state for very long, spontaneously and irregularly jumping from one unstable
Epstein Suite indexes the text; the original document lives at its official source. We don't host the original file — view it on the official release to read it in full.
View the original on the official releaseDocument text
Text is machine OCR and may contain errors. Confirm against the original source above.
state for very long, spontaneously and irregularly jumping from one unstable
dynamical state to another (1997). This suggests that meaningful tension between
experimental sample lengths long enough to minimize statistical error and short
enough to be stationary may be, for the biological sciences, more apparent than
relevant.
The studies reviewed below exploit measures arising from the view that the
noisy statistics of nonstationarity in biological processes are not a sign of
measurement error, but rather evidence consonant with the statistical physics of
nonequilibrium states and phase transitions (Stanley, 1971; Stauffer, 1985;
Yeomans, 1993). Very high amplitude fluctuations and multiple, up to infinite,
correlation lengths are characteristic of the normal, on-going biological dynamical
behaviors, which are apparently without characteristic amplitude and time scales.
From this point of view, if most or all information is widely distributed in the brain
(e.g., serial order of visual tasks involving motor cortical neurons, Carpenter et al,
1999) ) then the “binding problem” (see above) could also be solved by multiple, up
to infinite spatial and temporal correlation lengths in place of the current theories of
monofrequency resonances (Singer, 1993). Hierarchical neurodynamical
mechanisms communicating across many mechanistic temporal and spatial scales,
brain information transport analogous to the energy cascade of hydrodynamic
turbulent velocities (Tennekes and Lumley, 1972), would be likely in the parametric
vicinity of incipient bifurcations and phase transitions.
Three closely related techniques for quantifying the systematic changes in
average fluctuation amplitudes with n (scale, sample length) involve a “power law,”
linear slope relationship between the logarithm of an index of variability and the
logarithm of sample segment sizes. These easy, yet powerful methods were
brought to experimentalists’ attention by Benoit Mandelbrot (Montroll and Badger,
1974; Mandelbrot, 1983; Fedor, 1988; Bassingthwaighte et al, 1994; Liebovitch,
1998). To estimate the exponent in Hurst rescaled range analysis, we compute the
standard deviation and the range of the deviation of the running sum from the mean
on sequential subsamples of increasing size. The Hurst power law exponent is the
slope of the straight line formed by graphing the logarithm of the subsample length
208
HOUSE_OVERSIGHT_013708
Have a question about what this document contains?
Ask the documents