in patients with Parkinson's disease, and it may help in understanding the neurophysiological basis of DBS. However, the high interindividual variability in the somatosensory responses and poor tolerability of DBSOFF condition warrants larger patient groups and measurements also in non‐medicated patients.

Neuroplasticity Mechanisms in Frontal Brain Gliomas: A Preliminary Study.

BackgroundPathological brain processes may induce adaptive cortical reorganization, however, the mechanisms underlying neuroplasticity that occurs in the presence of lesions in eloquent areas are not fully explained. The aim of this study was to evaluate functional compensatory cortical activations in patients with frontal brain gliomas during a phonemic fluency task and to explore correlations with cognitive performance, white matter tracts microstructural alterations, and tumor histopathological and molecular characterization.MethodsFifteen patients with frontal glioma were preoperatively investigated with an MRI study on a 3T scanner and a subgroup underwent an extensive neuropsychological assessment. The hemispheric laterality index (LI) was calculated through phonemic fluency task functional MRI (fMRI) activations in the frontal, parietal, and temporal lobe parcellations. Diffusion-weighted images were acquired for all patients and for a group of 24 matched healthy volunteers. Arcuate Fasciculus (AF) and Frontal Aslant Tract (FAT) tractography was performed using constrained spherical deconvolution diffusivity modeling and probabilistic fiber tracking. All patients were operated on with a resective aim and underwent adjuvant therapies, depending on the final diagnosis.ResultsAll patients during the phonemic fluency task fMRI showed left hemispheric dominance in temporal and parietal regions. Regarding frontal regions (i.e., frontal operculum) we found right hemispheric dominance that increases when considering only those patients with tumors located on the left side. These latter activations positively correlate with verbal and visuo-spatial short-term memory, and executive functions. No correlations were found between the left frontal operculum and cognitive performance. Furthermore, patients with IDH-1 mutation and without TERT mutation, showed higher rightward frontal operculum fMRI activations and better cognitive performance in tests measuring general cognitive abilities, semantic fluency, verbal short-term memory, and executive functions. As for white matter tracts, we found left and right AF and FAT microstructural alterations in patients with, respectively, left-sided and right-side glioma compared to controls.ConclusionsCompensatory cortical activation of the corresponding region in the non-dominant hemisphere and its association with better cognitive performance and more favorable histopathological and molecular tumor characteristics shed light on the neuroplasticity mechanisms that occur in the presence of a tumor, helping to predict the rate of post-operative deficit, with the final goal of improving patients'quality of life.

Brain 18-FDG-PET patterns in early breast cancer subtypes: Relationship with headache.

e12560 Background: Brain metabolic response on 18F-fuorodeoxiglucose(FDG)-PET in breast cancer (BC) patients is not routinely investigated, although several bidirectional relationships have been described between BC (and BC therapies) and brain functions. For example, common forms of headaches, as migraine (Mi) and tension-type headache (TTH), seem to be oddly distributed among BC subtypes and possibly influence the outcome. Methods: We recruited patients with early BC referring to IRCCS Humanitas Research Hospital who received neoadjuvant chemotherapy. Demographic data, BC characteristics and headache diagnosis were recorded, through detailed interview and instrumental investigation. Ki67 was considered high if above 20%. All patients underwent dedicated 18F-FDG PET scan for the evaluation of brain metabolism. Semiquantitative image analysis was performed using Cortex ID software (GE), comparing patient’s scan with a control group by the means of Z-score. The difference between patients’ subgroups were assessed using One-way ANOVA model. Results: Twenty-three patients were recruited. The median age was 52.5±10.8 years; 65.2% were postmenopausal, 30% premenopausal, and one patient perimenopausal. Ten patients were diagnosed as triple-negative BC, 6 as HER2-positive and 7 as Luminal B/HER2+. Nearly 70% (16/23) of patients had high Ki67 values. All patients had ECOG PS 0. Ten patients were diagnosed with TTH, 9 with migraine of whom two with aura, and four patients had no headache. Eleven patients had active headache at the moment of the study. At the whole brain level, we found a significant increase of brain metabolism in the left hemisphere of BC patients with high Ki-67 (p=0.007). Moreover, the same result was found in parietal cortex and in general associative areas bilaterally. Instead, HER-2 positive BC patient showed a reduced metabolism in right temporal cortex compared to HER-2 negative (p=0.04). Grading and other tumor characteristics did not influence FDG-PET uptake. BC patients with TTH had a reduced activity in right medial frontal lobe compared with migraine patients (p=0.01). Those with an active headache had increased activity in posterior cingulate and reduced activity in visual networks (p=0.03). Conclusions: Although exploratory, this study suggests that BC subtypes could present different metabolic pattern of cerebral activity, particularly in dominant hemisphere and associative areas. The high prevalence of headache in our sample does not affect the above pattern, but it is associated with an altered activation in other networks, mainly cingulate and visual cortex, which are well-known areas involved in primary headache.

Laterality disorder and its association with an axial hypotonia and body spatial integration impairments may involve slowness and attention disorder: A case series of patients

IntroductionLateralization is a complex process that evolves during the development of the child leading to the organization of the functional dominance with a body side. However, laterality is poorly examined.ObjectivesThe aim of this study was to explore the features of patients with a laterality disorder evidenced by a non-dominance affirmed of the handedness.MethodsA retrospective review of 25 cases of patients (15 children of 8-9 years and 10 adults of 26-42 years old) presenting a laterality disorder. All patients were assessed with the standardized assessment of neuropsychomotor functions battery (NP-MOT).It enables physical assessment of muscular tone of limbs and axial tone (trunk), laterality (tonic, spontaneous gestural, psychosocial handedness, and usual with objects for hand, foot, and eye), body spatial integration (in relation to self, imitation, objects and map), auditory attention, and others motor functions.ResultsThe study findings revealed poor level of the dominant laterality for all the patients (< 2DS) regarding the proximal tonic laterality (elbows) and the psychosocial subtests of mimed gestures (tending to ambidexterity). In addition, it was found a hypotonic trunk and difficulties in body spatial integration and in asymmetrical bimanual tasks with slowness and failures, similar dexterity performance right/left.Strong correlations between all these features and the personal history match the difficulties to focus a long time an attention holding posture without to move, and associated to a fatigability.ConclusionsA deep standardized examination of the laterality and tone may explain some components of the behavior in relation with hemispheric dominance impairment.DisclosureNo significant relationships.

Auditory cortical plasticity after cochlear implantation in asymmetric hearing loss is related to spatial hearing: a PET H215O study.

In asymmetric hearing loss (AHL), the normal pattern of contralateral hemispheric dominance for monaural stimulation is modified, with a shift towards the hemisphere ipsilateral to the better ear. The extent of this shift has been shown to relate to sound localization deficits. In this study, we examined whether cochlear implantation to treat postlingual AHL can restore the normal functional pattern of auditory cortical activity and whether this relates to improved sound localization. The auditory cortical activity was found to be lower in the AHL cochlear implanted (AHL-CI) participants. A cortical asymmetry index was calculated and showed that a normal contralateral dominance was restored in the AHL-CI patients for the nonimplanted ear, but not for the ear with the cochlear implant. It was found that the contralateral dominance for the nonimplanted ear strongly correlated with sound localization performance (rho = 0.8, P < 0.05). We conclude that the reorganization of binaural mechanisms in AHL-CI subjects reverses the abnormal lateralization pattern induced by the deafness, and that this leads to improved spatial hearing. Our results suggest that cochlear implantation enables the reconstruction of the cortical mechanisms of spatial selectivity needed for sound localization.

Reorganization of Ventral Premotor Cortex After Ischemic Brain Injury: Effects of Forced Use

Background Physical use of the affected upper extremity can have a beneficial effect on motor recovery in people after stroke. Few studies have examined neurological mechanisms underlying the effects of forced use in non-human primates. In particular, the ventral premotor cortex (PMV) has been previously implicated in recovery after injury. Objective To examine changes in motor maps in PMV after a period of forced use following ischemic infarct in primary motor cortex (M1). Methods Intracortical microstimulation (ICMS) techniques were used to derive motor maps in PMV of four adult squirrel monkeys before and after an experimentally induced ischemic infarct in the M1 distal forelimb area (DFL) in the dominant hemisphere. Monkeys wore a sleeved jacket (generally 24 hrs/day) that forced limb use contralateral to the infarct in tasks requiring skilled digit use. No specific rehabilitative training was provided. Results At 3 mos post-infarct, ICMS maps revealed a significant expansion of the DFL representation in PMV relative to pre-infarct baseline (mean = +77.3%; n = 3). Regression analysis revealed that the magnitude of PMV changes was largely driven by M1 lesion size, with a modest effect of forced use. One additional monkey examined after ∼18 months of forced use demonstrated a 201.7% increase, unprecedented in non-human primate studies. Conclusions Functional reorganization in PMV following an ischemic infarct in the M1 DFL is primarily driven by M1 lesion size. Additional expansion occurs in PMV with extremely long periods of forced use but such extended constraint is not considered clinically feasible.

Localizing epileptic focus and assessing electrical stimulus effects on epilepsy in rats using stretchable micro electrocorticogram electrodes

Epilepsy is a chronic nervous disease with increasing incidence worldwide, while the accurate localization of epileptic focus and the corresponding treatment are still challenging due to the lack of effective tools to monitor and modulate the related brain neurological activities. In this work, stretchable micro electrocorticogram (mECoG) electrodes are developed and used to investigate penicillin-induced epilepsy in rats. The electrodes possess excellent stretchability, conformality, anti-interference ability and sufficient resolution to successfully monitor electroencephalogram (EEG) signals, which is superior to traditional rigid polyimide-based electrodes. Characteristic epileptic spike waves are detected and analyzed to study the epileptic focus and electrical stimulus effects during epileptic seizures. It is found that the spike waves occur first in the visual cortex which is likely to be the epileptic focus. Epileptic spike wave frequency quickly increases to 1.07 Hz where it reaches a plateau and remains stable. There is no dominant brain hemisphere that would show early warning of epileptic seizures. Electrical stimuli for various times are applied after administering penicillin. It is found that 15 min of electrical stimulus has the best restraining effect on epileptic seizures. The mECoG electrodes developed in this study show potentials for applications in stretchable biomedical devices.

Magnetoencephalography Language Mapping Using Auditory Memory Retrieval and Silent Repeating Task.

The study aims to (1) examine the spatiotemporal map of magnetoencephalography-evoked responses during an Auditory Memory Retrieval and Silent Repeating (AMRSR) task, and determine the hemispheric dominance for language, and (2) evaluate the accuracy of the AMRSR task in Wernicke and Broca area localization. In 30 patients with brain tumors and/or epilepsies, the AMRSR task was used to evoke magnetoencephalography responses. We applied Fast VEctor-based Spatial-Temporal Analyses with minimum L1-norm source imaging method to the magnetoencephalography responses for localizing the brain areas evoked by the AMRSR task. The Fast-VEctor-based Spatial-Temporal Analysis found consistent activation in the posterior superior temporal gyrus around 300 to 500 ms, and another activation in the frontal cortex (pars opercularis and/or pars triangularis) around 600 to 900 ms, which were localized to the Wernicke area (BA 22) and Broca area (BA 44 and BA 45), respectively. The language-dominant hemispheric laterization elicited by the AMRSR task was comparable with the result from an Auditory Dichotic task result given to the same patient, with the exception that AMRSR is more sensitive on bilateral language laterization cases on finding the Wernicke and Broca areas. For all patients who successfully finished the AMRSR task, Fast-VEctor-based Spatial-Temporal Analysis could establish accurate and robust localizations of Broca and Wernicke area and determine hemispheric dominance. For subjects with normal auditory functionality, the AMRSR paradigm evaluation showed significant promise in providing reliable assessments of cerebral language dominance and language network localization.

Factors Predicting Outcome After Intracranial EEG Evaluation in Patients With Medically Refractory Epilepsy.

The aim of this study was to identify predictors of a resective surgery and subsequent seizure freedom following intracranial EEG (ICEEG) for seizure-onset localization. This is a retrospective chart review of 178 consecutive patients with medically refractory epilepsy who underwent ICEEG monitoring from 2002 to 2015. Univariable and multivariable regression analysis identified independent predictors of resection vs other options. Stepwise Akaike information criteria with the aid of clinical consideration were used to select the best multivariable model for predicting resection and outcome. Discrete time survival analysis was used to analyze the factors predicting seizure-free outcome. Cumulative probability of seizure freedom was analyzed using Kaplan-Meier curves and compared between resection and nonresection groups. Additional univariate analysis was performed on 8 select clinical scenarios commonly encountered during epilepsy surgical evaluations. Multivariable analysis identified the presence of a lesional MRI, presurgical hypothesis suggesting temporal lobe onset, and a nondominant hemisphere implant as independent predictors of resection (p < 0.0001, area under the receiver operating characteristic curve 0.80, 95% CI 0.73-0.87). Focal ICEEG onset and undergoing a resective surgery predicted absolute seizure freedom at the 5-year follow-up. Patients who underwent resective surgery were more likely to be seizure-free at 5 years compared with continued medical treatment or neuromodulation (60% vs 7%; p < 0.0001, hazard ratio 0.16, 95% CI 0.09-0.28). Even patients thought to have unfavorable predictors (nonlesional MRI or extratemporal lobe hypothesis or dominant hemisphere implant) had ≥50% chance of seizure freedom at 5 years if they underwent resection. Unfavorable predictors, including having nonlesional extratemporal epilepsy, should not deter a thorough presurgical evaluation, including with invasive recordings in many cases. Resective surgery without functional impairment offers the best chance for sustained seizure freedom and should always be considered first. This study provides Class II evidence that the presence of a lesional MRI, presurgical hypothesis suggesting temporal lobe onset, and a nondominant hemisphere implant are independent predictors of resection. Focal ICEEG onset and undergoing resection are independent predictors of 5-year seizure freedom.

Orthographic neighborhood effects during lateralized lexical decision are abolished with bilateral presentation.

Words presented to the right visual field (RVF) are processed more rapidly than those in the left visual field (LVF), presumably because of more direct links to the language dominant left cerebral hemisphere. This effect is moderated by a word's orthographic neighborhood size (N), with LVF facilitation and RVF inhibition for words with a large N. Across two experiments, we sought to further examine lateralized N effects. Experiment 1 examined how hemispheric dominance for language influenced lateralized N effects, in 140 left-handers using a visual half-field task with bilateral presentation. Neither participants with a right ear advantage on a dichotic listening task nor participants with no right ear advantage showed the expected N effect, making the results ambiguous: it could be that left-handers fail to show N effects, or the effect could be abolished by some procedural aspect. Experiment 2 looked to test these options by testing 56 right-handers who responded to the same stimulus set under the original bilateral presentation condition and under unilateral presentation. N effects were found under unilateral but not bilateral presentation. We had adopted bilateral presentation because it had been recommended as better than unilateral presentation for controlling fixation and visual stimulation; our results indicate that this is not a minor methodological modification: it can dramatically affect lateralized N effects. (PsycInfo Database Record (c) 2022 APA, all rights reserved).

P560. Impaired Obesity Awareness May Be Related to Interhemispheric Imbalance in the Posterior Parietal Areas

The prevalence of obesity is higher in individuals with schizophrenia (40-60%) than the general population. Approximately 80% of overweight individuals fail to achieve sustained weight loss. Several factors may affect adherence to interventions, including impaired obesity awareness. Individuals with poor awareness may underestimate their weight, minimize the risks of obesity and decline or discontinue treatment. This novel study aims to evaluate the neuroanatomical model of impaired illness awareness (IA) in individuals with obesity using fMRI. Based on brain regions identified in other conditions, including schizophrenia, that feature impaired IA, it is proposed that impaired IA may be related to interhemispheric imbalance, specifically left hemisphere dominance in the posterior parietal area (PPA) and medial prefrontal cortex (mPFC).

The Effect of Repetitive Transcranial Magnetic Stimulation of Cerebellar Swallowing Cortex on Brain Neural Activities: A Resting-State fMRI Study

ObjectiveThe effects and possible mechanisms of cerebellar high-frequency repetitive transcranial magnetic stimulation (rTMS) on swallowing-related neural networks were studied using resting-state functional magnetic resonance imaging (rs-fMRI).MethodA total of 23 healthy volunteers were recruited, and 19 healthy volunteers were finally included for the statistical analysis. Before stimulation, the cerebellar hemisphere dominant for swallowing was determined by the single-pulse TMS. The cerebellar representation of the suprahyoid muscles of this hemisphere was selected as the target for stimulation with 10 Hz rTMS, 100% resting motor threshold (rMT), and 250 pulses, with every 1 s of stimulation followed by an interval of 9 s. The motor evoked potential (MEP) amplitude of the suprahyoid muscles in the bilateral cerebral cortex was measured before and after stimulation to evaluate the cortical excitability. Forty-eight hours after elution, rTMS was reapplied on the dominant cerebellar representation of the suprahyoid muscles with the same stimulation parameters. Rs-fMRI was performed before and after stimulation to observe the changes in amplitude of low-frequency fluctuation (ALFF) and regional homology (ReHo) at 0.01–0.08 Hz, 0.01–0.027 Hz, and 0.027–0.073 Hz.ResultsAfter cerebellar high-frequency rTMS, MEP recorded from swallowing-related bilateral cerebral cortex was increased. The results of rs-fMRI showed that at 0.01–0.08 Hz, ALFF was increased at the pons, right cerebellum, and medulla and decreased at the left temporal lobe, and ReHo was decreased at the left insular lobe, right temporal lobe, and corpus callosum. At 0.01–0.027 Hz, ALFF was decreased at the left temporal lobe, and ReHo was decreased at the right temporal lobe, left putamen, and left supplementary motor area.ConclusionRepetitive transcranial magnetic stimulation of the swallowing cortex in the dominant cerebellar hemisphere increased the bilateral cerebral swallowing cortex excitability and enhanced pontine, bulbar, and cerebellar spontaneous neural activity, suggesting that unilateral high-frequency stimulation of the cerebellum can excite both brainstem and cortical swallowing centers. These findings all provide favorable support for the application of cerebellar rTMS in the clinical practice.

Do Adults with Stroke have Altered Interhemispheric Inhibition? A Systematic Review with Meta-Analysis

ObjectiveInterhemispheric inhibition is an important cortical mechanism to support motor control. Altered interhemispheric inhibition has been the target of neuromodulation interventions. This systematic review investigated the evidence for altered interhemispheric inhibition in adults with unilateral neurological conditions: stroke, amyotrophic lateral sclerosis, cerebral palsy, complex regional pain syndrome, traumatic brain injury, and cerebral palsy MethodsWe pre-registered the protocol and followed PRISMA guidelines. Five databases were systematically searched to identify studies reporting interhemispheric inhibition measures in unilateral neurological conditions and healthy controls. Data were grouped according to the measure (ipsilateral silent period and dual-coil), stimulated hemisphere, and stage of the condition (subacute and chronic). Results1372 studies were identified, of which 14 were included (n = 226 adults with stroke and 161 age-matched controls). Ipsilateral silent period-duration was longer in people with stroke than in controls (stimulation of dominant hemisphere) regardless of stroke stage. Motor evoked potential was less suppressed in people with sub-acute stroke (stimulation of the unaffected hemisphere) than controls (stimulation of dominant hemisphere) and this reversed in chronic stroke. ConclusionDetection of altered interhemispheric inhibition appears to be dependent on the measure of interhemispheric inhibition and the stage of recovery. SignificanceRebalancing interhemispheric inhibition using neuromodulation is considered a promising line of treatment for stroke rehabilitation. Our results did not find compelling evidence to support consistent alterations in interhemispheric inhibition in adults with stroke.

Dysfunction in the Interaction of Information Between and Within the Bilateral Primary Sensory Cortex.

BackgroundInterhemispheric and intrahemispheric long-range synchronization and information communication are crucial features of functional integration between the bilateral hemispheres. Previous studies have demonstrated that disrupted functional connectivity (FC) exists in the bilateral hemispheres of patients with carpal tunnel syndrome (CTS), but they did not clearly clarify the phenomenon of central dysfunctional connectivity. This study aimed to further investigate the potential mechanism of the weakened connectivity of primary somatosensory cortex (S1) based on a precise template.MethodsPatients with CTS (n = 53) and healthy control subjects (HCs) (n = 23) participated and underwent resting-state functional magnetic resonance imaging (rs-fMRI) scanning. We used FC to investigate the statistical dependency of the whole brain, effective connectivity (EC) to analyze time-dependent effects, and voxel-mirrored homotopic connectivity (VMHC) to examine the coordination of FC, all of which were adopted to explore the change in interhemispheric and intrahemispheric S1.ResultsCompared to the healthy controls, we significantly found a decreased strength of the two connectivities in the interhemispheric S1hand, and the results of EC and VMHC were basically consistent with FC in the CTS. The EC revealed that the information output from the dominant hemisphere to the contralateral hemisphere was weakened.ConclusionThis study found that maladjusted connections between and within the bilateral S1 revealed by these methods are present in patients with CTS. The dominant hemisphere with deafferentation weakens its effect on the contralateral hemisphere. The disturbance in the bilateral S1 provides reliable evidence to understand the neuropathophysiological mechanisms of decreased functional integration in the brains of patients with CTS.