Infraslow oscillations in postanoxic encephalopathy
Infraslow activity, defined as voltage fluctuations with frequencies below 0.1 Hz, represents an important component of physiological and pathological brain function.
Michel van Putten will present recent data showing that infraslow activity is preserved in ICU patients with a postanoxic encephalopathy, irrespective of neurological outcome. In ~50% of patients with "burst-suppression with identical bursts", bursts appeared in clusters and clusters of bursts were phase-locked to the infraslow oscillations. In two patients, infraslow activity was present while the EEG showed no rhythmic activity above 0.5 Hz. The presence of infraslow activity in the absence of rhythms > 0.5 Hz lends support to a thalamic driver of these oscillations. Phase-locking of identical bursts likely reflects modulations of cortical excitability by infraslow activity.
Liesbeth Wijers will discuss simulations of burst suppression with identical bursts in a minimal computational model in the absence or presence of infraslow oscillations. The model used is a self-excitatory network that exhibits burst suppression due to short-term and long-term synaptic depression (Tabak et al., “Modeling of spontaneous activity in developing spinal cord using activity-dependent depression in an excitatory network.,” The Journal of neuroscience, vol. 20, Apr. 2000). A slow oscillation was added as external input to the population. The resulting simulations nicely mimic the phase locking of the bursts to the infraslow activity, as observed in our ICU patients.
Wednesday 15 October 2014, 16:30 - 17:30 h
Building Carré - room CR 3.718