Symmetric temporal patterns in cortical spike trains during performance of a short-term memory task

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.

Variability in neuronal activity in primate cortex during working memory tasks

Persistent elevated neuronal activity has been identified as the neuronal correlate of working memory. It is generally assumed in the literature and in computational and theoretical models of working memory that memory-cell activity is stable and replicable; however, this assumption may be an artifact of the averaging of data collected across trials, and needs experimental verification. In this study, we introduce a classification scheme to characterize the firing frequency trends of cells recorded from the cortex of monkeys during performance of working memory tasks. We examine the frequency statistics and variability of firing during baseline and memory periods. We also study the behavior of cells on individual trials and across trials, and explore the stability of cellular firing during the memory period. We find that cells from different firing-trend classes possess markedly different statistics. We also find that individual cells show substantial variability in their firing behavior across trials, and that firing frequency also varies markedly over the course of a single trial. Finally, the average frequency distribution is wider, the magnitude of the frequency increases from baseline to memory smaller, and the magnitude of frequency decreases larger than is generally assumed. These results may serve as a guide in the evaluation of current theories of the cortical mechanisms of working memory.

Patterned firing of parietal cells in a haptic working memory task

Abstract Cells in the somatosensory cortex of the monkey are known to exhibit sustained elevations of firing frequency during the short-term mnemonic retention of tactile information in a haptic delay task. In this study, we examine the possibility that those firing elevations are accompanied by changes in firing pattern. Patterns are identified by the application of a pattern-searching algorithm to the interspike intervals of spike trains. By sequential use of sets of pattern templates with a range of temporal resolutions, we find patterned activity in the majority of the cells investigated. In general, the degree of patterning significantly increases during active memory. Surrogate analysis suggests that the observed patterns may not be simple linear stochastic functions of instantaneous or average firing frequency. Therefore, during the active retention of a memorandum, the activity of a 'memory cell' may be characterized not only by changes in frequency but also by changes in pattern.

Innate spatial-temporal reasoning and the identification of genius

The teaching of mathematics is invariably language-based, but spatial-temporal (ST) reasoning (making a mental image and thinking ahead in space and time) is crucial to the understanding of math. Here we report that Big Seed, a demanding ST video game, based upon the mathematics of knot theory and previously applied to understanding DNA structure and function, can be used to reveal innate ST reasoning. Big Seed studies with middle and elementary school children provide strong evidence that ST reasoning ability is not only innate but far exceeds optimistic expectations based on age, the percentage of children achieving exceptional ST performance in less than 7 h of training, and retention of ability. A third grader has been identified as a genius (functionally defined) in ST performance. Big Seed may be used for training and assessing 'creativity' (functionally defined) and ST reasoning as well as discovering genius.

The Mozart Effect

This review deals with the Mozart Effect, an improvement of performance while listening to Mozart music. Previous studies have shown improved spatial temporal reasoning and improved IQ test results and neurophysiological changes, mainly increased coherence among different groups of subjects. This review emphasizes the effect on epileptiform patterns, both generalized and focal; provides an example of a chronic effect over a period of 1-2 days; addresses the distinctive aspects of the music to account for this phenomenon and shows that long-term periodicity in the power of the music is a special quality; and deals with the melodic line and shows that Mozart repeats the melodic line much more frequently than other well-known composers. It is likely that the superorganization of the cerebral cortex resonates with great organization found in Mozart music.

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.

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

Theoretical models of higher cognitive function predict that cortical activity will exhibit families of spatial-temporal patterns of activity whose individual members are related to each other by specific symmetry transformations. In the trion model, it is suggested that these inherent symmetries play a vital role in how we think and reason. We have developed a method of analysis (SYMMETRIC analysis), which detects families of patterns in EEG data, and characterizes the symmetry relationships between members of those pattern families. Using this analysis, significant symmetry families have been found in EEG and single unit spike train data. If symmetry is a crucial aspect of brain function, it is possible that different pathologies are associated with specific types of symmetry relationships in brain activity that could be detected in EEG data by a SYMMETRIC analysis.

High-frequency transitions in cortical spike trains related to short-term memory

Single-unit spike trains recorded from parietal cortex of monkeys performing a tactile short-term memory task show characteristic fluctuations (transitions) in their firing frequency that are related to memory. Spike trains recorded during the memory period, when the animal must retain information for the short term, show a higher rate of such transitions than spike trains recorded during intertrial baseline periods. In the present study, an analysis of multiple temporal resolutions over which these transitions are observed reveals that the memory-related transitions occur most prominently in the 25-50 Hz range. The results of this study suggest that, in the monkey, high frequency fluctuations of neuronal discharge in the parietal cortex are correlated with haptic short-term memory. The presence of such fluctuations are also consistent with theoretical models of short-term memory.

The "Mozart effect" on epileptiform activity

The "Mozart Effect," using the Piano Sonata in D Major (K.448), was examined in patients with seizures. In 23 of 29 instances significant decreases in epileptiform activity were noted from patients even in coma, with status epilepticus or with periodic lateralized epileptiform discharges (PLEDs). The effect may be immediate or require 40-300 sec to manifest itself. The change in the amount of ictal activity in one patient in coma was from 62% before the music to 21% during Mozart. Amplitudes of these discharges also have often decreased. Examples of PLEDs on both temporal areas are shown in which the effect was only on the left temporal area but in other patients only on the right temporal area. Brain maps during the music showed theta and alpha activity decreased on the central areas, while delta waves increased on the frontal midline area. The basis of this effect is likely that the superorganization of the cerebral cortex with its highly structured radial columns seen throughout both hemispheres may resonate with the superior architecture of Mozart's music.

Key components of the Mozart effect

The results of studies intended to replicate the enhancement of spatial-temporal reasoning following exposure to 10 min. of Mozart's Sonata for Two Pianos in D Major (K.448) have been varied. While some studies have replicated the effect, others have not. We suggest that researchers' diverse choice of dependent measures may account for these varied results. This paper provides a neurophysiological context for the enhancement and considers theoretical and experimental factors, including the choice of dependent measures, the presentation order of the conditions, the selection of the musical composition, and the inclusion of a distractor task, that may contribute to the various findings. More work is needed before practical applications can be derived.