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Background EEG analytic phase 1 Walter J Freeman Origin, structure, and role of background EEG activity. Part 2. Analytic phase
No full textEssential contributions to surgical preparation and training of animals, data acquisition, and data analysis by John Barrie, Gyöngyi Gaál, and Linda Rogers are gratefully acknowledged. Background EEG analytic phase 2 Walter J Freeman 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 o
Entrevista a Walter J. Freeman
No full textEl profesor Walter J. Freeman, mundialmente conocido por sus aportaciones a la fisiología y la psicología de la percepción, ha sido invitado por el departamento de Filosofía de la U.I.B. para dar una conferencia bajo el título de "On the fallacy of assigning an origin to consciousness". Durante su estancia en Palma de Mallorca, en el mes de noviembre de 1994, el profesor Freeman ha tenido la amabilidad de conceder esta entrevista a Psicothema. En ella el profesor Freeman aborda algunos de los aspectos más relevantes y controvertidos acerca de la existencia de procesos caóticos en el cerebro y de sus consecuencias para la psicología cognitiva. La entrevista tuvo lugar en lengua inglesa: lo que se transcribe es una traducción que ha sido revisada personalmente por el propio profesor Freeman. Algunas de las expresiones se ofrecen, en cursivas, en el original anglosajón
Entrevista a Walter J. Freeman
No full textEl profesor Walter J. Freeman, mundialmente conocido por sus aportaciones a la fisiología y la psicología de la percepción, ha sido invitado por el departamento de Filosofía de la U.I.B. para dar una conferencia bajo el título de "On the fallacy of assigning an origin to consciousness". Durante su estancia en Palma de Mallorca, en el mes de noviembre de 1994, el profesor Freeman ha tenido la amabilidad de conceder esta entrevista a Psicothema. En ella el profesor Freeman aborda algunos de los aspectos más relevantes y controvertidos acerca de la existencia de procesos caóticos en el cerebro y de sus consecuencias para la psicología cognitiva. La entrevista tuvo lugar en lengua inglesa: lo que se transcribe es una traducción que ha sido revisada personalmente por el propio profesor Freeman. Algunas de las expresiones se ofrecen, en cursivas, en el original anglosajón
Matter and mind are entangled in two streams of images guiding behavior and informing the subject through awareness.
No full textWalter J. Freeman Journal Article e--Reprint
No full textthis report is to present measurements of EEG frequencies from 3 species of mammals, and to compare the results with values reported in the literature for other species. Data are presented on the distribution of burst frequencies from OB, AON, and PC of cat and rabbit, and from OB and PC of the rat. The span of frequencies observed in these species was from 35 to 85 c/se
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Vortices in brain waves
Full text linkInteractions by mutual excitation in neural populations in human and animal brains cre- ate a mesoscopic order parameter that is recorded in brain waves (electroencephalogram, EEG). Spatially and spectrally distributed oscillations are imposed on the background activity by inhibitory feedback in the gamma range (30–80 Hz). Beats recur at theta rates (3–7 Hz), at which the order parameter transiently approaches zero and micro- scopic activity becomes disordered. After these null spikes, the order parameter resurges and initiates a frame bearing a mesoscopic spatial pattern of gamma amplitude modu- lation that governs the microscopic activity, and that is correlated with behavior. The brain waves also reveal a spatial pattern of phase modulation in the form of a cone. Using the formalism of the dissipative many-body model of brain, we describe the null spike as a singularity, the following amplitude pattern as a ground state, and the phase cone as the manifestation of a stabilizing vortex.
Adaptation of the generalized Carnot cycle to describe thermodynamics of cerebral cortex
No full textThe brain is a thermodynamic system operating far from equilibrium. Its function is to extract microscopic sensory information from the volleys of action potentials (pulses) that are delivered by immense arrays of sensory receptors, construct the macroscopic meaning of the information, and store, retrieve, and update that meaning by incorporating it into its knowledge base. The function is executed repetitively in the action-perception-assimilation cycle. Each cycle commences by a phase transition, in which the immense population comprising each sensory cortex condenses from a gas-like state to a liquid-like state. It ends with return of the cortex to the expectant gas-like state. We have modeled the microscopic thermodynamics of the cycle using quantum field theory. Our new result is modeling cortical macroscopic thermodynamics with the generalized Carnot cycle, in which the energy required for the construction of knowledge is supplied by brain metabolism and is dissipated as heat by the cerebral circulation. What makes the application possible is the unprecedented precision with which spatial patterns of ECoG are measured, thus providing precise state variables with which to represent energy vs. entropy. We present experimental evidence that these isothermal processes are coupled by adiabatic cooling and heating. We postulate that the action-perception-assimilation cycle comprises minimally three consecutive Carnot cycles required for basic perception, assimilation, and decision, and more cycles with greater complexity of cognitive tasks at hand
Dissipation of ‘dark energy’ by cortex in knowledge retrieval
Full text linkWe have devised a thermodynamic model of cortical neurodynamics expressed at the classical level by neural networks and at the quantum level by dissipative quantum field theory. Our model is based on features in the spatial images of cortical activity newly revealed by high-density electrode arrays. We have incorporated the mechanism and necessity for so-called dark energy in knowledge retrieval. We have extended the model first using the Carnot cycle to define our measures for energy, entropy and temperature, and then using the Rankine cycle to incorporate criticality and phase transitions. We describe the dynamics of two interactive fields of neural activity that express knowledge, one at high and the other at low energy density, and the two operators that create and annihilate the fields. We postulate that the extremely high density of energy sequestered briefly in cortical activity patterns can account for the vividness, richness of associations, and emotional intensity of memories recalled by stimuli
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