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Neurophysiology is a broad discipline involved in the recording and analysis of biological signals of multiple modalities relevant to the nervous system. Neurophysiological studies have contributed substantially to the understanding of the neurobiological underpinnings of psychiatric disease. In clinical psychiatry, EEG and other studies are secondary to the clinical assessment for a reliable diagnosis and prognostication of psychiatric disease, and should not be interpreted in isolation. However, in some clinical situations, such as non-epileptic seizures, they can be confirmatory of the diagnosis. In this chapter, we start with an overview of basic principles in neurophysiology, from cellular and molecular to systems neuroscience. We then describe the technical aspects, rationale, indications and limitations of the most commonly used neurophysiological tests in clinically psychiatry. We outline the main neurophysiological abnormalities present in primary psychiatric disorders and in their differential diagnoses (delirium, epilepsy, dementia, focal cerebral lesions and sleep disorders), as well as the neurophysiological effect of psychotropic medications. We also describe recent advances in neuromodulation techniques, linking diagnosis to therapy.
This paper reports the methods and preliminary findings of Germina, an ongoing cohort study to identify biomarkers and trajectories of executive functions and language development in the first 3 years of life. 557 mother-infant dyads (mean age of mothers 33.7 years, 65.2% white, 48.7% male infants) have undergone baseline and are currently collecting data for other timepoints. A linear regression was used to predict baseline Bayley-III using scores derived from data-driven sparse partial least squares utilizing a multiple holdout framework of 15 domains. Significant associations were found between socioeconomic/demographic characteristics (B = 0.29), epigenetics (B = 0.11), EEG theta (B = 0.14) and beta activity (B = 0.11), and microbiome functional pathways (B = 0.08) domains, and infant development measured by the Bayley-III at T1, suggesting potential interventions to prevent impairments.
Based on facial expression experiments, childhood adversity may be associated with threat-related information processing bias. Yet, it is unclear whether this generalizes to other threat-related stimuli, such as social and non-social visual scenes.
Methods
We combined fast periodic visual stimulation with frequency-tagging electroencephalography (EEG) and eye-tracking to assess automatic and implicit neural discrimination, neural salience and preferential looking towards negative versus neutral social and non-social visual scenes in young adults aged 16–24 years (51 with childhood adversity and psychiatric symptoms and 43 controls).
Results
Controls showed enhanced negative-neutral neural discrimination within a social versus non-social context. However, this facilitating effect of social content was absent in those with adversity, suggesting a selective alteration in social threat processing. Moreover, individual differences in adversity severity, and more specifically threat experiences (but not neglect experiences), were associated with decreased neural discrimination of negative versus neutral social scenes, corresponding to similar findings in facial expression processing, indicating the robustness of adversity-related deficits in threat-safety discrimination across social visual stimuli.
Conclusions
The adversity-related decreased threat-safety discrimination might impact individuals’ perception of social cues in daily life and relate to poor social functioning and future development of psychopathology.
Recent neuroimaging studies have demonstrated that the heterogeneous antidepressant responsiveness in patients with major depressive disorder (MDD) is associated with diverse resting-state functional brain network (rsFBN) topology; however, only limited studies have explored the rsFBN using electroencephalography (EEG). In this study, we aimed to identify EEG-derived rsFBN-based biomarkers to predict pharmacotherapeutic responsiveness.
Methods
The resting-state EEG signals were acquired for demography-matched three groups: 98 patients with treatment-refractory MDD (trMDD), 269 those with good-responding MDD (grMDD), and 131 healthy controls (HCs). The source-level rsFBN was constructed using 31 sources as nodes and beta-band power envelope correlation (PEC) as edges. The degree centrality (DC) and clustering coefficients (CCs) were calculated for various sparsity levels. Network-based statistic and one-way analysis of variance models were employed for comparing PECs and network indices, respectively. The multiple comparisons were controlled by the false discovery rate.
Results
Patients with trMDD were characterized by the altered dorsal attention network and salience network. Specifically, they exhibited hypoconnection between eye fields and right parietal regions (p = 0.0088), decreased DC in the right supramarginal gyrus (q = 0.0057), and decreased CC in the reward circuit (qs < 0.05). On the other hand, both MDD groups shared increased DC but decreased CC in the posterior cingulate cortex.
Conclusions
We confirmed that network topology was more severely deteriorated in patients with trMDD, particularly for the attention-regulatory networks. Our findings suggested that the altered rsFBN topologies could serve as potential pathologically interpretable biomarkers for predicting antidepressant responsiveness.
Nearly 25% of people with intellectual disability (PwID) have epilepsy compared to 1% of the UK general population. PwID are commonly excluded from research, eventually affecting their care. Understanding seizures in PwID is particularly challenging because of reliance on subjective external observation and poor objective validation. Remote electroencephalography (EEG) monitoring could capture objective data, but particular challenges and implementation strategies for this population need to be understood.
Aim
This co-production aimed to explore the accessibility and potential impact of a remote, long-term EEG tool (UnEEG 24/7 SubQ) for PwID and epilepsy.
Method
We conducted six, 2-hour long workshops; three with people with mild intellectual disability and three with families/carers of people with moderate–profound intellectual disability. Brief presentations, easy read information and model demonstrations were used to explain the problem and device. A semi-structured guide developed by a communication specialist and art-based techniques facilitated discussion with PwID. For family/carers, active listening was employed. All conversations were recorded and transcribed. Artificial intelligence-based coding and thematic analysis (ATLAS.ti and ChatGPT) were synthesised with manual theming to generate insights.
Results
Co-production included four PwID, five family members and seven care professionals. Three main themes were identified: (1) perceived benefits for improving seizure understanding, informing care and reducing family and carer responsibility to accurately identify seizures; (2) the device was feasible for some PwID but not all; and (3) appropriate person-centred communication is essential for all stakeholders to reduce concerns.
Conclusions
The workshops identified key benefits and implementing barriers to SubQ in PwID.
Depression is transmitted within families, but the mechanisms involved in such transmission are not clearly defined. A potential marker of familial risk is the neural response to errors, which may play a role in depression symptoms and is known to be partially heritable. Here, 97 mother-daughter dyads completed a Flanker task while electroencephalography markers of error monitoring were recorded: the error-related negativity (ERN) and response-locked delta and theta power. We assessed whether these measures of neural response to errors 1) were associated with history of recurrent major depressive disorder (MDD) and current depression symptoms among mothers, 2) were correlated among mother-daughter dyads, and 3) were associated with maternal history of recurrent MDD and maternal symptoms of depression among daughters. A history of recurrent MDD was associated with blunted delta and increased theta among mothers. Across mothers, delta and theta were negatively and positively associated, respectively, with current depression symptoms. Mothers’ and daughters’ ERN were positively correlated. Finally, current maternal depression symptoms were negatively associated with delta power in daughters. These results suggest that neural responses to errors may be implicated in the intergenerational transmission of depression. These results also support the relevance of delta oscillations to understanding pathways to depression.
The Hierarchical Taxonomy of Psychopathology (HiTOP) offers a promising framework to identify the neurobiological mechanisms of psychopathology. Many forms of psychopathology are characterized by dysfunctional emotional reactivity. The late positive potential (LPP) is an event-related potential component that provides an index of neurobiological emotional reactivity. Several categorical disorders have demonstrated a similar association with the emotion-modulated LPP. It is possible that higher-order dimensional representations of psychopathology might explain the comparable results. The present study examined the association between HiTOP-consistent pathological personality dimensions across multiple levels of the hierarchy and neurobiological emotional reactivity.
Methods
The sample included 215 18–35-year-old adults (86% female) who were oversampled for psychopathology. Participants completed the emotional interrupt task while electroencephalography was recorded to examine the LPP. Participants also completed the Comprehensive Assessment of Traits relevant to Personality Disorders to assess pathological personality.
Results
At the spectra level, higher negative emotionality was associated with a larger emotion-modulated LPP, while higher detachment was associated with a smaller emotion-modulated LPP. There were no associations between higher-order psychopathology levels and the emotion-modulated LPP. Compared to categorical diagnoses, spectra-level personality pathology dimensions significantly improved the prediction of the emotion-modulated LPP.
Conclusions
The present study indicates that HiTOP spectra levels of negative emotionality and detachment demonstrate unique associations with neurobiological emotional reactivity. The study highlights the utility of examining dimensional and hierarchical, rather than categorical, representations of psychopathology in the attempt to identify the neurobiological origins of psychopathology.
Schizotypal traits include abnormalities in cognition, behavior, and interpersonal relationships that are similar, yet less severe than psychotic symptomology. It is estimated that approximately 5% of the general population displays psychotic symptoms and experiences that can be considered schizotypal in nature, but there is little research examining the neurological correlates of these traits. The mismatch negativity (MMN) event-related potential is an objective measure of auditory change detection derived from electroencephalography. The current study contributes to the limited body of evidence examining the neurobiological underpinnings of schizotypy in a non-clinical sample using the MMN. Participants were recruited from the general population and divided into high and low-schizotypy groups for comparison. Individuals with high schizotypal traits displayed reduced MMN amplitudes in response to frequency and location deviants, and longer MMN latencies in response to location deviants. Specific sub-traits of schizotypy were uniquely related to frequency and location amplitudes, suggesting the previously reported inconsistencies in the literature may be due to diverse samples and differing deviant tone types. Finally, impulsivity and sensation-seeking likely contributed to the slower processing seen in location deviance detection. Ultimately, the current results provide evidence that the neurobiological abnormalities seen in clinical populations of schizotypal personality disorder and psychosis also extend to non-clinical populations.
The electroencephalographic (EEG) signal is the electric potential recorded on the scalp, and it is believed to originate from the combined activity of large populations of neurons. In forward models of EEG signals, one typically (i) represents neuronal sources in terms of effective current dipoles, (ii) defines a head model, which is a specification of the conductivity profile for the medium between the sources and the recording position (brain tissue, cerebrospinal fluid, skull, scalp), and (iii) uses volume-conductor theory to compute the resulting electric potential at the scalp. In this chapter, we introduce the key theory and computational frameworks for modeling EEG signals. We illustrate how biophysically detailed models of neurons can be reduced to approximate equivalent dipoles, and we discuss further ways to simplify neural simulations in order to reduce the computational cost. Using a combination of computational modeling and analytical approximations, we analyze how various factors are involved in shaping the EEG signal.
It is common to study the electric activity of neurons by measuring the electric potential in the extracellular space of the brain. However, interpreting such measurements requires knowledge of the biophysics underlying the electric signals. Written by leading experts in the field, this volume presents the biophysical foundations of the signals as well as results from long-term research into biophysics-based forward-modeling of extracellular brain signals. This includes applications using the open-source simulation tool LFPy, developed and provided by the authors. Starting with the physical theory of electricity in the brain, this book explains how this theory is used to simulate neuronal activity and the resulting extracellular potentials. Example applications of the theory to model representations of real neural systems are included throughout, making this an invaluable resource for students and scientists who wish to understand the brain through analysis of electric brain signals, using biophysics-based modeling.
Electroencephalography is an accessible, portable, noninvasive and safe means of evaluating a patient’s brain activity. It can aid in diagnosis and management decisions for post-cardiac arrest patients with seizures, myoclonus and other non-epileptic movements. It also plays an important role in a multimodal approach to neuroprognostication predicting both poor and favorable outcomes. Individuals ordering, performing and interpreting these tests, regardless of the indication, should understand the supporting evidence, logistical considerations, limitations and impact the results may have on postarrest patients and their families as outlined herein.
This chapter offers a thorough guide to the techniques and instruments used to understand how the brain develops in humans. It covers key learning goals, such as examining how behaviors change as people grow, how studying typical and atypical development inform each other, and what we can and cant learn about brain structure using non-invasive brain scans. It also explains the two main ways we measure brain function. Starting with some back history on methodological tools, this chapter sets the stage for deeper insights into brain development and its impact on our abilities. It highlights the dynamic nature of the field, influenced by both animal studies and rapidly evolving and improving analytical tools and methods. With a focus on methods for studying children, we explore more advanced techniques used in different age groups. Furthermore, this chapter stresses the importance of a scientific mindset and adaptability when new evidence comes to light. It serves as a vital reference for understanding the tools and approaches in developmental cognitive neuroscience.
The modulation of brain circuits of emotion is a promising pathway to treat borderline personality disorder (BPD). Precise and scalable approaches have yet to be established. Two studies investigating the amygdala-related electrical fingerprint (Amyg-EFP) in BPD are presented: one study addressing the deep-brain correlates of Amyg-EFP, and a second study investigating neurofeedback (NF) as a means to improve brain self-regulation.
Methods
Study 1 combined electroencephalography (EEG) and simultaneous functional magnetic resonance imaging to investigate the replicability of Amyg-EFP-related brain activation found in the reference dataset (N = 24 healthy subjects, 8 female; re-analysis of published data) in the replication dataset (N = 16 female individuals with BPD). In the replication dataset, we additionally explored how the Amyg-EFP would map to neural circuits defined by the research domain criteria. Study 2 investigated a 10-session Amyg-EFP NF training in parallel to a 12-weeks residential dialectical behavior therapy (DBT) program. Fifteen patients with BPD completed the training, N = 15 matched patients served as DBT-only controls.
Results
Study 1 replicated previous findings and showed significant amygdala blood oxygenation level dependent activation in a whole-brain regression analysis with the Amyg-EFP. Neurocircuitry activation (negative affect, salience, and cognitive control) was correlated with the Amyg-EFP signal. Study 2 showed Amyg-EFP modulation with NF training, but patients received reversed feedback for technical reasons, which limited interpretation of results.
Conclusions
Recorded via scalp EEG, the Amyg-EFP picks up brain activation of high relevance for emotion. Administering Amyg-EFP NF in addition to standardized BPD treatment was shown to be feasible. Clinical utility remains to be investigated.
Memory is a critical piece of the human experience and impairments in neural memory networks can have devastating consequences for the affected person. A subtype of memory, episodic memory generates context for the present based on past experience and allows us to make predictions about the future. Episodic memories become stable fixtures through long-term memory consolidation. It is believed that consolidation of episodic memory requires a dynamic interplay between connected hippocampal-cortical networks, mainly during sleep. Sleep oscillations, slow oscillations and thalamocortical spindles, coupled with hippocampal sharp wave ripples (SWR) is proposed to be mechanistically involved in establishing the crucial cortical-subcortical dialog. The current study aimed to determine alterations in typical sleep oscillations and oscillation coupling in patients with and without structural hippocampal damage and correlate them with neuropsychological measures believed to be sensitive to hippocampal dysfunction, i.e., Rey Auditory Verbal Learning Task (RAVLT) and Verbal Paired Associates (VPA-II).
Participants and Methods:
We used intracranial electroencephalography (iEEG) in 14 patients with epilepsy to directly record hippocampal and neocortical oscillations and neuropsychological measures obtained prior to implantation. Half of the participants were diagnosed with mesial temporal sclerosis (MTS) in the left hippocampus and healthy tissue in the right hippocampus. The other half did not have MTS and had either mesial temporal epilepsy without MTS or extra-temporal seizures. We analyzed hippocampal SWR output from both hippocampi and characterized neocortical slow oscillations and spindles and their coupling for each participant. We correlated electrophysiological data with behavioral results of neuropsychological testing in order to characterize the clinical relevance.
Results:
SWR analysis revealed significant differences in the frequency, t(7639) = 15.52, p>.001, p > .001), amplitude, t(7664) = -23.93, p > .001, and waveforms (p > .001) of SWR in the sclerotic versus healthy hippocampi. Patients with a sclerotic hippocampus but relatively preserved verbal memory scores (RAVLT, VPA-II) showed increased SWR amplitudes in the contralateral hippocampus compared to patients with low verbal memory scores. Additionally, we found differences between hemispheres in phase amplitude coupling of SWRs to spindles and SOs (p > 0.001). Results of our correlational analysis were variable and dependent upon additional factors, such as age of onset and diagnosis duration.
Conclusions:
Results from this work will aid in establishing a criterion for characterizing a relationship between subcortical and cortical oscillations as they relate to memory performance. Besides aiding our understanding of the neural mechanisms underpinning memory consolidation this will ideally help with developing neurophysiological biomarkers that may predict possible memory decline in resective or ablative neurosurgery absent of structural lesion. In addition, this work may potentially provide first evidence of a neurophysiological biomarker directly recorded from the human hippocampus to support possible reorganization of memory functioning in the non-sclerotic hippocampus.
Improving the timeline for intervention in Alzheimer's disease (AD) has considerable potential to delay and mitigate disability and suffering. Neuropsychological assessment is useful for distinguishing AD from normal aging and other dementias but is less useful in preclinical detection due to its limited sensitivity. The N400 (N4), a language-based EEG event-related potential (ERP) related to semantic functioning, is a promising candidate marker of AD with potential to improve early detection and monitoring of AD. For example, studies have shown that individuals with AD show a reduced N4 "effect"—a smaller difference in the size of the N4 to semantically congruent vs. incongruent word-pairs. The goal of this study is to assess the presence of the N4 effect in healthy seniors, and those with amnestic mild cognitive impairment (MCI) or mild AD, and to evaluate associations between performance on the Repeatable Battery for the Assessment of Neuropsychological Status (RBANS) and the N4 across these samples.
Participants and Methods:
Fifty older adults (intact=27, combined MCI/mild AD group=23; "impaired") completed neuropsychological testing, including the RBANS, as part of a larger study. Participants were re-contacted and returned for EEG assessment between several weeks to one year later. During EEG recording, participants completed a word-pair judgement paradigm, which involved distinguishing between semantically congruent and incongruent word-pairs. Data was collected and analyzed according to customized N4 analysis scripts provided as part of ERPCORE, an online resource for acquiring and analyzing common ERP components (Kappenman et al., 2021; https://osf.io/thsqg/). The change in N4 amplitude between congruent and incongruent trials (the N4 effect) was used as an index of participants' semantic functioning. Participants' N4 effect was quantified using the mean amplitude from 300-550 milliseconds poststimulus at electrode Cz.
Results:
Repeated measures ANOVAs indicated a significant effect of trial type on the N400 amplitude in the intact individuals (F(1, 26)=77.66, p<.001), which remained significant in the sample as a whole (F(1, 48)=65.18, p<.001). Although intact participants numerically showed a larger N4 effect (intact: M=-4.02, SD=2.37; impaired: M=-2.60, SD=3.40), the expected group-by-trial interaction was not significant (F(1, 48)=3.01, p=.089). Correlational analyses revealed no significant associations between the N4 effect and the RBANS Total Scale scores (r=-.14, p=.32), nor for the Immediate Memory (r=-.002, p=.99), Visuospatial/Constructional (r=-.069, p=.63), Language (r=-.15, p=.30) Attention (r=-.21, p=.14), or Delayed Memory (r=-.18 p=.58) indexes.
Conclusions:
Results confirmed the presence of the N4 effect in intact participants and in the sample as a whole. Although the N4 effect was numerically smaller in the impaired group as expected, this difference was not significant in the present sample. Likewise, we observed no evidence for associations between the size of N4 effect and performance on RBANS indexes. Overall, the present study provides mixed evidence for the utility of the N4 as a biomarker in mild AD. Factors that may have contributed to the lack of associations between the N4 effect and the RBANS include the limited sample size and variable lengths of time between participants' initial cognitive assessments and EEG testing.
Since seminal work by Sherrington, the term interoception refers to the ability to sense modifications of internal bodily states as opposed to the ability to sense stimuli coming from outside the body itself. Despite conceptual changes regarding the afferent signals subserving this type of inner perception, the core of this definition is still valid and widely accepted. The critical contribution of internal state perception to self-regulation as well as higher-order cognitive processes has led to the development of psychometric and observational measures trying to capture individual interoceptive skills, focusing especially on the ability to orient attention to internal sensations. Nonetheless, despite growing interest in interoceptive attention (IAtt), little is known about neurofunctional correlates of our ability to redirect attention to internal sensations and consciously process them, as well as on potential objective biomarkers of IAtt performance.
Participants and Methods:
This study included 36 volunteers who were asked to complete a heart-beat counting task (HCT), a common IAtt task. During both resting-state and HCT, central electrophysiological (EEG, 32 electrodes) and cardiovascular activity (ECG, I lead) were recorded. eLORETA was used to estimate both task-related and resting-state intracortical sources of EEG signals. Statistical non-parametric mapping (SnPM) was used to draw and investigate contrast statistical maps between rest- and task-related cortical current density.
Results:
Contrast analyses comparing HCT and resting revealed higher Alpha frequency current density estimates during the task, with primary cortical seed in the right parahippocampal gyrus. Regression analyses of the relationship between IAtt scores and task-related changes in intracortical current density during HCT revealed a positive relationship for the Beta frequency bands with primary cortical seeds in the cingulate gyrus and insula.
Conclusions:
Findings add to available literature by further specifying the electrophysiological signature of interoceptive attentiveness, and suggest specific electrophysiological markers as objective measures of individual IAtt skills.
Onset of Alzheimer’s disease (AD) pathology is estimated to begin 20-30 years prior to clinical symptom onset. Resting state EEG may yield useful early biomarkers of pathology, but its use along the AD clinical continuum is still limited, especially in individuals who are at high risk for AD but have yet to show symptoms. EEG waveform oscillations are classified based by frequency range (alpha, beta, theta, delta). Changes within these frequency bands have been identified in individuals with AD-dementia as compared to those with MCI and normal aging. Typical changes involve increases in low frequency power bands of delta and theta and decreases in beta and alpha frequencies, particularly in more posterior brain regions. However, these methods have yet to be explored in cognitively normal individuals who are at high risk for AD, as work has shown between individuals with MCI and healthy older adults.
Participants and Methods:
We compared differences in resting state EEG between older adults (age 60+) at high risk for AD (positive family history, genetic risk defined as carrying 1 + ApoE ε4 alleles) and individuals at low risk (negative family history, no ε4 allele). We collected 1) neuropsychological test performance; 2) self-report measures of subjective cognitive complaints and cognitive reserve; and 3) five minutes of eyes-open resting state EEG using 64-channel active electrodes. Clusters of three electrodes were average for regions and absolute power within 5 frequency bands was calculated. Theta/beta ratio was calculated by dividing absolute power of bands at its respective site. Correlations between absolute power for specific regions, self-report measures, and neuropsychological test scores.
Results:
Analysis of 20 individuals collected to date (14 high risk, 6 low risk) found associations (p<0.05) between risk group and beta and gamma power across multiple electrode clusters, with high-risk individuals having higher power. Significant correlations were also found between calculated measures of cognitive reserve and posterior theta/beta ratio, subjective cognitive complaints and beta power, and neuropsychological test composites of learning performance with delta and executive functioning with frontal theta power.
Conclusions:
This work provides preliminary evidence for differences in resting state EEG activity in those at risk for AD, prior to onset of clinical symptoms. Future work will examine patients with mild cognitive impairment as a comparison group to characterize resting state EEG across the early AD continuum.
Recent work has shown that dysfunctional brain EEG responses to anesthetic drugs can be an indicator of both preoperative cognitive impairment and postoperative delirium risk. However, since excessive anesthetic dosage can also cause abnormal EEG brain responses, it is unclear how to tell to what extent such abnormal brain EEG responses reflect latent neurocognitive impairment versus excessive anesthetic dosage. Further, it is unclear what underlying mechanisms might underlie the link between phenotypes (such as delirium and cognitive impairment) and these abnormal neurophysiologic responses to anesthetic drugs.
Participants and Methods:
Dual center prospective cohort design. 139 total older surgical patients from two academic centers underwent intraoperative EEG monitoring with the bispectral index (BIS) EEG monitor during anesthesia and surgery, and postoperative delirium screening by geriatrician interview (Duke cohort) or by trained research staff (Mt Sinai cohort). We developed the Duke Anesthesia Resistance Scale (DARS), defined as the average BIS EEG values divided by the quantity 2.5 minus the age adjusted end tidal anesthetic gas concentration). We then examined the relationship between the DARS and postoperative delirium risk using the Youden index to identify an optimal low DARS threshold for delirium risk, and we used multivariable logistic regression to control for potential confounders.
Results:
Neither BIS scores nor inhaled anesthetic dosage differed significantly between patients with vs without postoperative delirium. Yet, patients with delirium had lower DARS scores than those who did not develop delirium (27.92 vs 32.88, p=0.015). A DARS threshold of 28.7 maximized the Youden index for the association between the DARS and delirium. In multivariable models adjusting for site (Duke vs Mt Sinai) and individual patient risk factors, DARS values <28.7 were associated with a 3.79 fold increased odds ratio (95% CI 1.63-9.10; p=0.03) for postoperative delirium. These results remained unchanged after adjusting for intraoperative medications including opioids, benzodiazepines, propofol, phenylephrine and ketamine. Patients with structural/functional MRI or CSF biomarker evidence of preclinical/prodromal Alzheimer's disease and/or neurovascular pathology were more likely to show altered anesthetic-induced EEG activity patterns.
Conclusions:
Lower scores on a processed EEG-based scale of neurophysiologic resistance to anesthetic induced brain activity changes were independently associated with a nearly 4 fold increased delirium risk. The altered anesthetic-induced brain EEG patterns in patients who go on to develop postoperative delirium may reflect latent pre-clinical/pro-dromal Alzheimer's disease and/or neurovascular pathology.
Concurrent electroencephalography (EEG) during neuropsychological assessment offers a promising method to understand realtime neural and cognitive processes during task performance. For example, previous studies using experimental tasks suggest that midline-frontal theta power (MFT) could serve as a measure of mental exertion and subjective difficulty. The RBANS provides an opportunity to examine this issue in neuropsychological assessment, as a widely-used screening battery that was explicitly developed with subtests that vary according to difficulty within its five domains. This study investigated the effects of task difficulty, cognitive domain, and age on elicitation of MFT during rest and RBANS administration.
Participants and Methods:
EEG was recorded during eyes-closed and eyes-open resting periods and RBANS administration in a sample of 45 healthy younger adults (n = 21; mean age = 23.29, SD = 3.27, range = 19-33; 48% female) and older adults (n = 24; mean age = 70.58, SD = 5.77, range = 59-83; 83% female). MFT was defined as the highest peak above the overall power spectrum within 4-8Hz from electrode Fz, and operationalized as a binary variable (present/absent). A multilevel generalized logistic regression model was run to assess the main effects of Age (Younger, Older), Difficulty (Easy, Hard), Domain (Rest, Immediate Memory, Visuospatial/Constructional, Language, Attention, Delayed Memory), and their potential interactions, on the presence of MFT.
Results:
In the full sample, the Coding, Figure Recall, and Picture Naming subtests were numerically most likely to elicit MFT (71.1%, 66.7%, and 62.2%, respectively), whereas Semantic Fluency, Eyes-Closed Rest, and List Recall had the lowest likelihoods (37.7%, 31%, 28.9%). Older adults were also numerically less likely to exhibit MFT (37.50% present) compared to younger adults (62.24% present). An analysis of deviance revealed a significant effect of Age (F(1,43) = 7.22, p = .01) and a significant interaction between Difficulty and Domain (F(5,220) = 4.78, p < .001). Specifically, Hard subtests in the Visuospatial/Constructional (Figure Copy; b = -2.63, p < .05) and Language (Semantic Fluency; b = -2.92, p < .01) Domains were less likely to elicit MFT than the Easy subtests (i.e., Line Orientation and Picture Naming, respectively).
Conclusions:
Results indicated that MFT can be reliably measured during neuropsychological assessment, and varies in relation to both age and task-related factors. Consistent with previous studies, older adults exhibited less MFT than younger adults in general, possibly suggesting a failure to recruit the relevant networks. Further, present findings suggest that the presence of MFT varies not only by the type of task but also by the level of difficulty. Future research with larger samples can clarify whether and how the amount of MFT elicited during specific subtests relates to objective and subjective difficulty. Overall, MFT can reliably be elicited by cognitive tasks and bears further study as a measure of real-time neural expenditure.
Binge-eating disorder (BED) co-occurs with neurobehavioral alterations in the processing of disorder-relevant content such as visual food stimuli. Whether neurofeedback (NF) directly targeting them is suited for treatment remains unclear. This study sought to determine feasibility and estimate effects of individualized, functional near-infrared spectroscopy-based real-time NF (rtfNIRS-NF) and high-beta electroencephalography-based NF (EEG-NF), assuming superiority over waitlist (WL).
Methods
Single-center, assessor-blinded feasibility study with randomization to rtfNIRS-NF, EEG-NF, or WL and assessments at baseline (t0), postassessment (t1), and 6-month follow-up (t2). NF comprised 12 60-min food-specific rtfNIRS-NF or EEG-NF sessions over 8 weeks. Primary outcome was the binge-eating frequency at t1 assessed interview-based. Secondary outcomes included feasibility, eating disorder symptoms, mental and physical health, weight management-related behavior, executive functions, and brain activity at t1 and t2.
Results
In 72 patients (intent-to-treat), the results showed feasibility of NF regarding recruitment, attrition, adherence, compliance, acceptance, and assessment completion. Binge eating improved at t1 by −8.0 episodes, without superiority of NF v. WL (−0.8 episodes, 95% CI −2.4 to 4.0), but with improved estimates in NF at t2 relative to t1. NF was better than WL for food craving, anxiety symptoms, and body mass index, but overall effects were mostly small. Brain activity changes were near zero.
Conclusions
The results show feasibility of food-specific rtfNIRS-NF and EEG-NF in BED, and no posttreatment differences v. WL, but possible continued improvement of binge eating. Confirmatory and mechanistic evidence is warranted in a double-blind randomized design with long-term follow-up, considering dose–response relationships and modes of delivery.