Spatiotemporal analysis of the neuromagnetic response to rhythmic auditory stimulation: rate dependence and transient to steady-state transition.
OBJECTIVE
Whole head magnetoencephalography was used to investigate the spatiotemporal dynamics of neuromagnetic brain activity associated with rhythmic auditory stimulation.


METHODS
In order to characterize the evolution of the auditory responses we applied a Karhunen-Loève decomposition and k-means cluster analysis to globally compare spatial patterns of brain activity at different latencies and stimulation rates. Tones were presented binaurally at 27 different stimulation rates within a perceptually and behaviorally relevant range from 0.6 to 8.1 Hz.


RESULTS
Over this range, we observed a linear increase of the amplitude of the main auditory response at 100 ms latency (N1m) with increasing inter-stimulus interval, and qualitative changes of the overall spatiotemporal dynamics of the auditory response. In particular, a transition occurred between a transient evoked response at low frequencies, and a continuous steady-state response at high frequencies.


CONCLUSIONS
We show the onset of temporal overlap between responses to successive tones that leads to this transition. Response overlap begins to occur near 2 Hz, marking the onset of a continuous perceptual representation.
Carver
Frederick W
FW
Center for Complex Systems and Brain Sciences, Florida Atlantic University, Boca Raton, FL 33431, USA. carver@walt.ccs.fau.edu
Fuchs
Armin
A
Jantzen
K J
KJ
Kelso
J A Scott
JA
D000161:Acoustic Stimulation / Q000379:methods*; D000328:Adult; D001303:Auditory Cortex / Q000502:physiology*; D016000:Cluster Analysis; D005072:Evoked Potentials, Auditory / Q000502:physiology*; D005260:Female; D006801:Humans; D015225:Magnetoencephalography / Q000379:methods*; D008297:Male