Contralateral Activity Research Articles

No Evidence of Improved Emotion Perception Through Unilateral Hand Contraction.

Previous studies have identified improved cognitive performance from unilateral hand contraction to effect contralateral hemisphere activation. As little is known of whether this activation can improve emotion perception, this study examined any differences in perception accuracy and reaction times of matching photographs of human facial expressions presented to the left or right visual fields after left versus right hemisphere activation triggered by unilateral hand contractions. We used photographs of happy, sad, and neutral facial expressions presented briefly and simultaneously (two photographs in each presentation) either unilaterally (intrahemisphere condition) or bilaterally (interhemisphere condition). We recruited 68 university student participants (aged 19–23 years) and randomly assigned half of them to squeeze a dynamometer with the right hand, while the other half squeezed with the left hand, prior to performing the Dimond face-matching task. Matching of happy faces was faster than matching of sad faces. In females (but not males), perception accuracy was higher when stimuli were presented in the right (vs. left) visual field. We found no difference in emotion perception of photographs in either unilateral (intrahemispheric) or bilateral (interhemispheric) stimuli presentations as a function of hand contractions.

Independent representations of ipsilateral and contralateral limbs in primary motor cortex.

Several lines of research demonstrate that primary motor cortex (M1) is principally involved in controlling the contralateral side of the body. However, M1 activity has been correlated with both contralateral and ipsilateral limb movements. Why does ipsilaterally-related activity not cause contralateral motor output? To address this question, we trained monkeys to counter mechanical loads applied to their right and left limbs. We found >50% of M1 neurons had load-related activity for both limbs. Contralateral loads evoked changes in activity ~10ms sooner than ipsilateral loads. We also found corresponding population activities were distinct, with contralateral activity residing in a subspace that was orthogonal to the ipsilateral activity. Thus, neural responses for the contralateral limb can be extracted without interference from the activity for the ipsilateral limb, and vice versa. Our results show that M1 activity unrelated to downstream motor targets can be segregated from activity related to the downstream motor output.

Neural basis of episodic memory in the intermediate term after medial temporal lobe resection.

How the brain supports intermediate-term preservation of memory in patients who have undergone unilateral medial temporal lobe resection (MTLR) has not yet been demonstrated. To understand the neural basis of episodic memory in the intermediate term after surgery for temporal lobe epilepsy (TLE), the authors investigated the relationship between the activation of the hippocampus (HIP) during successful memory encoding and individual memory capacity in patients who had undergone MTLR. They also compared hippocampal activation with other parameters, including structural volumes of the HIP, duration of illness, and age at seizure onset. Thirty-five adult patients who had undergone unilateral MTLR at least 1 year before recruiting and who had a favorable seizure outcome were enrolled (17 left MTLR, 18 right MTLR; mean follow-up 6.31 ± 2.72 years). All patients underwent a standardized neuropsychological examination of memory function and functional MRI scanning with a memory-encoding paradigm of words and figures. Activations of the HIP during successful memory encoding were calculated and compared with standard neuropsychological memory scores, hippocampal volumes, and other clinical variables. Greater activation in the HIP contralateral to the side of the resection was related to higher postoperative memory scores and greater postoperative memory improvement than the preoperative baseline in both patient groups. Specifically, postoperative verbal memory performance was positively correlated with contralateral right hippocampal activation during word encoding in the left-sided surgery group. In contrast, postoperative visual memory performance was positively correlated with contralateral left hippocampal activation during figure encoding in the right-sided surgery group. Activation of the ipsilateral remnant HIP was not correlated with any memory scores or volumes of the HIP; however, it had a negative correlation with the seizure-onset age and positive correlation with the duration of illness in both patient groups. For the first time, a neural basis that supports effective intermediate-term episodic memory after unilateral MTLR has been characterized. The results provide evidence that engagement of the HIP contralateral rather than ipsilateral to the side of resection is responsible for effective memory function in the intermediate term (> 1 year) after surgery in patients who have undergone left MTLR and right MTLR. Engagement of the material-specific contralesional HIP, verbal memory in the left-sided surgery group, and visual memory in the right-sided surgery group were observed.

Factors Influencing Aphasia Outcome in Patients with Occlusive Stroke

AbstractBackground: Aphasia related to ischemic stroke is a major health problem affecting the quality of life profoundly.Aim of Study: Is to assess factors influencing aphasia outcome in patients with occlusive stroke and the role of functional magnetic resonance imaging in detection the patterns of post-stroke language recovery.Patients and Methods: This was a prospective cohort study done at Neuropsychiatry Department and Center of Psychiatry, Neurology and Neurosurgery, Diagnostic Radiol-ogy, Tanta University, from January 2017 to January 2018. Aphasia Rapid Test (ART) at day 1 and follow-up at day 8 which is a bed side clinical test to assess aphasia severity, Diffusion Tensor Imaging (DTI) and fMRI were done at day 8 to assess aphasia severity. A total of 34 cases were finally included in this study after fulfilling the inclusion and exclusion criteria, 12 patients who had receptive or global aphasia, were not suitable for fMRI, their native language Arabic, age Results: The total number of the studied patients was 34 of them 18 patients (52.9%) were males and 16 patients were females (47.1%). The age of the studied patients ranged from 28-79 years. The older group of patients had severe language disability also those with global aphasia and perisylvian lesion, risk factors as HTN, DM, Cardiac Disease, Dyslipidemia had worse prognosis, those with no reconstruction of the Arcuate Fasiculus in DTI and fMRI data analysis showed negative effect of the site contralateral to lesion.Conclusion: Age was a significant factor with the higher age group had the worst prognosis regarding aphasia. Large lesion sizes and those with damage to strategic language areas had a bad prognosis. fMRI and DTI were the cornerstone of our study and they were a highly reliable tools in the prognosis of language outcome, with those who had activity in the perilesional and bilateral activity (perilesional and contralateral homotopic) in fMRI to have better outcome than those with only contralateral activity, also DTI to delineate the AF and the degree of its integrity and reconstitution.

Chemical Stimulation of Renal Tissue Induces Sympathetic Activation and a Pressor Response via the Paraventricular Nucleus in Rats.

Sympathetic activation and the kidney play critical roles in hypertension and chronic heart failure. The role of the kidney in sympathetic activation is still not well known. In this study, we revealed an excitatory renal reflex (ERR) in rats induced by chemical stimulation of the kidney that regulated sympathetic activity and blood pressure. The ERR was induced by renal infusion of capsaicin, and evaluated by the changes in renal sympathetic outflow, blood pressure, and heart rate. Renal infusion of capsaicin dose-dependently increased the contralateral renal sympathetic nerve activity, mean arterial pressure, and heart rate. Capsaicin in the cortico-medullaryborder had greater effects than in the cortex or medulla. Intravenous infusion of capsaicin had no significant effects. The effects of renal infusion of capsaicin were abolished by ipsilateral renal denervation, but were not affected by bilateral sinoaortic denervation. Renal infusion of capsaicin increased the ipsilateral renal afferent activity. The ERR was also induced by renal infusion of bradykinin, adenosine, and angiotensin II, but not by ATP. Renal infusion of capsaicin increased c-Fos expression in the paraventricular nucleus (PVN) of hypothalamus. Lesion of neurons in the PVN with kainic acid abolished the capsaicin-induced ERR. These findings indicate that chemical stimulation of kidney causes an excitatory reflex, leading to sympathetic activation, pressor response, and accelerated heart rate. The PVN is an important central nucleus in the pathway of the ERR.

Dopaminergic modulation of motor network compensatory mechanisms in Parkinson's disease.

The dopaminergic system has a unique gating function in the initiation and execution of movements. When the interhemispheric imbalance of dopamine inherent to the healthy brain is disrupted, as in Parkinson's disease (PD), compensatory mechanisms act to stave off behavioral changes. It has been proposed that two such compensatory mechanisms may be (a) a decrease in motor lateralization, observed in drug-naïve PD patients and (b) reduced inhibition - increased facilitation. Seeking to investigate the differential effect of dopamine depletion and subsequent substitution on compensatory mechanisms in non-drug-naïve PD, we studied 10 PD patients and 16 healthy controls, with patients undergoing two test sessions - "ON" and "OFF" medication. Using a simple visually-cued motor response task and fMRI, we investigated cortical motor activation - in terms of laterality, contra- and ipsilateral percent BOLD signal change and effective connectivity in the parametric empirical Bayes framework. We found that decreased motor lateralization persists in non-drug-naïve PD and is concurrent with decreased contralateral activation in the cortical motor network. Normal lateralization is not reinstated by dopamine substitution. In terms of effective connectivity, disease-related changes primarily affect ipsilaterally-lateralized homotopic cortical motor connections, while medication-related changes affect contralaterally-lateralized homotopic connections. Our findings suggest that, in non-drug-naïve PD, decreased lateralization is no longer an adaptive cortical mechanism, but rather the result of maladaptive changes, related to disease progression and long-term dopamine replacement. These findings highlight the need for the development of noninvasive therapies, which would promote the adaptive mechanisms of the PD brain.

Dynamic Activation Patterns of the Motor Brain Revealed by Diffuse Optical Tomography.

Diffuse optical tomography (DOT), a subset of functional near-infrared spectroscopy (fNIRS), is a noninvasive functional imaging modality for studying the human brain in normal and diseased conditions. It measures changes in concentrations of oxygenated hemoglobin (HbO) and deoxygenated hemoglobin (Hb) in the blood vasculature of the brain. In contrast to functional magnetic resonance imaging (fMRI), the gold standard in human brain imaging, DOT offers the advantage of higher temporal resolution, portability, lower cost, multiple contrasts and usability for persons who cannot otherwise utilize MRI-based imaging modalities, including bedridden patients and infants, etc. The goal of the present study was to evaluate performance of a DOT method in studying dynamic patterns of brain activations involving motor control. CW-fNIRS data were acquired in four sessions from a healthy male participant when he performed a motor task in a block-design experiment. Results from experimental data showed pronounced activity in the primary motor cortex (M1), contralateral to the clenching hand. It was further observed that the M1 activity was consistent over four sessions. Furthermore, temporal dynamics of motor activity at each session further revealed well-sequenced activation patterns among M1, premotor cortex (PMC), and supplementary motor area (SMA). Timed ipsilateral motor activity suppression was also observed several seconds after the onset of contralateral M1 activity. More importantly, these temporal dynamics were similarly observed in all four sessions. These preliminary results suggest that the DOT method has the sensitivity, reliability, and spatio-temporal resolutions to study activities originated from the motor cortices. A full-scope evaluation and validation in more participants on the motor system can establish it as a promising neuroimaging tool to study, such as, infants at the risk of cerebral palsy or elders with Parkinson's due to its portability and usability in clinical environments.

Differential Changes in the Lateralized Activity of Identified Projection Neurons of Motor Cortex in Hemiparkinsonian Rats.

In the parkinsonian state, the motor cortex and basal ganglia (BG) undergo dynamic remodeling of movement representation. One such change is the loss of the normal contralateral lateralized activity pattern. The increase in the number of movement-related neurons responding to ipsilateral or bilateral limb movements may cause motor problems, including impaired balance, reduced bimanual coordination, and abnormal mirror movements. However, it remains unknown how individual types of motor cortical neurons organize this reconstruction. To explore the effect of dopamine depletion on lateralized activity in the parkinsonian state, we used a partial hemiparkinsonian model [6-hydroxydopamine (6-OHDA) lesion] in Long–Evans rats performing unilateral movements in a right–left pedal task, while recording from primary (M1) and secondary motor cortex (M2). The lesion decreased contralateral preferred activity in both M1 and M2. In addition, this change differed among identified intratelencephalic (IT) and pyramidal tract (PT) cortical projection neurons, depending on the cortical area. We detected a decrease in lateralized activity only in PT neurons in M1, whereas in M2, this change was observed in IT neurons, with no change in the PT population. Our results suggest a differential effect of dopamine depletion in the lateralized activity of the motor cortex, and suggest possible compensatory changes in the contralateral hemisphere.

Quantitative and Visual Characteristics of Primary Central Nervous System Lymphoma on 18F-FDG-PET.

Primary central nervous system lymphomas (PCNSLs) are rare progressive brain tumors, whose managements are significantly different from other solid tumors, especially glioblastomas. Therefore, an early diagnosis is of great significance. 18F-fluorodeoxyglucose (FDG)-positron emission tomography (PET), which can measure the glucose metabolic rate in the brain, is an increasingly common tool for early diagnosis. Twenty-five immunocompetent patients with PCNSL were reviewed in this study to describe the general characteristics of PCNSL patients' 18F-FDG-PET scans. Quantitative features included a radically enhanced maximum standardized uptake value (SUVmax) with a mean value of 23.8 ± 7.9 and a 5.8 ± 1.8 mean ratio of tumor-to-normal contralateral cortex activity (T/N). Visual characteristics, such as favored locations in the brain, lesion numbers, tumor shape, metabolic inhibition, and structural shift were determined as well. PCNSL was found to favor the cortex, especially the frontal lobe, followed by the basal ganglia and corpus callosum. All PCNSLs were near the lateral ventricular area. Tumor shapes were subdivided into three groups: diffuse, round, and irregular patterns. Reduced radiation was observed in the ipsilateral cortex, the basal ganglia and the contralateral cerebellum. The lateral ventricles were prone to be compressed on the side ipsilateral to the tumor, pushing the midline towards the contralateral side of the brain. In conclusion, aside from SUVmax and T/N values, other visual characteristics are also available to facilitate the differentiation of PCNSLs from other brain conditions on 18F-FDG-PET scans.

P69-S Cutaneous silent period behavior in different motor neuron diseases phenotypes

Background The cutaneous silent period (CSP) corresponds to a reduced electric activity of a contracting muscle, after electrical stimulation of sensory fibers. The afferent volley causes a presynaptic inhibition of spinal motor neurons (LMN) modulated by complex spinal circuits. CSP behavior in different motor neuron diseases (MND) phenotypes is unknown. Materials and methods We included 20 MND patients and 15 controls. CSP was obtained by applying electrical stimulation of the 5th finger. Surface EMG recordings were obtained from ADM muscle. CSP duration was defined by the time between a drop of rectified averaged EMG below 80%, and the final return above 80%, of baseline EMG. The mean duration was obtained from 10 consecutive curves obtained before and during co-contraction of the contralateral ADM muscle. Results MND patients had a median age of 59 years. 12 were diagnosed as amyotrophic lateral sclerosis (ALS), 6 as progressive muscular atrophy (PMA), 2 as primary lateral sclerosis (PLS). Median CSP duration was similar between controls and patients. During contralateral ADM contraction, CSP duration did not change in controls, patients with ALS and PMA, but decreased by 28% in PLS patients. Conclusions We present preliminary results suggesting that CSP behavior is not homogenous in different phenotypes of MND. We previously observed that reflex contralateral activation of the homonymous contralateral hand muscles is frequent in patients with PLS, indicating spinal cord hyperexcitability. Our CSP results suggest that this method can contribute to dissect the mechanisms underlying abnormal LMN excitability in patients with corticospinal tract lesion.

Force irradiation effect of kinesiotaping on contralateral muscle activation

We aimed to determine the force irradiation effect of kinesiotaping (KT) on contralateral muscle activity during unilateral muscle contraction. Forty healthy (26 females, 14 males) subjects were divided into two groups: KT and control groups. KT was applied on the biceps brachii at the contralateral limb (non-dominant limb) in the KT group, whereas no taping was applied to the control group. All participants performed unilateral isometric, concentric, and eccentric contractions with their dominant upper limbs (exercised limb) by means of an isokinetic dynamometer, while the contralateral limb was in the resting condition, neutral position, and motionless during the testing procedure. During the exercise, contralateral biceps brachii muscle activity was recorded by surface electromyography (EMG). To quantify the muscle activation, EMG signals were expressed as a percentage of the maximal isometric voluntary contraction, which is referred to as %EMGmax. The KT group showed significantly higher %EMGmax in the biceps brachii compared to the control group at the contralateral limb during the isometric, concentric, and eccentric contractions (p = 0.035, p = 0.046, and p = 0.002, respectively) The median values of the contralateral muscle activity were 2.74 %EMGmax and 6.62 %EMGmax during the isometric contraction for the control and KT groups, respectively (p = 0.035). During the concentric contraction, the median values of the contralateral muscle activity were 1.61 %EMGmax and 9.39 %EMGmax for the control and KT groups, respectively (p = 0.046). The median values of the contralateral muscle activity were 4.49 %EMGmax and 22.89 %EMGmax for the eccentric contraction for the control and KT groups, respectively (p = 0.002). In conclusion, KT application on the contralateral limb increased the contralateral muscle activation in the biceps brachii during the unilateral isometric, concentric, and eccentric contractions.

RETRACTED ARTICLE: EEG oscillatory patterns in the different processing phase during motor imagery

Motor imagery refers to the psychological realization of movements without movement or muscle activity; it is a research hotspot in neurophysiology, neuroimaging, neurology, and psychology; and it is used as a neurological rehabilitation of brain-computer interface technology. The foundation is widely studied. The EEG signal has a millisecond time resolution, which can facilitate the acquisition of neural signal changes in the body movement process. This article has selected the finger and thumb index finger movements as the task of motion imaging. Under the guidance of image and video, the characteristics of the brain electrical shock patterns during the finger-to-finger movement, thumb and forefinger pairing and unfolding were studied. The brain electrical signals of 15 healthy subjects were collected during the experiment, and the signals were analyzed for source location and information flow network. The result of source location analysis indicated that the activation of brain regions was mainly in the contra lateral SMA region, PMC region, and M1 region. However, the subjects were right-handed, so the characteristics of contra lateral activation were not obvious in the right-handed motor imaging process. Imagine that the opposite side of the pinching process is more powerful than the imaginary finger and the activation range is wider. The results of dynamic information flow of EEG signals at different stages of motor imaging show obvious contra lateral activation characteristics. The DTF analysis of the left-hand motion imaging finger pair pinching and unfolding shows that the information flow mainly flows from the right side of the brain to the left in the imagination process, while the right-hand motion imaging process is opposite, and the information flow mainly flows from the left side of the brain to the right side. The left hand imagines that the finger-to-pinch process is simpler and the number of connections is smaller than the information flow of the imagined finger deployment process. The right hand imagines that the finger-to-kneading process looks more complex than the imagined finger-expanding process, and the number of connections is more. However, its more connections appear mainly in the occipital region of the visual stimulus, the information flow in the frontal and parietal lobes is simple, and the number of connections is reduced. This article explores the relationship among the different movement phases of hand motion imaging and the change of EEG signals. The results show that the brain oscillation modes are similar and different, and the finger deployment process is used as a follow-up of the finger-to-kneading process. The process of knowing should be relatively simple.

Self-regulation of language areas using real-time functional MRI in stroke patients with expressive aphasia.

The objectives of this study were to test (i) If stroke patients with expressive Aphasia could learn to up-regulate the Blood Oxygenation Level Dependent (BOLD) signal in language areas of the brain, namely Inferior Frontal Gyrus (Broca's area) and Superior Temporal Gyrus (Wernicke's area), with real-time fMRI based neurofeedback of the BOLD activation and functional connectivity between the language areas; and (ii) acquired up-regulation could lead to an improvement in expression of language. The study was performed on three groups: Group 1 (n = 4) of Test patients and group 2 (n = 4) of healthy volunteers underwent the neurofeedback training, whereas group 3 (n = 4) of Control patients underwent treatment as usual. Language performance and recovery were assessed using western aphasia battery and picture naming tasks, before and after the neurofeedback training. Results show that the Test group had significant increase in activation of the Broca's area and its right homologue, while the Normal group achieved the greatest activation during neurofeedback. For the Test group both perilesional and contralateral activations were observed. The improvement in language ability of the test patients was not significantly greater than that of the control patients. Neurofeedback training in Aphasia patients induced significant activation of the Broca's area, Wernicke's area and their right homologues, although healthy individuals achieved greater activations in these regions than the patient groups. Training also activated perilesional areas of Rolandic operculum, precentral gyrus and postcentral gyrus for the Test patients significantly. However, lack of behavioral and symptom modifications in the Test group calls for improvements in the efficacy of the approach.

Daily acute, but not chronic, intermittent hypoxia enhances phrenic motor plasticity in chronic cervical spinal cord injury

Daily acute intermittent hypoxia (dAIH; 3–15 hypoxic episodes per day) is a promising therapeutic strategy to improve respiratory function after incomplete spinal cord injury by inducing spinal respiratory motor plasticity. Conversely, chronic intermittent hypoxia (CIH; >100 episodes per day) elicits multisystem pathology and is a hallmark of moderate sleep apnea, a condition highly prevalent in individuals with cervical spinal injury. In intact rats, 7 days of dAIH preconditioning enhances phrenic motor facilitation whereas it is abolished by 7 days of CIH, an effect likely due to CIH‐induced neuroinflammation. Since the impact of prolonged CIH (> 1 wk) or dAIH on the capacity for phrenic motor facilitation with chronic spinal cord injury has not been explored, we compared the effect of 28 days of normoxia (21% O2; 8hrs/day), dAIH (10, 5 min episodes of 10.5% O2 with 5 min normoxic intervals/day) or CIH (2 min hypoxic episodes with 2 min intervals; 8 hrs/day) on phrenic output in rats with chronic C2 spinal hemisection (C2Hx). Neurophysiology experiments were conducted one day after the final hypoxic exposure; bilateral phrenic nerve activity and moderate AIH‐induced phrenic long‐term facilitation (pLTF) were assessed. Ipsilateral phrenic nerve activity during baseline conditions and maximal chemoreflex activation was: 1) reduced in all injury groups vs intact rats (p<0.0001 and p<0.009, respectively); and 2) unaffected by dAIH or CIH (p>0.94 and p>0.98, respectively). No group differences in contralateral phrenic nerve activity were observed in either condition (p>0.49 and p>0.18, respectively). dAIH enhanced ipsilateral pLTF vs. all other groups (p=0.01); in contrast, CIH had no effect on pLTF (p=0.43). In conclusion, neither dAIH nor CIH had any detectable impact on phrenic nerve activity in rats with chronic C2Hx, but dAIH enhanced the capacity for additional pLTF. Further work is needed to explore: 1) mechanisms of enhanced respiratory plasticity following dAIH; 2) if detrimental effects of CIH can be resolved by treatments that mitigate inflammation; and 3) how enhanced/restored phrenic motor plasticity can be harnessed to improve breathing ability in individuals with chronic cervical spinal cord injury.Support or Funding InformationNIH: OT2OD023854, K12 HDO55929 (EGR), T32 HD055929 (LLA); Department of Defense: SCI160123 (EGR)This abstract is from the Experimental Biology 2019 Meeting. There is no full text article associated with this abstract published in The FASEB Journal.

Neuronal mechanisms of motion detection underlying blindsight assessed by functional magnetic resonance imaging (fMRI)

Brain imaging offers a valuable tool to observe functional brain plasticity by showing how sensory inputs reshape cortical activations after a visual impairment. Following a unilateral post-chiasmatic lesion affecting the visual cortex, patients may suffer a contralateral visual loss referred to homonymous hemianopia. Nevertheless, these patients preserve the ability to unconsciously detect, localize and discriminate visual stimuli presented in their impaired visual field. To investigate this paradox, known as blindsight, we conducted a study using functional magnetic resonance imaging (fMRI) to evaluate the structural and functional impact of such lesion in a 33-year old patient (ML), who suffers a complete right hemianopia without macular sparing and showing strong evidences of blindsight. We thus performed whole brain and sliced thalamic fMRI scan sequences during an event-related motion detection task. We provided evidence of the neuronal fingerprint of blindsight by acquiring and associating neural correlates, specific structures and functional networks of the midbrain during blindsight performances which may help to better understand this condition. Accurate performance demonstrated the presence of residual vision and the ability to unconsciously perceive motion presented in the blind hemifield, although her reaction time was significantly higher in her blind-field. When the normal hemifield was stimulated, we observed significant contralateral activations in primary and secondary visual areas as well as motion specific areas, such as the supramarginal gyrus and middle temporal area. We also demonstrated sub-thalamic activations within the superior colliculi (SC) and the pulvinar. These results suggest a role of secondary subcortical structures in normal spontaneous motion detection. In a similar way, when the lesioned hemifield was stimulated, we observed contralateral activity in extrastriate areas with no activation of the primary lesioned visual cortex. Moreover, we observed activations within the SC when the blind hemifield was stimulated. However, we observed unexpected ipsilateral activations within the same motion specific areas, as well as bilateral frontal activations. These results highlight the importance of abnormal secondary pathways bypassing the primary visual area (V1) in residual vision. This reorganization in the structure and function of the visual pathways correlates with behavioral changes, thus offering a plausible explanation for the blindsight phenomenon. Our results may potentially impact the development of rehabilitation strategies to target subcortical pathways.

The development of functional and directed corticomuscular connectivity during tonic ankle muscle contraction across childhood and adolescence

In adults, oscillatory activity in the sensorimotor cortex is coherent with contralateral muscle activity at beta frequencies (15–35 Hz) during tonic contraction. This functional coupling reflects the involvement of the sensorimotor cortex, the corticospinal pathway, and likely also ascending sensory feedback in the task at hand. However, little is known about the developmental trajectory of task-related corticomuscular connectivity relating to the voluntary control of the ankle muscles. To address this, we recorded electroencephalography (EEG) from the vertex (Cz) and electromyography (EMG) from ankle muscles (proximal and distal anterior tibial, TA; soleus, SOL; gastrocnemius medialis, GM) in 33 participants aged 7–23 yr during tonic dorsi- and plantar flexion requiring precise maintenance of a submaximal torque level. Coherence was calculated for Cz-TA, Cz-SOL, TA-TA, and SOL-GM signal pairs. We found strong, positive associations between age and beta band coherence for Cz-TA, Cz-SOL, and TA-TA, suggesting that oscillatory corticomuscular connectivity is strengthened during childhood development and adolescence. Directionality analysis indicated that the primary interaction underlying this age-related increase was in the descending direction. In addition, performance during dorsi- and plantar flexion tasks was positively associated with age, indicating more precise control of the ankle joint in older participants. Performance was also positively associated with beta band coherence, suggesting that participants with greater coherence also exhibited greater precision. We propose that these results indicate an age-related increase in oscillatory corticospinal input to the ankle muscle motoneuron pools during childhood development and adolescence, with possible implications for maturation of precision force control. Within the theoretical framework of predictive coding, we suggest that our results may reflect an age-related increase in reliance on feedforward control as the developing nervous system becomes better at predicting the sensory consequences of movement. These findings may contribute to the development of novel intervention strategies targeting improved sensorimotor control in children and adolescents with central motor disorders.

Impact of years of blindness on neural circuits underlying auditory spatial representation

Early visual deprivation impacts negatively on spatial bisection abilities. Recently, an early (50–90 ms) ERP response, selective for sound position in space, has been observed in the visual cortex of sighted individuals during the spatial but not the temporal bisection task.Here, we clarify the role of vision on spatial bisection abilities and neural correlates by studying late blind individuals. Results highlight that a shorter period of blindness is linked to a stronger contralateral activation in the visual cortex and a better performance during the spatial bisection task. Contrarily, not lateralized visual activation and lower performance are observed in individuals with a longer period of blindness.To conclude, the amount of time spent without vision may gradually impact on neural circuits underlying the construction of spatial representations in late blind participants. These findings suggest a key relationship between visual deprivation and auditory spatial abilities in humans.

Sensorimotor Oscillations During a Reciprocal Touch Paradigm With a Human or Robot Partner.

Robots provide an opportunity to extend research on the cognitive, perceptual, and neural processes involved in social interaction. This study examined how sensorimotor oscillatory electroencephalogram (EEG) activity can be influenced by the perceived nature of a task partner – human or robot – during a novel “reciprocal touch” paradigm. Twenty adult participants viewed a demonstration of a robot that could “feel” tactile stimulation through a haptic sensor on its hand and “see” changes in light through a photoreceptor at the level of the eyes; the robot responded to touch or changes in light by moving a contralateral digit. During EEG collection, participants engaged in a joint task that involved sending tactile stimulation to a partner (robot or human) and receiving tactile stimulation back. Tactile stimulation sent by the participant was initiated by a button press and was delivered 1500 ms later via an inflatable membrane on the hand of the human or on the haptic sensor of the robot partner. Stimulation to the participant’s finger (from the partner) was sent on a fixed schedule, regardless of partner type. We analyzed activity of the sensorimotor mu rhythm during anticipation of tactile stimulation to the right hand, comparing mu activity at central electrode sites when participants believed that tactile stimulation was initiated by a robot or a human, and to trials in which “nobody” received stimulation. There was a significant difference in contralateral mu rhythm activity between anticipating stimulation from a human partner and the “nobody” condition. This effect was less pronounced for anticipation of stimulation from the robot partner. Analyses also examined beta rhythm responses to the execution of the button press, comparing oscillatory activity when participants sent tactile stimulation to the robot or the human partner. The extent of beta rebound at frontocentral electrode sites following the button press differed between conditions, with a significantly larger increase in beta power when participants sent tactile stimulation to a robot partner compared to the human partner. This increase in beta power may reflect greater predictably in event outcomes. This new paradigm and the novel findings advance the neuroscientific study of human–robot interaction.

Implicit visual cues tune oscillatory motor activity during decision-making

Motor decisions entails a buildup of choice-selective activity in the motor cortex. The rate of this buildup crucially depends on the amount of evidence favoring the selection of each action choice in the visual environment. Though numerous studies have characterized how sensory evidence drives motor activity when processed consciously, very little is known about the neural mechanisms that underlie the integration of implicit sources of information.Here, we used electroencephalography to investigate the impact of implicit visual cues on response-locked potentials and oscillatory activity in the motor cortex during decision-making. Subjects were required to select between left and right index finger responses according to the motion direction of a cloud of dots presented in one of three possible colors. Unbeknown to the participants, the color cue could bring evidence either in favor of or against the selection of the correct response.Implicit color cues tuned choice-selective oscillatory activity in the low beta range (16–25 Hz), boosting the buildup of contralateral activity when evidence favored the selection of the correct action, while weakening it when evidence biased against the correct response. This modulation of oscillatory activity influenced the speed at which the correct action was eventually chosen. Implicit cues also altered oscillatory activity in a non-selective way in the low frequency oscillation (1–7 Hz) and high beta ranges (25–35 Hz), impacting both contralateral and ipsilateral activity. The current findings yield a critical extension of prior observations by indicating that the integration of both explicit and implicit sources of evidence tunes oscillatory motor activity during decision-making.

Abnormal subcortical activity in congenital mirror movement disorder with RAD51 mutation

Congenital mirror movement disorder (CMMD) is characterized by unintended, nonsuppressible, homologous mirroring activity contralateral to the movement on the intended side of the body. In healthy controls, unilateral movements are accompanied with predominantly contralateral cortical activity, whereas in CMMD, in line with the abnormal behavior, bilateral cortical activity is observed for unilateral motor tasks. However, task-related activities in subcortical structures, which are known to play critical roles in motor actions, have not been investigated in CMMD previously. We investigated the functional activation patterns of the motor components in CMMD patients. By using linkage analysis and exome sequencing, common mutations were revealed in seven affected individuals from the same family. Next, using functional magnetic resonance imaging (fMRI) we investigated cortical and subcortical activity during manual motor actions in two right-handed affected brothers and sex, age, education, and socioeconomically matched healthy individuals. Genetic analyses revealed heterozygous RAD51 c.401C>T mutation which cosegregated with the phenotype in two affected members of the family. Consistent with previous literature, our fMRI results on these two affected individuals showed that mirror movements were closely related to abnormal cortical activity in M1 and SMA during unimanual movements. Furthermore, we have found previously unknown abnormal task-related activity in subcortical structures. Specifically, we have found increased and bilateral activity during unimanual movements in thalamus, striatum, and globus pallidus in CMMD patients. These findings reveal further neural correlates of CMMD, and may guide our understanding of the critical roles of subcortical structures for unimanual movements in healthy individuals.