General anesthesia is an interesting brain state. Similar to sleep, it is a reversible state, during which consciousness is switched off. However the brain is still active, and most notabely sensory information still travels through the sensory pathway and reaches the sensory cortex. However, we do not have awareness of this sensory information during general anesthesia.
Also similar to sleep, during anesthesia it is possible to observe different brain states, depending on the depth of anesthesia and the the type of anesthetic. Interestingly, allthough a large number of sensory neurophysiology experiments are performed during general anesthesia, it is intriguing how rarely processing during different anesthesia states is specifically addressed in studies.
We are interested in sensory responses during different varying anesthetic depths. This is interesting for better control of measurements during general anesthesia of sensory evoked responses (Land et al. 2013). On the other hand, it allows to study effects of general anesthetics on the cortical network, and how it influences the dynamics in a level-dependent manner. This also may allow to understand better the mechanisms that are apparently suppressed during anesthesia, that are necessary for conscious experience. We have studied auditory and visual responses during isoflurane anesthesia in the visual cortex of mice (Land et al. 2012). We found non-linear effects during high anesthesia levels with isoflurane, where auditory stimulation evoked activity within the visual cortex.
Land, R., Engler, G., Kral, A. & Engel, A. K. Auditory Evoked Bursts in Mouse Visual Cortex during Isoflurane Anesthesia. PLoS One 7, e49855 (2012).
Land, R., Engler, G., Kral, A. & Engel, A. K. Response properties of local field potentials and multiunit activity in the mouse visual cortex. Neuroscience 254, 141–51 (2013).