Human cortical traveling waves: dynamical properties and correlations with responses.

The spatiotemporal behavior of human EEG oscillations is investigated. Traveling waves in the alpha and theta ranges are found to be common in both prestimulus and poststimulus EEG activity. The dynamical properties of these waves, including their speeds, directions, and durations, are systematically characterized for the first time, and the results show that there are significant changes of prestimulus spontaneous waves in the presence of an external stimulus.

Thalamocortical changes in major depression probed by deconvolution and physiology-based modeling.

Auditory event-related potentials (ERPs) have been extensively studied in patients with depression, but most studies have focused on purely phenomenological analysis methods, such as component scoring. In contrast, this study applies two recently developed physiology-based methods-fitting using a thalamocortical model of neuronal activity and waveform deconvolution - to data from a selective-attention task in four subject groups (49 patients with melancholic depression, 34 patients with non-melancholic depression, 111 participants with subclinical depressed mood, and 98 healthy controls), to yield insight into physiological differences in attentional processing between participants with major depression and controls. This approach found evidence that: participants with depressed mood, regardless of clinical status, shift from excitation in the thalamocortical system towards inhibition; that clinically depressed participants have decreased relative response amplitude between target and standard waveforms; and that patients with melancholic depression also have increased thalamocortical delays.

Age trends in auditory oddball evoked potentials via component scoring and deconvolution.

Objective: This study examines developmental and aging trends in auditory evoked potentials (AEPs) by applying two analysis methods to a large database of healthy subjects.

Methods: AEPs and reaction times were recorded from 1498 healthy subjects aged 6-86 years using an auditory oddball paradigm. AEPs were analyzed using a recently published deconvolution method and conventional component scoring.

Deconvolution analysis of target evoked potentials.

This paper demonstrates a method for analyzing target evoked potentials in an auditory oddball task, using Wiener deconvolution to separate the brain's task-dependent properties from its task-invariant response. It is shown that a target response can be deconvolved, and the result contains two delta-like peaks separated by approximately 100 ms, implying that targets resemble a superposition of two standard responses. The latencies and areas of these delta-like peaks give quantitative measures of the evoked potential, providing a method of analysis that is simpler and more physiologically meaningful than peak scoring.

Variability of model-free and model-based quantitative measures of EEG.

Variable contributions of state and trait to the electroencephalographic (EEG) signal affect the stability over time of EEG measures, quite apart from other experimental uncertainties. The extent of intraindividual and interindividual variability is an important factor in determining the statistical, and hence possibly clinical significance of observed differences in the EEG. This study investigates the changes in classical quantitative EEG (qEEG) measures, as well as of parameters obtained by fitting frequency spectra to an existing continuum model of brain electrical activity.

Longitudinal changes in neuroanatomy and neural activity in early schizophrenia.

Although there is substantial evidence indicating that patients with first-episode schizophrenia exhibit both anatomical and electrophysiological abnormalities, there has been little research investigating the relationship between these two indices. We acquired structural magnetic resonance images and resting electroencephalographic recordings from 19 patients with schizophrenia, both at the time of their first presentation to mental health services and 2-3 years subsequently. Patients' grey matter images were parcellated into four brain lobes, and slow-wave, alpha- and beta-electroencephalographic power was calculated in four corresponding cortical regions.

Mode of functional connectivity in amygdala pathways dissociates level of awareness for signals of fear.

Many of the same regions of the human brain are activated during conscious attention to signals of fear and in the absence of awareness for these signals. The neural mechanisms that dissociate level of awareness from activation in these regions remain unknown. Using functional magnetic resonance imaging with connectivity analysis in healthy human subjects, we demonstrate that level of awareness for signals of fear depends on mode of functional connectivity in amygdala pathways rather than discrete patterns of activation in these pathways.

Brain maturation in adolescence: concurrent changes in neuroanatomy and neurophysiology.

Adolescence to early adulthood is a period of dramatic transformation in the healthy human brain. However, the relationship between the concurrent structural and functional changes remains unclear. We investigated the impact of age on both neuroanatomy and neurophysiology in the same healthy subjects (n = 138) aged 10 to 30 years using magnetic resonance imaging (MRI) and resting electroencephalography (EEG) recordings.

Neurophysiologically-based mean-field modelling of tonic cortical activity in post-traumatic stress disorder (PTSD), schizophrenia, first episode schizophrenia and attention deficit hyperactivity disorder (ADHD).

A recently developed quantitative model of cortical activity is used that permits data comparison with experiment using a quantitative and standardized means. The model incorporates properties of neurophysiology including axonal transmission delays, synaptodendritic rates, range-dependent connectivities, excitatory and inhibitory neural populations, and intrathalamic, intracortical, corticocortical and corticothalamic pathways. This study tests the ability of the model to determine unique physiological properties in a number of different data sets varying in mean age and pathology.

Estimation of neurophysiological parameters from the waking EEG using a biophysical model of brain dynamics.

This paper presents the results from using electroencephalographic (EEG) data to estimate the values of key neurophysiological parameters using a detailed biophysical model of brain activity. The model incorporates spatial and temporal aspects of cortical function including axonal transmission delays, synapto-dendritic rates, range-dependent connectivities, excitatory and inhibitory neural populations, and intrathalamic, intracortical, corticocortical and corticothalamic pathways. Parameter estimates were obtained by fitting the model's theoretical spectrum to EEG spectra from each of 100 healthy human subjects.