Tool-use practice induces changes in intrinsic functional connectivity of parietal areas

Comparing movement-related cortical potential between real and simulated movement tasks from an ecological validity perspective

Introduction

Concerns regarding the ecological validity of movement-related cortical potential (MRCP) experimental tasks that are related to motor learning have recently been growing. Therefore, we compared MRCP during real movement task (RMT) and simulated movement task (SMT) from an ecological validity perspective.

Methods

The participants performed both RMT and SMT, and MRCP were measured using electroencephalogram (EEG). EEG was based on the 10-20 method, with electrodes placed in the motor cortex (C3 and C4) and supplementary motor cortex (FCz [between Fz and Cz] and Cz) areas. This experiment examined the MRCP using Bereitschaftspotential (BP) and negative slope (NS') onset times, and BP, NS', and motor potential (MP) amplitudes during the task.

Results

The results revealed that the SMT exhibited later BP and NS' onset times and smaller BP, NS', and MP amplitudes than the RMT. Furthermore, in RMT, the onset time of MRCP was delayed, and the amplitude of MRCP was smaller in the second half of the 200 times task than in the first half, whereas in SMT, there was no change in onset time and amplitude. The SMT showed a different MRCP than the RMT, suggesting that the ecological validity of the task should be fully considered when investigating the cortical activity associated with motor skill learning using MRCP.

Conclusion

Ecological validity of the study should be fully considered when investigating the cortical activity associated with motor skill learning using MRCP. Moreover, it is important to understand the differences between the two methods when applied clinically.

A randomized controlled trial of changes in resting-state functional connectivity associated with short-term motor learning of chopstick use with the non-dominant hand

INTRODUCTION

This study identified the offline brain networks associated with motor learning of non-dominant hand chopstick use within-session.

METHODS

40 healthy right-handed adults were randomly assigned to the practice and control groups (20 each). The performance, resting-state functional connectivity (RSFC), and their correlation were compared within and between groups. Both groups repeated 9 cycles of 30 s task and rest. During the task, the practice group performed the chopstick-use practice with their left hand, while the control group held chopsticks without acquiring any skills. During the rest, both groups fixated their gaze on a fixation point. The number of times candies were moved using chopsticks with the left hand in 30 s was used to evaluate the performance. RSFC was obtained by resting-state fMRI scanning and extracting Z-scores between the right primary motor cortex and all other brain regions.

RESULTS

Both the groups improved in the post-task performance; the practice group improved more. The RSFC of the two networks increased in the practice group. One network was the RSFC between the right M1 and the right cerebellar Crus I, positively correlated with performance in the post-task. Another was the RSFC between the right M1 and the left cerebellar Crus II, positively correlated with skills in the amount of change pre- and post-task.

CONCLUSION

Offline enhancement of RSFC in these networks was shown to contribute to early chopstick-use motor learning with the left hand. These results serve as a basis for future studies on compensatory networks in individuals with stroke.

Left anterior supramarginal gyrus activity during tool use action observation after extensive tool use training

The advanced use of complex tools is considered a primary characteristic of human evolution and technological advancement. However, questions remain regarding whether humans possess unique underlying brain networks that support advanced tool-using abilities. Specifically, previous studies have demonstrated the presence of a structurally and functionally unique region in the left anterior supramarginal gyrus (aSMG), that is consistently active during tool use action observation. This region has been proposed as a primary hub for integrating semantic and technical information to form action plans with tools. However, it is still largely unknown how tool use motor learning affects left aSMG activation or connectivity with other brain regions. To address this, participants with little experience using chopsticks observed an experimenter using chopsticks to perform a novel task while undergoing two functional magnetic resonance imaging (fMRI) scans. Between the scans, participants underwent four weeks of behavioral training where they learned to use chopsticks and achieve proficiency in the observed task. Results demonstrated a significant change in effective connectivity between the left aSMG and the left anterior intraparietal sulcus (aIPS), a region involved in object affordances and planning grasping actions. These findings suggest that during unfamiliar tool use, the left aSMG integrates semantic and technical information to communicate with regions involved with grasp selection, such as the aIPS. This communication then allows appropriate grasps to be planned based on the physical properties of the objects involved and their potential interactions.

Association between handgrip strength asymmetry and cognitive function across ethnicity in rural China: a cross-sectional study

Background

Recently, the association between handgrip strength (HGS) asymmetry and cognition has been revealed, but evidences are still scarce. Particularly, the association between asymmetric HGS and cognitive performance in various cognitive domains is unclear and whether this association is stable across ethnic groups is unknown.

Method

The population was from a longitudinal study in rural areas of Fuxin, Liaoning, China. The Chinese version of Montreal Cognitive Assessment-Basic (MOCA-BC) was used to evaluate the cognitive function. The HGS ratio was calculated as maximal non-dominant HGS divided by maximal dominant HGS. HGS ratio <0.9 or >1.1 was classified as asymmetric dominant/non-dominant HGS, respectively. Generalized linear models were used to analyze the relationship between asymmetric HGS and cognitive function adjusted for HGS, handedness, wave, age, sex, education, ethnicity, smoking, drinking, physical labor level, BMI, hypertension, diabetes and dyslipidemia.

Result

A total of 2,969 participants ≥50 years were included in this study. Adjusted for HGS and other confunding variables, there was an inverted U-shaped association between HGS ratio and MoCA-BC scores (P _non-linear = 0.004). The association between HGS ratio and MoCA-BC scores was inconsistent among ethnic groups (P _interaction = 0.048). In Han, only asymmetric non-dominant HGS was associated with lower cognitive scores [β = -0.67, 95% confidence interval (CI): -1.26 ∼-0.08, P = 0.027]; in Mongolians, asymmetric dominant HGS(β = -0.60, 95% CI: -1.35 ∼ 0.15, P = 0.115) and asymmetric non-dominant HGS (β = -0.56, 95% CI: -1.42 ∼ 0.31, P = 0.206) were all associated with lower cognitive scores, although no statistical significance was found. Asymmetric non-dominant HGS and lower HGS, but not asymmetric dominant HGS were all independently associated with impairment of Delayed Recall (OR = 1.35, 95% CI: 1.05 ∼ 1.74; OR _{per 5 kg decrease} = 1.10, 95% CI: 1.01 ∼ 1.21) and Fluency (OR = 1.43, 95% CI: 1.15 ∼ 1.78; OR _{per 5 kg decrease} = 1.10, 95% CI: 1.02 ∼ 1.19). Both asymmetric dominant HGS (OR = 1.34, 95% CI: 1.07 ∼ 1.67) and lower HGS (OR _{per 5 kg decrease} = 1.21, 95% CI: 1.10 ∼ 1.32) were associated with impairment of visuoperception.

Conclusion

HGS and HGS asymmetry were all independently related to lower global cognitive performance. The association between HGS asymmetry and cognitive function varies among ethnic groups.

Functional alteration due to structural damage is network dependent: insight from multiple sclerosis

Little is known about how the brain's functional organization changes over time with respect to structural damage. Using multiple sclerosis as a model of structural damage, we assessed how much functional connectivity (FC) changed within and between preselected resting-state networks (RSNs) in 122 subjects (72 with multiple sclerosis and 50 healthy controls). We acquired the structural, diffusion, and functional MRI to compute functional connectomes and structural disconnectivity profiles. Change in FC was calculated by comparing each multiple sclerosis participant's pairwise FC to controls, while structural disruption (SD) was computed from abnormalities in diffusion MRI via the Network Modification tool. We used an ordinary least squares regression to predict the change in FC from SD for 9 common RSNs. We found clear differences in how RSNs functionally respond to structural damage, namely that higher-order networks were more likely to experience changes in FC in response to structural damage (default mode R2 = 0.160-0.207, P < 0.001) than lower-order sensory networks (visual network 1 R2 = 0.001-0.007, P = 0.157-0.387). Our findings suggest that functional adaptability to structural damage depends on how involved the affected network is in higher-order processing.

The parietal lobe evolution and the emergence of material culture in the human genus

Traditional and new disciplines converge in suggesting that the parietal lobe underwent a considerable expansion during human evolution. Through the study of endocasts and shape analysis, paleoneurology has shown an increased globularity of the braincase and bulging of the parietal region in modern humans, as compared to other human species, including Neandertals. Cortical complexity increased in both the superior and inferior parietal lobules. Emerging fields bridging archaeology and neuroscience supply further evidence of the involvement of the parietal cortex in human-specific behaviors related to visuospatial capacity, technological integration, self-awareness, numerosity, mathematical reasoning and language. Here, we complement these inferences on the parietal lobe evolution, with results from more classical neuroscience disciplines, such as behavioral neurophysiology, functional neuroimaging, and brain lesions; and apply these to define the neural substrates and the role of the parietal lobes in the emergence of functions at the core of material culture, such as tool-making, tool use and constructional abilities.

Functional Connectivity and Networks Underlying Complex Tool-Use Movement in Assembly Workers: An fMRI Study

The aim of this study was to identify the functional connectivity and networks utilized during tool-use in real assembly workers. These brain networks have not been elucidated because the use of tools in real-life settings is more complex than that in experimental environments. We evaluated task-related functional magnetic resonance imaging in 13 assembly workers (trained workers, TW) and 27 age-matched volunteers (untrained workers, UTW) during a tool-use pantomiming task, and resting-state functional connectivity was also analyzed. Two-way repeated-measures analysis of covariance was conducted with the group as a between-subject factor (TW > UTW) and condition (task > resting) as a repeated measure, controlling for assembly time and accuracy as covariates. We identified two patterns of functional connectivity in the whole brain within three networks that distinguished TW from UTW. TW had higher connectivity than UTW between the left middle temporal gyrus and right cerebellum Crus II (false discovery rate corrected p-value, p-FDR = 0.002) as well as between the left supplementary motor area and the pars triangularis of the right inferior frontal gyrus (p-FDR = 0.010). These network integrities may allow for TW to perform rapid tool-use. In contrast, UTW showed a stronger integrity compared to TW between the left paracentral lobule and right angular gyrus (p-FDR = 0.004), which may reflect a greater reliance on sensorimotor input to acquire complex tool-use ability than that of TW. Additionally, the fronto-parietal network was identified as a common network between groups. These findings support our hypothesis that assembly workers have stronger connectivity in tool-specific motor regions and the cerebellum, whereas UTW have greater involvement of sensorimotor networks during a tool-use task.

Chopstick operation training with the left non-dominant hand

Background

Training a non-dominant hand is important for rehabilitating people who are required to change handedness. However, improving the dexterity in using chopsticks with a non-dominant hand through training remains unclear. This study is aimed to measure whether chopstick training improves non-dominant hand chopstick operation skills and leads to acquisition of skill levels similar to those of the dominant hand.

Methods

This single-blinded randomized controlled trial enrolled 34 healthy young right-handed subjects who scored >70 points on the Edinburgh Handedness Questionnaire Inventory. They were randomly allocated to training or control groups. The training group participated in a 6-week chopstick training program with the non-dominant left hand, while the control group did not. Asymmetry of chopstick operation skill, perceived psychological stress, and oxygen-hemoglobin concentration as a brain activity measure in each hemisphere were measured before and after training.

Results

Participants in the training group had significantly lower asymmetry than those in the control group during the post-training assessment (F[1,30] ≥ 5.54, p ≤ 0.03, partial η² ≥ 0.156). Only perceived psychological stress had a significantly higher asymmetry during the post-training assessment (t[15] = 3.81, p < 0.01).

Conclusion

Six weeks of chopstick training improved non-dominant chopstick operation skills, and a performance level similar to that of the dominant hand was acquired.

Are there any differential responses to concussive injury in civilian versus athletic populations: a neuroimaging study

Accurate identification and classification of patients suffering from mild traumatic brain injury (mTBI) is a significant challenge faced by clinicians and researchers. To examine if there are different pathophysiological responses to concussive injury in different populations, evaluated here comparing collegiate athletes versus age-matched non-athletes. Resting-state fMRI data were acquired in the acute phase of concussion from 30 collegiate athletes and from 30 injury and age matched non-athletes. Resting-state functional connectivity measures revealed group differences with reduced connectivity in the anterior cingulate cortex (p < .05) and posterior cingulate cortex (p < 0.05) hubs of the Default Mode Network in the athletes. Given the known positive effects of exercise on brain functional reserves and neural efficiency concept, we expected less pronounced effect of concussion in athletic population. In contrast, there were significant decreases in functional connectivity in athletes that could be a result of previous repetitive subconcussive impacts and history of concussion.

Early Impairment of Chopsticks Skills in Parkinsonism Suggests Progressive Supranuclear Palsy

Background and Purpose

Chopsticks are a primary eating utensil in East Asia, but systematic assessments of chopsticks skills in parkinsonian disorders is lacking. We aimed to identify any differences in chopsticks skills in the early stages of Parkinson's disease (PD) and atypical parkinsonism (AP), including progressive supranuclear palsy (PSP), multiple system atrophy (MSA), and corticobasal syndrome (CBS).

Methods

We consecutively recruited 111 patients with PD and 74 with AP (40 with PSP, 30 with MSA, and 4 with CBS) who were in a drug-naïve state. The motor and cognitive functions of the patients were evaluated using a standardized protocol. Everyday chopsticks skills were evaluated using a chopsticks questionnaire developed in-house. The chopsticks skills test (CST) involved counting the number of pills that the subject was able to carry using chopsticks between two dishes separated by 20 cm within 20 seconds.

Results

Patient responses to the questionnaire indicating poor chopsticks skills (“I cannot pick up some of the food items” or “I cannot use chopsticks anymore”) were present in 23.0% of AP patients and 30% of PSP patients, compared to only 5.6% of PD patients [odd ratio (OR)=5.07 and OR=7.29, p≤0.001 in both]. The performance in the CST was worse in PSP than in PD (p<0.001). The CST results were correlated with hand motor skills including in the coinrotation test, timed figure-tapping test, and motor Unified Parkinson's Disease Rating Scale scores in all of the patient groups (p<0.001). In PSP, a decline in visuospatial function and frontal executive function was associated with a poor performance in the CST in addition to poor motor performance (p<0.05).

Conclusions

Impairments in chopsticks skills were more common in PSP than in PD during the early stages of parkinsonism. This suggests that early functional impairment of chopsticks skills can be used as a warning sign for PSP.

Toward natural grasping with a tool: effects of practice and required accuracy on the kinematics of tool-use grasping

Studies have suggested that the proficiency of an end effector is the primary factor that defines kinematics of reach-to-grasp movements across the types of effectors, such as the hand or a tool. In particular, the duration of the plateau, or the time of static open aperture (i.e., the distance between tips of effectors), is typically longer for tool use compared with natural grasping with a hand. This study investigated how improvement in the proficiency of tool use modifies the kinematics of reach-to-grasp movements. To clarify the effects of required accuracy on the kinematics in tool-use grasping, movement speed and difficulty of grasping were manipulated. The results showed that plateau duration, the length of which indicates that reaching and grasping components are temporally dissociated, shortened as tool-use practice proceeded. These results indirectly support the idea that shortened plateau duration was induced by improvement in the proficiency of tool use. Moreover, plateau duration was shortened at faster movement speeds or under conditions not requiring accurate grasping, even without any practice of tool-use grasping. Additional analyses found that plateau duration did not scale with movement time. These results suggest that the kinematic features supposed to be characteristic of tool-use grasping are not inevitable but are greatly influenced by a strategy that is not intentionally but rather automatically implemented to compensate for the lack of proficiency of end effectors, in agreement with the idea that the brain focuses on the tips of an end effector regardless of its effector type in reach-to-grasp movements.NEW & NOTEWORTHY This study is the first reporting the relation between characteristic aperture time profile, called plateau duration, and movement time of tool-use grasping. The results suggest that improved coordination between reaching and grasping components was induced by improvement in the proficiency of tool use but not by just shortened movement time. The results also indicate the possibility that the constraints for calculations in motor planning are essentially the same between hand-use grasping and tool-use grasping.

Real-time biofeedback integrated into neuromuscular training reduces high-risk knee biomechanics and increases functional brain connectivity: A preliminary longitudinal investigation

Prospective evidence indicates that functional biomechanics and brain connectivity may predispose an athlete to an anterior cruciate ligament injury, revealing novel neural linkages for targeted neuromuscular training interventions. The purpose of this study was to determine the efficacy of a real-time biofeedback system for altering knee biomechanics and brain functional connectivity. Seventeen healthy, young, physically active female athletes completed 6 weeks of augmented neuromuscular training (aNMT) utilizing real-time, interactive visual biofeedback and 13 served as untrained controls. A drop vertical jump and resting state functional magnetic resonance imaging were separately completed at pre- and posttest time points to assess sensorimotor adaptation. The aNMT group had a significant reduction in peak knee abduction moment (pKAM) compared to controls (p = .03, d = 0.71). The aNMT group also exhibited a significant increase in functional connectivity between the right supplementary motor area and the left thalamus (p = .0473 after false discovery rate correction). Greater percent change in pKAM was also related to increased connectivity between the right cerebellum and right thalamus for the aNMT group (p = .0292 after false discovery rate correction, r²  = .62). No significant changes were observed for the controls (ps > .05). Our data provide preliminary evidence of potential neural mechanisms for aNMT-induced motor adaptations that reduce injury risk. Future research is warranted to understand the role of neuromuscular training alone and how each component of aNMT influences biomechanics and functional connectivity.

Acquisition of chopstick-operation skills with the non-dominant hand and concomitant changes in brain activity

Despite their common use as eating utensils in East Asia, chopsticks require complex fine motor-skills for adequate operation and are thus most frequently used with the dominant hand; however, the effect of training time on the proficiency of using chopsticks with the non-dominant hand, as well as the brain activity underlying changes in skill, remain unclear. This study characterised the effect of time spent training in chopstick operation with the non-dominant hand on chopstick-use proficiency and the related brain activity to obtain data that may help individuals who are obliged to change handedness due to neurological disease to learn to use their non-dominant hand in performing daily activities. Thirty-two healthy right-handed students were randomly allocated to training (n = 16) or control (n = 16) groups; the former received 6 weeks of training in chopstick use with their non-dominant (left) hand, and the latter received none. After training, significant improvements in the execution speed and smoothness of upper extremity joints were observed in the training group. Moreover, left dorsolateral prefrontal cortex activity significantly decreased, and bilateral premotor cortex activity significantly increased across training. These results indicated that 6 weeks of chopstick training with the non-dominant hand effectively improved chopstick operation.

Nonlinear neuroplasticity corresponding to sports experience: A voxel-based morphometry and resting-state functional connectivity study

We aimed to investigate the structural neuroplasticity associated with different levels of sports experience and its effect on the corresponding resting-state functional circuitry. We recruited 18 skilled baseball batters (SB), 19 intermediate baseball batters (IB), and 17 healthy controls (HC), and used magnetic resonance imaging methods to compare their regional gray-matter volume (GMV) and seed-based resting-state functional connectivity (rsFC). Our results revealed that a quadratic function could better depict intergroup differences in regional GMV than a linear function. In particular, the IB showed lower or higher regional GMV than the other two groups. The difference in GMV in the supplementary motor area and areas belonging to the ventral stream, including the middle temporal gyrus and middle temporal pole, might be possibly related to baseball-specific motor and perceptual experience, such as inhibitory action control and pitch identification. On the other hand, the stronger rsFC seeded from the right middle temporal pole to the default mode network, particularly in the precuneus, in the SB and IB relative to that in the HC might be possibly associated with the theory of mind, such as deciding whether to swing or not against the pitcher by detecting the spatial information of pitches. In conclusion, our three-group design enabled the capture of the unique and transient changes that occur during the intermediate phase of expertise development. Our findings indicated that structural and functional brain changes do not necessarily linearly increase as a function of experience as previously suggested by the literature.

Age-Dependent Modulations of Resting State Connectivity Following Motor Practice

Recent work in young adults has demonstrated that motor learning can modulate resting state functional connectivity. However, evidence for older adults is scarce. Here, we investigated whether learning a bimanual tracking task modulates resting state functional connectivity of both inter- and intra-hemispheric regions differentially in young and older individuals, and whether this has behavioral relevance. Both age groups learned a set of complex bimanual tracking task variants over a 2-week training period. Resting-state and task-related functional magnetic resonance imaging scans were collected before and after training. Our analyses revealed that both young and older adults reached considerable performance gains. Older adults even obtained larger training-induced improvements relative to baseline, but their overall performance levels were lower than in young adults. Short-term practice resulted in a modulation of resting state functional connectivity, leading to connectivity increases in young adults, but connectivity decreases in older adults. This pattern of age differences occurred for both inter- and intra-hemispheric connections related to the motor network. Additionally, long-term training-induced increases were observed in intra-hemispheric connectivity in the right hemisphere across both age groups. Overall, at the individual level, the long-term changes in inter-hemispheric connectivity correlated with training-induced motor improvement. Our findings confirm that short-term task practice shapes spontaneous brain activity differentially in young and older individuals. Importantly, the association between changes in resting state functional connectivity and improvements in motor performance at the individual level may be indicative of how training shapes the short-term functional reorganization of the resting state motor network for improvement of behavioral performance.

Higher extrinsic and lower intrinsic connectivity in resting state networks for professional Baduk (Go) players

INTRODUCTION

Dedication and training to a profession results in a certain level of expertise. This expertise, like any other skill obtained in our lifetime, is encoded in the brain and may be reflected in our brain's connectome. This property can be observed by mapping resting state connectivity. In this study, we examine the differences in resting state functional connectivity in four major networks between professional "Baduk" (Go) players and normal subjects.

METHODS

Resting state fMRI scans were acquired for professional "Baduk" (Go) players and normal controls. Major resting state networks were identified using independent component analysis and compared between the two groups. Networks which were compared include the default mode network, the left and right fronto-parietal network, and the salience network.

RESULTS

We found that normal subjects showed increased connectivity within certain areas of each target network. Professional players, however, showed higher connectivity to regions outside the traditional regions of each given network. Close examination of these regions revealed that regions shown to have higher connectivity in professional players have been revealed to be relevant in expertise for board games.

CONCLUSION

The findings in this study suggest that continuous training results in greater integration between regions and networks, which are necessary for high-level performance. The differences observed in our study between normal controls and professional players also shed light on the difference in brain connectivity which can arise through lifestyle and specialization in a specific field.

The Dancing Brain: Structural and Functional Signatures of Expert Dance Training

Dance - as a ritual, therapy, and leisure activity - has been known for thousands of years. Today, dance is increasingly used as therapy for cognitive and neurological disorders such as dementia and Parkinson's disease. Surprisingly, the effects of dance training on the healthy young brain are not well understood despite the necessity of such information for planning successful clinical interventions. Therefore, this study examined actively performing, expert-level trained college students as a model of long-term exposure to dance training. To study the long-term effects of dance training on the human brain, we compared 20 young expert female Dancers with normal body mass index with 20 age- and education-matched Non-Dancers with respect to brain structure and function. We used diffusion tensor, morphometric, resting state and task-related functional MRI, a broad cognitive assessment, and objective measures of selected dance skill (Dance Central video game and a balance task). Dancers showed superior performance in the Dance Central video game and balance task, but showed no differences in cognitive abilities. We found little evidence for training-related differences in brain volume in Dancers. Dancers had lower anisotropy in the corticospinal tract. They also activated the action observation network (AON) to greater extent than Non-Dancers when viewing dance sequences. Dancers showed altered functional connectivity of the AON, and of the general motor learning network. These functional connectivity differences were related to dance skill and balance and training-induced structural characteristics. Our findings have the potential to inform future study designs aiming to monitor dance training-induced plasticity in clinical populations.

The Exercising Brain: Changes in Functional Connectivity Induced by an Integrated Multimodal Cognitive and Whole-Body Coordination Training

This study investigated the impact of “life kinetik” training on brain plasticity in terms of an increased functional connectivity during resting-state functional magnetic resonance imaging (rs-fMRI). The training is an integrated multimodal training that combines motor and cognitive aspects and challenges the brain by introducing new and unfamiliar coordinative tasks. Twenty-one subjects completed at least 11 one-hour-per-week “life kinetik” training sessions in 13 weeks as well as before and after rs-fMRI scans. Additionally, 11 control subjects with 2 rs-fMRI scans were included. The CONN toolbox was used to conduct several seed-to-voxel analyses. We searched for functional connectivity increases between brain regions expected to be involved in the exercises. Connections to brain regions representing parts of the default mode network, such as medial frontal cortex and posterior cingulate cortex, did not change. Significant connectivity alterations occurred between the visual cortex and parts of the superior parietal area (BA7). Premotor area and cingulate gyrus were also affected. We can conclude that the constant challenge of unfamiliar combinations of coordination tasks, combined with visual perception and working memory demands, seems to induce brain plasticity expressed in enhanced connectivity strength of brain regions due to coactivation.

Rapid Responsiveness to Practice Predicts Longer-Term Retention of Upper Extremity Motor Skill in Non-Demented Older Adults

Skill acquisition is a form of motor learning that may provide key insights into the aging brain. Although previous work suggests that older adults learn novel motor tasks slower and to a lesser extent than younger adults, we have recently demonstrated no significant effect of chronological age on the rates and amounts of skill acquisition, nor on its long-term retention, in adults over the age of 65. To better understand predictors of skill acquisition in non-demented older adults, we now explore the relationship between early improvements in motor performance due to practice (i.e., rapid responsiveness) and longer-term retention of an upper extremity motor skill, and whether the extent of rapid responsiveness was associated with global cognitive status. Results showed significant improvements in motor performance within the first five (of 150) trials, and that this “rapid responsiveness” was predictive of skill retention 1 month later. Notably, the extent of rapid responsiveness was not dependent on global cognitive status, as measured by the Montreal Cognitive Assessment (MoCA). Thus, rapid responsiveness appears to be an important variable in longer-term neurorehabilitative efforts with older adults, regardless of their cognitive status.

Functional connectivity MRI tracks memory networks after maze learning in rodents

Learning and memory employs a series of cognitive processes which require the coordination of multiple areas across the brain. However in vivo imaging of cognitive function has been challenging in rodents. Since these processes involve synchronous firing among different brain loci we explored functional connectivity imaging with resting-state fMRI. After 5-day training on a hidden platform watermaze task, notable signal correlations were seen between the hippocampal CA3 and other structures, including thalamus, septum and cingulate cortex, compared to swim control or naïve animals. The connectivity sustained 7 days after training and was reorganized toward the cortex, consistent with views of memory trace distribution leading to memory consolidation. These data demonstrates that, after a cognitive task, altered functional connectivity can be detected in the subsequently sedated rodent using in vivo imaging. This approach paves the way to understand dynamics of area-dependent distribution processes in animal models of cognition.

The white matter structural network underlying human tool use and tool understanding

The ability to recognize, create, and use complex tools is a milestone in human evolution. Widely distributed brain regions in parietal, frontal, and temporal cortices have been implicated in using and understanding tools, but the roles of their anatomical connections in supporting tool use and tool conceptual behaviors are unclear. Using deterministic fiber tracking in healthy participants, we first examined how 14 cortical regions that are consistently activated by tool processing are connected by white matter (WM) tracts. The relationship between the integrity of each of the 33 obtained tracts and tool processing deficits across 86 brain-damaged patients was investigated. WM tract integrity was measured with both lesion percentage (structural imaging) and mean fractional anisotropy (FA) values (diffusion imaging). Behavioral abilities were assessed by a tool use task, a range of conceptual tasks, and control tasks. We found that three left hemisphere tracts connecting frontoparietal and intrafrontal areas overlapping with left superior longitudinal fasciculus are crucial for tool use such that larger lesion and lower mean FA values on these tracts were associated with more severe tool use deficits. These tracts and five additional left hemisphere tracts connecting frontal and temporal/parietal regions, mainly overlapping with left superior longitudinal fasciculus, inferior frontooccipital fasciculus, uncinate fasciculus, and anterior thalamic radiation, are crucial for tool concept processing. Largely consistent results were also obtained using voxel-based symptom mapping analyses. Our results revealed the WM structural networks that support the use and conceptual understanding of tools, providing evidence for the anatomical skeleton of the tool knowledge network.

Non-monotonic reorganization of brain networks with Alzheimer's disease progression

Background: Identification of stage-specific changes in brain network of patients with Alzheimer's disease (AD) is critical for rationally designed therapeutics that delays the progression of the disease. However, pathological neural processes and their resulting changes in brain network topology with disease progression are not clearly known.

Methods: The current study was designed to investigate the alterations in network topology of resting state fMRI among patients in three different clinical dementia rating (CDR) groups (i.e., CDR = 0.5, 1, 2) and amnestic mild cognitive impairment (aMCI) and age-matched healthy subject groups. We constructed density networks from these 5 groups and analyzed their network properties using graph theoretical measures.

Results: The topological properties of AD brain networks differed in a non-monotonic, stage-specific manner. Interestingly, local and global efficiency and betweenness of the network were rather higher in the aMCI and AD (CDR 1) groups than those of prior stage groups. The number, location, and structure of rich-clubs changed dynamically as the disease progressed.

Conclusions: The alterations in network topology of the brain are quite dynamic with AD progression, and these dynamic changes in network patterns should be considered meticulously for efficient therapeutic interventions of AD.

Neural substrates of motor and non-motor symptoms in Parkinson's disease: a resting FMRI study

Background

Recently, non-motor symptoms of Parkinson’s disease (PD) have been considered crucial factors in determining a patient’s quality of life and have been proposed as the predominant features of the premotor phase. Researchers have investigated the relationship between non-motor symptoms and the motor laterality; however, this relationship remains disputed. This study investigated the neural connectivity correlates of non-motor and motor symptoms of PD with respect to motor laterality.

Methods

Eight-seven patients with PD were recruited and classified into left-more-affected PD (n = 44) and right-more affected PD (n = 37) based on their MDS-UPDRS (Movement Disorder Society-sponsored revision of the Unified Parkinson’s Disease Rating Scale) motor examination scores. The patients underwent MRI scanning, which included resting fMRI. Brain regions were labeled as ipsilateral and contralateral to the more-affected body side. Correlation analysis between the functional connectivity across brain regions and the scores of various symptoms was performed to identify the neural connectivity correlates of each symptom.

Results

The resting functional connectivity centered on the ipsilateral inferior orbito-frontal area was negatively correlated with the severity of non-motor symptoms, and the connectivity of the contralateral inferior parietal area was positively correlated with the severity of motor symptoms (p < 0.001, |r| > 0.3).

Conclusions

These results suggest that the inferior orbito-frontal area may play a crucial role in non-motor dysfunctions, and that the connectivity information may be utilized as a neuroimaging biomarker for the early diagnosis of PD.

Hemispheric lateralization in top-down attention during spatial relation processing: a Granger causal model approach

Magnetoencephalography was recorded during a matching-to-sample plus cueing paradigm, in which participants judged the occurrence of changes in either categorical (CAT) or coordinate (COO) spatial relations. Previously, parietal and frontal lobes were identified as key areas in processing spatial relations and it was shown that each hemisphere was differently involved and modulated by the scope of the attention window (e.g. a large and small cue). In this study, Granger analysis highlighted the patterns of causality among involved brain areas--the direction of information transfer ran from the frontal to the visual cortex in the right hemisphere, whereas it ran in the opposite direction in the left side. Thus, the right frontal area seems to exert top-down influence, supporting the idea that, in this task, top-down signals are selectively related to the right side. Additionally, for CAT change preceded by a small cue, the right frontal gyrus was not involved in the information transfer, indicating a selective specialization of the left hemisphere for this condition. The present findings strengthen the conclusion of the presence of a remarkable hemispheric specialization for spatial relation processing and illustrate the complex interactions between the lateralized parts of the neural network. Moreover, they illustrate how focusing attention over large or small regions of the visual field engages these lateralized networks differently, particularly in the frontal regions of each hemisphere, consistent with the theory that spatial relation judgements require a fronto-parietal network in the left hemisphere for categorical relations and on the right hemisphere for coordinate spatial processing.

Resting-State fMRI

Although brain plasticity is greatest in the first few years of life, the brain continues to be shaped by experience throughout adulthood. Advances in fMRI have enabled us to examine the plasticity of large-scale networks using blood oxygen level–dependent (BOLD) correlations measured at rest. Resting-state functional connectivity analysis makes it possible to measure task-independent changes in brain function and therefore could provide unique insights into experience-dependent brain plasticity in humans. Here, we evaluate the hypothesis that resting-state functional connectivity reflects the repeated history of co-activation between brain regions. To this end, we review resting-state fMRI studies in the sensory, motor, and cognitive learning literature. This body of research provides evidence that the brain’s resting-state functional architecture displays dynamic properties in young adulthood.

Strengthening connections: functional connectivity and brain plasticity

The ascendancy of functional neuroimaging has facilitated the addition of network-based approaches to the neuropsychologist's toolbox for evaluating the sequelae of brain insult. In particular, intrinsic functional connectivity (iFC) mapping of resting state fMRI (R-fMRI) data constitutes an ideal approach to measuring macro-scale networks in the human brain. Beyond the value of iFC mapping for charting how the functional topography of the brain is altered by insult and injury, iFC analyses can provide insights into experience-dependent plasticity at the macro level of large-scale functional networks. Such insights are foundational to the design of training and remediation interventions that will best facilitate recovery of function. In this review, we consider what is currently known about the origin and function of iFC in the brain, and how this knowledge is informative in neuropsychological settings. We then summarize studies that have examined experience-driven plasticity of iFC in healthy control participants, and frame these findings in terms of a schema that may aid in the interpretation of results and the generation of hypotheses for rehabilitative studies. Finally, we outline some caveats to the R-fMRI approach, as well as some current developments that are likely to bolster the utility of the iFC paradigm for neuropsychology.

Windowed correlation: a suitable tool for providing dynamic fMRI-based functional connectivity neurofeedback on task difficulty

The goal of neurofeedback training is to provide participants with relevant information on their ongoing brain processes in order to enable them to change these processes in a meaningful way. Under the assumption of an intrinsic brain-behavior link, neurofeedback can be a tool to guide a participant towards a desired behavioral state, such as a healthier state in the case of patients. Current research in clinical neuroscience regarding the most robust indicators of pathological brain processes in psychiatric and neurological disorders indicates that fMRI-based functional connectivity measures may be among the most important biomarkers of disease. The present study therefore investigated the general potential of providing fMRI neurofeedback based on functional correlations, computed from short-window time course data at the level of single task periods. The ability to detect subtle changes in task performance with block-wise functional connectivity measures was evaluated based on imaging data from healthy participants performing a simple motor task, which was systematically varied along two task dimensions representing two different aspects of task difficulty. The results demonstrate that fMRI-based functional connectivity measures may provide a better indicator for an increase in overall (motor) task difficulty than activation level-based measures. Windowed functional correlations thus seem to provide relevant and unique information regarding ongoing brain processes, which is not captured equally well by standard activation level-based neurofeedback measures. Functional connectivity markers, therefore, may indeed provide a valuable tool to enhance and monitor learning within an fMRI neurofeedback setup.

Neurocognitive biases and the patterns of spontaneous correlations in the human cortex

When the brain is 'at rest', spatiotemporal activity patterns emerge spontaneously, that is, in the absence of an overt task. However, what these patterns reveal about cortical function remains elusive. In this article, we put forward the hypothesis that the correlation patterns among these spontaneous fluctuations (SPs) reflect the profile of individual a priori cognitive biases, coded as synaptic efficacies in cortical networks. Thus, SPs offer a new means for mapping personal traits in both neurotypical and atypical cases. Three sets of observations and related empirical evidence provide support for this hypothesis. First, SPs correspond to activation patterns that occur during typical task performance. Second, individual differences in SPs reflect individual biases and abnormalities. Finally, SPs can be actively remodeled in a long-term manner by focused and intense cortical training.