EMG | NINE Lab

Age-related Reorganization of Corticomuscular Connectivity During Locomotor Perturbations

Sun, 28 Sep 2025 00:00:00 +0000

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Abstract

Locomotor perturbations elicit cortical and muscular responses that help minimize motor errors through neural processes involving multiple brain regions. The anterior cingulate cortex monitors motor errors, the supplementary motor areas integrate sensory and executive control, and the posterior parietal cortices process sensorimotor predictions, while muscles show increased activation and co-contraction patterns. With aging, these neural control strategies shift; older adults demonstrate less flexible cortical and muscular responses, using compensatory overactivation and simpler muscle synergies to maintain performance comparable to young adults. We investigated corticomuscular connectivity patterns during perturbed recumbent stepping in seventeen young adults (age 25±4.9 years) and eleven older adults (age 68±3.6 years) using high-density EEG (128 electrodes) and EMG from six bilateral muscles. Brief mechanical perturbations (200ms of increased resistance) were applied at left or right leg extension-onset or mid-extension during continuous stepping at 60 steps per minute. We applied independent component analysis, source localization, and direct directed transfer function to quantify bidirectional information flow between cortical clusters and muscles in theta (3-8 Hz), alpha (8-13 Hz), and beta (13-35 Hz) bands. Young adults demonstrated concentrated electrocortical sources in anterior cingulate cortex, bilateral supplementary motor areas, and bilateral posterior parietal cortices, with strong theta-band synchronization following perturbations. In contrast, older adults showed fewer differentiated cortical sources, particularly lacking distinct anterior cingulate activity, and exhibited only minimal synchronization changes. Baseline corticomuscular connectivity was significantly stronger in older adults compared to young adults (p=0.012), suggesting fundamental differences in resting motor control states. During perturbations, young adults employed flexible, task-specific connectivity modulation involving error-processing networks, with the anterior cingulate showing selective bidirectional connectivity changes with specific muscles. Older adults relied on more diffuse (i.e., not focused to specific brain area) connectivity patterns dominated by motor and posterior parietal cortices, with strong connections to multiple upper and lower limb muscles simultaneously. These findings reveal an age-related strategic reorganization from dynamic, error-driven neural control to a more constrained, stability-focused approach that may reflect compensation for sensorimotor changes. The distinct connectivity signatures establish perturbed recumbent stepping as a valuable tool for assessing corticomuscular communication and provide normative benchmarks for developing targeted rehabilitation interventions to restore efficient motor control in aging and neurological populations.

Key findings: Young vs. older adult corticomuscular connectivity

Citation

@ARTICLE{Shirazi2025-cmc,
  title    = "Age-related Reorganization of Corticomuscular Connectivity During
              Locomotor Perturbations",
  author   = "Shirazi, Seyed Yahya and Tasin, Shahamat Mustavi and Huang,
              Helen J",
  journal  = "bioRxiv",
  pages    = "2025.09.28.679054",
  month    =  "28~" # sep,
  year     =  2025,
  doi      = "10.1101/2025.09.28.679054",
  language = "en"
}

Age-related Reorganization of Corticomuscular Connectivity During Locomotor Perturbations

Sat, 28 Sep 2024 00:00:00 +0000

Download

Paper
Code and data available upon request

Abstract

Key findings: Young vs. older adult corticomuscular connectivity

Citation

@ARTICLE{Shirazi2025-cmc,
  title    = "Age-related Reorganization of Corticomuscular Connectivity During
              Locomotor Perturbations",
  author   = "Shirazi, Seyed Yahya and Tasin, Shahamat Mustavi and Huang,
              Helen J",
  journal  = "bioRxiv",
  pages    = "2025.09.28.679054",
  month    =  "28~" # sep,
  year     =  2025,
  doi      = "10.1101/2025.09.28.679054",
  language = "en"
}

The Lab Streaming Layer for Synchronized Multimodal Recording

Wed, 14 Feb 2024 00:00:00 +0000

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Abstract

Accurately recording the interactions of humans or other organisms with their environment or other agents requires synchronized data access via multiple instruments, often running independently using different clocks. Active, hardware-mediated solutions are often infeasible or prohibitively costly to build and run across arbitrary collections of input systems. The Lab Streaming Layer (LSL) offers a software-based approach to synchronizing data streams based on per-sample time stamps and time synchronization across a common LAN. Built from the ground up for neurophysiological applications and designed for reliability, LSL offers zero-configuration functionality and accounts for network delays and jitters, making connection recovery, offset correction, and jitter compensation possible. These features ensure precise, continuous data recording, even in the face of interruptions. The LSL ecosystem has grown to support over 150 data acquisition device classes as of Feb 2024, and establishes interoperability with and among client software written in several programming languages, including C/C++, Python, MATLAB, Java, C#, JavaScript, Rust, and Julia. The resilience and versatility of LSL have made it a major data synchronization platform for multimodal human neurobehavioral recording and it is now supported by a wide range of software packages, including major stimulus presentation tools, real-time analysis packages, and brain-computer interfaces. Outside of basic science, research, and development, LSL has been used as a resilient and transparent backend in scenarios ranging from art installations to stage performances, interactive experiences, and commercial deployments. In neurobehavioral studies and other neuroscience applications, LSL facilitates the complex task of capturing organismal dynamics and environmental changes using multiple data streams at a common timebase while capturing time details for every data frame.

The overall LSL design for synchronized data recording

Citation

@ARTICLE{Kothe2024-zm,
  title    = "The Lab Streaming Layer for Synchronized Multimodal Recording",
  author   = "Kothe, Christian and Shirazi, Seyed Yahya and Stenner, Tristan and
              Medine, David and Boulay, Chadwick and Crivich, Matthew I and
              Mullen, Tim and Delorme, Arnaud and Makeig, Scott",
  journal  = "bioRxiv",
  pages    = "2024.02.13.580071",
  month    =  feb,
  year     =  2024,
  language = "en"
}