We recorded single-unit spiking (713 clusters), microwire LFPs and iEEG from 13 patients implanted with depth electrodes while playing sounds (click-trains, words, music) during wakefulness and sleep, studying auditory responses (observed mainly in lateral temporal lobe). Amplitude of spike and gamma responses was similar in wake and NREM sleep, with modest or no attenuation in […]
Loss of consciousness happens abruptly, but does the neuronal activity in our brains also change suddenly? Here we gradually deepen anaesthesia in rats whilst playing aounds and recording how their neurons fire in the auditory cortex. We found a range of different changes with anaesthesia, but all of them changed gradually with increased anaesthesia, and […]
One of the most obvious affects of anaesthesia is that our patients are disconnected from their sensory environment: they don’t respond to questions, they don’t see the operation and they don’t feel the pain of surgery. However it is far from obvious where in the sensory hierarchy this disconnection occures. In this project we used […]
A reduced responsiveness to external stimuli is the main characteristic of sleep. In this study we show that the LC, a small nucleus in the brainstem and the main source of noradrenaline, plays a central role in our ability to disconnect from the environment during sleep. We recorded rats cerebral cortical activity (Electroencephalogram; EEG) in […]
We have recorded simultaneously the auditory responses of neurons in the auditory and perirhinal cortices. While the former, a low order sensory region, showed similar response magnitudes across vigilance states, the higher order area showed robust attenuations in both NREM and REM sleep. Furthermore, the latency of neurons has been found to predict the response […]
An identical sensory stimulus may or may not be incorporated into perceptual experience, depending on the behavioral and cognitive state of the organism. What determines whether a sensory stimulus will be perceived? Here we tested whether noradrenaline signaling may play a key role. We pharmacologically down- and upregulated noradrenaline signaling in healthy volunteers using clonidine […]
Despite the persistence of some sensory processing during sleep, it is unclear whether high-level cognitive processes such as speech parsing are also preserved. We used a novel Concurrent Hierarchical Tracking (CHT) approach for studying the depth of speech processing across wakefulness and sleep while tracking neuronal activity with EEG. We found that responses to the […]
We studied how natural loss of consciousness during sleep affects visual processing using high density scalp EEG in healthy human participants. We found attenuated fast frequency following responses in the visual cortex in sleep (N/REM) compared to wakefulness while slow and onset responses were stronger in sleep. These results supports the view that during sleep […]
Sleep deprivation has widespread health effects, including increased risk of hypertension, diabetes, obesity, heart attack, and stroke. In addition, it leads to car accidents and medical errors. During sleep deprivation, homeostatic and circadian processes interact to build up sleep pressure, which results in slow behavioral performance (cognitive lapses). Here we used intracranial electrodes to record […]
A long held hypothesis postulated that brain waves called sleep spindles inhibit transmission of information from thalamus to cortex. In here we disputed this claim by showing neurons in the primary auditory cortex (first station after the thalamus) respond similarly to sounds, regardless of the occurrence of sleep spindles.
