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Neuromodulation : Journal of the... May 2024Spinal neurostimulation is a therapy for otherwise intractable chronic pain. Spinal neurostimulation includes stimulation of the spinal cord (SCS), dorsal root ganglion... (Review)
Review
INTRODUCTION
Spinal neurostimulation is a therapy for otherwise intractable chronic pain. Spinal neurostimulation includes stimulation of the spinal cord (SCS), dorsal root ganglion (DRGS), and dorsal root entry zone (DREZS). New paresthesia-free neurostimulation paradigms may rely on different mechanisms of action from those of conventional tonic neurostimulation. The aim of this systematic review is to assess the existing knowledge on the effect of spinal neurostimulation on somatosensory processing in patients with chronic pain. We therefore reviewed the existing literature on the effect of various spinal neurostimulation paradigms on the supraspinal somatosensory evoked response (SER).
MATERIALS AND METHODS
Multiple scientific data bases were searched for studies that assessed the effect of spinal neurostimulation on the supraspinal SER, evoked by painful or nonpainful peripheral stimuli in patients with chronic pain. We found 205 studies, of which 24 were included. Demographic data, study design, and study outcome were extracted.
RESULTS
Of the 24 included studies, 23 used electroencephalography to assess the SER; one study used magnetoencephalography. Fifteen studies evaluated tonic SCS; six studies (also) evaluated paresthesia-free paradigms; three studies evaluated the effect of tonic DRGS or DREZS. Sixteen studies used nonpainful stimuli to elicit the SER, 14 observed a decreased SER amplitude. Ten studies used painful stimuli to elicit the SER, yielding mixed results.
DISCUSSION
The included studies suggest that both paresthesia-based and paresthesia-free spinal neurostimulation paradigms can decrease (part of) the SER elicited by a nonpainful peripheral stimulus. The observed SER amplitude reduction likely is the effect of various spinal and supraspinal mechanisms of spinal neurostimulation that also contribute to pain relief.
CONCLUSIONS
Spinal neurostimulation modulates the processing of a peripherally applied nonpainful stimulus. For painful stimuli, the results are not conclusive. It is not yet clear whether paresthesia-free neurostimulation affects the SER differently from paresthesia-based neurostimulation.
PubMed: 38752944
DOI: 10.1016/j.neurom.2024.04.003 -
Journal of Affective Disorders Jun 2024Electrophysiologic measures provide an opportunity to inform mechanistic models and possibly biomarker prediction of response. Serotonergic psychedelics (SPs) (i.e.,... (Review)
Review
Spectral signatures of psilocybin, lysergic acid diethylamide (LSD) and ketamine in healthy volunteers and persons with major depressive disorder and treatment-resistant depression: A systematic review.
BACKGROUND
Electrophysiologic measures provide an opportunity to inform mechanistic models and possibly biomarker prediction of response. Serotonergic psychedelics (SPs) (i.e., psilocybin, lysergic acid diethylamide (LSD)) and ketamine represent new investigational and established treatments in mood disorders respectively. There is a need to better characterize the mechanism of action of these agents.
METHODS
We conducted a systematic review investigating the spectral signatures of psilocybin, LSD, and ketamine in persons with major depressive disorder (MDD), treatment-resistant depression (TRD), and healthy controls.
RESULTS
Ketamine and SPs are associated with increased theta power in persons with depression. Ketamine and SPs are also associated with decreased spectral power in the alpha, beta and delta bands in healthy controls and persons with depression. When administered with SPs, theta power was increased in persons with MDD when administered with SPs. Ketamine is associated with increased gamma band power in both healthy controls and persons with MDD.
LIMITATIONS
The studies included in our review were heterogeneous in their patient population, exposure, dosing of treatment and devices used to evaluate EEG and MEG signatures. Our results were extracted entirely from persons who were either healthy volunteers or persons with MDD or TRD.
CONCLUSIONS
Extant literature evaluating EEG and MEG spectral signatures indicate that ketamine and SPs have reproducible effects in keeping with disease models of network connectivity. Future research vistas should evaluate whether observed spectral signatures can guide further discovery of therapeutics within the psychedelic and dissociative classes of agents, and its prediction capability in persons treated for depression.
Topics: Humans; Psilocybin; Ketamine; Lysergic Acid Diethylamide; Depressive Disorder, Major; Depression; Healthy Volunteers; Hallucinogens
PubMed: 38570038
DOI: 10.1016/j.jad.2024.03.165 -
Brain Connectivity Apr 2024Persisting imbalance and falls in community-dwelling traumatic brain injury (TBI) survivors are linked to reduced long-term survival. However, a detailed understanding... (Review)
Review
Persisting imbalance and falls in community-dwelling traumatic brain injury (TBI) survivors are linked to reduced long-term survival. However, a detailed understanding of the impact of TBI upon the brain mechanisms mediating imbalance is lacking. To understand the state of the art concerning the brain mechanisms mediating imbalance in TBI, we performed a systematic review of the literature. PubMed, Web of Science, and Scopus were searched and peer-reviewed research articles in humans, with any severity of TBI (mild, moderate, severe, or concussion), which linked a postural balance assessment (objective or subjective) with brain imaging (through computed tomography, T1-weighted imaging, functional magnetic resonance imaging [fMRI], resting-state fMRI, diffusion tensor imaging, magnetic resonance spectroscopy, single-photon emission computed tomography, electroencephalography, magnetoencephalography, near-infrared spectroscopy, and evoked potentials) were included. Out of 1940 articles, 60 were retrieved and screened, and 25 articles fulfilling inclusion criteria were included. The most consistent finding was the link between imbalance and the cerebellum; however, the regions within the cerebellum were inconsistent. The lack of consistent findings could reflect that imbalance in TBI is due to a widespread brain network dysfunction, as opposed to focal cortical damage. The inconsistency in the reported findings may also be attributed to heterogeneity of methodology, including data analytical techniques, small sample sizes, and choice of control groups. Future studies should include a detailed clinical phenotyping of vestibular function in TBI patients to account for the confounding effect of peripheral vestibular disorders on imbalance and brain imaging.
Topics: Humans; Brain Injuries, Traumatic; Postural Balance; Brain; Magnetic Resonance Imaging
PubMed: 38343363
DOI: 10.1089/brain.2023.0064 -
Brain Structure & Function Mar 2024This systematic review with a meta-analysis aimed to identify the altered brain structure and function in carpal tunnel syndrome (CTS) by summarizing the literature... (Meta-Analysis)
Meta-Analysis
This systematic review with a meta-analysis aimed to identify the altered brain structure and function in carpal tunnel syndrome (CTS) by summarizing the literature about magnetic resonance imaging (MRI), functional magnetic resonance imaging (fMRI), and magnetoencephalography (MEG) outcomes compared to healthy controls (HC). CTS is the most common nerve entrapment in the arm associated with altered peripheral and central nociceptive system. PRISMA guidelines were used to report the outcomes. Six databases were searched for relevant literature (Web of Science, Scopus, PubMed, Sage, EBSCO host, and Cochrane). Eligible studies comparing MRI, fMRI, and MEG findings in people with CTS (present for at least 2 months) and HC through the following parameters: (1) interdigit cortical separation distance, (2) white and grey matter changes, (3) peak latency of M20 wave and recovery function of N20 from the somatosensory cortex (SI), and (4) surface area of activated digit cortical representation. The results from different studies were pooled and a meta-analysis was done. From 17 included, there was a significant reduction of interdigit cortical separation distance of index-middle and index-little fingers in the CTS (SMD = - 0.869, 95% CI (- 1.325, - 0.413), p-value = 0.000) and (SMD = - 0.79, 95% CI (- 1.217, - 0.364), p-value = 0.000), respectively. Middle-little fingers interdigit separation showed no difference (SMD = - 0.2, 95% CI (- 0.903, 1.309), p-value = 0.718). There is evidence supporting the altered brain structure and function in CTS as evidenced by reduction of interdigit cortical separation distance, and excessive blurring and disinhibition of SI, with low resting state functional connectivity. Thus, centrally directed therapeutic approaches might complement peripheral treatments.
Topics: Humans; Carpal Tunnel Syndrome; Brain Mapping; Magnetic Resonance Imaging; Fingers; Somatosensory Cortex
PubMed: 38165482
DOI: 10.1007/s00429-023-02737-5 -
NeuroImage. Clinical 2023Fatigue is a highly prevalent and disabling symptom of many disorders and syndromes, resulting from different pathomechanisms. However, whether and how different...
Fatigue is a highly prevalent and disabling symptom of many disorders and syndromes, resulting from different pathomechanisms. However, whether and how different mechanisms converge and result in similar symptomatology is only partially understood, and transdiagnostic biomarkers that could further the diagnosis and treatment of fatigue are lacking. We, therefore, performed a transdiagnostic systematic review (PROSPERO: CRD42022330113) of quantitative resting-state electroencephalography (EEG) and magnetoencephalography (MEG) studies in adult patients suffering from pathological fatigue in different disorders. Studies investigating fatigue in healthy participants were excluded. The risk of bias was assessed using a modified Newcastle-Ottawa Scale. Semi-quantitative data synthesis was conducted using modified albatross plots. After searching MEDLINE, Web of Science Core Collection, and EMBASE, 26 studies were included. Cross-sectional studies revealed increased brain activity at theta frequencies and decreased activity at alpha frequencies as potential diagnostic biomarkers. However, the risk of bias was high in many studies and domains. Together, this transdiagnostic systematic review synthesizes evidence on how resting-state M/EEG might serve as a diagnostic biomarker of pathological fatigue. Beyond, this review might help to guide future M/EEG studies on the development of fatigue biomarkers.
Topics: Adult; Humans; Biomarkers; Cross-Sectional Studies; Electroencephalography; Fatigue; Magnetoencephalography
PubMed: 37632989
DOI: 10.1016/j.nicl.2023.103500 -
Biological Psychiatry May 2023Predictive models in neuroimaging are increasingly designed with the intent to improve risk stratification and support interventional efforts in psychiatry. Many of... (Review)
Review
Predictive models in neuroimaging are increasingly designed with the intent to improve risk stratification and support interventional efforts in psychiatry. Many of these models have been developed in samples of children school-aged or older. Nevertheless, despite growing evidence that altered brain maturation during the fetal, infant, and toddler (FIT) period modulates risk for poor mental health outcomes in childhood, these models are rarely implemented in FIT samples. Applications of predictive modeling in children of these ages provide an opportunity to develop powerful tools for improved characterization of the neural mechanisms underlying development. To facilitate the broader use of predictive models in FIT neuroimaging, we present a brief primer and systematic review on the methods used in current predictive modeling FIT studies. Reflecting on current practices in more than 100 studies conducted over the past decade, we provide an overview of topics, modalities, and methods commonly used in the field and under-researched areas. We then outline ethical and future considerations for neuroimaging researchers interested in predicting health outcomes in early life, including researchers who may be relatively new to either advanced machine learning methods or using FIT data. Altogether, the last decade of FIT research in machine learning has provided a foundation for accelerating the prediction of early-life trajectories across the full spectrum of illness and health.
Topics: Child; Child, Preschool; Humans; Infant; Machine Learning; Neuroimaging
PubMed: 36759257
DOI: 10.1016/j.biopsych.2022.10.014 -
Brain Topography Mar 2023Background Magnetoencephalography (MEG) and electroencephalography (EEG) record two main types of data: continuous measurements at rest or during sleep, and... (Review)
Review
Background Magnetoencephalography (MEG) and electroencephalography (EEG) record two main types of data: continuous measurements at rest or during sleep, and event-related potentials/evoked magnetic fields (ERPs/EMFs) that involve specific and repetitive tasks. In this systematic review, we summarized longitudinal studies on recovery from post-stroke aphasia that used continuous or event-related temporal imaging (EEG or MEG). Methods We searched PubMed and Scopus for English articles published from 1950 to May 31, 2022. Results 34 studies were included in this review: 11 were non-interventional studies and 23 were clinical trials that used specific rehabilitation methods, neuromodulation, or drugs. The results of the non-interventional studies suggested that poor language recovery was associated with slow-wave activity persisting over time. The results of some clinical trials indicated that behavioral improvements were correlated with significant modulation of the N400 component. Discussion Compared with continuous EEG, ERP/EMF may more reliably identify biomarkers of therapy-induced effects. Electrophysiology should be used more often to explore language processes that are impaired after a stroke, as it may highlight treatment challenges for patients with post-stroke aphasia.
Topics: Humans; Male; Female; Electroencephalography; Evoked Potentials; Aphasia; Stroke; Magnetoencephalography
PubMed: 36749552
DOI: 10.1007/s10548-023-00941-4 -
Neuromodulation : Journal of the... Dec 2023Transcranial alternating current stimulation (tACS) has been one of numerous investigation methods used for their potential to modulate brain oscillations; however, such... (Review)
Review
BACKGROUND
Transcranial alternating current stimulation (tACS) has been one of numerous investigation methods used for their potential to modulate brain oscillations; however, such investigations have given contradictory results and a lack of standardization.
OBJECTIVES
In this systematic review, we aimed to assess the potential of tACS to modulate alpha spectral power. The secondary outcome was the identification of tACS methodologic key parameters, adverse effects, and sensations.
MATERIALS AND METHODS
Studies in healthy adults who were receiving active and sham tACS intervention or any differential condition were included. The main outcome assessed was the increase/decrease of alpha spectral power through either electroencephalography or magnetoencephalography. Secondary outcomes were methodologic parameters, sensation reporting, and adverse effects. Risks of bias and the study quality were assessed with the Cochrane assessment tool.
RESULTS
We obtained 1429 references, and 20 met the selection criteria. A statistically significant alpha-power increase was observed in nine studies using continuous tACS stimulation and two using intermittent tACS stimulation set at a frequency within the alpha range. A statistically significant alpha-power increase was observed in three more studies using a stimulation frequency outside the alpha range. Heterogeneity among stimulation parameters was recognized. Reported adverse effects were mild. The implementation of double blind was identified as challenging using tACS, in part owing to electrical artifacts generated by stimulation on the recorded signal.
CONCLUSIONS
Most assessed studies reported that tACS has the potential to modulate brain alpha power. The optimization of this noninvasive brain stimulation method is of interest mostly for its potential clinical applications with neurological conditions associated with perturbations in alpha brain activity. However, more research efforts are needed to standardize optimal parameters to achieve lasting modulation effects, develop methodologic alternatives to reduce experimental bias, and improve the quality of studies using tACS to modulate brain activity.
Topics: Adult; Humans; Transcranial Direct Current Stimulation; Alpha Rhythm; Electroencephalography; Brain; Sensation; Randomized Controlled Trials as Topic
PubMed: 36725385
DOI: 10.1016/j.neurom.2022.12.007 -
Molecular Autism Jan 2023The long-described atypicalities of memory functioning experienced by people with autism have major implications for daily living, academic learning, as well as... (Review)
Review
The long-described atypicalities of memory functioning experienced by people with autism have major implications for daily living, academic learning, as well as cognitive remediation. Though behavioral studies have identified a robust profile of memory strengths and weaknesses in autism spectrum disorder (ASD), few works have attempted to establish a synthesis concerning their neural bases. In this systematic review of functional neuroimaging studies, we highlight functional brain asymmetries in three anatomical planes during memory processing between individuals with ASD and typical development. These asymmetries consist of greater activity of the left hemisphere than the right in ASD participants, of posterior brain regions-including hippocampus-rather than anterior ones, and presumably of the ventral (occipito-temporal) streams rather than the dorsal (occipito-parietal) ones. These functional alterations may be linked to atypical memory processes in ASD, including the pre-eminence of verbal over spatial information, impaired active maintenance in working memory, and preserved relational memory despite poor context processing in episodic memory.
Topics: Humans; Autistic Disorder; Autism Spectrum Disorder; Magnetic Resonance Imaging; Brain; Functional Neuroimaging; Brain Mapping
PubMed: 36627713
DOI: 10.1186/s13229-022-00525-2 -
Progress in Neuro-psychopharmacology &... Apr 2023There are growing application of machine learning models to study the intricacies of non-linear and non-stationary characteristics of electroencephalography (EEG) and... (Review)
Review
There are growing application of machine learning models to study the intricacies of non-linear and non-stationary characteristics of electroencephalography (EEG) and magnetoencephalography (MEG) data in neurobiologically complex and heterogeneous conditions such as autism spectrum disorder (ASD). Such tools have potential diagnostic applications, and given the highly heterogeneous presentation of ASD, might prove fruitful in early detection and therefore could facilitate very early intervention. We conducted a systematic review (PROSPERO ID#CRD42021257438) by searching PubMed, EMBASE, and PsychINFO for machine learning approaches for EEG and MEG analyses in ASD. Thirty-nine studies were identified, of which the majority (18) used support vector machines for classification; other successful methods included deep learning. Thirty-seven studies were found to employ EEG and two were found to employ MEG. This systematic review indicate that machine learning methods can be used to classify ASD, predict ASD diagnosis in high-risk infants as early as 3 months of age, predict ASD symptom severity, and classify states of cognition in ASD with high accuracy. Replication studies testing validity, reproducibility and generalizability in tandem with randomized controlled trials in ASD populations will likely benefit the field.
Topics: Infant; Humans; Magnetoencephalography; Autism Spectrum Disorder; Reproducibility of Results; Electroencephalography; Machine Learning
PubMed: 36574922
DOI: 10.1016/j.pnpbp.2022.110705