Human mediotemporal EEG characteristics during propofol anesthesia

Abstract

Evidence for a response-control-related kind of declarative memory during deep propofol anesthesia has recently been reported. Connectivity within the mediotemporal lobe (MTL), and in particular rhinal-hippocampal synchronization within the gamma band, has been shown to be crucial for declarative memory formation. Thus, we analyzed EEG recordings obtained from the scalp, as well as directly from within the hippocampus and from the anterior parahippocampal gyrus, which is covered by rhinal cortex, in patients with unilateral temporal lobe epilepsy during propofol anesthesia, which preceded electrode explantation. For the gamma band a power decrease starting with induction of anesthesia was observed at scalp position Cz, but a power increase was detected at MTL locations. In contrast to prior results for sleep recordings, rhinal-hippocampal coherence did not decrease within the gamma band at deeper levels of anesthesia. These findings may represent an indirect electrophysiological correlate of partially intact declarative memory formation during deep propofol sedation. Furthermore, we investigated how well the plasma propofol level, as well as different stages of anesthesia including the burst suppression phase, could be monitored by different spectral as well as by nonlinear EEG measures. We observed that conventional spectral power measures, most prominently those recorded from mediotemporal locations, are most closely correlated with the plasma propofol level, whereas different stages of anesthesia can be distinguished best by nonconventional spectral as well as nonlinear measures.

Effects of the anesthetic agent propofol on neural populations

“…the increase and then decrease of spectral power in the d-, h-, a-and b-band. This biphasic behavior has been found both in rats (Dutta et al 1997) and humans (Kuizenga et al 2001;Fell et al 2005;Han et al 2005).…”

“…the power increase and decrease at low and high frequencies while increasing the anesthetics concentration (Fell et al 2005;Dutta et al 1997;Forrest et al 1994). In the following, we first study the increase and decrease of the power at low frequencies, and then reveal the biphasic power spectrum also at higher frequencies.…”

“…The effect of spatial modes on the power spectrum in neural populations has been investigated in great detail by Robinson's group (Rennie et al 2002;Robinson et al 2001Robinson et al , 2004Robinson 2003). Further we mention the study of Fell et al (2005), who measured synchronously the EEG on the scalp and Local Field Potentials intracranially in humans as a function of the propofol concentration. They found, amongst other effects, that the power spectra of EEG and LFP had similar dependences on the propofol concentration.…”

“…In addition to these studies of microscopic actions, much research has been devoted to macroscopic effects of AA, such as the cardiovascular response of subjects to AAs (Mustola et al 2003;Musizza et al 2007) and the power spectrum of the subjects' resting electroencephalogram (EEG) as a function of the blood concentration of AAs (Forrest et al 1994;Dutta et al 1997;Kuizenga et al 2001;Fell et al 2005;Han et al 2005). The resting EEG power spectrum especially reflects the anesthetic action in a characteristic way and permits the classification of the depth of anesthesia by so-called monitors, see e.g.…”

Poliovirus Protein 3A Binds and Deregulates LIS1, Causing Block of Membrane Protein Trafficking and Deregulation of Cell Division

“…On the contrary, LIS1 overexpression causes Golgi membranes dispersal compare. 19,24,36,37 On the other hand, cells expressing 3A or LIS1 truncation mutants fail to progress through mitosis, dying after several hours of division attempts. Similar impact of 3A and LIS1 mutants on the process of cell division further strengthen functionality of 3A-LIS1 interaction.…”