Case Studies in Neuroscience: an epidural stimulating interface unveils the intrinsic modulation of electrically motor evoked potentials in behaving rats.

2021 ◽  
Author(s):  
Giuliano Taccola ◽  
Stanislav Culaclii ◽  
Hui Zhong ◽  
Parag N. Gad ◽  
Wentai Liu ◽  
...  
Keyword(s):  
Evoked Potentials ◽  
Motor Evoked Potentials ◽  
New Technology ◽  
Motor Threshold ◽  
Hindlimb Muscles ◽  
Cord Injury ◽  
Electrical Pulses ◽  
Stochastic Modulation ◽  
Experimental Treatments ◽  
Awake Rats

In intact and spinal injured anesthetized animals, stimulation levels that did not induce any visible muscle twitches, were used to elicit motor evoked potentials (MEPs) of varying amplitude, reflecting the temporal and amplitude dynamics of the background excitability of spinal networks. To characterize the physiological excitability states of neuronal networks driving movement, we designed five experiments in awake rats chronically implanted with an epidural stimulating interface, with and without a spinal cord injury (SCI). Firstly, an uninjured rat at rest underwent a series of single electrical pulses at sub motor-threshold intensity, which generated responses that were continuously recorded from flexor and extensor hindlimb muscles, showing an intrinsic patterned modulation of MEPs. Responses were recruited by increasing strengths of stimulation and the amplitudes were moderately correlated between flexors and extensors. Next, after SCI, four awake rats at rest showed electrically induced MEPs, varying largely in amplitude of both flexors and extensors that were mainly synchronously modulated. After full anesthesia, MEP amplitudes were largely reduced, although stimulation still generated random baseline changes, unveiling an intrinsic stochastic modulation. The current five cases demonstrate a methodology that can be feasibly replicated in a broader group of awake and behaving rats to further define experimental treatments involving neuroplasticity. Beside validating a new technology for a neural stimulating interface, the present data support the broader message that there were intrinsic patterned and stochastic modulation of baseline excitability reflecting the dynamics of physiological states of spinal networks.

Multi-limb acquisition of motor evoked potentials and its application in spinal cord injury

2010 ◽  
Vol 193 (2) ◽  
pp. 210-216 ◽  
Author(s):  
Shrivats Iyer ◽  
Anil Maybhate ◽  
Alessandro Presacco ◽  
Angelo H. All
Keyword(s):  
Spinal Cord ◽  
Spinal Cord Injury ◽  
Evoked Potentials ◽  
Motor Evoked Potentials ◽  
Cord Injury

scholarly journals A novel bone-thinning technique for transcranial stimulation motor-evoked potentials in rats

2021 ◽  
Vol 11 (1) ◽  
Author(s):  
Yuyo Maeda ◽  
Takashi Otsuka ◽  
Takafumi Mitsuhara ◽  
Takahito Okazaki ◽  
Louis Yuge ◽  
...  
Keyword(s):  
Evoked Potentials ◽  
Animal Studies ◽  
Histological Analysis ◽  
Motor Evoked Potentials ◽  
Neurological Dysfunction ◽  
Onset Latency ◽  
Sprague Dawley ◽  
Cord Injury ◽  
A New Technique ◽  
Injury Models

AbstractTranscranial electrical stimulated motor-evoked potentials (tcMEPs) are widely used to evaluate motor function in humans, and even in animal studies, tcMEPs are used to evaluate neurological dysfunction. However, there is a dearth of reports on extended tcMEP recordings in both animal models and humans. Therefore, this study examined a new technique for stably recording tcMEPs over several weeks in six healthy female Sprague–Dawley rats. We thinned the skull bone using the skull base and spinal surgery technique to reduce electrical resistance for electrical stimulation. tcMEPs were recorded on days 1, 7, 14, 21, and 28 after surgery. The onset latency and amplitude of tcMEPs from the hindlimbs were recorded and evaluated, and histological analysis was performed. Stable amplitude and onset latency could be recorded over several weeks, and histological analysis indicated no complications attributable to the procedure. Thus, our novel technique allows for less invasive, safer, easier, and more stable extended tcMEP recordings than previously reported techniques. The presently reported technique may be applied to the study of various nerve injury models in rats: specifically, to evaluate the degree of nerve dysfunction and recovery in spinal cord injury, cerebral infarction, and brain contusion models.

scholarly journals Reflex wind-up in early chronic spinal injury: plasticity of motor outputs

2017 ◽  
Vol 117 (5) ◽  
pp. 2065-2074 ◽  
Author(s):  
Michael D. Johnson ◽  
Alain Frigon ◽  
Marie-France Hurteau ◽  
Charlette Cain ◽  
C. J. Heckman
Keyword(s):  
Temporal Summation ◽  
Spinal Injury ◽  
Recovery Period ◽  
Chronic Phase ◽  
Compound Action Potential ◽  
Recovery Process ◽  
Spinal Reflexes ◽  
Hindlimb Muscles ◽  
Cord Injury ◽  
Electrical Pulses

In this study we evaluate temporal summation (wind-up) of reflexes in select distal and proximal hindlimb muscles in response to repeated stimuli of the distal tibial or superficial peroneal nerves in cats 1 mo after complete spinal transection. This report is a continuation of our previous paper on reflex wind-up in the intact and acutely spinalized cat. To evaluate reflex wind-up in both studies, we recorded electromyographic signals from the following left hindlimb muscles: lateral gastrocnemius (LG), tibialis anterior (TA), semitendinosus (ST), and sartorius (Srt), in response to 10 electrical pulses to the tibial or superficial peroneal nerves. Two distinct components of the reflex responses were considered, a short-latency compound action potential (CAP) and a longer duration bout of sustained activity (SA). These two response types were shown to be differentially modified by acute spinal injury in our previous work (Frigon A, Johnson MD, Heckman CJ. J Physiol 590: 973-989, 2012). We show that these responses exhibit continued plasticity during the 1-mo recovery period following acute spinalization. During this early chronic phase, wind-up of SA responses returned to preinjury levels in one muscle, the ST, but remained depressed in all other muscles tested. In contrast, CAP response amplitudes, which were initially potentiated following acute transection, returned to preinjury levels in all muscles except for Srt, which continued to show marked increase. These findings illustrate that spinal elements exhibit considerable plasticity during the recovery process following spinal injury and highlight the importance of considering SA and CAP responses as distinct phenomena with unique underlying neural mechanisms. NEW & NOTEWORTHY This research is the first to assess temporal summation, also called wind-up, of muscle reflexes during the 1-mo recovery period following spinal injury. Our results show that two types of muscle reflex activity are differentially modulated 1 mo after spinal cord injury (SCI) and that spinal reflexes are altered in a muscle-specific manner during this critical period. This postinjury plasticity likely plays an important role in spasticity experienced by individuals with SCI.

Objective assessment of cervical spinal cord injury levels by transcranial magnetic motor-evoked potentials

2006 ◽  
Vol 66 (5) ◽  
pp. 475-483 ◽  
Author(s):  
Christopher B. Shields ◽  
Yi Ping Zhang ◽  
Lisa B.E. Shields ◽  
Darlene A. Burke ◽  
Steven D. Glassman
Keyword(s):  
Spinal Cord ◽  
Spinal Cord Injury ◽  
Evoked Potentials ◽  
Motor Evoked Potentials ◽  
Cervical Spinal Cord ◽  
Objective Assessment ◽  
Cervical Spinal Cord Injury ◽  
Cord Injury

scholarly journals Neuromodulation of motor-evoked potentials during stepping in spinal rats

2013 ◽  
Vol 110 (6) ◽  
pp. 1311-1322 ◽  
Author(s):  
Parag Gad ◽  
Igor Lavrov ◽  
Prithvi Shah ◽  
Hui Zhong ◽  
Roland R. Roy ◽  
...  
Keyword(s):  
Spinal Cord ◽  
Electrical Stimulation ◽  
Evoked Potentials ◽  
Motor Evoked Potentials ◽  
Motor Task ◽  
Hindlimb Muscles ◽  
Epidural Spinal Cord Stimulation ◽  
Highly Correlated ◽  
Muscle Responses

The rat spinal cord isolated from supraspinal control via a complete low- to midthoracic spinal cord transection produces locomotor-like patterns in the hindlimbs when facilitated pharmacologically and/or by epidural electrical stimulation. To evaluate the role of epidural electrical stimulation in enabling motor control (eEmc) for locomotion and posture, we recorded potentials evoked by epidural spinal cord stimulation in selected hindlimb muscles during stepping and standing in adult spinal rats. We hypothesized that the temporal details of the phase-dependent modulation of these evoked potentials in selected hindlimb muscles while performing a motor task in the unanesthetized state would be predictive of the potential of the spinal circuitries to generate stepping. To test this hypothesis, we characterized soleus and tibialis anterior (TA) muscle responses as middle response (MR; 4–6 ms) or late responses (LRs; >7 ms) during stepping with eEmc. We then compared these responses to the stepping parameters with and without a serotoninergic agonist (quipazine) or a glycinergic blocker (strychnine). Quipazine inhibited the MRs induced by eEmc during nonweight-bearing standing but facilitated locomotion and increased the amplitude and number of LRs induced by eEmc during stepping. Strychnine facilitated stepping and reorganized the LRs pattern in the soleus. The LRs in the TA remained relatively stable at varying loads and speeds during locomotion, whereas the LRs in the soleus were strongly modulated by both of these variables. These data suggest that LRs facilitated electrically and/or pharmacologically are not time-locked to the stimulation pulse but are highly correlated to the stepping patterns of spinal rats.

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