<Neuroscientist speculation mode on> It is interesting to speculate
that the feelings of meaningfulness and profound insights are related
to the temporal lobe epilepsy syndrome. And also the model that
hippocampal region CA1 does novelty/familiarity detection of
experiences (see for example "Encoding and Retrieval of Episodic
Memories: Role of Cholinergic and GABAergic Modulation in the
Huippocampus" by Michael E. Hasselmo, Bradley P. Wyble and Gene
V. Wallenstein in Hippocampus 6:693-708 (1996)). Is marijuana use
linked to feelings of Deja vu or its opposite? If this holds, it could
mess up the familiarity/novelty detection systems, making the user
think that a new experience was familiar or an old experience fresh
and new. <Neuroscientist speculation mode on>
Effects of hippocampal brain damage on auditory and visual recent
memory: comparison with marijuana-intoxicated subjects.
Biol Psychiatry 1980 Dec;15(6):841-858
Drew WG, Weet CR, De Rossett SE, Batt JR
A battery of tests clinically employed for the estimation of auditory
and visual recent memory dysfunction was administered to eight
subjects having circumscribed damage to the temporal lobe. It was
hypothesized that the performance of subjects with temporal lobe
lesions would qualitatively resemble that of subjects intoxicated with
marijuana. Where comparisons could be made, the performance of these
"temporal lobe" patients paralleled the performance of subjects
acutely intoxicated with known doses of delta 9-THC. Results are
discussed in terms of cannabinoid actions on hippocampal functioning
and, in general, support the hypothesis that the action of marijuana
in the brain may focus in the hippocampal region and produce
behavioral changes similar to that resulting from traumatic injury or
removal of the region.
Improvement of memory in rodents by the selective CB1
cannabinoid receptor antagonist, SR 141716.
Psychopharmacology (Berl) 1996 Jul;126(2):165-172
Terranova JP, Storme JJ, Lafon N, Perio A, Rinaldi-Carmona M, Le Fur
G, Soubrie P
Social short-term memory in rodents is based on the recognition of a
juvenile by an adult conspecific when the juvenile is presented on two
successive occasions. Cannabimimetics are claimed to induce memory
deficits in both humans and animals. In the brain, they mainly bind to
CB1 receptors for which anandamide is a purported endogenous
ligand. SR 141716, a specific antagonist of CB1 receptors,
dose-dependently reverses biochemical and pharmacological effects of
cannabimimetics. More particularly, it antagonizes the inhibition of
hippocampal long-term potentiation induced by WIN 55,212-2 and
anandamide, and it increases arousal when given alone. The present
experiments study the ability of SR 141716 (from 0.03 to 3 mg/kg SC)
to facilitate short-term olfactory memory in the social recognition
test in rodents. SR 141716 improved social recognition in a long
intertrial paradigm with a threshold dose of 0.1 mg/kg SC. At 1 mg/kg,
it antagonized the memory disturbance elicited by retroactive
inhibition. Scopolamine (0.06 mg/kg IP) partially reversed its
memory-enhancing effect. Moreover, SR 141716 reduced memory deficit in
aged rats (0.03-0.1 mg/kg) and mice (0.3-1 mg/kg). As SR 141716 is not
known to exhibit any pharmacological activity which is not mediated by
CB1 receptors, the results strongly support the concept that blockade
of CB1 receptors plays an important role in consolidation of
short-term memory in rodents and suggest there may be a role for an
endogenous cannabinoid agonist tone (anandaminergic) in forgetting.
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