Presentation, surgical outcome, and supplementary motor area syndrome risk of posterior superior frontal gyrus tumors.

OBJECTIVE: Following resection of posterior superior frontal gyrus (PSFG) tumors, patients can experience supplementary motor area (SMA) syndrome consisting of contralateral hemiapraxia and/or speech apraxia. Given the heterogeneity of PSFG tumors, the authors sought to determine the risk of postoperative deficits and assess predictors of outcomes for all intraparenchymal PSFG tumors undergoing surgery (biopsy or resection), regardless of histology. METHODS: This was a retrospective single-center cohort study of adult PSFG-region tumors undergoing biopsy or resection by a single surgeon. RESULTS: A total of 106 consecutive patients undergoing 123 procedures (21 biopsies, 102 resections) fulfilled inclusion and exclusion criteria. Anaplastic astrocytomas were the most frequent among resected tumors (39% vs 29%), while glioblastomas were most common among biopsies (38% vs 27%) (p < 0.0001). The biopsy cohort was more likely to have tumor involvement outside the PSFG (90% vs 62%) (p = 0.011), most commonly in the motor cortex (67% vs 31%) (p = 0.005). Seizures were the most common presenting symptom in the resection cohort (p = 0.017), while motor deficits were more common in the biopsy cohort (58% vs 29%) (p < 0.001). Immediate postoperative neurological deficits occurred in 71 cases (58%), but only 3 of the deficits were permanent at 6 months of follow-up (2%). Postoperative SMA syndrome occurred in 48 cases (47%) and was significantly associated with involvement of the motor cortex (p = 0.018) or cingulate gyrus (p = 0.023), which were also significant in multivariate analysis as risk factors for SMA syndrome. However, postoperative SMA syndrome was not significantly associated with overall survival (p = 0.51). There were no perioperative deaths, but corpus callosum involvement (p < 0.001), contrast enhancement (p = 0.003), and glioblastoma pathology (p = 0.038) predicted worse overall survival in patients undergoing resection. CONCLUSIONS: Nearly half of all patients undergoing resection of PSFG-region tumors experience a postoperative SMA syndrome. Individuals with corpus callosum and/or motor cortex involvement may be at an increased risk of experiencing SMA syndrome. However, these deficits are usually transient, and the risk of permanent new deficits is very low (3%). Preoperative characteristics including corpus callosum involvement and tumor enhancement-in addition to pathology-might serve as predictors of overall survival within this patient population.

Simulating tDCS electrode placement to stimulate both M1 and SMA enhances motor performance and modulates cortical excitability depending on current flow direction.

Introduction: The conventional method of placing transcranial direct current stimulation (tDCS) electrodes is just above the target brain area. However, this strategy for electrode placement often fails to improve motor function and modulate cortical excitability. We investigated the effects of optimized electrode placement to induce maximum electrical fields in the leg regions of both M1 and SMA, estimated by electric field simulations in the T1and T2-weighted MRI-based anatomical models, on motor performance and cortical excitability in healthy individuals. Methods: A total of 36 healthy volunteers participated in this randomized, triple-blind, sham-controlled experiment. They were stratified by sex and were randomly assigned to one of three groups according to the stimulation paradigm, including tDCS with (1) anodal and cathodal electrodes positioned over FCz and POz, respectively, (A-P tDCS), (2) anodal and cathodal electrodes positioned over POz and FCz, respectively, (P-A tDCS), and (3) sham tDCS. The sit-to-stand training following tDCS (2 mA, 10 min) was conducted every 3 or 4 days over 3 weeks (5 sessions total). Results: Compared to sham tDCS, A-P tDCS led to significant increases in the number of sit-to-stands after 3 weeks training, whereas P-A tDCS significantly increased knee flexor peak torques after 3 weeks training, and decreased short-interval intracortical inhibition (SICI) immediately after the first session of training and maintained it post-training. Discussion: These results suggest that optimized electrode placement of the maximal EF estimated by electric field simulation enhances motor performance and modulates cortical excitability depending on the direction of current flow.

Hyperacusis in Tinnitus Individuals Is Associated with Smaller Gray Matter Volumes in the Supplementary Motor Area Regardless of Hearing Levels.

Recent evidence suggests a connection between hyperacusis and the motor system of the brain. For instance, our recent study reported that hyperacusis in participants with tinnitus and hearing loss is associated with smaller gray matter volumes in the supplementary motor area (SMA). Given that hearing loss can affect gray matter changes in tinnitus, this study aimed to determine if the changes reported in our previous findings of smaller SMA gray matter volumes in hyperacusis persist in the absence of hearing loss. Data for this study were gathered from four prior studies conducted between 2004 and 2019 at the University Medical Centre Groningen (UMCG). A total of 101 participants with tinnitus and either clinically normal hearing (normal hearing with tinnitus or NHT, n = 35) or bilateral sensorineural hearing loss (hearing loss with tinnitus or HLT, n = 66) were included across four studies. Hyperacusis was determined by a score of ≥22 on the Hyperacusis Questionnaire (HQ). In the NHT group, 22 (63%) participants scored ≥22 on the HQ (NHT with hyperacusis: mean age 44.1 years, 12 females), while in the HLT group, 25 (38%) participants scored ≥22 on the HQ (HLT with hyperacusis: mean age 59.5 years, 10 females). The 2 × 2 between-group ANOVAs revealed that hyperacusis is associated with smaller SMA gray matter volumes, regardless of hearing levels. Notably, the smaller SMA gray matter volumes in hyperacusis were primarily influenced by the attentional subscales of the HQ. The association between hyperacusis and the motor system may indicate a constant alertness to sounds and a readiness for motor action.

Causal computations of supplementary motor area on spatial impulsivity.

Spatial proximity to important stimuli often induces impulsive behaviour. How we overcome impulsive tendencies is what determines behaviour to be adaptive. Here, we used virtual reality to investigate whether the spatial proximity of stimuli is causally related to the supplementary motor area (SMA) functions. In two experiments, we set out to investigate these processes using a virtual environment that recreates close and distant spaces to test the causal contributions of the SMA in spatial impulsivity. In an online first experiment (N = 93) we validated and measured the influence of distant stimuli using a go/no-go task with close (21 cm) or distant stimuli (360 cm). In experiment 2 (N = 28), we applied transcranial static magnetic stimulation (tSMS) over the SMA (double-blind, crossover, sham-controlled design) to test its computations in controlling impulsive tendencies towards close vs distant stimuli. Reaction times and error rates (omission and commission) were analysed. In addition, the EZ Model parameters (a, v, Ter and MDT) were computed. Close stimuli elicited faster responses compared to distant stimuli but also exhibited higher error rates, specifically in commission errors (experiment 1). Real stimulation over SMA slowed response latencies (experiment 2), an effect mediated by an increase in decision thresholds (a). Current findings suggest that impulsivity might be modulated by spatial proximity, resulting in accelerated actions that may lead to an increase of inaccurate responses to nearby objects. Our study also provides a first starting point on the role of the SMA in regulating spatial impulsivity.

BOLD signal variability as potential new biomarker of functional neurological disorders.

BACKGROUND: Functional neurological disorder (FND) is a common neuropsychiatric condition with established diagnostic criteria and effective treatments but for which the underlying neuropathophysiological mechanisms remain incompletely understood. Recent neuroimaging studies have revealed FND as a multi-network brain disorder, unveiling alterations across limbic, self-agency, attentional/salience, and sensorimotor networks. However, the relationship between identified brain alterations and disease progression or improvement is less explored. METHODS: This study included resting-state functional magnetic resonance imaging (fMRI) data from 79 patients with FND and 74 age and sex-matched healthy controls (HC). First, voxel-wise BOLD signal variability was computed for each participant and the group-wise difference was calculated. Second, we investigated the potential of BOLD signal variability to serve as a prognostic biomarker for clinical outcome in 47 patients who attended a follow-up measurement after eight months. RESULTS: The results demonstrated higher BOLD signal variability in key networks, including the somatomotor, salience, limbic, and dorsal attention networks, in patients compared to controls. Longitudinal analysis revealed an increase in BOLD signal variability in the supplementary motor area (SMA) in FND patients who had an improved clinical outcome, suggesting SMA variability as a potential state biomarker. Additionally, higher BOLD signal variability in the left insula at baseline predicted a worse clinical outcome. CONCLUSION: This study contributes to the understanding of FND pathophysiology, emphasizing the dynamic nature of neural activity and highlighting the potential of BOLD signal variability as a valuable research tool. The insula and SMA emerge as promising regions for further investigation as prognostic and state markers.

Cortical modulations before lower limb motor blocks are associated with freezing of gait in Parkinson's disease: an EEG source localization study.

BACKGROUND: Freezing of gait (FOG) is a debilitating symptom of Parkinson's disease (PD) characterized by paroxysmal episodes in which patients are unable to step forward. A research priority is identifying cortical changes before freezing in PD-FOG. METHODS: We tested 19 patients with PD who had been assessed for FOG (n=14 with FOG and 5 without FOG). While seated, patients stepped bilaterally on pedals to progress forward through a virtual hallway while 64-channel EEG was recorded. We assessed cortical activities before and during lower limb motor blocks (LLMB), defined as a break in rhythmic pedaling, and stops, defined as movement cessation following an auditory stop cue. This task was selected because LLMB correlates with FOG severity in PD and allows recording of high-quality EEG. Patients were tested after overnight withdrawal from dopaminergic medications ("off" state) and in the "on" medications state. EEG source activities were evaluated using individual MRI and standardized low resolution brain electromagnetic tomography (sLORETA). Functional connectivity was evaluated by phase lag index between seeds and pre-defined cortical regions of interest. RESULTS: EEG source activities for LLMB vs. cued stops localized to right posterior parietal area (Brodmann area 39), lateral premotor area (Brodmann area 6), and inferior frontal gyrus (Brodmann area 47). In these areas, PD-FOG (n=14) increased alpha rhythms (8-12 Hz) before LLMB vs. typical stepping, whereas PD without FOG (n=5) decreased alpha power. Alpha rhythms were linearly correlated with LLMB severity, and the relationship became an inverted U-shape when assessing alpha rhythms as a function of percent time in LLMB in the "off" medication state. Right inferior frontal gyrus and supplementary motor area connectivity was observed before LLMB in the beta band (13-30 Hz). This same pattern of connectivity was seen before stops. Dopaminergic medication improved FOG and led to less alpha synchronization and increased functional connections between frontal and parietal areas. CONCLUSIONS: Right inferior parietofrontal structures are implicated in PD-FOG. The predominant changes were in the alpha rhythm, which increased before LLMB and with LLMB severity. Similar connectivity was observed for LLMB and stops between the right inferior frontal gyrus and supplementary motor area, suggesting that FOG may be a form of "unintended stopping." These findings may inform approaches to neurorehabilitation of PD-FOG.

Reduced TMS-evoked EEG oscillatory activity in cortical motor regions in patients with post-COVID fatigue.

OBJECTIVE: Persistent fatigue is a major symptom of the so-called 'long-COVID syndrome', but the pathophysiological processes that cause it remain unclear. We hypothesized that fatigue after COVID-19 would be associated with altered cortical activity in premotor and motor regions. METHODS: We used transcranial magnetic stimulation combined with EEG (TMS-EEG) to explore the neural oscillatory activity of the left primary motor area (l-M1) and supplementary motor area (SMA) in a group of sixteen post-COVID patients complaining of lingering fatigue as compared to a sample of age-matched healthy controls. Perceived fatigue was assessed with the Fatigue Severity Scale (FSS) and Fatigue Rating Scale (FRS). RESULTS: Post-COVID patients showed a remarkable reduction of beta frequency in both areas. Correlation analysis exploring linear relation between neurophysiological and clinical measures revealed a significant inverse correlation between the individual level of beta oscillations evoked by TMS of SMA with the individual scores in the FRS (r(15) = -0.596; p = 0.012). CONCLUSIONS: Post-COVID fatigue is associated with a reduction of TMS-evoked beta oscillatory activity in SMA. SIGNIFICANCE: TMS-EEG could be used to identify early alterations of cortical oscillatory activity that could be related to the COVID impact in central fatigue.

Treating refractory obsessive compulsive disorder with cathodal transcranial direct current stimulation over the supplementary motor area: a large multisite randomized sham-controlled double-blind study.

Background: The present study evaluated the therapeutic efficacy and tolerability of 10 transcranial direct current stimulation (tDCS) sessions in treatment-resistance obsessive-compulsive disorder (OCD) patients using a multisite double-blind sham-controlled design. Methods: Eighty treatment-resistance outpatients suffering from obsessive-compulsive disorder were randomized to receive either active or sham transcranial direct current stimulation. The cathode was positioned over the supplementary motor area and the anode over the right supraorbital area. Patients were evaluated at baseline, end of treatment (day 14), one-month follow-up (day 45), and three-month follow-up (day 105) on the Yale-Brown Obsessive Compulsive Scale. Results: Although a significant interaction between time and treatment was observed, the primary endpoint-measuring the change in Yale-Brown obsessive compulsive scale scores after two weeks-was not achieved. Conversely, the secondary endpoint, which concerned the change in Yale-Brown obsessive compulsive scale scores after three months, was successfully met. It is important to note, however, that there were no significant differences in the percentage of responders and remitters at any of the post-treatment assessments. This suggests that the treatment may not have had a clinically relevant impact. Patients well received the transcranial direct current stimulation treatment, indicating its good tolerability. Conclusion: This is the largest controlled trial using transcranial direct current stimulation in treatment-resistance obsessive-compulsive disorder patients. Our results indicate the importance of studying the placebo effect in transcranial direct current stimulation and the necessity to consider a long follow-up time to best evaluate the effects of the intervention. Clinical trial registration: ClinicalTrials.gov, identifier NCT03304600.

Effects of transcranial alternating current stimulation to the supplementary motor area on motor learning.

Transcranial alternating current stimulation (tACS) is a noninvasive method for brain stimulation that artificially modulates oscillatory brain activity in the cortical region directly beneath the electrodes by applying a weak alternating current. Beta (ß) oscillatory activity in the supplementary motor area (SMA) is involved in motor planning and maintenance, whereas gamma (γ) oscillatory activity is involved in the updating of motor plans. However, the effect of applying tACS to the SMA on motor learning has not yet been investigated. This study assessed the effects of applying tACS to the SMA on motor learning. Forty-two right-handed healthy adults (age 20.6 ± 0.5 years, 24 men and 18 women) were included. Motor learning was assessed using a visuomotor tracking task with pinch tension of the right thumb and right forefinger. Each trial lasted 60 s, and the error rates were measured. Conductive rubber electrodes were attached to the SMA and the left shoulder for tACS. Stimulation was applied at an intensity of 1.0 mA and frequencies of 70 and 20 Hz in the γ-tACS and ß-tACS treatment groups, respectively. The sham group was only administered a fade-in/out. The visuomotor tracking task was performed for 10 trials before tACS and 10 trials after tACS. Two trials were conducted on the following day to determine motor skill retention. The average deviation measured during 60 s was considered the error value. Pre-stimulation learning rate was calculated as the change in error rate. Post-stimulation learning rate and retention rate were calculated as the change in error rate after stimulation and on the day after stimulation, respectively. In both the stimulation groups, differences in pre-stimulation learning, post-stimulation learning, and retention rates were not significant. However, in the γ-tACS group, baseline performance and pre-stimulation learning rate were positively correlated with post-stimulation learning rate. Therefore, applying γ-tACS to the SMA can increase post-stimulation learning rate in participants exhibiting low baseline performance and high pre-stimulation learning rate. Our findings suggest that motor learning can be effectively enhanced by applying γ-tACS to the SMA based on an individual's motor and learning abilities.

Akinetic mutism following bilateral parasagittal meningioma occupied supplementary motor area removal and the spontaneous recovery of symptoms.

Background: Resection of bilateral parasagittal meningiomas of the dominant cortex is challenging. Some postoperative consequences are difficult to predict due to their low incidence. However, it is essential to recognize reversible symptoms. Akinetic mutism is a devastating but reversible symptom that occurs after supplementary motor area (SMA) injury. This report aims to provide more information to support the clinical progression of this syndrome. Case Description: A 47-year-old woman presented with psychomotor retardation and subtle weakness, particularly on the left side. A palpable mass was identified at the head vertex. Magnetic resonance imaging revealed bilateral parasagittal meningiomas with bone and sinus invasion of the SMA. A craniotomy was performed to remove the intracapsular tumor. Two days after the operation, the patient developed gradual deterioration in her motor function until it became a lock-in-like syndrome. Then, 1.5 months after treatment in the hospital and rehabilitation unit, she gradually improved her motor, cognitive, and psychomotor skills. Total recovery was achieved after 1 year. Conclusion: Surgery for lesions involving bilateral SMA can cause akinetic mutism. The typical manifestation of this syndrome may be devastating. However, it is reversible, and patients can regain full motor and cognitive functions over time without specific treatments. It is crucial to persevere and continue to provide the best care to the patient until recovery.

Prolonged intermittent theta burst stimulation for post-stroke aphasia: protocol of a randomized, double-blinded, sham-controlled trial.

Background: Post-stroke aphasia (PSA) is one of the most devastating symptoms after stroke, yet limited treatment options are available. Prolonged intermittent theta burst stimulation (piTBS) is a promising therapy for PSA. However, its efficacy remains unclear. Therefore, we aim to investigate the efficacy of piTBS over the left supplementary motor area (SMA) in improving language function for PSA patients and further explore the mechanism of language recovery. Methods: This is a randomized, double-blinded, sham-controlled trial. A total of 30 PSA patients will be randomly allocated to receive either piTBS stimulation or sham stimulation for 15 sessions over a period of 3 weeks. The primary outcome is the Western Aphasia Battery Revised (WAB-R) changes after treatment. The secondary outcomes include The Stroke and Aphasia Quality of Life Scale (SAQOL-39 g), resting-state electroencephalogram (resting-state EEG), Event-related potentials (ERP), brain derived neurotrophic factor (BDNF). These outcome measures are assessed before treatment, after treatment, and at 4-weeks follow up. This study was registered in Chinese Clinical Trial Registry (No. ChiCTR23000203238). Discussion: This study protocol is promising for improving language in PSA patients. Resting-state EEG, ERP, and blood examination can be used to explore the neural mechanisms of PSA treatment with piTBS. Clinical trial registration: https://www.chictr.org.cn/index.html, ChiCTR2300074533.

Effects of Combining Transcranial Direct Current Stimulation With Balance Training on Anticipatory Postural Adjustments in Persons With Chronic Ankle Instability.

BACKGROUND: The combination of transcranial direct current stimulation (tDCS) with balance training could integrate central and peripheral neural mechanisms. This study aimed to investigate the effects of concurrent balance training and tDCS over the supplementary motor area (SMA) on anticipatory postural adjustments during gait initiation (GI) in persons with chronic ankle instability (CAI). HYPOTHESIS: Balance training will increase the center of pressure (COP) velocity and displacement during GI phases in all participants, and those receiving real tDCS will show greater increases. STUDY DESIGN: Randomized controlled trial. LEVEL OF EVIDENCE: Level 2. METHODS: A total of 32 subjects were allocated to 2 groups: (1) intervention (balance training plus real tDCS) and (2) control (balance training plus sham tDCS). Outcome measures were COP-related parameters (displacement and velocity) during phases of GI (anticipatory, weight transition, and locomotor). RESULTS: The results showed that, in the anticipatory phase, the anteroposterior displacement of the COP was increased significantly at posttest relative to pretest across both groups, F(1,30) = 5.733, P = 0.02. In addition, both groups revealed an increase in the mediolateral COP velocity at posttest, F(1,30) = 10.523, P < 0.01. In the weight transition phase, both groups had higher mediolateral COP velocity at posttest, F(1,30) = 30.636, P < 0.01. In the locomotor phase, in both groups, the anteroposterior COP velocity was increased significantly at posttest compared with pretest, F(1,30) = 5.883, P = 0.02. CONCLUSION: Both groups demonstrated improvements in the anticipatory and execution phases of GI. Since no between-group difference was found, it can be interpreted that the anodal tDCS applied over the SMA has no added value over sham stimulation. CLINICAL RELEVANCE: Balance training is beneficial for persons with CAI and can improve the anticipation and execution phases of GI without the aid of brain stimulation.

Anatomical analysis of white fiber tracts in SMA and its implications related to en-masse tumor resection technique.

OBJECTIVE: Anatomy and connections of the supplementary motor area (SMA) are studied essentially to analyze the SMA syndrome. Experience with surgical treatment of 19 tumors located in SMA is analyzed. MATERIAL AND METHODS: The cortical anatomy and subcortical connectivity of the SMA was studied on ten previously frozen and formalin fixed human cadaveric brain specimens. The white fiber dissection was performed using Klingler's method. Nineteen patients with low grade gliomas in the region of the SMA treated surgically were clinically analyzed. RESULTS: The white fiber connections of the SMA include short arcuate connections with the pre-central, middle and inferior frontal gyri, the medial part of the SLF, the cingulum, the frontal aslant tract (FAT), the claustro-cortical fibers, the fronto-striatal tract and the crossed frontal aslant tract. All tumors were operated using en-masse surgical technique described by us and its subsequent modifications that focused on attempts towards preservation of related critical fiber tracts namely FAT, cingulum and corpus callosum presumed to be responsible for postoperative SMA syndrome. Eight patients developed an SMA syndrome in the immediate post-operative period. Eleven patients did not develop any post-operative neurological deficits. In all these 11 patients it was apparent that the cingulum, FAT and the corpus callosal fibers were preserved during surgery by modifying the tumor resection technique. CONCLUSIONS: SMA syndrome is a frequent occurrence following surgery in patients with tumors in the region of the SMA complex. Surgical strategy that preserves the cingulum and the FAT can prevent the occurrence of the SMA syndrome.

A modified neural circuit framework for semantic memory retrieval with implications for circuit modulation to treat verbal retrieval deficits.

Word finding difficulty is a frequent complaint in older age and disease states, but treatment options are lacking for such verbal retrieval deficits. Better understanding of the neurophysiological and neuroanatomical basis of verbal retrieval function may inform effective interventions. In this article, we review the current evidence of a neural retrieval circuit central to verbal production, including words and semantic memory, that involves the pre-supplementary motor area (pre-SMA), striatum (particularly caudate nucleus), and thalamus. We aim to offer a modified neural circuit framework expanded upon a memory retrieval model proposed in 2013 by Hart et al., as evidence from electrophysiological, functional brain imaging, and noninvasive electrical brain stimulation studies have provided additional pieces of information that converge on a shared neural circuit for retrieval of memory and words. We propose that both the left inferior frontal gyrus and fronto-polar regions should be included in the expanded circuit. All these regions have their respective functional roles during verbal retrieval, such as selection and inhibition during search, initiation and termination of search, maintenance of co-activation across cortical regions, as well as final activation of the retrieved information. We will also highlight the structural connectivity from and to the pre-SMA (e.g., frontal aslant tract and fronto-striatal tract) that facilitates communication between the regions within this circuit. Finally, we will discuss how this circuit and its correlated activity may be affected by disease states and how this circuit may serve as a novel target engagement for neuromodulatory treatment of verbal retrieval deficits.

Cortico-cortical connectivity is influenced by levodopa in tremor-dominant Parkinson's disease.

Resting tremor is the most common presenting motor symptom in Parkinson's disease (PD). The supplementary motor area (SMA) is a main target of the basal-ganglia-thalamo-cortical circuit and has direct, facilitatory connections with the primary motor cortex (M1), which is important for the execution of voluntary movement. Dopamine potentially modulates SMA and M1 activity, and both regions have been implicated in resting tremor. This study investigated SMA-M1 connectivity in individuals with PD ON and OFF dopamine medication, and whether SMA-M1 connectivity is implicated in resting tremor. Dual-site transcranial magnetic stimulation was used to measure SMA-M1 connectivity in PD participants ON and OFF levodopa. Resting tremor was measured using electromyography and accelerometry. Stimulating SMA inhibited M1 excitability OFF levodopa, and facilitated M1 excitability ON levodopa. ON medication, SMA-M1 facilitation was significantly associated with smaller tremor than SMA-M1 inhibition. The current findings contribute to our understanding of the neural networks involved in PD which are altered by levodopa medication and provide a neurophysiological basis for the development of interventions to treat resting tremor.

Isolation of Distinct Networks Driving Action and Cognition in Psychomotor Processes.

BACKGROUND: Psychomotor disturbances are observed across psychiatric disorders and often manifest as psychomotor slowing, agitation, disorganized behavior, or catatonia. Psychomotor function includes both cognitive and motor components, but the neural circuits driving these subprocesses and how they relate to symptoms have remained elusive for centuries. METHODS: We analyzed data from the HCP-EP (Human Connectome Project for Early Psychosis), a multisite study of 125 participants with early psychosis and 58 healthy participants with resting-state functional magnetic resonance imaging and clinical characterization. Psychomotor function was assessed using the 9-hole pegboard task, a timed motor task that engages mechanical and psychomotor components of action, and tasks assessing processing speed and task switching. We used multivariate pattern analysis of whole-connectome data to identify brain correlates of psychomotor function. RESULTS: We identified discrete brain circuits driving the cognitive and motor components of psychomotor function. In our combined sample of participants with psychosis (n = 89) and healthy control participants (n = 52), the strongest correlates of psychomotor function (pegboard performance) (p < .005) were between a midline cerebellar region and left frontal region and presupplementary motor area. Psychomotor function was correlated with both cerebellar-frontal connectivity (r = 0.33) and cerebellar-presupplementary motor area connectivity (r = 0.27). However, the cognitive component of psychomotor performance (task switching) was correlated only with cerebellar-frontal connectivity (r = 0.19), whereas the motor component (processing speed) was correlated only with cerebellar-presupplementary motor area connectivity (r = 0.15), suggesting distinct circuits driving unique subprocesses of psychomotor function. CONCLUSIONS: We identified cerebellar-cortical circuits that drive distinct subprocesses of psychomotor function. Future studies should probe relationships between cerebellar connectivity and psychomotor performance using neuromodulation.

A revision of the dorsal origin of the frontal aslant tract (FAT) in the superior frontal gyrus: a DWI-tractographic study.

The frontal aslant tract (FAT) is a white matter tract connecting the superior frontal gyrus (SFG) to the inferior frontal gyrus (IFG). Its dorsal origin is identified in humans in the medial wall of the SFG, in the supplementary motor complex (SM-complex). However, empirical observation shows that many FAT fibres appear to originate from the dorsal, rather than medial, portion of the SFG. We quantitatively investigated the actual origin of FAT fibres in the SFG, specifically discriminating between terminations in the medial wall and in the convexity of the SFG. We analysed data from 105 subjects obtained from the Human Connectome Project (HCP) database. We parcelled the cortex of the IFG, dorsal SFG and medial SFG in several regions of interest (ROIs) ordered in a caudal-rostral direction, which served as seed locations for the generation of streamlines. Diffusion imaging data (DWI) was processed using a multi-shell multi-tissue CSD-based algorithm. Results showed that the number of streamlines originating from the dorsal wall of the SFG significantly exceeds those from the medial wall of the SFG. Connectivity patterns between ROIs indicated that FAT sub-bundles are segregated in parallel circuits ordered in a caudal-rostral direction. Such high degree of coherence in the streamline trajectory allows to establish pairs of homologous cortical parcels in the SFG and IFG. We conclude that the frontal origin of the FAT is found in both dorsal and medial surfaces of the superior frontal gyrus.

Fronto-Cerebellar Diaschisis and Cognitive Dysfunction after Pontine Stroke: A Case Series and Systematic Review.

It is well known that cortical damage may affect cognitive functions, whereas subcortical damage, especially brainstem stroke, would be far less likely to cause cognitive decline, resulting in this condition being overlooked. Few studies have focused on cognitive dysfunction after a pontine stroke. Here, we begin with describing our nine new case reports of in-depth neuropsychological findings from patients with pontine stroke. The dominant domain of cognitive dysfunction was commonly characterized by executive dysfunction, almost in line with previous studies. The severity was relatively mild. We give an overview of the available literature on cognitive decline following a pontine stroke. This is followed by discussions regarding the prognosis of the cognitive disabilities. Based on previous neuroimaging findings, we would like to get to the core of the neuropathology underlying the cognitive declines in the context of "diaschisis", a phenomenon of a broad range of brain dysfunctions remote from the local lesions. Specifically, our unique paper, with two modalities of neuroimaging techniques, may help us better understand the pathology. SPECT scans yield evidence of frontal and thalamic hyper-perfusion and cerebellar hypo-perfusion in patients with pontine stroke. Functional near-infrared spectroscopy, when focusing on the supplementary motor area (SMA) as one of the hyper-perfusion areas, exhibits that SMA responses may be subject to the severity of cognitive decline due to a pontine stroke and would also be related to the recovery. Finally, we posit that cognitive decline due to pontine stroke could be explained by the failure of hierarchical cognitive processing in the fronto-ponto-cerebellar-thalamic loop.

Permanent deterioration of fine motor skills after the resection of tumors in the supplementary motor area.

Supplementary motor area syndrome (SMAS) represents a common neurosurgical sequela. The incidence and time frame of its occurrence have yet to be characterized after surgery for brain tumors. We examined patients suffering from a brain tumor preoperatively, postoperatively, and during follow-up examinations after three months, including fine motor skills testing and transcranial magnetic stimulation (TMS). 13 patients suffering from a tumor in the dorsal part of the superior frontal gyrus underwent preoperative, early postoperative, and 3-month follow-up testing of fine motor skills using the Jebsen-Taylor Hand Function Test (JHFT) and the Nine-Hole Peg Test (NHPT) consisting of 8 subtests for both upper extremities. They completed TMS for cortical motor function mapping. Test completion times (TCTs) were recorded and compared. No patient suffered from neurological deficits before surgery. On postoperative day one, we detected motor deficits in two patients, which remained clinically stable at a 3-month follow-up. Except for page-turning, every subtest indicated a significant worsening of function, reflected by longer TCTs (p < 0.05) in the postoperative examinations for the contralateral upper extremity (contralateral to the tumor manifestation). At 3-month follow-up examinations for the contralateral upper extremity, each subtest indicated significant worsening compared to the preoperative status despite improvement to the immediate postoperative level. We also detected significantly longer TCTs (p < 0.05) postoperatively in the ipsilateral upper extremity. This study suggests a long-term worsening of fine motor skills even three months after SMA tumor resection, indicating the necessity of targeted physical therapy for these patients.

The role of preSMA and STS in face recognition: A transcranial magnetic stimulation (TMS) study.

Current models propose that facial recognition is mediated by two independent yet interacting anatomo-functional systems: one processing facial features mainly mediated by the Fusiform Face Area and the other involved in the extraction of dynamic information from faces, subserved by Superior Temporal Sulcus (STS). Also, the pre-Supplementary Motor Area (pre-SMA) is implicated in facial expression processing as it is involved in its motor mimicry. However, the literature only shows evidence of the implication of STS and preSMA for facial expression recognition, without relating it to face recognition. In addition, the literature shows a facilitatory role of facial motion in the recognition of unfamiliar faces, particularly for poor recognizers. The present study aimed at studying the role of STS and preSMA in unfamiliar face recognition in people with different face recognition skills. 34 healthy participants received repetitive transcranial magnetic stimulation over the right posterior STS, pre-SMA and as sham during a task of matching of faces encoded through: facial expression, rigid head movement or as static (i.e., absence of any facial or head motion). All faces were represented without emotional content. Results indicate that STS has a direct role in recognizing identities through rigid head movement and an indirect role in facial expression processing. This dissociation represents a step forward with respect to current face processing models suggesting that different types of motion involve separate brain and cognitive processes. PreSMA interacts with face recognition skills, increasing the performance of poor recognizers and decreasing that of good recognizers in all presentation conditions. Together, the results suggest the use of at least partially different mechanisms for face recognition in poor and good recognizers and a different role of STS and preSMA in face recognition.