scholarly journals Directed functional connectivity matures with motor learning in a cortical pattern generator

2013 ◽  
Vol 109 (4) ◽  
pp. 913-923 ◽  
Author(s):  
Nancy F. Day ◽  
Kyle L. Terleski ◽  
Duane Q. Nykamp ◽  
Teresa A. Nick
Keyword(s):  
Functional Connectivity ◽  
Motor Skills ◽  
Travelling Waves ◽  
Leading Edge ◽  
Pattern Generator ◽  
Directed Network ◽  
Adult Males ◽  
Rostrocaudal Axis ◽  
Control Circuits ◽  
Activation Sequence

Sequential motor skills may be encoded by feedforward networks that consist of groups of neurons that fire in sequence ( Abeles 1991 ; Long et al. 2010 ). However, there has been no evidence of an anatomic map of activation sequence in motor control circuits, which would be potentially detectable as directed functional connectivity of coactive neuron groups. The proposed pattern generator for birdsong, the HVC ( Long and Fee 2008 ; Vu et al. 1994 ), contains axons that are preferentially oriented in the rostrocaudal axis ( Nottebohm et al. 1982 ; Stauffer et al. 2012 ). We used four-tetrode recordings to assess the activity of ensembles of single neurons along the rostrocaudal HVC axis in anesthetized zebra finches. We found an axial, polarized neural network in which sequential activity is directionally organized along the rostrocaudal axis in adult males, who produce a stereotyped song. Principal neurons fired in rostrocaudal order and with interneurons that were rostral to them, suggesting that groups of excitatory neurons fire at the leading edge of travelling waves of inhibition. Consistent with the synchronization of neurons by caudally travelling waves of inhibition, the activity of interneurons was more coherent in the orthogonal mediolateral axis than in the rostrocaudal axis. If directed functional connectivity within the HVC is important for stereotyped, learned song, then it may be lacking in juveniles, which sing a highly variable song. Indeed, we found little evidence for network directionality in juveniles. These data indicate that a functionally directed network within the HVC matures during sensorimotor learning and may underlie vocal patterning.

Flow Behavior of a Centrifugal Compressor With Vaneless Diffuser at Design and Off Design Conditions

2012 ◽  
Author(s):  
Chuang Gao ◽  
Weiguang Huang ◽  
Haiqing Liu ◽  
Hongwu Zhang ◽  
Jundang Shi
Keyword(s):  
Centrifugal Compressor ◽  
Flow Behavior ◽  
Travelling Waves ◽  
Leading Edge ◽  
Pressure Oscillation ◽  
Rotating Stall ◽  
Vaneless Diffuser ◽  
Unstable Flow ◽  
Flow Recirculation ◽  
Static Performance

This paper concerns with the numerical and experimental aspects of both steady and unsteady flow behavior in a centrifugal compressor with vaneless diffuser and downstream collector. Specifically, the appearance of flow instabilities i.e., rotating stall and surge is investigated in great detail. As the first step, the static performance of both stage and component was analyzed and possible root cause of system surge was put forward based on the classic stability theory. Then the unsteady pressure data was utilized to find rotating stall and surge in frequency domain which could be classified as mild surge and deep surge. With the circumferentially installed transducers at impeller inlet, backward travelling waves during stall ramp could be observed. The modes of stall waves could be clearly identified which is caused by impeller leading edge flow recirculation at Mu = 0.96. However, for the unstable flow at Mu = 1.08, the system instability seems to be caused by reversal flow in vaneless diffuser where the pressure oscillation was strongest. Thus steady numerical simulation were performed and validated with the experimental performance data. With the help of numerical analysis, the conjectures are proved.

scholarly journals Disruption to functional networks in neonates with perinatal brain injury predicts motor skills at 8 months

2017 ◽  
Author(s):  
Annika C. Linke ◽  
Conor Wild ◽  
Leire Zubiaurre-Elorza ◽  
Charlotte Herzmann ◽  
Hester Duffy ◽  
...  
Keyword(s):  
Brain Injury ◽  
Functional Connectivity ◽  
Motor Skills ◽  
Brain Networks ◽  
Motor Impairment ◽  
Structural Mri ◽  
Perinatal Brain Injury ◽  
Diverse Range ◽  
Functional Brain ◽  
Functional Brain Networks

AbstractObjectiveFunctional connectivity magnetic resonance imaging (fcMRI) of neonates with perinatal brain injury could improve prediction of motor impairment before symptoms manifest, and establish how early brain organization relates to subsequent development. Methods: This cohort study is the first to describe and quantitatively assess functional brain networks and their relation to later motor skills in neonates with a diverse range of perinatal brain injuries. Infants (n=65, included in final analyses: n=53) were recruited from the neonatal intensive care unit (NICU) and were stratified based on their age at birth (premature vs. term), and on whether neuropathology was diagnosed from structural MRI. Functional brain networks and a measure of disruption to functional connectivity were obtained from 14 minutes of fcMRI acquired during natural sleep at term-equivalent age.ResultsDisruption to connectivity of the somatomotor and frontoparietal executive networks predicted motor impairment at 4 and 8 months. This disruption in functional connectivity was not found to be driven by differences between clinical groups, or by any of the specific measures we captured to describe the clinical course.ConclusionfcMRI was predictive over and above other clinical measures available at discharge from the NICU, including structural MRI. Motor learning was affected by disruption to somatomotor networks, but also frontoparietal executive networks, which supports the functional importance of these networks in early development. Disruption to these two networks might be best addressed by distinct intervention strategies.

039 Sleep Preferentially Supports Problem-Solving Skills via Greater Functional Connectivity Between the Caudate and Cerebral Cortex

SLEEP ◽  
2021 ◽  
Vol 44 (Supplement_2) ◽  
pp. A17-A17
Author(s):  
Nicholas van den Berg ◽  
Dylan Smith ◽  
Lydia Fang ◽  
Stuart Fogel
Keyword(s):  
Problem Solving ◽  
Functional Connectivity ◽  
Motor Skills ◽  
Cognitive Complexity ◽  
Rule Learning ◽  
Cognitive Strategy ◽  
Higher Order ◽  
Procedural Skills ◽  
Problem Solving Skills ◽  
Higher Order Learning

Abstract Introduction Sleep consolidates memory, including newly acquired procedural skills. One putative systems-level mechanism for this function of sleep is via sleep-dependent strengthening of functional connectivity between the putamen and the cortico-hippocampal-striatal-cerebellar network, which supports procedural motor skills. For procedural motor skills that also require problem solving and rule-learning, sleep preferentially benefits the cognitively complex aspects over the motor skills required to execute the solution itself. The caudate is implicated in higher-order cognitive components of skill learning, which include error monitoring and automizing new information. In the current study, we investigated how sleep alters functional connectivity in higher-order learning networks that support problem solving and rule learning-related procedural skills. Methods Participants (n = 38) were trained on a procedural skills task; the Tower of Hanoi (ToH), that requires the acquisition of a novel cognitive strategy (e.g., recursive logic), while undergoing functional magnetic resonance imaging (fMRI). After either a full night of sleep (n=19) or a full day of wakefulness (n=19), participants were retested on the same task in the fMRI. Resting state activity was acquired before (R1) and after the training session (R2), and before the retest session (R3). Results Behavioral performance on the ToH improved following sleep compared to wake (reduced number of errors: t(38)=2.92, p=0.006, d=1.24). Regions associated with higher-order learning and cognitive complexity (i.e., the caudate) and regions typically implicated in sequence learning (i.e., the putamen, hippocampus, cerebellum) were selected as regions of interest (ROI). Increased functional connectivity across the retention interval (R3-R2) was observed in the sleep vs. wake condition between the caudate and the motor cortex (t(36)=3.32, p=0.042, FWE). By contrast, changes in functional connectivity were not observed between the putamen and other ROIs. Conclusion These results suggest that sleep supports improved consolidation of motor skills that involve the acquisition of a novel cognitive strategy. Sleep enhanced functional connectivity in brain areas associated with higher-order cognitive skills (i.e., the caudate), but not regions typically associated with motor skills (i.e., the putamen) that are required to execute the solution to the cognitive procedural skill. Support (if any) Natural Science and Engineering Research Council of Canada

Progressive Time Delay Procedure for Teaching Motor Skills to Adults with Severe Mental Retardation

2001 ◽  
Vol 18 (1) ◽  
pp. 35-48 ◽  
Author(s):  
Shihui Chen ◽  
Ernest Lange ◽  
Paul Miko ◽  
Jiabei Zhang ◽  
Daniel Joseph
Keyword(s):  
Mental Retardation ◽  
Time Delay ◽  
Motor Skills ◽  
Probe Design ◽  
Severe Mental Retardation ◽  
Adult Males ◽  
Gross Motor ◽  
Gross Motor Skills ◽  
Progressive Time Delay ◽  
Multiple Probe

The purpose of this study was to investigate the effectiveness of the progressive time delay (PTD) procedure on teaching gross motor skills to adult males with severe mental retardation. A multiple probe design across three skills and replicated across 4 participants was utilized. Results indicated that a PTD procedure with a 0 to 5 s delay was effective in teaching 4 participants three gross motor skills (tee-ball batting, softball pitching, croquet striking) over a period of 13 weeks. Data on effectiveness were analyzed in terms of the number of instructional sessions (M = 9.58), the number of trials (M = 105.41), the number of min (M = 84.66), and the number of performing errors to criterion (M = 4.08%). A maintenance level (M = 96.87%) was also determined across 4 participants and three skills on the 1st, 4th, 14th, and 24th sessions after terminating the PTD instruction.

scholarly journals Mental practice modulates functional connectivity between the cerebellum and the primary motor cortex.

2021 ◽  
Author(s):  
Dylan Rannaud Monany ◽  
Florent Lebon ◽  
William Dupont ◽  
Charalambos Papaxanthis
Keyword(s):  
Functional Connectivity ◽  
Motor Cortex ◽  
Motor Skills ◽  
Primary Motor Cortex ◽  
Neural Circuit ◽  
Mental Practice ◽  
Practice Session ◽  
Forward Models ◽  
Before And After ◽  
Cerebellar Brain Inhibition

Our brain has the extraordinary capacity to improve motor skills through mental practice. Conceptually, this ability is attributed to internal forward models, which are neural networks that can predict the sensory consequences of motor commands. While the cerebellum is considered as a potential locus of internal forward models, evidence for its involvement in mental practice is missing. In our study, we employed single and dual transcranial magnetic stimulation technique to probe the level of corticospinal excitability and of cerebellar-brain inhibition, respectively, before and after a mental practice session or a control session. Motor skills (i.e., accuracy and speed) were measured using a sequential finger tapping-task. Here, we show that mental practice enhances both speed and accuracy. In parallel, the functional connectivity between the cerebellum and the primary motor cortex changes, with less inhibition from the first to the second, expressing the existence of neuroplastic changes within the cerebellum after mental practice. These findings reveal that the corticocerebellar loop is a major neural circuit for skill improvement after mental practice.

scholarly journals Spatiotemporal measurement of surfactant distribution on gravity–capillary waves

2015 ◽  
Vol 777 ◽  
pp. 523-543 ◽  
Author(s):  
Stephen L. Strickland ◽  
Michael Shearer ◽  
Karen E. Daniels
Keyword(s):  
Surface Waves ◽  
Travelling Waves ◽  
Leading Edge ◽  
Capillary Waves ◽  
Density Field ◽  
Faraday Waves ◽  
Non Invasive ◽  
Temporal Phase ◽  
Insoluble Surfactant ◽  
Biogenic Slicks

Materials adsorbed onto the surface of a fluid – for instance, crude oil, biogenic slicks or industrial/medical surfactants – will move in response to surface waves. Owing to the difficulty of non-invasive measurement of the spatial distribution of a molecular monolayer, little is known about the dynamics that couple the surface waves and the evolving density field. Here, we report measurements of the spatiotemporal dynamics of the density field of an insoluble surfactant driven by gravity–capillary waves in a shallow cylindrical container. Standing Faraday waves and travelling waves generated by the meniscus are superimposed to create a non-trivial surfactant density field. We measure both the height field of the surface using moiré imaging, and the density field of the surfactant via the fluorescence of NBD-tagged phosphatidylcholine, a lipid. Through phase averaging stroboscopically acquired images of the density field, we determine that the surfactant accumulates on the leading edge of the travelling meniscus waves and in the troughs of the standing Faraday waves. We fit the spatiotemporal variations in the two fields using an ansatz consisting of a superposition of Bessel functions, and report measurements of the wavenumbers and energy damping factors associated with the meniscus and Faraday waves, as well as the spatial and temporal phase shifts between them. While these measurements are largely consistent for both types of waves and both fields, it is notable that the damping factors for height and surfactant in the meniscus waves do not agree. This raises the possibility that there is a contribution from longitudinal waves in addition to the gravity–capillary waves.

scholarly journals Bio-inspired central pattern generator for development of Cartesian motor skills for a Quadruped Robot

2021 ◽  
Vol 12 (1) ◽  
pp. 066-085
Author(s):  
Farhad Asadi ◽  
Mahdi Khorram ◽  
S Ali A Moosavian
Keyword(s):  
Central Pattern Generator ◽  
Motor Skills ◽  
Step Length ◽  
Pattern Generator ◽  
Quadruped Robot ◽  
Reference Trajectory ◽  
Event Sequences ◽  
Gait Coordination ◽  
Zero Moment ◽  
Spatio Temporal

Central Pattern Generator (CPG) plays a significant role in the generation of diverse and stable gaits patterns for animals as well as controlling their locomotion. The main contributions of this paper are the ability to develop the Cartesian motor skills and coordinating legs of the quadruped robot for gait adaption and its nominal characteristics with CPG approach. Primary, a predefined relationship between an excitation signal and essential parameters of the CPG design is programmed. Next, the coordinated oscillator's rhythmic patterns by CPG and accordingly output gait diagrams for each foot of the robot are attained. Then, these desirable features such as predictive modulation and programming the gait event sequences including leg-lifting sequences and step length, duration of the time of each footstep within a gait, coordination of swing and stance phases of all legs are calculated in terms of different spatio_temporal vectors. Furthermore, a novel Cartesian footstep basis function is designed based on the robot characteristics and consequently, the associated spatio-temporal vectors can be inserted to it, which caused to spanning the space of possible gait timing in Cartesian space. Next, Cartesian footstep planner can be computed the swing foot trajectories in workspace along movement axes and then according to these footholds and feet placement, ZMP (Zero Moment Point) reference trajectory will be calculated and obtained. Therefore, COG (Center of Gravity) trajectory can be computed by designing a preview controller on the basis of the desired ZMP trajectory. Finally, to demonstrate the effectiveness of the proposed algorithm, it is implemented on a quadruped robot on both simulation or experimental implementations and the results are compared and discussed with other references.

scholarly journals Reduced asymmetry of the hand knob area and decreased sensorimotor u-fiber connectivity in middle-aged adults with autism

2021 ◽  
Author(s):  
Janice Hau ◽  
Ashley Baker ◽  
Chantal Chaaban ◽  
Jiwandeep S Kohli ◽  
R Joanne Jao Keehn ◽  
...  
Keyword(s):  
Functional Connectivity ◽  
Motor Skills ◽  
Right Hemisphere ◽  
Autism Spectrum ◽  
Middle Aged ◽  
Hand Knob ◽  
The Right ◽  
Middle Aged Adults ◽  
Adults With Asd ◽  
Fiber Connectivity

Individuals with autism spectrum disorder (ASD) frequently present with impairments in motor skills (e.g., limb coordination, handwriting and balance), which are observed across the lifespan but remain largely untreated. Many adults with ASD may thus experience adverse motor outcomes in aging, when physical decline naturally occurs. The 'hand knob' of the sensorimotor cortex is an area that is critical for motor control of the fingers and hands. However, this region has received little attention in ASD research, especially in adults after midlife. The hand knob area of the precentral (PrChand) and postcentral (PoChand) gyri was semi-manually delineated in 49 right-handed adults (25 ASD, 24 typical comparison [TC] participants, aged 41-70 years). Using multimodal (T1-weighted, diffusion-weighted, and resting-state functional) MRI, we examined the morphology, ipsilateral connectivity and laterality of these regions. Correlations between hand knob measures with motor skills and autism symptoms, and between structural and functional connectivity measures were also investigated. The right PrChand volume was greater, and typical leftward laterality of PrChand and PoChand volume was lower in the ASD than the TC group. Furthermore, we observed increased mean diffusivity of the right PoC-PrChand u-fibers in the ASD group. In the ASD group, right PoC-PrChand u-fiber volume was negatively associated with current autism severity, and positively associated with right PoC-PrChand functional connectivity (FC). Correlations of hand knob measures were observed with manual dexterity and coordination skills but did not survive multiple comparisons correction. Our findings suggest decreased morphological laterality and u-fiber connectivity of the sensorimotor network involved in hand function in middle-aged adults with ASD. The altered morphology may relate to atypical functional asymmetries found in ASD earlier in life, but additionally, could reflect an overreliance on right hemisphere motor circuits over time. The right PoC-PrChand u-fibers may underlie compensatory self-regulation of unwanted core motor behaviors seen in ASD.

scholarly journals Flexibility in motor timing constrains the topology and dynamics of pattern generator circuits

2015 ◽  
Author(s):  
Cengiz Pehlevan ◽  
Farhan Ali ◽  
Bence P. Ölveczky
Keyword(s):  
Neural Networks ◽  
Motor Skills ◽  
Temporal Structure ◽  
Pattern Generator ◽  
Network Activity ◽  
Recurrent Networks ◽  
Motor Timing ◽  
Feedforward Networks ◽  
Stereotyped Behaviors ◽  
Precise Movement

SummaryTemporally precise movement patterns underlie many motor skills and innate actions, yet the flexibility with which the timing of such stereotyped behaviors can be modified is poorly understood. To probe this, we induced adaptive changes to the temporal structure of birdsong. We find that the duration of specific song segments can be modified without affecting the timing in other parts of the song. We derive formal prescriptions for how neural networks can implement such flexible motor timing. We find that randomly connected recurrent networks, a common approximation for how neocortex is wired, do not generally conform to these, though certain implementations can approximate them. We show that feedforward networks, by virtue of their one-to-one mapping between network activity and time, are better suited. Our study provides general prescriptions for pattern generator networks that implement flexible motor timing, an important aspect of many motor skills, including birdsong and human speech.

scholarly journals Single-Trial Kernel-Based Functional Connectivity for Enhanced Feature Extraction in Motor-Related Tasks

Sensors ◽  
2021 ◽  
Vol 21 (8) ◽  
pp. 2750
Author(s):  
Daniel Guillermo García-Murillo ◽  
Andres Alvarez-Meza ◽  
German Castellanos-Dominguez
Keyword(s):  
Feature Extraction ◽  
Functional Connectivity ◽  
Motor Skills ◽  
Time Window ◽  
Brain Plasticity ◽  
Temporal Frequency ◽  
Gaussian Kernel ◽  
Single Trial ◽  
Subject Variability ◽  
Connectivity Measure

Motor learning is associated with functional brain plasticity, involving specific functional connectivity changes in the neural networks. However, the degree of learning new motor skills varies among individuals, which is mainly due to the between-subject variability in brain structure and function captured by electroencephalographic (EEG) recordings. Here, we propose a kernel-based functional connectivity measure to deal with inter/intra-subject variability in motor-related tasks. To this end, from spatio-temporal-frequency patterns, we extract the functional connectivity between EEG channels through their Gaussian kernel cross-spectral distribution. Further, we optimize the spectral combination weights within a sparse-based ℓ2-norm feature selection framework matching the motor-related labels that perform the dimensionality reduction of the extracted connectivity features. From the validation results in three databases with motor imagery and motor execution tasks, we conclude that the single-trial Gaussian functional connectivity measure provides very competitive classifier performance values, being less affected by feature extraction parameters, like the sliding time window, and avoiding the use of prior linear spatial filtering. We also provide interpretability for the clustered functional connectivity patterns and hypothesize that the proposed kernel-based metric is promising for evaluating motor skills.

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