Biology subjects

Shokur, S.

Publications and source records attributed to Shokur, S..

3 recordsLinked to original sources

bioRxiv2025

Decoupling simultaneous motor imagination and execution via orthogonal ECoG neural representations

The brain coordinates multiple parallel motor programs, ensuring synergy and preventing interference during movements. Yet, performance often degrades when brain-machine interfaces are used during concurrent tasks or ongoing movements. We suggest that latent neural representations may represent a strategy to solve this issue. In this study, we addressed this question using neural signals from a tetraplegic individual with partial residual motor function, implanted with a wireless epidural electrocorticography (ECoG) device. By adapting dimensionality reduction techniques, we found that motor execution and motor imagery span partially overlapping subspaces in mesoscale neural signals, shaped by specific frequency band contributions. Despite substantial shared variance, we show that identifying orthogonal, condition-specific dimensions enables successful decoding of executed and imagined movements, even when performed simultaneously. These findings show that ECoG signals can expose separable neural subspaces, allowing executed and imagined actions to be harnessed independently and in concert. This opens a promising avenue to develop brain-machine interfaces that can simultaneously control multiple external devices or operate alongside natural movements.

neuroscience↗

bioRxiv2022

Validation of manifold-based direct control for a brain-to-body neural bypass

Brain-body interfaces (BBIs) are neuroprostheses that can restore the connection between brain activity and body movements. They have emerged as a radical solution for restoring voluntary hand control in people with upper-limb paralysis. The BBI module decoding motor commands to actuate the limb from brain signals should provide the user with intuitive, accurate, and stable control. Here, we present the design and demonstration in a monkey of a novel brain decoding strategy based on the direct coupling between the activity of intrinsic neural ensembles and output variables, meant to achieve ease of learning and long-term robustness. We identified once an intrinsic low-dimensional space (called manifold) capturing the co-variation patterns of the monkeys neural activity associated to reach-to-grasp movements. We then tested the animals ability to directly control a computer cursor using cortical activation along the manifold axes and demonstrated rapid learning and stable high performance over 16 weeks of experiments. Finally, we showed that this brain decoding strategy can be effectively coupled to peripheral nerve stimulation to trigger hand movements. These results provide evidence that manifold-based direct control has promising characteristics for clinical applications of BBIs.

bioengineering↗

bioRxiv2019

Creating a neuroprosthesis for active tactile exploration of textures

Intracortical microstimulation (ICMS) of the primary somatosensory cortex (S1) can produce percepts that mimic somatic sensation and thus has potential as an approach to sensorize prosthetic limbs. However, it is not known whether ICMS could recreate active texture exploration--the ability to infer information about object texture by using ones fingertips to scan a surface. Here we show that ICMS of S1 can convey information about the spatial frequencies of invisible virtual gratings through a process of active tactile exploration. Two rhesus monkeys scanned pairs of visually identical screen objects with the fingertip of a hand avatar, controlled via a joystick and later via a brain-machine interface, to find the one with denser virtual gratings. The gratings consisted of evenly spaced ridges that were signaled through ICMS pulses generated when the avatars fingertip crossed each ridge. The monkeys learned to interpret these ICMS patterns evoked by the interplay of their voluntary movements and the virtual textures of each object. Discrimination accuracy across a range of grating densities followed Webers law of just-noticeable differences (JND), a finding that matches normal cutaneous sensation. Moreover, one monkey developed an active scanning strategy where avatar velocity was integrated with the ICMS pulses to interpret the texture information. We propose that this approach could equip upper-limb neuroprostheses with direct access to texture features acquired during active exploration of natural objects.

neuroscience↗