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SUMMARY:Self-similar behaviour in the brain: the correlations in rest-stat
 e fMRI. - Prof Henrik Jensen\, Imperial College London
DTSTART:20120529T100000Z
DTEND:20120529T110000Z
UID:TALK38367@talks.cam.ac.uk
CONTACT:Petra Vertes
DESCRIPTION:Adaptive behaviour\, cognition and emotion are the result of\n
 a bewildering variety of brain spatio-temporal activity patterns. An\nimpo
 rtant problem in neuroscience is to understand the mechanism by which the 
 human brain’s 100 billion neurons and 100 trillion synapses manage to pr
 oduce this large repertoire of cortical configurations in a flexible manne
 r. In addition\, it is recognized that temporal correlations across such c
 onfigurations cannot be arbitrary\, but they need to meet two conflicting 
 demands: while diverse cortical areas should remain functionally segregate
 d from each other\, they must still perform as a collective\, i.e. they ar
 e functionally integrated. Here\, we investigate these large-scale dynamic
 al properties by inspecting the character of the spatio-temporal correlati
 ons of brain resting-state activity. In physical systems\, these correlati
 ons in space and time are captured by measuring the correlation coefficien
 t between a signal recorded at two different points in space at two differ
 ent times. We show that this two-point correlation function extracted from
  resting-state functional magnetic resonance imaging data exhibits self-si
 milarity in space and time. In space\, self-similarity is revealed by cons
 idering three successive spatial coarse-graining steps while in time it is
  revealed by the 1/f frequency behaviour of the power spectrum. The uncove
 red dynamical self-similarity implies that the brain is spontaneously at a
  continuously changing (in space and time) intermediate state between two 
 extremes\, one of excessive cortical integration and the other of complete
  segregation. This dynamical property may be seen as an important marker o
 f brain well-being in both health and disease.
LOCATION:BCNI seminar room\, Sir William Hardy Building\, Downing Site
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