Multisite Simultaneous Neural Recording of Motor Pathway in Free-Moving Rats

Neural interfaces typically focus on one or two sites in the motoneuron system simultaneously due to the limitation of the recording technique, which restricts the scope of observation and discovery of this system. Herein, we built a system with various electrodes capable of recording a large spectrum of electrophysiological signals from the cortex, spinal cord, peripheral nerves, and muscles of freely moving animals. The system integrates adjustable microarrays, floating microarrays, and microwires to a commercial connector and cuff electrode on a wireless transmitter. To illustrate the versatility of the system, we investigated its performance for the behavior of rodents during tethered treadmill walking, untethered wheel running, and open field exploration. The results indicate that the system is stable and applicable for multiple behavior conditions and can provide data to support previously inaccessible research of neural injury, rehabilitation, brain-inspired computing, and fundamental neuroscience.

Transcranial Electrical Motor Evoked Potential in Predicting Positive Functional Outcome of Patients after Decompressive Spine Surgery: Review on Challenges and Recommendations towards Objective Interpretation

Spine surgeries impose risk to the spine’s surrounding anatomical and physiological structures especially the spinal cord and the nerve roots. Intraoperative neuromonitoring (IONM) is a technology developed to monitor the integrity of the spinal cord and the nerve roots via the surgery. Transcranial motor evoked potential (TcMEP) (one of the IONM modalities) is adopted to monitor the integrity of the motor pathway of the spinal cord and the motor nerve roots. Recent research suggested that the IONM is conducive as a prognostic tool towards the patient’s functional outcome. This paper summarizes the researches of IONM being adopted as a prognostic tool. In addition, this paper highlights the problems associated with the signal parameters as the improvement criteria in the previous researches. Lastly, we review the challenges of TcMEP to achieve a prognostic tool focusing on the factors that could interfere with the generation of a stable TcMEP response. The final section will discuss recommendations for IONM technology to achieve an objective prognostic tool.

Transcranial magnetic stimulation in neurorehabilitation: experience and prospects

Diagnostic transcranial magnetic stimulation (TMS) is a valuable neurophysiological technique. The use of TMS has fundamentally changed the therapy and diagnosis of nervous diseases, introducing the possibility of direct assessment of conduction along the motor pathway in the central region, neuroplasticity, the ratio of central inhibition and excitation, and the effect on neuroplasticity and neurogenesis. The technique is safe, has a low cost and there is no need to purchase expensive consumables, it is applicable for a wide range of diseases in both adult and pediatric practice. The issues of the TMS use in CVA, depression, cerebral palsy and neurodegenerative diseases (amyotrophic lateral sclerosis, parkinsonism) have been studied to the greatest extent. When carrying out TMS in children, it should be borne in mind that signs of incomplete myelination of the motor pathways, which are normally observed, may look like pathological changes (demyelination or axonal disorders). The basic principles of TMS in both adults and children have been established and known, and the age norms have been determined, which makes it possible to widely implement this technique in applied neurophysiological practice. In the rehabilitation process, TMS can be used as a tool for personalizing and monitoring the effectiveness of rehabilitation treatment.

Maximally efficient prediction in the early fly visual system may support evasive flight maneuvers

The visual system must make predictions to compensate for inherent delays in its processing. Yet little is known, mechanistically, about how prediction aids natural behaviors. Here, we show that despite a 20-30ms intrinsic processing delay, the vertical motion sensitive (VS) network of the blowfly achieves maximally efficient prediction. This prediction enables the fly to fine-tune its complex, yet brief, evasive flight maneuvers according to its initial ego-rotation at the time of detection of the visual threat. Combining a rich database of behavioral recordings with detailed compartmental modeling of the VS network, we further show that the VS network has axonal gap junctions that are critical for optimal prediction. During evasive maneuvers, a VS subpopulation that directly innervates the neck motor center can convey predictive information about the fly’s future ego-rotation, potentially crucial for ongoing flight control. These results suggest a novel sensory-motor pathway that links sensory prediction to behavior.

Neural correlations are attenuated in the transformation from the frontal cortex to movement

Correlated activity between neurons can cause variability in behavior across trials. The extent to which correlated activity affects behavior depends on the properties of its translation into movement. We developed a novel method that estimates the contribution of correlations in the frontal eye field (FEF) to pursuit eye movements. We defined a distance metric between the behavior on different trials. Based on this metric, we applied a sequence of shuffles to the neuronal responses, allowing trials to be matched with increasingly distant trials. Correlations between neurons were strongly attenuated when applying even the most constrained shuffle. Thus, only a small fraction of FEF correlations affects the behavior. We used simulations to validate our approach and demonstrate its generalizability over different models. We show that the attenuation of correlated activity through the motor pathway could stem from the interplay between the structure of the correlations and the decoder of FEF activity.

Cellular transcriptomics reveals evolutionary identities of songbird vocal circuits

Birds display advanced behaviors, including vocal learning and problem-solving, yet lack a layered neocortex, a structure associated with complex behavior in mammals. To determine whether these behavioral similarities result from shared or distinct neural circuits, we used single-cell RNA sequencing to characterize the neuronal repertoire of the songbird song motor pathway. Glutamatergic vocal neurons had considerable transcriptional similarity to neocortical projection neurons; however, they displayed regulatory gene expression patterns more closely related to neurons in the ventral pallium. Moreover, while γ-aminobutyric acid–releasing neurons in this pathway appeared homologous to those in mammals and other amniotes, the most abundant avian class is largely absent in the neocortex. These data suggest that songbird vocal circuits and the mammalian neocortex have distinct developmental origins yet contain transcriptionally similar neurons.

Modified McKenzie procedure for the treatment of fixed painful torticollis

Spasmodic torticollis is characterized by involuntary movements of the neck muscles. In this video, the authors present the case of a 48-year-old man with painful right-sided rotational torticollis with contributions from both the suboccipital and the left sternocleidomastoid (SCM) muscles. He underwent a suboccipital craniectomy and C1–2 laminectomy with selective denervation of bilateral suboccipital and left-sided SCM muscles (modified McKenzie procedure). At the 2-week follow-up, he showed significant improvement and was able to rotate his neck about 70° toward the midline. Surgical treatment of spasmodic torticollis focuses on interrupting the motor pathway responsible for head turning. The modified McKenzie procedure is valuable, especially when other therapies fail.The video can be found here: https://youtu.be/TK-WybKnGJM

Teaching NeuroImages: All hemiparesis are not contralateral

A 56-yr-old hypertensive male presented with left-sided weakness of 2-h duration. He made complete recovery from right hemiparesis due to left parietal infarct. Examination showed dysarthria and left hemiparesis (NIHSS 8/42). MR-brain showed both left parietal acute infarct and gliosis from old infarct (Figure-1). He was successfully thrombolysed with intravenous alteplase. Present stroke was diagnosed as ipsilateral hemiparesis, confirmed by DTI (Figure-2). Ipsilateral hemiparesis, mostly seen with posterior fossa malformations and remote infarctions, results from injury to uncrossed corticospinal tract (CST) in patients of remote brain injury or with no decussation of CST or injury to ipsilateral extrapyramidal motor pathway.