Premotor Research Articles

Spatiotemporal integration of contextual and sensory information within the cortical hierarchy in human pain experience

Pain is not a mere reflection of noxious input. Rather, it is constructed through the dynamic integration of current predictions with incoming sensory input. However, the temporal dynamics of the behavioral and neural processes underpinning this integration remain elusive. In the current study involving 59 human participants, we identified a series of brain mediators that integrated cue-induced expectations with noxious inputs into ongoing pain predictions using a semicircular scale designed to capture rating trajectories. Temporal mediation analysis revealed that during the early-to-mid stages of integration, the frontoparietal and dorsal attention network regions, such as the lateral prefrontal, premotor, and parietal cortex, mediated the cue effects. Conversely, during the mid-to-late stages of integration, the somatomotor network regions mediated the effects of stimulus intensity, suggesting that the integration occurs along the cortical hierarchy from the association to sensorimotor brain systems. Our findings advance the understanding of how the brain integrates contextual and sensory information into pain experience over time.

Abstract 4121198: Structural Network Alterations After Cardiopulmonary Bypass In a Juvenile Porcine Model

Background: Cardiopulmonary bypass (CPB) can trigger inflammatory and oxidative stresses in the developing brain. Clinical studies showed altered brain network structure in children after infant cardiac surgery. However, the impact of CPB on structural connectivity remains poorly understood. This study aims to determine the effects of CPB on structural connectivity and underlying cellular events using a juvenile porcine model. Methods: CPB (150 min total) was performed on 2-week-old Yorkshire piglets. High-resolution diffusion tensor imaging (DTI) and neurite orientation dispersion and density (NODDI) imaging were performed 4 weeks post-CPB in a total of 12 animals (Control; n=7, CPB; n=5). Structural connectivity assay together with histological analysis was conducted to assess the brain network organization. Results: Our network analysis (Image 1) revealed a CPB-induced reduction of structural connections in particular nodes, such as in the anterior prefrontal cortex (APC), primary somatosensory cortex, substantia nigra (SN), and globus pallidus (GP). In contrast, there was an increase in the premotor cortex (PreMC), primary motor cortex (PriMC), dorsal posterior cingulate cortex (DPCC), and somatosensory cortex (SAC). Three-dimensional images were generated based on these altered nodes, and tractography was generated to indicate changed fiber tracking (Image 2). We found reduced network connections between the basal ganglia and frontal cortex, and increased connections between the motor and posterior region. DTI and NODDI indicated that microstructures of the superior corona radiata (SCR), internal capsule (PLIC), and anterior prefrontal (AP-WM), motor (PreM-/PriM-WM), and somatosensory white matter (SA-WM) were significantly altered after CPB (Image 3). While Iba1+ microglia was activated across all brain regions after CPB (P<.05), CPB-induced oligodendrocyte immatureness was identified in the WMs involved in APC-SN and APC-GP pathways (P<.05). Notably, CPB increased the number of mature oligodendrocytes in motor and SA-WMs (P<.05) where structural connections were increased after CPB. In addition, we found SN dopaminergic neuron injury after CPB (P<.05). Conclusion: CPB altered structural network organization in the developing brain. Spatial differences in oligodendrocyte responses and susceptibility of specific subpopulations of neurons may contribute to the unique connectivity alterations observed after CPB.

Altered callosal morphology in post-stroke cognitive impairment

Stroke is the second leading cause of death and cognitive impairment. Post-stroke cognitive impairment (PSCI) is one of the most common sequelae among stroke survivors, yet its underlying neural mechanisms remain largely unclear. The corpus callosum (CC) plays a crucial role in interhemispheric integration and hemispheric segregation, with changes in CC morphology potentially overlapping with the spectrum of PSCI. This study aimed to investigate the morphological changes in the CC and their diagnostic value in PSCI patients. Structural MRI, neurobehavioral, and clinical data were collected from 104 PSCI patients and 54 demographically matched healthy controls. Significant reductions in CC area, circularity, and genu thickness were observed in PSCI patients, with these changes strongly correlating with global cognitive function. Subgroup analysis revealed that CC circularity significantly decreased when lesions were located in the posterior circulation, while both CC area and circularity markedly decreased with anterior circulation lesions. Receiver Operating Characteristic analyses identified the midbody areas of the CC as having high diagnostic value, with area under the curve values of 0.748 and 0.746, respectively. Further validation analyses suggest that the transcallosal fibers in these CC subregions are connected to the premotor, dorsal attention, and frontoparietal system. These findings show that areal CC atrophy in PSCI patients, particularly in regions with transcallosal connections to the premotor cortex and frontoparietal network, parallels global cognitive impairment. This suggests that CC morphology may serve as a potential imaging marker for the diagnosis and prognosis of PSCI.

Characterising the contribution of auditory and somatosensory inputs to TMS-evoked potentials following stimulation of prefrontal, premotor, and parietal cortex

Abstract Transcranial magnetic stimulation (TMS) results in a series of deflections in electroencephalography (EEG) recordings known as a TMS-evoked potential (TEP). However, it remains unclear whether these responses reflect neural activity resulting from transcranial stimulation of the cortex, the sensory experiences of TMS, or a combination of the two. Across three experiments (total n = 135), we recorded EEG activity following TMS to the dorsolateral prefrontal cortex, premotor cortex, and parietal cortex as well as a sensory control condition (stimulation of the shoulder or electrical stimulation of the scalp with a click sound). We found that TEPs showed a stereotypical frontocentral N100/P200 complex following TMS of all cortical sites and control conditions, regardless of TMS intensity or the type of sensory control. In contrast, earlier TEPs (<60 ms) showed site-specific characteristics which were largest at the site of stimulation, although TEP topographies were distorted in a subgroup of individuals due to residual TMS-evoked muscle artefact despite cleaning with independent component analysis. Self-reported sensory experiences differed across sites, with prefrontal stimulation resulting in stronger auditory (click sound perception) and somatosensory input (scalp muscle twitch, discomfort) than premotor or parietal stimulation, a pattern that was reflected in the amplitude of later (N100/P200), but not earlier (<60 ms), TEP peak amplitudes. Later TEPs were also larger in individuals who experienced stronger click sound perception and, to a lesser extent, TMS-evoked scalp muscle twitches. Increasing click sound perception by removing auditory masking increased N100/P200 amplitudes without altering earlier peaks, an effect which was more prominent at sites with more successful masking. Together, these findings suggest that the frontocentral N100/P200 complex primarily represents a generalised sensory response resulting from TMS-related auditory and somatosensory input when present. In contrast, early TEP peaks likely primarily reflect activity resulting from transcranial stimulation of the cortex when artefacts were adequately accounted for. The results have important implications for designing and interpreting TEP studies, especially when comparing TEPs between stimulation sites and participant groups showing differences in sensory experiences following TMS.

Frontoparietal Structural Network Disconnections Correlate With Outcome After a Severe Stroke.

Structural disconnectome analyses have provided valuable insights into how a stroke lesion results in widespread network disturbances and how these relate to deficits, recovery patterns, and outcomes. Previous analyses have primarily focused on patients with relatively mild to moderate deficits. However, outcomes vary among survivors of severe strokes, and the mechanisms of recovery remain poorly understood. This study assesses the association between lesion-induced network disconnection and outcome after severe stroke. Thirty-eight ischaemic stroke patients underwent MRI brain imaging early after stroke and longitudinal clinical follow-up. Lesion information was integrated with normative connectome data to infer individual disconnectome profiles on a localized regional and region-to-region pathway level. Ordinal logistic regressions were computed to link disconnectome information to the modified Rankin Scale after 3-6 months. Disconnections of ipsilesional frontal, parietal, and temporal cortical brain areas were significantly associated with a worse motor outcome after a severe stroke, adjusted for the initial deficit, lesion volume, and age. The analysis of the underlying pathways mediating this association revealed location-specific results: For frontal, prefrontal, and temporal brain areas, the association was primarily driven by relatively sparse intrahemispheric disconnections. In contrast, the ipsilesional primary motor cortex, the dorsal premotor cortex, and various parietal brain regions showed a remarkable involvement of either frontoparietal intrahemispheric or additionally interhemispheric disconnections. These results indicate that localized disconnection of multiple regions embedded in the structural frontoparietal network correlates with worse outcomes after severe stroke. Specifically, primary motor and parietal cortices might gain particular importance as they structurally link frontoparietal networks of both hemispheres. These data shed novel light on the significance of distinct brain networks for recovery after a severe stroke.

Effects of robot-assisted hand function therapy on brain functional mechanisms: a synchronized study using fNIRS and sEMG

BackgroundRobot-assisted hand function therapy is pivotal in the rehabilitation of patients with stroke; however, its therapeutic mechanism remains elusive. Currently, research examining the impact of robot-assisted hand function therapy on brain function in patients with stroke is scarce, and there is a lack of studies investigating the correlation between muscle activity and alterations in brain function.ObjectiveThis study aimed to investigate the correlation between forearm muscle movement and brain functional activation by employing the synchronized use of functional near-infrared spectroscopy and surface electromyography methods. Moreover, it sought to compare neural activity patterns during different rehabilitation tasks and refine the mechanism of robot-assisted hand function therapy for post-stroke hand function impairments.MethodsStroke patients with hand dysfunction underwent three sessions of robot-assisted hand function therapy within 2 weeks to 3 months of onset. The fNIRS-sEMG synchronous technique was used to observe brain function and forearm muscle activation. Ten participants were randomly assigned to receive mirror, resistance, or passive rehabilitation training. During the intervention, cortical and muscle activation information was obtained using fNIRS and electromyographic signals. The primary outcomes included changes in oxyhemoglobin concentration and root mean square of surface electromyography.ResultsCompared to the resting state, the Oxy-Hb concentration in the brain regions involved in three rehabilitation tasks with robot-assisted hand function therapy significantly increased (p < 0.05). Mirror therapy significantly enhanced the prefrontal cortex and the superior frontal cortex activation levels. In contrast, resistance therapy significantly promoted the activation of the supplementary motor area and the premotor cortex. Passive rehabilitation tasks showed some activation in the target brain area premotor cortex region. Robot-assisted hand function therapy has shown that forearm muscle movement is closely related to oxygenated hemoglobin concentration activity in specific brain regions during different rehabilitation tasks.ConclusionThe simultaneous sEMG-fNIRS study found a significant correlation between muscle movement and brain activity after stroke, which provides an important basis for understanding the treatment mechanism of hand function impairment.

Task-switching mechanisms under methamphetamine cravings: sex differences in cued and voluntary task-switching

IntroductionThis study explored the effects of task-switching type and sex on the task-switching ability of methamphetamine abstainers, as well as the differences in brain mechanisms under drug cravings under drug cravings using near-infrared spectroscopy.MethodsCraving-inducing videos were used to arouse 20 methamphetamine abstainers (including 10 men), whose switching ability was then assessed using voluntary and cued task-switching exercises.ResultsDuring task-switching under methamphetamine cravings, the activation of the premotor cortex (PMC), supplementary motor area (SMA), frontal eye field (FEF), and dorsolateral prefrontal cortex (DLPFC) in women was significantly stronger than in men, while the activation of FEF in men was significantly stronger than in women. Voluntary task-switching induced stronger FEF activation than cued task-switching. During the latter, women exhibited stronger activation in the anterior prefrontal cortex (aPFC) than men.DiscussionBoth men and women showed brain lateralization during task-switching under methamphetamine cravings. Men tended to adopt proactive control and use a top-down dominant strategy to start a new task. Women, however, tend to use a bottom-up strategy focusing on inhibiting old tasks and emotional switching. Moreover, in cued task-switching, the result shows women paid more attention to emotional processing than did men, which suggests that different task-switching training programs should be developed according to sex.

Directional Subthalamic Deep Brain Stimulation Better Improves Gait and Balance Disorders in Parkinson's Disease Patients: A Randomized Controlled Study.

To investigate the effects of directional subthalamic deep brain stimulation (STN-dDBS) on gait and balance disorders, including freezing of gait (FOG), in patients with advanced Parkinson's disease (PD). We included 10 participants who underwent STN-DBS and presented severe preoperative FOG, in a randomized, double-blind, crossover study. We used segmented DBS electrodes to investigate whether directing the predicted volume of tissue activated (VTA) to overlap the central STN preferentially improved gait and balance disorders compared to directional DBS applied in the more posterior STN (sensorimotor). We also assessed non-directional (ring-mode) STN-DBS. Our primary outcome was gait and balance control measured using instrumented gait recordings. Each patient had a pre-operative structural and diffusion-weighted imaging to model individual VTAs and to examine cortico-subthalamic connectivity. We used linear mixed-effects models to contrast the effects of central STN-dDBS, posterior STN-dDBS, and ring-mode STN-DBS. Central STN-dDBS produced significantly better improvement in gait and balance control compared to posterior STN-dDBS (p = 0.027), with fewer FOG episodes (p < 0.001). Conversely, ring-mode STN-DBS resulted in worsened postural control compared to central STN-dDBS (p = 0.009). The cortico-subthalamic connectivity with the STN VTAs involved mostly primary sensorimotor, premotor, and medial frontal cortices, with a higher overall cortico-STN connectivity with ring-mode STN-DBS. Central STN-dDBS represents the best option to improve gait and balance disorders in PD patients, including FOG. Our findings raise the possibility of reprogramming STN-DBS toward the central area in selected patients with disabling FOG and/or postural instability after surgery. ANN NEUROL 2024.

Investigation of the transcallosal ventral premotor cortex connection in humans using transcranial magnetic stimulation

Background: The premotor cortex plays a role in the planning of movement. Previous transcranial magnetic stimulation (TMS) studies have shown ipsilateral premotor-to-motor inhibition in healthy subjects at rest. Moreover, this premotor-to-motor inhibition has been found to be modulated during preparation for movement, such as precision grip and whole hand grasp. Cooperation between the bilateral ventral premotor cortices may play a functional role. We aimed to investigate the influence of the contralateral on the ipsilateral ventral premotor cortex.Methods: Fourteen right-handed healthy subjects (six women and eight men; mean age, 37 years; standard deviation, 14 years) completed the study. We used a three single-pulse TMS paradigm (preconditioning, conditioning and test pulse) to sequentially stimulate the right ventral premotor cortex, left ventral premotor cortex and left primary motor cortex.Results: We found that in healthy subjects at rest, stimulating the contralateral ventral premotor cortex resulted in reversal of the resting premotor-to-motor inhibition.Conclusions: Our results suggest that the contralateral ventral premotor cortex exerts an inhibitory influence on the ipsilateral ventral premotor cortex, which may be a component of bi-hemispheric control of manual tasks. This is the first study to evaluate the functional connectivity between the bilateral ventral premotor cortices.

From Sound to Movement: Mapping the Neural Mechanisms of Auditory–Motor Entrainment and Synchronization

Background: Humans exhibit a remarkable ability to synchronize their actions with external auditory stimuli through a process called auditory–motor or rhythmic entrainment. Positive effects of rhythmic entrainment have been demonstrated in adults with neurological movement disorders, yet the neural substrates supporting the transformation of auditory input into timed rhythmic motor outputs are not fully understood. We aimed to systematically map and synthesize the research on the neural correlates of auditory–motor entrainment and synchronization. Methods: Following the PRISMA-ScR guidelines for scoping reviews, a systematic search was conducted across four databases (MEDLINE, Embase, PsycInfo, and Scopus) for articles published between 2013 and 2023. Results: From an initial return of 1430 records, 22 studies met the inclusion criteria and were synthesized based on the neuroimaging modality. There is converging evidence that auditory–motor synchronization engages bilateral cortical and subcortical networks, including the supplementary motor area, premotor cortex, ventrolateral prefrontal cortex, basal ganglia, and cerebellum. Specifically, the supplementary motor area and the basal ganglia are essential for beat-based timing and internally guided rhythmic movements, while the cerebellum plays an important role in tracking and processing complex rhythmic patterns and synchronizing to the external beat. Self-paced tapping is associated with additional activations in the prefrontal cortex and the basal ganglia, suggesting that tapping in the absence of auditory cues requires more neural resources. Lastly, existing studies indicate that movement rate and the type of music further modulate the EEG power in the alpha and beta frequency bands. Conclusions: These findings are discussed in the context of clinical implications and rhythm-based therapies.

Meta-learning of human motor adaptation via the dorsal premotor cortex

Meta-learning enables us to learn how to learn the same or similar tasks more efficiently. Decision-making literature theorizes that a prefrontal network, including the orbitofrontal and anterior cingulate cortices, underlies meta-learning of decision making by reinforcement learning. Recently, computationally similar meta-learning has been theorized and empirically demonstrated in motor adaptation. However, it remains unclear whether meta-learning of motor adaptation also relies on a prefrontal network. Considering hierarchical information flow from the prefrontal to motor cortices, this study explores whether meta-learning is processed in the dorsolateral prefrontal cortex (DLPFC) or in the dorsal premotor cortex (PMd), which is situated upstream of the primary motor cortex, but downstream of the DLPFC. Transcranial magnetic stimulation (TMS) was delivered to either PMd or DLPFC during a motor meta-learning task, in which human participants were trained to regulate the rate and retention of motor adaptation to maximize rewards. While motor adaptation itself was intact, TMS to PMd, but not DLPFC, attenuated meta-learning, impairing the ability to regulate motor adaptation to maximize rewards. Further analyses revealed that TMS to PMd attenuated meta-learning of memory retention. These results suggest that meta-learning of motor adaptation relies more on the premotor area than on a prefrontal network. Thus, while PMd is traditionally viewed as crucial for planning motor actions, this study suggests that PMd is also crucial for meta-learning of motor adaptation, processing goal-directed planning of how long motor memory should be retained to fit the long-term goal of motor adaptation.

A subcortical feeding circuit linking an interoceptive node to jaw movement.

The brain processes an array of stimuli, enabling the selection of appropriate behavioural responses, but the neural pathways linking interoceptive inputs to outputs for feeding are poorly understood1-3. Here we delineate a subcortical circuit in which brain-derived neurotrophic factor (BDNF)-expressing neurons in the ventromedial hypothalamus (VMH) directly connect interoceptive inputs to motor centres, controlling food consumption and jaw movements. VMHBDNF neuron inhibition increases food intake by gating motor sequences of feeding through projections to premotor areas of the jaw. When food is unavailable, VMHBDNF inhibition elicits consummatory behaviours directed at inanimate objects such as wooden blocks, and inhibition of perimesencephalic trigeminal area (pMe5) projections evokes rhythmic jaw movements. The activity of these neurons is decreased during food consumption and increases when food is in proximity but not consumed. Activity is also increased in obese animals and after leptin treatment. VMHBDNF neurons receive monosynaptic inputs from both agouti-related peptide (AgRP) and proopiomelanocortin neurons in the arcuate nucleus (Arc), and constitutive VMHBDNF activation blocks the orexigenic effect of AgRP activation. These data indicate an Arc → VMHBDNF → pMe5 circuit that senses the energy state of an animal and regulates consummatory behaviours in a state-dependent manner.

An ANN models cortical-subcortical interaction during post-stroke recovery of finger dexterity.

Finger dexterity, and finger individuation in particular, is crucial for human movement, and disruptions due to brain injury can significantly impact quality of life. Understanding the neurological mechanisms responsible for recovery is vital for effective neurorehabilitation. This study explores the role of two key pathways in finger individuation: the corticospinal tract (CST) from the primary motor cortex and premotor areas, and the subcortical reticulospinal tract (RST) from the brainstem. We aimed to investigate how the cortical-reticular network reorganizes to aid recovery of finger dexterity following lesions in these areas. To provide a potential biologically plausible answer to this question, we developed an artificial neural network (ANN) to model the interaction between a premotor planning layer, a cortical layer with excitatory and inhibitory corticospinal outputs, and reticulospinal outputs controlling finger movements. The ANN was trained to simulate normal finger individuation and strength. A simulated stroke was then applied to the corticospinal (CS) area, reticulospinal (RS) area, or both, and the recovery of finger dexterity was analyzed. In the intact model, the ANN demonstrated a near-linear relationship between the forces of instructed and uninstructed fingers, resembling human individuation patterns. Post-stroke simulations revealed that lesions in both CS and RS regions led to increased unintended force in uninstructed fingers, immediate weakening of instructed fingers, improved control during early recovery, and increased neural plasticity. Lesions in the CS region alone significantly impaired individuation, while RS lesions affected strength and to a lesser extent, individuation. The model also predicted the impact of stroke severity on finger individuation, highlighting the combined effects of CS and RS lesions. This model provides insights into the interactive role of cortical and subcortical regions in finger individuation. It suggests that recovery mechanisms involve reorganization of these networks, which may inform neurorehabilitation strategies.

THE IMPACT OF THE FRONTAL ASLANT TRACT ON POST-OPERATIVE OUTCOMES IN GLIOMA SURGERY

Abstract AIMS The frontal aslant tract (FAT) has a role in speech and language functions and visual-motor activities. It is also not clear whether location of FAT relative to gliomas affects post-operative motor and language outcomes. Our hypothesis is FAT protects the cortico-spinal tract and other subcortical white matter tracts involved in speech. METHOD We conducted a retrospective cohort study. We used electronic patient records to search for all patients who had frontal tumours resected between Jan 2018 and August 2022. We included all adult patients (&amp;gt;18 years) with gliomas located in the SMA region and dorsal premotor cortex who had pre-op diffusion tensor imaging and underwent debulking / resection surgery. The patients were divided into 3 groups based on the location of the tumour relative to FAT. In group 1 patients had tumours located anterior to FAT, in group 2 patients had tumours infiltrating FAT and in group 3 patients had tumours located posterior to FAT. Our outcome measure was new post-operative language or motor deficit. RESULTS Our search yielded 197 patients, of these 43 fulfilled the inclusion criteria. Sixteen patients were included in group 1, 9 patients included in group 2 and 18 included in group 3. Pre-operative motor deficit was significantly more common in patients with tumours posterior to FAT (p=0.046). Post-operative motor deficit at hospital discharge was also more common on this group of patients (p=0.048). At 6 months follow up there was no significant difference post-operative motor and language deficits between the groups but there was a trend towards worse motor outcomes in patients with tumour located posterior to FAT. CONCLUSION There is a suggestion motor outcomes are worse in tumours located posterior to FAT. This can be considered when counselling patients for surgery with tumours related to FAT.

Functional role of area 8A in the posterior dorsolateral frontal region of the human brain: A single case study.

Area 8A has traditionally been considered to be the frontal eye field (FEF), i.e. the area for the motor production of eye movements. However, recent research has shown that the FEF lies posteriorly in premotor area 6. Research in macaque monkeys has demonstrated that, in contrast to premotor area 6, which is involved in the production of motor actions, area 8A is implicated in the cognitive allocation of attention to stimuli based on instruction cues. The aim of the present study was to elucidate the specific cognitive role of area 8A by examining a unique patient with a lesion restricted to area 8A, i.e. sparing the premotor cortex. This right-handed male patient underwent neuropsychological assessment and testing on two conditional associative-learning tasks: the motor hand conditional associative-learning task (MCALT) assessing the selection of motor actions based on instruction cues and the visual conditional associative-learning task (VCALT) assessing the selection of visual stimuli based on instruction cues. The patient's performance on the VCALT was significantly impaired compared to control subjects, but performance on the MCALT and on an Eye Movement Control Task was preserved. The present study provides evidence that area 8A is critical for the cognitive process regulating the allocation of attention to different stimuli in the environment, but not in the production of eye movements. These findings enhance understanding of the functional organization of the posterior dorsolateral frontal region in the human brain and suggest a specialized role of area 8A in high-level cognitive processes.

Abnormal individualized functional connectivity: A potential stimulation target for pediatric tourette syndrome

ObjectiveIn order to examine whether individualized peak functional connectivity could potentially serve as a target for repetitive transcranial magnetic stimulation (rTMS) therapy, we investigated the location of peak functional connectivity (FC) between the cortical motor area and the key brain region, the globus pallidus internus (GPi), in Tourette syndrome, and explored the relationship between the severity of the disease and these aberrant functional connections. MethodsThe study involved a cohort of 103 children diagnosed with Tourette syndrome and 66 age-matched typically developing children. The GPi was served as the seed, and the study compared individualized peak FC strength in the supplementary motor area (SMA) and premotor area between the two groups. Spatial distribution of peak FC in the motor area and GPi-based voxel-wise FC were also analyzed. ResultsChildren with Tourette syndrome exhibited lower peak FC in the left SMA when using left GPi as the seed. This reduction in peak FC demonstrated a significant and negative correlation with the Yale Global Tic Severity Scale scores. ConclusionsSMA-GPi FC is one of the key pathological circuit in Tourette syndrome. SignificanceThe individual peak FC location in the left SMA potentially serve as stimulation targets for rTMS treatment of TS.

The effect and mechanism of motor imagery based on action observation treatment on dysphagia in Wallenberg Syndrome: a randomized controlled trial.

The effect of motor imagery applied to dysphagia patients with Wallenberg syndrome has not yet been reported. This trial aimed to investigate the effect and mechanism of motor imagery based on action observation treatment in the rehabilitation of patients with dysphagia in Wallenberg syndrome. A randomized controlled trial. The setting was in-patient. Thirty patients with dysphagia of Wallenberg syndrome. The patients were divided into the experimental group and the control group. Both groups received conventional dysphagia treatment, and the experimental group underwent the addition of motor imagery based on action observation treatment to the control group once a day for 14 days. Overall swallowing function was assessed with specific scales before and after intervention. Meanwhile, the functional near infrared spectroscopy was used to detect changes in cerebral hemodynamics during the execution of volitional swallowing task and swallowing motor imagery. The standardized swallowing assessment score (P=0.030), Murray secretion scale score (P=0.044) and swallowing quality of life score (P=0.011) of the experimental group improved better than those of the control group. In addition, multiple brain regions of the cortical presented extensive activation (P<0.05) during the execution of swallowing motor imagery. Moreover, there were significant differences (P<0.05) in brain regions pre-motor and supplementary motor cortex, right primary motor cortex, and right primary somatosensory cortex of the experimental group before and after treatment. The present study indicated that motor imagery based on action observation treatment could improve swallowing function for patients with dysphagia of Wallenberg syndrome as an add-on training. As a top-down rehabilitation training, the mechanism of this therapy may be related to the selective activation of mirror neuron system. Motor imagery based on action observation treatment can be implemented as part of the therapeutic for dysphagia of Wallenberg syndrome.

Speech motor impairment in ALS is associated with multiregional cortical thinning beyond primary motor cortex.

Cortical thinning is well-documented in individuals with amyotrophic lateral sclerosis (ALS), yet its association with speech deterioration remains understudied. This study characterizes anatomical changes in the brain within the context of speech impairment patterns in individuals with ALS, providing insight into the disease's multiregional spread and biology. To evaluate patterns of cortical thickness in speakers with ALS with and without functional speech changes compared to healthy controls (HCs) using whole-brain and region of interest (ROI) analyses. Forty individuals with ALS and 22 HCs underwent a T1-weighted 3-Tesla magnetic resonance imaging (MRI). Individuals with ALS were divided into two groups based on the preserved speech [ps-ALS] (n = 18) or deteriorated speech [ds-ALS] (n = 22) as measured by the ALSFRSF-R speech subscore (=4 or <4 points, respectively). Sixteen a priori-defined and automatically segmented cortical and subcortical brain ROIs were selected based on their previously documented roles in speech production. Two cortical thickness analyses were performed: (1) group-level whole-brain surface-based analyses and (2) group-level ROI analyses. A case study of 6 ALS individuals examined the cortical thickness, and their speech was characterized using quantitative and qualitative measures. Based on the group-level whole-brain surface-based analyses, the ds-ALS group demonstrated significant cortical thinning compared to HCs in the left primary motor and somatosensory cortices and the right inferior parietal lobe with its adjacent lateral occipital cortical regions. The ps-ALS group demonstrated no significant cortical thinning compared to HCs. Based on the group-level ROI analyses, the ds-ALS group demonstrated significant cortical thinning compared to HCs in bilateral middle motor cortices, right posterior dorsal premotor cortex, and left anterior cingulate cortex. The case study analysis revealed that ALS speakers with speech features characteristic of spastic dysarthria exhibited cortical thinning, while those with speech features characteristic of flaccid dysarthria did not. Individuals with ALS have anatomical changes involving multiregional neocortical areas beyond the primary motor cortex that may manifest as subjective (i.e., clinical judgment) and objective (i.e., speaking rate) changes in speech production. Further longitudinal work in ALS is needed to better understand the link between MRI cortical thickness changes and bulbar dysfunction.

Assessing the Impact of Transcranial Magnetic Stimulation on Speech Perception in Noise.

Healthy aging is associated with reduced speech perception in noise (SPiN) abilities. The etiology of these difficulties remains elusive, which prevents the development of new strategies to optimize the speech processing network and reduce these difficulties. The objective of this study was to determine if sublexical SPiN performance can be enhanced by applying TMS to three regions involved in processing speech: the left posterior temporal sulcus, the left superior temporal gyrus, and the left ventral premotor cortex. The second objective was to assess the impact of several factors (age, baseline performance, target, brain structure, and activity) on post-TMS SPiN improvement. The results revealed that participants with lower baseline performance were more likely to improve. Moreover, in older adults, cortical thickness within the target areas was negatively associated with performance improvement, whereas this association was null in younger individuals. No differences between the targets were found. This study suggests that TMS can modulate sublexical SPiN performance, but that the strength and direction of the effects depend on a complex combination of contextual and individual factors.

The presence of drum and bass modulates responses in the auditory dorsal pathway and mirror-related regions to pop songs

In pop music, drum and bass components are crucial for generating the desire to move one’s body, primarily due to their role in delivering salient metrical cues. This study explored how the presence of drum and bass influences neural responses to unfamiliar pop songs. Using AI-based algorithms, we isolated the drum and bass components from the musical excerpts, creating two additional versions: one that included only the drum and bass (excluding vocals and other instruments), and another that excluded the drum and bass (consisting solely of vocals and other instruments). Twenty-five participants were subjected to fMRI scans while listening to these musical stimuli. Analysis of fMRI data indicated that the removal of drum and bass led to increased activity in the auditory dorsal pathway, suggesting that the absence of these metrical cues demands greater cognitive effort to process the beats. In contrast, the version featuring only drum and bass elicited stronger activation in frontal regions associated with mirror properties, including the right ventral premotor cortex (extending into the inferior frontal gyrus) and left dorsolateral prefrontal cortex, compared to the original version. Overall, this study contributed insights into the foundational role of drum and bass in imparting metrical salience to pop songs, enriching our understanding of listeners’ sensorimotor processing of musical genres that prominently feature these two elements.