Global descriptors of brain electrical activity
globalDescriptors.m: the implementation, including a comment on usage
wolf.data: a test data set (2 sec, 128 samples/sec, 21 channels)
Test run with window size 128 samples, step size 128 samples and 32 samples:
>> help globalDescriptors
compute global descriptors of EEG over a running window
gd = globalDescriptors(x, fSamp, N)
gd = globalDescriptors(x, fSamp, N, step)
x: data set (samples x channels)
fSamp: sampling frequency of the data
N: window size
step: step size, default = N
gd: global descriptors (samples x [Sigma, Phi, Omega])
>> load wolf.data
>> gd = globalDescriptors(wolf, 128, 128)
gd =
13.0956845194698 11.7792213798178 2.85878318691249
12.5536843261832 12.1529487415706 3.23859051965593
>> gd = globalDescriptors(wolf, 128, 128, 32)
gd =
13.0956845194698 11.7792213798178 2.85878318691249
13.2247103377395 11.7085290888065 2.983216508628
13.2258904456649 11.6568634752435 3.16669742861739
12.6761651000011 11.9714922729906 3.17961786915619
12.5536843261832 12.1529487415706 3.23859051965593
The system of global descriptors was introduced by
J. Wackermann (1999), Towards a quantitative characterisation of functional states of the brain: From the non-linear methodology to the global linear description. International Journal of Psychophysiology 34: 65–80
and recently comprehensively described by
J. Wackermann and C. Allefeld (2009). State space representation and global descriptors of brain electrical activity. In C. M. Michel et al., editors, Electrical Neuroimaging: A Systematic Introduction, pages 191-214. Cambridge University Press, 2009
Please direct questions regarding the methodology to J. Wackermann and questions regarding the implementation to C. Allefeld.