The Integrative Action of the Nervous System.

Freeman, Frank N.; Sherrington, Sir

doi:10.2307/2010953

Cited by 140 publications

(284 citation statements)

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“…A1.03, B. The Hilbert transform (Appendix 1.3) of v j (t) gave an estimate of the output, v' j (t), of the inhibitory neurons in the feedback limb of the negative feedback loop, which maintained an oscillation at the same frequency but with approximately a quarter cycle lag behind the output of the excitatory neurons (Freeman, 1975(Freeman, , 2000. The spatial ensemble average, v'(t), is shown by the red curve in Fig.…”

Section: Derivation Of Analytic Amplitude and Phasementioning

confidence: 99%

“…The coordinated activity manifests a "wave packet" (Freeman, 1975(Freeman, , 2003c) that requires synchronization of a shared carrier wave of the outputs of a large number of neurons over the area. The wave packet has a spatial AM pattern that is expressed in high and low intensities of the dendritic currents that determine the firing rates of the interacting neurons.…”

Section: A Hypothesis On Cortical Function Based In Background Activitymentioning

confidence: 99%

“…The oscillations in dendritic current group the action potentials near peaks in the beta and gamma ranges. The oscillations arise from negative feedback interactions among excitatory and inhibitory neurons densely in local neighborhoods (Freeman, 1975). Long axons of excitatory neurons with high conduction velocities support synchronization over large areas of cortex (Freeman, 2003b), creating small-world effects (Watts and Strogatz, 1998;Wang and Chen, 2003) in analogy to the rapid dissemination of information through social contacts.…”

Section: A Hypothesis On Cortical Function Based In Background Activitymentioning

confidence: 99%

“…The regulation has been modeled as a point attractor in a nonlinear system (Freeman, 1975). In the absence of input, which can be blocked by surgical intervention (Burns, 1958;Becker and Freeman, 1968;Gray and Skinner, 1988), activity in the stable state resembles noise in lacking emergent spatiotemporal structure and can be described as symmetric.…”

Section: A Hypothesis On Cortical Function Based In Background Activitymentioning

confidence: 99%

“…The same currents are largely responsible for local field potentials and EEG. The firing is grouped in time by oscillations in dendritic current in the beta (12-30 Hz) and gamma (30-80 Hz) ranges that arise from negative feedback among excitatory and inhibitory neurons (Freeman, 1975(Freeman, , 2004; Appendix 2.4 in Part 2) with facilitation by the molecular dynamics of synaptic receptors (Traub et al, 1996;Whittington et al, 2000;Kopell et al, 2000). The synchrony between pairs of EEG records can be measured by any of a variety of methods (Lachaux et al, 1999;Le Van Quyen et al, 2001;Quiroga et al, 2002), including the phase difference of oscillations in which they share the same frequency.…”

Section: Introductionmentioning

confidence: 99%

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Origin, structure, and role of background EEG activity. Part 1. Analytic amplitude

Freeman

2004

Clinical Neurophysiology

230

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Objective: To explain the neural mechanisms of spontaneous EEG by measuring the spatiotemporal patterns of synchrony among beta-gamma oscillations during perception. Methods: EEGs were measured from 8x8 (5.6x5.6 mm) arrays fixed on the surfaces of primary sensory areas in rabbits that were trained to discriminate visual, auditory or tactile conditioned stimuli (CSs) eliciting conditioned responses (CRs). EEG preprocessing was by (i) band pass filtering to extract the beta-gamma range (deleting theta-alpha); (ii) low-pass spatial filtering (not high-pass Laplacians used for localization), (iii) spatial averaging (not time averaging used for evoked potentials), and (iv) close spacing of 64 electrodes for simultaneous recording in each area (not sampling single signals from several areas); (v) novel algorithms were devised to measure synchrony and spatial pattern stability by calculating variances among patterns in 64-space derived from the 8x8 arrays (not by fitting equivalent dipoles). These methodological differences are crucial for the proposed new perspective on EEG. Results: Spatial patterns of beta-gamma EEG emerged following sudden jumps in cortical activity called "state transitions". Each transition began with an abrupt phase re-setting to a new value on every channel, followed sequentially by re-synchronization, spatial pattern stabilization, and a dramatic increase in pattern amplitude. State transitions recurred at varying intervals in the theta range. A novel parameter was devised to estimate the perceptual information in the betagamma EEG, which disclosed 2 to 4 patterns with high information content in the CS-CR interval on each trial; each began with a state transition and lasted ~.1 s. Conclusions:The function of each primary sensory neocortex was discontinuous; discrete spatial patterns occurred in frames like those in cinema. The frames before and after the CS-CR interval had low content. Significance: Derivation and interpretation of unit data in studies of perception might benefit from using multichannel EEG recordings to define distinctive epochs that are demarcated by state transitions of neocortical dynamics in the CS-CR intervals, particularly in consideration of the possibility that EEG may reveal recurring episodes of exchange and sharing of perceptual information among multiple sensory cortices. Simultaneously recorded, multichannel betagamma EEG might assist in the interpretation of images derived by fMRI, since high betagamma EEG amplitudes imply high rates of energy utilization. The spatial pattern intermittency provides a tag to distinguish gamma bursts from contaminating EMG activity in scalp recording in order to establish beta-gamma recording as a standard clinical tool. Finally, EEG cannot fail to have a major impact on brain theory.Background EEG analytic amplitude 3Walter J Freeman http://sulcus.berkeley.edu/wjf/EG_EEGPart1AnalyticAmplitude.pdf Cover Figure Legend:The EEG shows that neocortex processes information in frames like a cinema. The perceptual content is foun...

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Section: Derivation Of Analytic Amplitude and Phasementioning

confidence: 99%

Section: A Hypothesis On Cortical Function Based In Background Activitymentioning

confidence: 99%