How does clonidine/ the α- 2 adrenoreceptor work?
Boehnlein (2007). The case for clonidine.
Clonidine
Clonidine is an α2- adrenergic receptor agonist and suppresses sympathetic nervous
system outflow throughout the brain. Clonidine has been reported to imporve spatial
working memory performance in monkeys, and stimulation of α2 adrenoreceptors in the
prefrontal cortex strengthens prefrontal cortex regulation of behavior and reduces
distractibility.
Low dose clonidine significantly increased REM sleep and decreased non- REM sleep.
Medium- dose clonidine significantly reduced REM sleep and increased non- REM sleep.
The opposite actions of low and medium doses of clonidine on the proportion of REM to
non- REM sleep may indicate that low- dose clonidine mainly affects the α2- receptors on
locus coeruleus norepinephrine neurons presynaptically, reducing release of
norepinephrine, whereas medium dose clonidine acts more postsynaptically.
How does an noisy environment counteract the effect of
clonidine?
See the first experiment of Smith & Nut in the last learning goal.
What is the effect of clonidine on different cue conditions?
See the third experiment of Witte & Marocco in the last goal.
Differences in RT when administering low and high doses of
clonidine?
Meyer & Quenzer (2013). Organization and function of the noradrenergic system.
Norepinephrine is an important transmitter in both the dcentral and peripheral
nervous systems
The NE- containing neurons within the brain are located in the parts of the brainstem
called the pons and the medulla. Of particular interest is a structure known as the locus
coeruleus (LC), a small area of the pons that ocntains a dense collection of
noradrenergic neurons corresponding roughly to the A6 cell group. These cells send fibers
into almost all areas of the forebrain, thereby providing nearly all of the NE in the cortex,
limbic system, thalamus, and hypothalamus. The LC also provides noradrenergic input to
the cerebellum and spinal cord.
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