Neuroimaging the Effects of Intravenous Anesthetic on Amygdala Dependent Memory Processes
| Status: | Active, not recruiting |
|---|---|
| Conditions: | Healthy Studies |
| Therapuetic Areas: | Other |
| Healthy: | No |
| Age Range: | 18 - 50 |
| Updated: | 3/7/2019 |
| Start Date: | March 2007 |
| End Date: | December 2021 |
This study involves 90 healthy volunteers aged between 18 and 50 recruited from the general
community. It involves doing a set of simple memory tests while inside a fMRI machine. The
subject is given a very low dose of an anesthetic drug intravenously while in the scanner.
The subject then sees a sequence of pictures on a screen, and presses a button if they
remember seeing the picture before. While this is happening, the scanner will be capturing
images that tell us what parts of the brain are active. Hypothesis: patterns of hippocampal
and amygdala activation during the encoding and retrieval of memory,as measured by fMRI, will
be altered by intravenous anesthetics such that suppression of hippocampal and amygdala
activities will be dissociable. This dissociation pattern will be different between the drugs
propofol and thiopental.
community. It involves doing a set of simple memory tests while inside a fMRI machine. The
subject is given a very low dose of an anesthetic drug intravenously while in the scanner.
The subject then sees a sequence of pictures on a screen, and presses a button if they
remember seeing the picture before. While this is happening, the scanner will be capturing
images that tell us what parts of the brain are active. Hypothesis: patterns of hippocampal
and amygdala activation during the encoding and retrieval of memory,as measured by fMRI, will
be altered by intravenous anesthetics such that suppression of hippocampal and amygdala
activities will be dissociable. This dissociation pattern will be different between the drugs
propofol and thiopental.
Background: Subclinical doses of propofol produce anterograde amnesia, characterized by an
early failure of memory consolidation. It is unknown how propofol affects the
amygdala-dependent emotional memory system, which modulates consolidation in the hippocampus
in response to emotional arousal and neurohumoral stress. We present an event-related
functional magnetic resonance imaging study of the effects of propofol on the emotional
memory system in human subjects.
Methods: Thirty-five healthy subjectswere randomized to receive propofol, at an estimated
brain concentration of 0.90 μgml−1, or placebo. During drug infusion, emotionally arousing
and neutral images were presented in a continuous recognition task, while
blood-oxygen-level-dependent activation responses were acquired. After a drug-free interval
of 2 h, subsequent memory for successfully encoded items was assessed. Imaging analysis was
performed using statistical parametric mapping and behavioural analysis using signal
detection models.
early failure of memory consolidation. It is unknown how propofol affects the
amygdala-dependent emotional memory system, which modulates consolidation in the hippocampus
in response to emotional arousal and neurohumoral stress. We present an event-related
functional magnetic resonance imaging study of the effects of propofol on the emotional
memory system in human subjects.
Methods: Thirty-five healthy subjectswere randomized to receive propofol, at an estimated
brain concentration of 0.90 μgml−1, or placebo. During drug infusion, emotionally arousing
and neutral images were presented in a continuous recognition task, while
blood-oxygen-level-dependent activation responses were acquired. After a drug-free interval
of 2 h, subsequent memory for successfully encoded items was assessed. Imaging analysis was
performed using statistical parametric mapping and behavioural analysis using signal
detection models.
Inclusion Criteria:
- age b/w 18 and 50
- right-handed
- minimum of high school education
- fluent in English
- normal vocabulary
Exclusion Criteria:
- any significant medical/psychiatric comorbidity
- deficit in vision or hearing that would impede the study
- allergies to any of the study drugs, to soybeans, or eggs.
- history of head trauma
- family history of major psychiatric illness
- body mass index > 30 kg/m2
- claustrophobia
- prior exposure to IAPS pictures
- pregnancy
- permanent metal objects anywhere in the body
- a personal/family history of any porphyria
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