Mild Traumatic Brain Injuries and Their Implications on Changes in Event Related Potentials: A look into Visual Gating (P50)

Concussions are a prevalent injury that affect a wide range of individuals. Commonly seen amongst individuals who play contact sports, there are many underlying factors that doctors and clinicians have yet to understand which include properties such as proper diagnosis standards or lasting impacts. In this study, we look at those impacts by using electroencephalographic (EEG) measures to study the changes in event related potentials (ERPs) associated with sensory gating and how this cognitive property is affected in those who have a self-reported concussion. Here we show that a visual attention and gating mechanism exists in both populations (control and concussed) as seen by the P50 ERP after the presentation of our visual stimulus, which is dependent on the Order the stimulus is presented (1st or 2nd). Our findings show that those who have suffered a concussion show a difference in the ability to sensory gate which is prevalent by the differences in ERPs between the two groups

Central auditory detection and pre-attentive discrimination in children

Central auditory processes to detection and pre-attentive discrimination in children were studied using auditory event related potentials (AERP). Discrimination potentials were elicited by infrequent deviant stimuli embedded pseudo-randomly in a sequence of frequent standard stimuli. The major obligatory components of the AERP, P85-120, N1 and N2 were recorded to stimuli that varied in complexity (pure tones to words). A later component evoked by deviant stimuli, termed the mismatch negativity (MMN), thought to reflect pre-attentive auditory discrimination processes that occur within the duration of echoic memory, was also noticed.Five groups of children were studied. 1. Experiments in normal adult and children controls were carried out to validate the methodology. MMN to duration and frequency deviance was dissociated temporally but not spatially. 2. Intracranial recordings revealed cortical activation in the peri-sylvian and frontal regions that was dependent on the complexity and context of the stimuli. 3. Scalp recordings in children who had undergone hemispherectomy provided a model of the scalp distribution of AERPs arising from one hemisphere and a comparison to the intracranial recordings. Significant differences in AERP components to pure tones and syllables suggested optimal processing by the intact left hemisphere. 4. Recordings in awake children with benign rolandic epilepsy show an alteration in the topography of the P85-120 component of the AERP contralateral to the hemisphere generating spikes during sleep. As there is no structural lesion these findings suggest long term effects of epileptic spikes. 5. In a previously poorly described group of children with normal peripheral hearing who have difficulties in challenging acoustic environments, the AERPs were sensitive to deficits in a behavioural test of central auditory processing. Other findings included the increase in latencies of AERP components with more complex stimuli and differing morphology/topography of the obligatory and mismatch components both to each other and between adults and children

Augmentation of Brain Function: Facts, Fiction and Controversy. Volume III: From Clinical Applications to Ethical Issues and Futuristic Ideas

The final volume in this tripartite series on Brain Augmentation is entitled “From Clinical Applications to Ethical Issues and Futuristic Ideas”. Many of the articles within this volume deal with translational efforts taking the results of experiments on laboratory animals and applying them to humans. In many cases, these interventions are intended to help people with disabilities in such a way so as to either restore or extend brain function. Traditionally, therapies in brain augmentation have included electrical and pharmacological techniques. In contrast, some of the techniques discussed in this volume add specificity by targeting select neural populations. This approach opens the door to where and how to promote the best interventions. Along the way, results have empowered the medical profession by expanding their understanding of brain function. Articles in this volume relate novel clinical solutions for a host of neurological and psychiatric conditions such as stroke, Parkinson’s disease, Huntington’s disease, epilepsy, dementia, Alzheimer’s disease, autism spectrum disorders (ASD), traumatic brain injury, and disorders of consciousness. In disease, symptoms and signs denote a departure from normal function. Brain augmentation has now been used to target both the core symptoms that provide specificity in the diagnosis of a disease, as well as other constitutional symptoms that may greatly handicap the individual. The volume provides a report on the use of repetitive transcranial magnetic stimulation (rTMS) in ASD with reported improvements of core deficits (i.e., executive functions). TMS in this regard departs from the present-day trend towards symptomatic treatment that leaves unaltered the root cause of the condition. In diseases, such as schizophrenia, brain augmentation approaches hold promise to avoid lengthy pharmacological interventions that are usually riddled with side effects or those with limiting returns as in the case of Parkinson’s disease. Brain stimulation can also be used to treat auditory verbal hallucination, visuospatial (hemispatial) neglect, and pain in patients suffering from multiple sclerosis. The brain acts as a telecommunication transceiver wherein different bandwidth of frequencies (brainwave oscillations) transmit information. Their baseline levels correlate with certain behavioral states. The proper integration of brain oscillations provides for the phenomenon of binding and central coherence. Brain augmentation may foster the normalization of brain oscillations in nervous system disorders. These techniques hold the promise of being applied remotely (under the supervision of medical personnel), thus overcoming the obstacle of travel in order to obtain healthcare. At present, traditional thinking would argue the possibility of synergism among different modalities of brain augmentation as a way of increasing their overall effectiveness and improving therapeutic selectivity. Thinking outside of the box would also provide for the implementation of brain-to-brain interfaces where techniques, proper to artificial intelligence, could allow us to surpass the limits of natural selection or enable communications between several individual brains sharing memories, or even a global brain capable of self-organization. Not all brains are created equal. Brain stimulation studies suggest large individual variability in response that may affect overall recovery/treatment, or modify desired effects of a given intervention. The subject’s age, gender, hormonal levels may affect an individual’s cortical excitability. In addition, this volume discusses the role of social interactions in the operations of augmenting technologies. Finally, augmenting methods could be applied to modulate consciousness, even though its neural mechanisms are poorly understood. Finally, this volume should be taken as a debate on social, moral and ethical issues on neurotechnologies. Brain enhancement may transform the individual into someone or something else. These techniques bypass the usual routes of accommodation to environmental exigencies that exalted our personal fortitude: learning, exercising, and diet. This will allow humans to preselect desired characteristics and realize consequent rewards without having to overcome adversity through more laborious means. The concern is that humans may be playing God, and the possibility of an expanding gap in social equity where brain enhancements may be selectively available to the wealthier individuals. These issues are discussed by a number of articles in this volume. Also discussed are the relationship between the diminishment and enhancement following the application of brain-augmenting technologies, the problem of “mind control” with BMI technologies, free will the duty to use cognitive enhancers in high-responsibility professions, determining the population of people in need of brain enhancement, informed public policy, cognitive biases, and the hype caused by the development of brain- augmenting approaches

ℛSCZ: A Riemannian schizophrenia diagnosis framework based on the multiplexity of EEG-based dynamic functional connectivity patterns

Abnormal electrophysiological (EEG) activity has been largely reported in schizophrenia (SCZ). In the last decade, research has focused to the automatic diagnosis of SCZ via the investigation of an EEG aberrant activity and connectivity linked to this mental disorder. These studies followed various preprocessing steps of EEG activity focusing on frequency-dependent functional connectivity brain network (FCBN) construction disregarding the topological dependency among edges. FCBN belongs to a family of symmetric positive definite (SPD) matrices forming the Riemannian manifold. Due to its unique geometric properties, the whole analysis of FCBN can be performed on the Riemannian geometry of the SPD space. The advantage of the analysis of FCBN on the SPD space is that it takes into account all the pairwise interdependencies as a whole. However, only a few studies have adopted a FCBN analysis on the SPD manifold, while no study exists on the analysis of dynamic FCBN (dFCBN) tailored to SCZ. In the present study, I analyzed two open EEG-SCZ datasets under a Riemannian geometry of SPD matrices for the dFCBN analysis proposing also a multiplexity index that quantifies the associations of multi-frequency brainwave patterns. I adopted a machine learning procedure employing a leave-one-subject-out cross-validation (LOSO-CV) using snapshots of dFCBN from (N-1) subjects to train a battery of classifiers. Each classifier operated in the inter-subject dFCBN distances of sample covariance matrices (SCMs) following a rhythm-dependent decision and a multiplex-dependent one. The proposed ℛ SCZ decoder supported both the Riemannian geometry of SPD and the multiplexity index DC reaching an absolute accuracy (100 %) in both datasets in the virtual default mode network (DMN) source space

Electrophysiological and Neuropsychological Measures in Patients with Schizophrenia and their Unaffected Biological Siblings: A Family study

BACKGROUND: Various neuropsychological domains and P300 auditory event related potentials exhibit abnormalities in patients with schizophrenia and their first-degree relatives. The aim of the study is to compare the cognitive and P300 measurements in patients with schizophrenia, their unaffected biological siblings and normal controls. Also, to find the correlation between the clinical variables in patients with schizophrenia and P300 event related potentials and neuropsychological test. METHODS: 30 patients with paranoid schizophrenia according to ICD-10, 30 unaffected biological siblings of patients with schizophrenia and 30 normal controls were able to complete all neuropsychological test and P300 event related potential assessments. All participants were administered SCAN and the patients were also evaluated regarding the symptom severity. RESULTS: Both patients with schizophrenia and the unaffected biological siblings of patients with schizophrenia showed lower P300 amplitude and longer P300 latency when compared with the normal controls. When compared between them, patient and sibling groups showed a statistical difference in P300 event related potentials. The three groups showed statistically significant differences in Digit vigilance test, Visual 2-back test, Controlled oral word association test, Animal names test and Stroop test. PANSS total score and psychopathology scores were having a statistically significant correlation with the P300 event related potential and neuropsychological tests. CONCLUSION: The patients with schizophrenia and the unaffected biological siblings of patients with schizophrenia showed abnormalities in P300 event related potentials and neuropsychological test. These tests were also correlated well with the illness characteristics of patients with schizophrenia

Functional network analyses and dynamical modeling of proprioceptive updating of the body schema

Proprioception is an ability to perceive the position and speed of body parts that is important for construction of the body schema in the brain. Proper updating of the body schema is necessary for appropriate voluntary movement. However, the mechanisms mediating such an updating are not well understood. To study these mechanisms when the body part was at rest, electroencephalography (EEG) and evoked potentials studies were employed, and when the body was in motion, kinematic studies were performed. An experimental approach to elicit proprioceptive P300 evoked potentials was developed providing evidence that processing of novel passive movements is similar to processing of novel visual and auditory stimuli. The latencies of the proprioceptive P300 potentials were found to be greater than those elicited by auditory, but not different from those elicited by the visual stimuli. The features of the functional networks that generated the P300s were analyzed for each modality. Cross-correlation networks showed both common features, e.g. connections between frontal and parietal areas, and the stimulus-specific features, e.g. increases of the connectivity for temporal electrodes in the visual and auditory networks, but not in the proprioceptive ones. The magnitude of coherency networks showed a reduction in alpha band connectivity for most of the electrodes groupings for all stimuli modalities, but did not demonstrate modality-specific features. Kinematic study compared performances of 19 models previously proposed in the literature for movements at the shoulder and elbow joints in terms of their ability to reconstruct the speed profiles of the wrist pointing movements. It was found that lognormal and beta function models are most suitable for wrist speed profile modeling. In addition, an investigation of the blinking rates during the P300 potentials recordings revealed significantly lower rates in left-handed participants, compared to the right-handed ones. Future work will include expanding the experimental and analytical methodologies to different kinds of proprioceptive stimuli (displacements and speeds) and experimental paradigms (error-related negativity potentials), and comparing the models of the speed profiles produced by the feet to those of the wrists, as well as replicating the observations made on the blinking rates in a larger scale study