Sequential effects of propofol on functional brain activation induced by auditory language processing: an event-related functional magnetic resonance imaging study

• Published in: British journal of anaesthesia : BJA Vol. 92; no. 5; pp. 641 - 650
• Main Authors: Heinke, W, Fiebach, C.J., Schwarzbauer, C, Meyer, M, Olthoff, D, Alter, K
• Format: Journal Article
• Language: English
• Published: Oxford Elsevier Ltd 01.05.2004; Oxford University Press; Oxford Publishing Limited (England)
• Subjects: Acoustic Stimulation - methods; Adult; anaesthesia; anaesthesia, anaesthetic action; anaesthetic action; anaesthetics i.v; anaesthetics i.v., propofol; Anesthesia; Anesthesia. Intensive care medicine. Transfusions. Cell therapy and gene therapy; Anesthetics, Intravenous - blood; Anesthetics, Intravenous - pharmacology; auditory language processing; Biological and medical sciences; brain; Brain - drug effects; Brain - physiology; brain, auditory language processing; brain, functional magnetic resonance imaging; functional magnetic resonance imaging; Humans; Image Processing, Computer-Assisted - methods; Language; Magnetic Resonance Imaging - methods; Male; Medical sciences; propofol; Propofol - blood; Propofol - pharmacology; Speech Perception - drug effects; Speech Perception - physiology; anaesthetics i.v., propofol; brain, auditory language processing; anaesthesia, anaesthetic action; brain, functional magnetic resonance imaging; anaesthesia, anaesthetic action; anaesthetics i.v., propofol; brain, auditory language processing; brain, functional magnetic resonance imaging; Human; Biological fluid; Acquired; Induction; Central nervous system; anaesthetic action; anaesthetics i.v; Male; Activation; Nuclear magnetic resonance imaging; Encephalon; Blood plasma; General anesthetic; Language; Concentration effect; Block; Propofol; auditory language processing; brain; Magnetic field; propofol; brain; Strength; functional magnetic resonance imaging; Functional imaging; anaesthesia
• ISSN: 0007-0912; 1471-6771
• DOI: 10.1093/bja/aeh133

We have investigated the effect of propofol on language processing using event-related functional magnetic resonance imaging (MRI). Twelve healthy male volunteers underwent MRI scanning at a magnetic field strength of 3 Tesla while performing an auditory language processing task. Functional images were acquired from the perisylvian cortical regions that are associated with auditory and language processing. The experiment consisted of three blocks: awake state (block 1), induction of anaesthesia with 3 mg kg−1 propofol (block 2), and maintenance of anaesthesia with 3 mg kg−1 h−1 propofol (block 3). During each block normal sentences and pseudo-word sentences were presented in random order. The subjects were instructed to press a button to indicate whether a sentence was made up of pseudo-words or not. All subjects stopped responding during block two. The data collected before and after the subjects stopped responding during this block were analyzed separately. In addition, propofol plasma concentrations were measured and the effect-site concentrations of propofol were calculated. During wakefulness, language processing induced brain activation in a widely distributed temporofrontal network. Immediately after unresponsiveness, activation disappeared in frontal areas but persisted in both temporal lobes (block 2 second half, propofol effect-site concentration: 1.51 μg ml−1). No activation differences related to the task were observed during block 3 (propofol effect-site concentration: 4.35 μg ml−1). Our findings suggest sequential effects of propofol on auditory language processing networks. Brain activation firstly declines in the frontal lobe before it disappears in the temporal lobe.