Figure 1.
Experimental paradigm and behavioural responses. (A) Location of the recording sites. Neural recording is performed in the primary somatosensory cortex (S1, red), secondary somatosensory cortex (S2, blue) and ventral premotor cortex (PMv, grey). AS = acuate sulcus; CS = central sulcus; IPS = intraparietal sulcus; LS = lateral sulcus; PS = principal sulcus. (B) Behavioural task (multisensory task). Sequence of events during behavioural trials. At the start tone (pure tone 1000 Hz 100 ms) the animal initiates a trial by placing the hand (ipsilateral to the recording site) on the button in front of the animal. After a random delay, one of the four different sensory stimulus sets is presented for 250 ms. The animal is required to keep its hand on the button until the end of the trial in order to receive a liquid reward (correct response). The animal then has to release the button during the intertrial interval (ITI). One of the four stimulus sets (air puff, sound, simultaneous air puff and sound, or no stimulus) was randomly delivered to the animals in every trial regardless of their button response. Air puff was delivered at 12 psi to the lower face and a pure tone of 4000 Hz was delivered at 80 dB SPL (both for 250 ms). (C) Typical behavioural response during propofol anaesthesia and recovery. Top: The animal’s trial-by-trial button response. Correct responses (blue), failed attempts (black), and no response (red). Middle: Probability of the task engagement (purple) and task performance (orange). Bottom: The trial-by-trial reaction time (from start tone to button press). (D) Reaction times. Box plots for the reaction time over 30 trials during wakefulness (Awake), immediately prior to loss of consciousness (LOC), at return of consciousness (ROC), and at return of pre-anaesthetic performance (ROPAP). Outliers are shown with a black cross. There is a significant effect of anaesthetic-induced altered states of consciousness (awake, LOC, ROC, and ROPAP) on the reaction time [ANOVA F(3,59) = 25.6, P = 2.1 × 10−8]. An asterisk indicates a significant difference from the awake state (post hoc Turkey-Kramer test, P < 0.01). A hash symbol indicates a significant difference from LOC (P = 0.024). LOC is shown with a black arrow and dotted lines, ROC with a purple arrow and dotted lines, and ROPAP with an orange arrow and dotted lines (C). Propofol was infused at 200 μg/kg/min from 1800 to 5400 s (shaded area in C).