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Functional Characteristics of Nucleus Accumbens Neurons: Evidence Obtained From In Vivo Electrophysiological Recordings
Published in Peter W. Kalivas, Charles D. Barnes, Limbic Motor Circuits and Neuropsychiatry, 2019
Steven J. Henriksen, Jeannie Giacchino
We have recently recorded spontaneous activity from nucleus accumbens neurons in freely-moving, unanesthetized rats.84 We initiated these studies to compare baseline spontaneous activity and afferent evoked activity in conscious animals with what we have observed in the anesthetized preparation.23,24,83 Single accumbens neurons were recorded with either tungsten microelectrodes assembled in a moveable microdrive, or nichrome micro-wires (Figure 2). With this configuration we have been able to record the firing patterns of over a hundred accumbens neurons for tens of minutes up to several hours. The patterns of responsivity of these neurons to afferent stimulation appeared similar to what we have previously observed in anesthetized preparations. However, in contrast to the anesthetized rat, nucleus accumbens neurons in the awake, freely-moving rat demonstrated considerable spontaneous activity (4.08 ± 3.86 Hz) with both positive and negative correlations with behaviorally associated theta activity recorded from cortical EEG electrodes. However, there was no correlation of accumbens discharge rate and locomotor behavior, per se.
Postamputation pain
Published in Peter R Wilson, Paul J Watson, Jennifer A Haythornthwaite, Troels S Jensen, Clinical Pain Management, 2008
These clinical observations are supported by experimental studies. Following a nerve transection, formation of neuromas is seen universally. Such neuromas show spontaneous and abnormal evoked activity following mechanical or chemical stimulation (for review, see Devor64). The ectopic and increased spontaneous and evoked activity from the periphery is assumed to be the result of an increased expression of sodium channels.65 In the dorsal root ganglion (DRG) cells, changes also occur following a complete nerve cut. Cell bodies in the DRG show abnormal spontaneous activity and increased sensitivity to mechanical and neurochemical stimulation.66
Neuronal Representations of Bimanual Movements
Published in Alexa Riehle, Eilon Vaadia, Motor Cortex in Voluntary Movements, 2004
Eilon Vaadia, Simone Cardoso de Oliveira
Single-unit activity and local field potentials were recorded from homologous sites in the two hemispheres, from the primary motor cortex (M1) and from SMA proper. (For details on recording sites see Donchin et al.14) The activity of 8 to 30 isolated neurons and up to eight local field potential (LFP) channels was recorded each session. The data discussed in this article were recorded from 3 monkeys and included the activity of more than 438 neurons (232 in M1 and 206 in SMA). To detect evoked activity, we tested the firing rate in a 500-msec period from 100 msec
Spinal and supraspinal modulation of pain responses by hypnosis, suggestions, and distraction
Published in American Journal of Clinical Hypnosis, 2021
Bérengère Houzé, Anouk Streff, Mathieu Piché, Pierre Rainville
Not without interest, all the studies mentioned above focused on the effect of hypnotic hypoalgesia suggestions on SEPs components compared to control and to different conditions, and only few compared the effect of hypnotic hypoalgesia suggestions to that induced by hypnotic hyperalgesia suggestions (De Pascalis et al., 2015; Meier et al., 1993; Ray et al., 2002; Valentini et al., 2013). Studies reported a differential modulation of SEPs component according to the individual’s hypnotizability except for Meier et al.’s study which revealed no difference in modulation of brain potentials by the two antagonistic suggestions. Thus, this study has highlighted the possibility that changes in brain responses induced by these suggestions might reflect a nonspecific effect of suggestions on stimulus-evoked activity rather than a directional effect on pain responses. This implies that changes in EEG activity during hypno-hypoalgesia in previous studies may reflect a nonspecific hypnosis- or suggestion-related effect rather than a change in the pain-evoked response.
A review of auditory gain, low-level noise and sound therapy for tinnitus and hyperacusis
Published in International Journal of Audiology, 2020
Adam Sheppard, Christina Stocking, Massimo Ralli, Richard Salvi
An alternative to pharmacotherapies has been to boost acoustic stimulation to the cochlea thereby increasing the flow of information into the central auditory system. The ultimate goal being to increase sound induced neuroplastic changes in the central auditory pathway in order to reduce gain to normal levels (Moucha and Kilgard 2006; Norena and Eggermont 2006; Norena and Chery-Croze 2007). Electrophysiological studies with animal models have shown that prolonged exposure to low-level noise or tone pip ensembles can lower spontaneous and sound-evoked activity (i.e., hypoactivity) within the auditory cortex and sub-cortical nuclei (Lau et al. 2015b; Munguia, Pienkowski, and Eggermont 2013; Norena and Eggermont 2006; Pienkowski and Eggermont 2009a; Pienkowski and Eggermont 2010b). These studies have provided a scientific rationale for using low-level acoustic stimulation for the treatment of tinnitus and hyperacusis in humans. However, clinical outcomes with sound therapy or acoustic stimulation through hearing aids have provided mixed results (Hanley and Davis 2008; Hoare et al. 2014; Norena and Chery-Croze 2007; Searchfield, Kaur, and Martin 2010; Shekhawat, Searchfield, and Stinear 2013). This article will review: (1) the evidence related to enhanced central gain as a potential mechanism for the generation of tinnitus and hyperacusis, (2) the neuroplastic changes induced by prolonged, low-level sound stimulation, and (3) the clinical effectiveness of various sound therapies and amplification for the treatment of tinnitus and hyperacusis.
EMG-triggered stimulation post spinal cord injury: A case report
Published in Physiotherapy Theory and Practice, 2018
The existence of intact corticospinal fibers can be explored painlessly by using TMS. Noninvasive, single-pulse TMS is the gold standard for assessing the excitability of the primary motor cortex (M1) and the integrity of the corticospinal tract in humans. By stimulating the M1 area in one hemisphere, the evoked activity can be recorded from the contralateral muscles through surface electromyography (EMG) electrodes. These evoked responses are called MEPs. The characteristics of these TMS-induced MEPs (e.g. latency and amplitude) can be used to assess the excitability of the M1 area and the integrity of the corticospinal pathways (Farzan, 2014). Single-pulse TMS technique has been used extensively in human motor control research over the past 30 years (Di Lazzaro and Rothwell, 2014; Petersen et al., 2003).