Greater Cortical Activation Research Articles

Fronto-parietal cortex activation during walking in patients with Parkinson's disease adopting different postural strategies.

Cortical activation patterns in patients with Parkinson's disease (PD) may be influenced by postural strategies, but the underlying neural mechanisms remain unclear. Our aim is to examine the role of the fronto-parietal lobes in patients with PD adopting different postural strategies and the effect of dual task (DT) on fronto-parietal activation. Two groups of patients with PD adopting either the posture first strategy (PD-PF) or the posture second strategy (PD-PS) were examined respectively when in the "OFF" state while single-walking task (SW) and DT. Frontal and parietal lobe activity was assessed by functional near infrared spectroscopy (fNIRS) and measuring gait parameters. Linear mixed models were used for analyses. Patients with PD who adopted PS had greater cortical activation than those who adopted PF, and there was no difference between PF and PS in the behavioral parameters. For oxyhemoglobin levels, the task condition (SW vs. DT) had a main effect in fronto-parietal lobes. Postural strategy (PD-PF vs. PD-PS) a main effect in the left prefrontal cortex (LPFC), left parietal lobe (LPL), and right parietal lobe (RPL) regions. In the task of walking with and without the cognitive task, patients with PD adopting PS had higher activation in the LPL than those adopting PF. In DT, only PD patients who adopted PS had elevated oxyhemoglobin levels in the LPFC, right prefrontal cortex (RPFC), and LPL compared with the SW, whereas patients with PD who adopted PF showed no differences in any region. Different patterns of fronto-parietal activation exist between PD-PF and PD-PS. This may be because PD-PS require greater cortical functional compensation than those adopting PF.

Greater Cortical Activation and Motor Recovery Following Mirror Therapy Immediately after Peripheral Nerve Repair of the Forearm

Cortical reorganization occurs immediately after peripheral nerve injury, and early sensorimotor training is suggested during nerve regeneration. The effect of mirror therapy and classical sensory relearning on cortical activation immediately after peripheral nerve repair of the forearm is unknown. Six participants were randomly assigned to the mirror-therapy group or the sensory-relearning group. Sensorimotor training was conducted in a mirror box for 12 weeks. The mirror-therapy group used mirror reflection of the unaffected hand in order to train the affected hand, and the sensory-relearning group trained without mirror reflection. Semmes-Weinstein Monofilaments (SWM) test, static 2-point discrimination test (S-2PD), grip strength, and the Disabilities of the Arm, Shoulder and Hand (DASH) scores were measured at baseline, the end of the intervention (T1), and 3 months after the intervention (T2). Finger and manual dexterity were measured at T1 and T2, and a functional MRI (fMRI) was conducted at T1. All participants showed improvement in the SWM, S-2PD tests, upper extremity function, and grip strength after the intervention at T1, except for the participant who injured both the median and ulnar nerves in the sensory-relearning group. In addition, the mirror-therapy group had better outcomes in finger dexterity and manual dexterity, and fMRIs showed greater activation in the multimodal association cortices and ipsilateral brain areas during motor tasks. This study provides evidence-based results confirming the benefits of early sensorimotor relearning for cortical activation in peripheral nerve injury of the forearm and different neuroplasticity patterns between mirror therapy and classical sensor relearning.

Neurophysiological evidence of how quiet eye supports motor performance.

Prolonged quiet eye (QE) duration is associated with greater performance in various types of targeting and interceptive tasks. However, the mechanism by which QE affects performance remains debatable. This study aimed to test the validity of the pre-programming and online control hypotheses using electromyography (EMG), electrooculography (EOG) and electroencephalography (EEG) during a golf putting task. Twenty-one college students were recruited for this study. Each participant performed 100 golf putting trials during which the putting performance, EMG, EOG, and EEG signals were recorded. The QE duration including the pre- and post-movement initiation components, and movement-related cortical potentials (MRCPs) were analyzed off-line. We found that successful putts were associated with longer QEtotal (the total QE duration from QE onset to QE offset), QEpre (QE occurring before movement initiation), and QEpost (QE occurring after movement initiation) durations than failed putts. Greater cortical activation in the MRCPs was observed within the prefrontal, premotor, and parietal cortices during successful putts compared with failed putts. These findings suggest that QE serves both pre-programming and online control roles in supporting golf putting performance.

Abstract P218: Effects of Bilateral Transcutaneous Electrical Nerve Stimulation Combined With Task-Oriented Training on the Recovery of Upper Limb Motor Impairment in People With Chronic Stroke

Background: Transcutaneous electrical nerve stimulation(TENS) is an effective physiological intervention for people with stroke which aims at reducing muscle spasticity, enhancing muscle strength, and improving motor control and function. In view of the potentials to enhance greater cortical activation of the lesion side by eliciting spare neural pathways through bilateral intervention, this study examined whether the combined use of bilateral TENS (Bi-TENS) and task-oriented training (TOT) was superior to unilateral TENS(Uni-TENS)+TOT, placebo-TENS+TOT and no active treatment to improve the motor impairment of upper limb function in people with stroke. Method: There were 120 subjects with stroke(44 females, mean age=61.52±6.73 years, post-stroke duration=6.04±3.12years) being randomly allocated into 4 groups, including the Bi-group (n=30), Uni-group (n=30), placebo group (n=30) and control group (n=30). Subjects in the Bi-group, Uni-group and placebo group got 60 minutes TENS and TOT simultaneously per time for 20 times(3 times per week for 7 weeks). In the Bi-group, TENS stimulated the radial and median nerves of the bilateral upper limbs. In the Uni-group, TENS and placebo-TENS stimulated the affected and unaffected side, respectively. In the placebo group, placebo-TENS were placed on bilateral sides. In the control group, subjects did not receive any active treatment. Level of motor impairment was assessed by the Fugl-Meyer Assessment of Upper Extremity (FMA-UE). Result: The Bi-group had a significant greater improvement in FMA-UE than the Uni-group(mean change=2.02, p=0.005), placebo group (mean change=2.49, p=0.001) and control group(mean change=3.08, p<0.001) at post-intervention. The Bi-group(mean change=3.25, p<0.001) and Uni-group(mean change=1.23, p=0.015) showed a significant within-group improvement in FMA-UE since 10 sessions of treatment. No significant change was found in the placebo and control groups. Conclusion: Bi-TENS is superior to Uni-TENS, placebo-TENS and no active treatment in augmenting the recovery of upper limb motor impairment in people with chronic stroke. Author Disclosures: The authors received research support from the Health and Medical Research Fund12131821 from the Food and Health Bureau, HKSAR.

Association of Asthenopia with Sustained Attention, Accommodation and Encephalographic Activity

Purpose: Greater accommodative lag and vergence deficits have been linked to attentional deficits similar to those observed in attention deficit hyperactivity disorder (ADHD). The purpose of the present study was to assess the effect of accommodative-vergence stress on sustained attention, lens accommodation and frontal electroencephalographic activity in young adults with high and low symptoms of asthenopia. Methods: Forty-six college students participated in the study. Based on their scores on the Convergence Insufficiency Symptom Survey (CISS), 18 participants were assigned to the high CISS symptom group, while 21 participants comprised the low CISS symptom group. All of the participants completed a test of sustained attention (Conners CPT) twice while wearing -2.00 D lenses and normally in a counterbalanced order one week apart. Their dynamic accommodative responses and electroencephalographic activity (EEG) during attentional testing was also recorded. Results: The results showed that the high CISS symptom group performed a significantly greater number of commissions, perseverations and poorer target detectability than the low CISS symptom group across both testing sessions. Accommodative lag was significantly smaller in the non-stress condition compared to the -2.0 D stress condition for both groups. The low CISS symptom group, however, showed lower high beta power (21- 29Hz) during completion of Conners CPT than the high CISS symptom group, suggesting greater cortical activation in the high CISS symptom group. Conclusions: Overall the results of the study demonstrated that symptoms of asthenopia are also correlated with symptoms of inattention and predict performance deterioration in sustained attention. Additional increase in accommodative-vergence stress, however, was not shown to disrupt performance of the high symptom group to a greater extent than in the low symptom group possibly due to the absence of accommodative deficits in the high symptom group, absence of sustained vergence deficits and/or a relatively short duration of accommodative-vergence stress.

Difference in cortical activation during use of volar and dorsal hand splints: a functional magnetic resonance imaging study.

There have been no studies reported on the difference in cortical activation during use of volar and dorsal hand splints. We attempted to investigate the difference in cortical activation in the somatosensory cortical area during use of volar and dorsal hand splints by functional magnetic resonance imaging (fMRI). We recruited eight healthy volunteers. fMRI was performed while subjects who were fitted with volar or dorsal hand splints performed grasp-release movements. Regions of interest were placed on the primary motor cortex (M1), primary somatosensory cortex (S1), posterior parietal cortex (PPC), and secondary somatosensory cortex (S2). Results of group analysis of fMRI data showed that the total numbers of activated voxels in all ROIs were significantly higher during use of volar hand splint (3,376) compared with that (1,416) during use of dorsal hand splint. In each ROI, use of volar hand splint induced greater activation in all ROIs (M1: 1,748, S1: 1,455, PPC: 23, and S2: 150) compared with use of dorsal hand splint (M1: 783, S1: 625, PPC: 0, and S2: 8). The peak activated value was also higher during use of volar hand splint (t-value: 17.29) compared with that during use of dorsal hand splint (t-value: 13.11). Taken together, use of volar hand splint induced greater cortical activation relevant to somatosensory function than use of dorsal hand splint. This result would be important for the physiatrist and therapist to apply appropriate somatosensory input in patients with brain injury.

Aging causes a reorganization of cortical and spinal control of posture

Classical studies in animal preparations suggest a strong role for spinal control of posture. In humans it is now established that the cerebral cortex contributes to postural control of unperturbed and perturbed standing. The age-related degeneration and accompanying functional changes in the brain, reported so far mainly in conjunction with simple manual motor tasks, may also affect the mechanisms that control complex motor tasks involving posture. This review outlines the age-related structural and functional changes at spinal and cortical levels and provides a mechanistic analysis of how such changes may be linked to the behaviorally manifest postural deficits in old adults. The emerging picture is that the age-related reorganization in motor control during voluntary tasks, characterized by differential modulation of spinal reflexes, greater cortical activation and cortical disinhibition, is also present during postural tasks. We discuss the possibility that this reorganization underlies the increased coactivation and dual task interference reported in elderly. Finally, we propose a model for future studies to unravel the structure-function-behavior relations in postural control and aging.

Imitation and the developing social brain: infants’ somatotopic EEG patterns for acts of self and other

A leading question in developmental social-cognitive neuroscience concerns the nature and function of neural links between action perception and production in early human development. Here we document a somatotopic pattern of activity of the sensorimotor EEG mu rhythm in 14-month-old infants. EEG was recorded during interactive trials in which infants activated a novel object using their own hands or feet ("execution" trials) and watched an experimenter use her hands or feet to achieve the same goal ("observation" trials). At central electrodes overlying sensorimotor hand areas (C3/C4), mu rhythm power was reduced (indicating greater cortical activation) during infants' execution of hand acts compared to foot acts. For the central electrode overlying the sensorimotor foot area (Cz), mu power was reduced during the execution of foot versus hand acts. Strikingly similar somatotopic patterns were found in both the action execution and observation conditions. We hypothesize that these somatotopic patterns index an intercorporeal mapping of corresponding body parts between self and other. We further propose that infants' ability to identify self-other equivalences at the level of body parts underlies infant imitation and is an ontogenetic building block for the feelings of intersubjectivity we experience when socially engaged with other people.

Early Behavioral Intervention Is Associated With Normalized Brain Activity in Young Children With Autism

A previously published randomized clinical trial indicated that a developmental behavioral intervention, the Early Start Denver Model (ESDM), resulted in gains in IQ, language, and adaptive behavior of children with autism spectrum disorder. This report describes a secondary outcome measurement from this trial, EEG activity. Forty-eight 18- to 30-month-old children with autism spectrum disorder were randomized to receive the ESDM or referral to community intervention for 2 years. After the intervention (age 48 to 77 months), EEG activity (event-related potentials and spectral power) was measured during the presentation of faces versus objects. Age-matched typical children were also assessed. The ESDM group exhibited greater improvements in autism symptoms, IQ, language, and adaptive and social behaviors than the community intervention group. The ESDM group and typical children showed a shorter Nc latency and increased cortical activation (decreased α power and increased θ power) when viewing faces, whereas the community intervention group showed the opposite pattern (shorter latency event-related potential [ERP] and greater cortical activation when viewing objects). Greater cortical activation while viewing faces was associated with improved social behavior. This was the first trial to demonstrate that early behavioral intervention is associated with normalized patterns of brain activity, which is associated with improvements in social behavior, in young children with autism spectrum disorder.

Quiet eye and the Bereitschaftspotential: visuomotor mechanisms of expert motor performance

Concurrent exploration of the Bereitschaftspotential (BP) and quiet eye period (QE) was implemented to assess potential mechanisms underlying psychomotor skills that differentiate expert and near-expert performers. Twenty golfers were classified by their USGA handicap rating as either a high handicap (HH; near-expert) or low handicap (LH; expert) to permit skill-based inferences. Participants completed 90 trials during which QE duration, BP activity, and putting performance were recorded. The application of single-subject analyses illustrated that LH golfers were more accurate and less variable in their performance than the HH group. Systematic differences in QE duration and BP were also observed, with experts exhibiting a prolonged quiet eye period and greater cortical activation in the right-central region compared with non-experts. A significant association between cortical activation and QE duration was also noted. The results of this investigation lend support to the motor programming/preparation function of the QE period. Practical and theoretical implications are presented and suggestions for future empirical work provided.

Sex differences in functional brain activation during noxious visceral stimulation in rats

Studies in healthy human subjects and patients with irritable bowel syndrome suggest sex differences in cerebral nociceptive processing. Here we examine sex differences in functional brain activation in the rat during colorectal distention (CRD), a preclinical model of acute visceral pain. [14C]-iodoantipyrine was injected intravenously in awake, non-restrained female rats during 60- or 0-mmHg CRD while electromyographic abdominal activity (EMG) and pain behavior were recorded. Regional cerebral blood flow-related tissue radioactivity was analyzed by statistical parametric mapping from autoradiographic images of three-dimensionally reconstructed brains. Sex differences were addressed by comparing the current data with our previously published data collected from male rats. While sex differences in EMG and pain scores were modest, significant differences were noted in functional brain activation. Females showed widespread changes in limbic (amygdala, hypothalamus) and paralimbic structures (ventral striatum, nucleus accumbens, raphe), while males demonstrated broad cortical changes. Sex differences were apparent in the homeostatic afferent network (parabrachial nucleus, thalamus, insular and dorsal anterior cingulate cortices), in an emotional–arousal network (amygdala, locus coeruleus complex), and in cortical areas modulating these networks (prefrontal cortex). Greater activation of the ventromedial prefrontal cortex and broader limbic/paralimbic changes in females suggest greater engagement of affective mechanisms during visceral pain. Greater cortical activation in males is consistent with the concept of greater cortical inhibitory effects on limbic structures in males, which may relate to differences in attentional and cognitive attribution to visceral stimuli. These findings show remarkable similarities to reported sex differences in brain responses to visceral stimuli in humans.