Detecting symmetric patterns in EEG data: a new method of analysis

Mapping brain injury with symmetrical-channels' EEG signal analysis--a pilot study

A technique for detecting brain injury at the bedside has great clinical value, but conventional imaging techniques (such as computed tomography [CT] and magnetic resonance imaging) are impractical. In this study, a novel method–the symmetrical channel electroencephalogram (EEG) signal analysis–was developed for this purpose. The study population consisted of 45 traumatic brain injury patients and 10 healthy controls. EEG signals in resting and stimulus states were acquired, and approximate entropy (ApEn) and slow-wave coefficient were extracted to calculate the ratio values of ApEn and SWC for injured and uninjured areas. Statistical analyses showed that the ratio values for both ApEn and SWC between injured and uninjured brain areas differed significantly (P < 0.05) for both resting and name call stimulus states. A set of criteria (range of ratio values) to determine whether a brain area is injured or uninjured was proposed and its reliability was verified by statistical analyses and CT images.

The acute effect of music on interictal epileptiform discharges

This study was a prospective, randomized, single-blinded, crossover, placebo-controlled, pilot clinical trial investigating the effect of Mozart's Sonata for Two Pianos (K448) on the frequency of interictal epileptiform discharges (IEDs) from the EEGs of children with benign childhood epilepsy with centrotemporal spikes, or "rolandic" epilepsy. The goal was to demonstrate decreased frequency of IEDs with exposure to K448. Four subjects were recruited and 4-hour awake EEG recordings performed. IED frequency per minute was averaged over each of three epochs per hour. Mean IED count per epoch, standard deviations, and variance were calculated. Only complete waking epochs were analyzed. Two subjects demonstrated sufficient waking IEDs for statistical analysis, consisting of three epochs of K448-related effects. Significant decreases in IEDs per minute (33.7, 50.6, and 33.9%) were demonstrated comparing baseline with exposure to K448, but not to control music (Beethoven's Für Elise).

Symmetry reversal in schizophrenia

Schizophrenia is associated with cortical asymmetries concentrated in the left fronto-temporal hemisphere. In order to look for functional asymmetries between the two hemispheres, the stimulus-response times of patients were split into smaller periods and the interhemispheric and intrahemispheric correlations between these periods were investigated. Three groups were compared to each other: 22 patients with schizophrenia (Diagnostic and Statistical Manual of Mental Disorders, 4th edn; DSM-IV) treated with neuroleptics; 24 psychiatric neuroleptic-treated patients without schizophrenia; and 30 healthy subjects. All subjects were investigated by simple (one stimulus-one response) and complex (two stimuli-two responses), auditory and visual, right-hemispheric and left-hemispheric stimulus-response tasks. There were no intrahemispheric but significant interhemispheric correlations between the two auditory and between the two visual time fragments in both the healthy and the neuroleptic control group. In contrast there was a significant intrahemispheric correlation between the auditory and visual time fragment in the left hemisphere of patients with schizophrenia and no interhemispheric correlation between the auditory times. The reduction of the interhemispheric auditory correlation is interpreted as an auditory disintegration, the appearance of the left-hemispheric audiovisual correlation as an audiovisual 'hyperintegration' in patients with schizophrenia. It is questionable as to whether these findings are due to schizophrenia or to the neuroleptic treatment.

Music enhances spatial-temporal reasoning: towards a neurophysiological basis using EEG

Motivated by predictions from the structured trion model of the cortex, based on Mountcastle's columnar organizational principle, behavioral experiments have demonstrated a causal short-term enhancement of spatial-temporal reasoning in college students following listening to a Mozart Sonata (K.448) but not in control conditions. An EEG coherence study reported presence of right frontal and left temporoparietal activity induced by listening to the Mozart Sonata, which carried over into the spatial-temporal tasks in three of the seven subjects. In this paper, we present further predictions from the trion model and discuss how the new SYMMETRIC analysis method can be used in EEG recordings to help determine the neurophysiological basis of specific music enhancing spatial-temporal reasoning. We conclude with potential clinical applications of major significance.