Prepyriform electrical activity after loss of peripheral or central input, or both

Becker, Cordula; Freeman, Walter J.

doi:10.1016/0031-9384(68)90119-4

Cited by 57 publications

(21 citation statements)

References 8 publications

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“…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. Input above a certain threshold induces a state transition that manifests the response of the neocortex, by which it seeks to regain its stable state.…”

Section: A Hypothesis On Cortical Function Based In Background Activitymentioning

confidence: 99%

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

Freeman

2004

Clinical Neurophysiology

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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: A Hypothesis On Cortical Function Based In Background Activitymentioning

confidence: 99%

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

Freeman

2004

Clinical Neurophysiology

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“…The local negative feedback interaction between excitatory and inhibitory neurons supports bulbar oscillations in the gamma range, but only under barrages of input relayed from odorant receptors through the olfactory bulb. When the nasal passages are blocked or the olfactory nerve to the bulb is cut, the gamma oscillations disappear (Becker and Freeman, 1968) in both the bulb and prepyriform cortex, leaving only unstructured background activity: random pulse trains having constant mean rates with SD equal to the means, forming a sheet of steady state activity resembling white noise with dendritic potentials resembling colored noise with 1/f spectra. Owing to the lack of structure the basal state is "symmetric".…”

Section: A Neural Mechanism For Self-organized Criticality In Neocortexmentioning

confidence: 99%

Origin, structure, and role of background EEG activity. Part 2. Analytic phase

Freeman

2004

Clinical Neurophysiology

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Objective: To explain spontaneous EEG through measurements of spatiotemporal patterns of phase among beta-gamma oscillations.Methods: High-density 8x8 intracranial arrays were fixed over sensory cortices of rabbits. EEGs were spatially low pass filtered, temporally band pass filtered and segmented in overlapping windows stepped at 2 ms. Phase was measured with the cosine as the temporal basis function, using both Fourier and Hilbert transforms to compensate for their respective limitations. Spatial patterns in 2-D phase surfaces were measured with the geometric form of the cone as the spatial basis function.Results: Two fundamental state variables were measured at each digitizing step in the 64 EEGs: the rate of change in phase with time (frequency) and the rate of change in phase with distance (gradient). The parameters of location, diameter, duration, and phase velocity of the cone of phase were derived from these two state variables. Parameter distributions including recurrence intervals extending into the low theta range were fractal; the mean values varied with window duration and interelectrode distance. Conclusions:The formation of spatial amplitude patterns began with phase transitions that were documented by phase discontinuities and phase cones. The multiplicity of overlapping cones indicated that sensory neocortices maintained a scale-free state of self-organized criticality (SOC) in each hemisphere as the basis for its rapid integration of sensory input with prior learning stored in cortical synaptic webs. Further evidence came from the fractal properties of the phase parameters and the self-similarity of phase patterns in the ms/mm to m/s ranges.Significance: These EEG data suggest that neocortical dynamics is analogous to the dynamics of self-stabilizing systems, such as a sand pile that maintains its critical angle by avalanches, and a pan of boiling water that maintains its critical temperature by bubbles that release heat. Betagamma oscillations stem from the ability of neocortex to maintain its stability under continuous sensory bombardment. Modeling implies that the critical parameter of neocortex (analogous to angle of repose or temperature) is the mean firing rates of neurons that are homeostatically regulated by refractory periods everywhere at all times in cortex. The advantage of SOC in perception may be the ability it gives neocortex to generate instantaneous global phase transitions (avalanches, bubbles) large enough to include the multiple sensory areas that are necessary to form Gestalts (multisensory percepts).Background EEG analytic phase 3Walter J Freeman

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“…The amplitude and frequency of this oscillation may reflect previous olfactory experience and the behavior of the animal (Boeijinga and Lopes da Silva 1989;Bressler 1988;Chabaud et al 2000;Freeman 1960;Freeman and Schneider 1982;Freeman and Viana di Prisco 1986;Kay and Freeman 1998;Ravel et al 2003). The gamma oscillation appears to originate in the OB as it is abolished in PC by removal of the OB (Becker and Freeman 1968) and preserved in the OB when conduction through the olfactory peduncle is blocked by cooling (Gray and Skinner 1988). The negative feedback loop between excitatory mitral and tufted cells and inhibitory granule cells has been proposed to be the underlying generator Rall and Shepherd 1968).…”

Section: Introductionmentioning

confidence: 96%

“…Early reports refer to an oscillation, at about half the frequency of the gamma oscillation, that is more prominent in PC than in the OB (Becker and Freeman 1968;Bressler 1984;Freeman 1959). More recently, a 15-to 35-Hz beta oscillation has been described in the OB, PC, entorhinal cortex, and dentate gyrus that is induced by olfactory stimulation with certain organic solvents or components of predator secretions (Chapman et al 1998;Vanderwolf 1992;Zibrowski and Vanderwolf 1997).…”

Section: Introductionmentioning

confidence: 99%

Beta and Gamma Oscillations in the Olfactory System of the Urethane-Anesthetized Rat

Neville

Haberly

2003

Journal of Neurophysiology

275

268

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. Beta and gamma oscillations in the olfactory system of the urethane-anesthetized rat. J Neurophysiol 90: 3921-3930, 2003. First published August 13, 2003 10.1152/jn.00475.2003. Fast oscillations in the beta (15-40 Hz in awake rats) and gamma (50 -100 Hz) frequency ranges are prominent in field potentials induced by odorants in the mammalian olfactory bulb (OB) and piriform cortex (PC). Whereas the gamma oscillation has been studied for Ͼ50 yr, the beta oscillation has attracted attention only recently, and its origin, mechanism, and relationship to gamma are unknown. To address these questions, we have examined responses induced by odorants in the urethane-anesthetized rat-a preparation well-suited for the analysis of mechanisms. We found that both oscillations could be induced by odorants in a concentrationdependent manner. Analysis with a concentration series and spectral methods revealed that the beta and gamma oscillations were distinct and not harmonically related, indicating generation by independent mechanisms. The beta oscillation was synchronous at sites Յ4 mm apart in the OB, the greatest distance tested. In contrast, the gamma oscillation was synchronous in some experiments and asynchronous in others (frequency differed slightly at different sites, resulting in progressive phase shifts). Current source-density analysis indicated that, for both oscillations, the field potentials in the OB were generated by synaptic currents in granule cells. The two oscillations were differently affected by surgical interruption of the lateral olfactory tract. This lesion abolished the beta oscillation, whereas the gamma oscillation was still induced in the OB. Our results confirm previous reports that the gamma oscillation is generated within the OB but indicate that the beta oscillation requires the participation of PC.

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Prepyriform electrical activity after loss of peripheral or central input, or both

Cited by 57 publications

References 8 publications

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

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

Origin, structure, and role of background EEG activity. Part 2. Analytic phase

Beta and Gamma Oscillations in the Olfactory System of the Urethane-Anesthetized Rat

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