[Comp-neuro] Poulet 2008 [ Brain state regulates membrane potentialsynchrony; resting state; signal-to-noise ]

ajmandell ajmandell at charter.net
Sat Aug 2 16:43:43 CEST 2008

Wonder if multiple dynamical measures on complexity and entropy in membrane potential fluctuations wouldn't reveal compensatory relationships between them such that the form and not necessarily the "total content" is changing?

Entropy Conservation in Brain Systems

Mandell and Selz

CHAOS 7:67- 81 (1), 1997

"Can conservation relations be computed for global brain observables? Many indicators of whole brain energy utilization,

such as rates of oxygen and glucose metabolism, are almost invariant across dramatic changes in states of consciousness

from high arousal to deep sleep. Theoretical developments in statistical mechanics, born of Kolmogorov,

Sinai, Pesin, Bowen, and Ruelle under the rubric of ‘‘thermodynamic formalism,’’ suggest the possibility of

more abstract conservation laws involving brain information generation. In the context of developmental motor,

neuroendocrine, and computational experiments, it is shown that a particular ‘‘topological’’ entropy, the logarithmic

rate of generation of new, distinct observations,can be conserved across substantial alterations in dynamical

state through reciprocal changes in more internal .fractional dimensional. versus more external Lyapunov characteristic exponential. novel emanations"

  ----- Original Message ----- 
  From: Malcolm Dean 
  To: comp-neuro at neuroinf.org 
  Sent: Thursday, July 31, 2008 3:41 PM
  Subject: [Comp-neuro] Poulet 2008 [ Brain state regulates membrane potentialsynchrony; resting state; signal-to-noise ]

  "...a change in brain state dynamically and profoundly regulates cortical membrane potential synchrony during behaviour. The change in brain state is regulated by an internally generated signal... Active cortical brain states may therefore serve to augment the total cortical information processing capacity through decorrelation of membrane potential synchrony while increasing signal-to-noise ratios for AP initiation."

  Nature advance online publication 16 July 2008
  Internal brain state regulates membrane potential synchrony in barrel cortex of behaving mice
  James F. A. Poulet & Carl C. H. Petersen

  Internal brain states form key determinants for sensory perception, sensorimotor coordination and learning1, 2. A prominent reflection of different brain states in the mammalian central nervous system is the presence of distinct patterns of cortical synchrony, as revealed by extracellular recordings of the electroencephalogram, local field potential and action potentials. Such temporal correlations of cortical activity are thought to be fundamental mechanisms of neuronal computation3, 4, 5, 6, 7, 8, 9, 10, 11. However, it is unknown how cortical synchrony is reflected in the intracellular membrane potential (V m) dynamics of behaving animals. Here we show, using dual whole-cell recordings from layer 2/3 primary somatosensory barrel cortex in behaving mice, that the V m of nearby neurons is highly correlated during quiet wakefulness. However, when the mouse is whisking, an internally generated state change reduces the V m correlation, resulting in a desynchronized local field potential and electroencephalogram. Action potential activity was sparse during both quiet wakefulness and active whisking. Single action potentials were driven by a large, brief and specific excitatory input that was not present in the V m of neighbouring cells. Action potential initiation occurs with a higher signal-to-noise ratio during active whisking than during quiet periods. Therefore, we show that an internal brain state dynamically regulates cortical membrane potential synchrony during behaviour and defines different modes of cortical processing.


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