Optical Imaging of the Motor Cortex Following Antidromic Activation of the Corticospinal Tract after Spinal Cord Injury

Abstract

Spinal cord injury (SCI) disrupts neuronal networks of ascending and descending tracts at the site of injury, leading to a loss of motor function. Restoration and new circuit formation are important components of the recovery process, which involves collateral sprouting of injured and uninjured fibers. The present study was conducted to determine cortical responses to antidromic stimulation of the corticospinal tracts, to compare changes in the reorganization of neural pathways within normal and spinal cord-injured rats, and to elucidate differences in spatiotemporal activity patterns of the natural progression and reorganization of neural pathways in normal and SCI animals using optical imaging. Optical signals were recorded from the motor cortex in response to electrical stimulation of the ventral horn of the L1 spinal cord. Motor evoked potentials (MEPs) were evaluated to demonstrate endogenous recovery of physiological functions after SCI. A significantly shorter N1 peak latency and broader activation in the MEP optical recordings were observed at 4 weeks after SCI, compared to 1 week after SCI. Spatiotemporal patterns in the cerebral cortex differed depending on functional recovery. In the present study, optical imaging was found to be useful in revealing functional changes and may reflect conditions of reorganization and/or changes in surviving neurons after SCI.

Effects of Neuromuscular Electrical Stimulation in People with Spinal Cord Injury

“…A large (mean=45%) increase in CSAQF was observed, which is clinically important since the muscle atrophy that is typically associated with chronic SCI has detrimental effect on metabolic, cardiovascular and functional systems (6) which meaningfully impact life expectancy (6,34). Previous researchers have reported less increase (20%) after an 8-week intervention (19) and others reported similar large increases in CSA after NMES training (35%-45%) after 12 to 24 weeks of training, albeit using different pulse widths (250/600 µs) at similar frequencies (30)(31)(32)(33)(34)(35) (16, 18, 20, 35). Thus, our training stimulated the same increase in CSA (45%) in 12 weeks as others have obtained after a similar period using currents up to 200 mA (18), although the maximum current intensity in our study being 99 mA.…”

“…The subjects were asked to keep their physical training routine consistent for the duration of the experiment. All subjects were asked to consciously attempt to contract their QF muscles while the NMES protocol was being delivered, due to evidence showing that consciously thinking about moving a part of the body activates a part of the cerebral cortex and may allow for a better sensory integration of the information (32). We certify that all applicable institutional and governmental regulations concerning the ethical use of human volunteers were followed during this research.…”

Μελέτη Των Νευρωνικών Κυκλωμάτων Του Εγκεφάλου Σε Ασθενείς Με Κάκωση Νωτιαίου Μυελού

“…Παρόλα αυτά, τα τρωκτικά αποτελούν το πιο διαδοµένο (άνω του 72% των σχετικών µελετών), και πιθανώς το πιο εφικτό µοντέλο για προκαταρκτικές µελέτες προκλητής ΚΝΜ [71]. Αυτές οι µελέτες έχουν την δυνατότητα να παρέχουν και πληροφορίες για τις λειτουργικές χωροχρονικές διεργασίες των νευρωνικών κυκλωµάτων του εγκεφάλου µετά από ΚΝΜ [72].…”