Electroencephalographic activities during reading tasks in young adults : separate measures for localized and widespread brain functions

Based on these reports, we expected to find: 1) a frontal increase in 4-8 Hz amplitude during reading tasks as compared with a resting baseline, as affected by working memory mechanisms; 2) a bilateral decrease of 8-10 Hz (as compared with baseline) as affected by arousal and attentional processes; 3) a unilateral decrease of 8-12 Hz in the left hemisphere due to cognitive effort, as affected by the symbolic and analytic decoding nature of reading to which this latter band would selectively react; and 4)an increase of the 38-42 Hz activity, as affected by scanning and problem solving functions of reading. No prediction was made for the 0.5-4 Hz,12-21 Hz, and 21-32 Hz bands

Peak Alpha Frequency: an Electroencephalographic Measure of Cognitive Preparedness

Background. Electroencephalographic (EEG) peak alpha frequency (PAF) has been shown to correlate with a variety of phenomena, including age, memory performance in healthy and demented individuals, different emotional states, schizophrenia, anxiety, recovery from stroke, cerebral blood flow (CBF) velocity, brain oxygenation, as well as acute administration of stimulant and nootropic substances. These studies have shown that PAF varies between healthy and clinical individuals, with the latter consistently having lower PAF. Moreover, PAF varies between healthy individuals, reflecting cognitive performance, with better performance being associated with increased PAF. Finally, PAF varies within individuals both between developmental stages and between different cognitive tasks, or physiological states induced by administration of various substances. The present study suggests that among other phenomena PAF reflects a trait or state of cognitive preparedness, using three independent datasets from healthy and brain injured individuals. Based on the preceding literature, the following hypotheses were generated. First, that PAF is an index of optimal brain function, being suppressed under traumatic brain injury (TBI). Second, that PAF is negatively correlated with time since TBI, and that it is increased after cognitive rehabilitation of individuals with TBI. Third, that PAF shows cognitive preparedness within individuals, reflecting task performance differences at different days. Fourth, that PAF is increased after tasks more in those individuals who had it lower at initial baseline, being affected by the task that forces them to correct their initial unpreparedness. Method. Dataset A involved EEG recordings from 15 healthy young adults before, during, and after a set of reading tasks (task duration 5-20 minutes) . Dataset B involved EEG recordings from 10 individuals with TBI and 12 healthy age and sex matched controls, before, during, and after tasks of visual and auditory attention (task duration 20 minutes) (Captain\u27s Log, Braintrain). Dataset C involved EEG recordings from 19 healthy young adults before and after a 3-minute working memory task (WAIS-R Digit Span). In this dataset, the procedure has been repeated in two different days, so within individual differences in PAF and performance could be measured. EEG was recorded at 19 scalp electrodes using the 10/20 international electrode placement system. Average PAF for each recording was reported using the EEG Workstation 2.0 software (NovatechEEG, inc.). Results. PAF showed significantly lower values in individuals with TBI as compared to matched healthy controls during a post-task eyes-open baseline. PAF recorded at day 1 was significantly correlated with Digit Span performance of the same day but not with Digit Span performance of day 2. Likewise, PAF recorded at day 2 was significantly correlated with Digit Span performance of the same day but not with Digit Span performance of day 1. Moreover, PAF was significantly increased after Digit Span for those participants who had it below the sample median before the task, whereas it did not increase significantly for those who had it above the sample median. However, this was not replicated with PAF before and after reading tasks. Finally, PAF was not found to be significantly correlated to time since TBI, and it did not increase significantly after cognitive rehabilitation of individuals with TBI. Conclusions. As expected, individuals with brain injury had lower PAF from healthy controls, confirming the consistent direction of PAF differences between normal brain function and pathology, as is the case with other neurological or psychiatric syndromes, including stroke, dementia, and schizophrenia. Interestingly, these differences between individuals with TBI and non-clinical controls were mostly prominent during a baseline that followed a set of cognitive tasks, resembling other physiological indices that require stressing the organ to be assessed (e.g. electrocardiogram). In addition to its sensitivity to gross brain pathology, PAF was found to be particularly sensitive to brain states within individuals during different days. PAF significantly predicted cognitive performance on a working memory task that was performed immediately after EEG recording, whereas it did not predict performance within a few days. In addition to predict performance, PAF was found to be affected by a working memory task, extending previous research and supporting a strong dual relationship between PAF and cognitive performance. The nature and duration of this state of relationship, however, needs further investigation. Although a short working memory task increased PAF in individuals who had it lower immediately before the task, a longer set of reading tasks failed to replicate this phenomenon. It is suggested that EEG normative databases include PAF into their statistical reports and that neurofeedback protocols to increase PAF are attempted to improve cognitive performance in both clinical and non-clinical populations

EEG neurofeedback: a brief overview and an example of peak alpha frequency training for cognitive enhancement in the elderly

Clinical Neuropsychologist, 21(1): pp. 110-129.Neurofeedback (NF) is an electroencephalographic (EEG) biofeedback technique for training individuals to alter their brain activity via operant conditioning. Research has shown that NF helps reduce symptoms of several neurological and psychiatric disorders, with ongoing research currently investigating applications to other disorders and to the enhancement of non-disordered cognition. The present article briefly reviews the fundamentals and current status of NF therapy and research and illustrates the basic approach with an interim report on a pilot study aimed at developing a new NF protocol for improving cognitive function in the elderly. EEG peak alpha frequency (PAF) has been shown to correlate positively with cognitive performance and to correlate negatively with age after childhood. The present pilot study used a double-blind controlled design to investigate whether training older individuals to increase PAF would result in improved cognitive performance. The results suggested that PAF NF improved cognitive processing speed and executive function, but that it had no clear effect on memory. In sum, the results suggest that the PAF NF protocol is a promising technique for improving selected cognitive functions

Predicting Long-Term Recovery of Consciousness in Prolonged Disorders of Consciousness Based on Coma Recovery Scale-Revised Subscores: Validation of a Machine Learning-Based Prognostic Index.

peer reviewedPrognosis of prolonged Disorders of Consciousness (pDoC) is influenced by patients' clinical diagnosis and Coma Recovery Scale-Revised (CRS-R) total score. We compared the prognostic accuracy of a novel Consciousness Domain Index (CDI) with that of clinical diagnosis and CRS-R total score, for recovery of full consciousness at 6-, 12-, and 24-months post-injury. The CDI was obtained by a combination of the six CRS-R subscales via an unsupervised machine learning technique. We retrospectively analyzed data on 143 patients with pDoC (75 in Minimally Conscious State; 102 males; median age = 53 years; IQR = 35; time post-injury = 1-3 months) due to different etiologies enrolled in an International Brain Injury Association Disorders of Consciousness Special Interest Group (IBIA DoC-SIG) multicenter longitudinal study. Univariate and multivariate analyses were utilized to assess the association between outcomes and the CDI, compared to clinical diagnosis and CRS-R. The CDI, the clinical diagnosis, and the CRS-R total score were significantly associated with a good outcome at 6, 12 and 24 months. The CDI showed the highest univariate prediction accuracy and sensitivity, and regression models including the CDI provided the highest values of explained variance. A combined scoring system of the CRS-R subscales by unsupervised machine learning may improve clinical ability to predict recovery of consciousness in patients with pDoC

Risk factors for 2-year mortality in patients with prolonged disorders of consciousness: An international multicentre study.

peer reviewedBACKGROUND AND PURPOSE: Patients with prolonged disorders of consciousness (pDoC) have a high mortality rate due to medical complications. Because an accurate prognosis is essential for decision-making on patients' management, we analysed data from an international multicentre prospective cohort study to evaluate 2-year mortality rate and bedside predictors of mortality. METHODS: We enrolled adult patients in prolonged vegetative state/unresponsive wakefulness syndrome (VS/UWS) or minimally conscious state (MCS) after traumatic and nontraumatic brain injury within 3 months postinjury. At enrolment, we collected demographic (age, sex), anamnestic (aetiology, time postinjury), clinical (Coma Recovery Scale-Revised [CRS-R], Disability Rating Scale, Nociception Coma Scale-Revised), and neurophysiologic (electroencephalogram [EEG], somatosensory evoked and event-related potentials) data. Patients were followed up to gather data on mortality up to 24 months postinjury. RESULTS: Among 143 traumatic (n = 55) and nontraumatic (n = 88) patients (VS/UWS, n = 68, 19 females; MCS, n = 75, 22 females), 41 (28.7%) died within 24 months postinjury. Mortality rate was higher in VS/UWS (42.6%) than in MCS (16%; p < 0.001). Multivariate regression in VS/UWS showed that significant predictors of mortality were older age and lower CRS-R total score, whereas in MCS female sex and absence of alpha rhythm on EEG at study entry were significant predictors. CONCLUSIONS: This study demonstrated that a feasible multimodal assessment in the postacute phase can help clinicians to identify patients with pDoC at higher risk of mortality within 24 months after brain injury. This evidence can help clinicians and patients' families to navigate the complex clinical decision-making process and promote an international standardization of prognostic procedures for patients with pDoC

Multicenter prospective study on predictors of short-term outcome in disorders of consciousness

peer reviewe

Remission of drug-resistant epileptic psychosis following left selective amygdalohippocampectomy

We describe two female patients with drug-resistant mesial temporal lobe epilepsy and chronic drug-resistant psychosis. In both patients, MRI scans revealed left mesial temporal sclerosis. After clinical assessment, ictal video/EEG monitoring, and a neuropsychological evaluation including Wada testing, the patients underwent selective left amygdalohippocampectomy. Since the operation, the two patients have remained free of seizures for 17 and 15 months. During the same period, both patients have sustained a full remission of the psychosis. (C) 2008 Elsevier Inc. All rights reserved