Marijuana wreaks havoc on brain's memory cells

[nabraxas]

* 11:38 20 November 2006

* NewScientist.com news service

* Roxanne Khamsi

Smoking marijuana often causes temporary problems with memory and learning. Now researchers think they know why.

The active ingredient in the drug, tetrahydrocannabinoid (THC), disrupts the way nerves fire in the brain’s memory centre, a new study shows.

David Robbe at Rutgers University in New Jersey, US, and colleagues gave rats an injected dose of THC, proportional to the amount inhaled by a person smoking an average-sized marijuana joint.

The team monitored the drug’s effect using wire probes placed in a memory centre in the animals’ brains – the hippocampus. The probes monitored the nerve impulses as they fired.

Normally, cells in hippocampus fire in sync, creating a current with a total voltage of around 1 millivolt. But THC reduced the synchrony of the firing. The drug did not change the total number of firings produced, just their tendency to occur at the same time – and this reduced the combined output voltage of the nerve signals by about 50%.

Abnormal firing occurs because THC binds to a receptor on the surface of the nerve cell, and so indirectly blocks the flow of current, Robbe believes.

Encore!

Nerves need to signal in sync to send a powerful message within the brain, Robbe notes. He likens the process to an audience clapping together – rather than randomly – to make their desire for an encore performance known.

Rats that had more synchronous nerve signalling in their brains performed better on a memory test, the team found. In this test, the animals had to choose whether to turn right or left in a T-shaped maze. In order to receive a treat, they had to turn in the direction opposite to the one they chose in their previous run.

Normal rats accurately alternate their routes about 90% of the time. But rats given THC, which caused asynchronous nerve firing, chose a random direction on each run, and so chose the correct route 50% of the time.

The disruptive effect of THC wore off within a few hours. Robbe says he hopes to find out whether chronic exposure to the drug causes lasting effects on the hippocampus in rats. Scientists studying people have found that long-term marijuana users gradually become worse at learning and remembering things (see Pot-smoking your way to memory loss).

Previous experiments have shown that THC can disrupt the signalling of nerve cells in a Petri dish. But Robbe says this is the first detailed account of what happens to memory cells in a live animal. He adds that the new findings help explain why people high on marijuana sometime lose their train of thought in mid-sentence, forgetting what they were saying.

Journal reference: Nature Neuroscience (DOI: 10.1038/nn1801)

http://www.newscientist.com/article.ns?id=...line-news_rss20

[transDiMenTional]

I had a really good response to this but i forget what it was

bummer

[BlackDragon]

 

 

[apothecary]

I thought the binding of THC to the Hippocampus and the resulting alteration of standard behaviour along those lines was already well known?

I was reading about it on the archive.org copy of pharmcentral.com (which is a 2003 copy)

In addition to activity at G-peptide receptors, sustained use of marijuana may decrease serotonin levels and reduce release of corticotropin releasing hormone (CRH), which regulates release of adrenalin compounds. The short-term memory loss induced by THC occurs through inhibition of mnemonic pathways in the hippocampus. Similar inhibition occurs with antimuscarinic drugs like scopolamine. Effects on sleep regulation are most obvious during withdrawal.

[Μορφέας]

It doesnt take genious to realise weed makes you dumb and forgetful.

[BlackDragon]

Granted most find the "sluggy and forgetful" side of this herb, but what of those that find the opposite, like enhanced work, ability and creativity?

There is far more to its effects than just THC also. Turpines and other Cana-likes are responsible for the majority of the differing effects between species.. I think the whole "pot" analysis thing is half bunk in the first place.

Extracted pure THC produced those results, not whole bud including all the other combined canna likes(CBD,CBN's and other rotational isomers, aromatics etc.)

It would help if they started looking at indica Vs sativas and based their pharmacology from there. Yes, they both have the know THC, but the physical/metnal effects that differ between them is quite substantial.. Scientificaly you definalty could not use both species as a controll together, it wouldnt make sense. Thats why they take the easy way out with just isolating THC and ignoring the other compounds and aromatics.

Seems rather one eyed to me....

Bd.

Edited November 23, 2006 by BlackDragon

[naja naja]

It doesnt take genious to realise weed makes you dumb and forgetful.

Guess thats why my I.Q. is 134 even after 8 years of heavy, daily smoking of 15%+ THC strains.

Definately makes u forgetful, but it doesn't make u dumb.

Edited November 23, 2006 by naja naja

[apothecary]

Acetylcholine is responsible for the major memory functions in the brain.

A study has shown that THC preserves endogenous acetylcholine levels (google: marijuana acetylcholine scripps).

However, because the G-peptide receptors that marijuana effects subtend several primary neurological subsystems (dopamine, acetylcholine, etc) long term marijuana (especially if coupled with tobacco) use may cause an anticholinergic effects that is the source of the forgetfulness.

Or in laymans terms:

[Μορφέας]

I correct myself, it doesnt make you dumb, my friend got an enter score of 95% on his VCE last year and had smoked pot everyday since yr10 lol

[spiders]

I remember reading entire books and not remembering a thing about the story line, characters or the contents of the previous page...

[naja naja]

lol, I do that all the time and then I realize the reason why is because I'm completely uninterested in wat I am reading. Had the same prob in school too. I don't have enough room in my brain to devote to pointless drivel, so I can't even remeber it short term. If I read interesting stuff, I remember it no probs.

[spiders]

you'd be fucked in my job then ! ;)

nah these were good books - im sure i enjoyed them, but that is all i can say about them. But even doing the dishes is interesting after a smoke...

[trixxy3]

But even doing the dishes is interesting after a smoke...

Not to mention tv soaps.

[Northern Gnome]

lol, I do that all the time and then I realize the reason why is because I'm completely uninterested in wat I am reading. Had the same prob in school too. I don't have enough room in my brain to devote to pointless drivel, so I can't even remeber it short term. If I read interesting stuff, I remember it no probs.

Identical IQ, same problem. Humm..... I have a high enough IQ to know they aren't related, yet why?

I remember what I find interesting, or what I have been happy or unhappy about but the rest, duh..... dumb.

[whit3rabbit]

Not to mention tv soaps.

Bold and the Beautiful

I remember reading entire books and not remembering a thing about the story line, characters or the contents of the previous page...

I can never remember the whole story, but I remember parts of it as actual memories because I imagine it as a movie in my head and then later I think 'When did I do that? Oh yeah, it was in that story'.

[coin]

i think most people understand that IQ does not have much to do with overall 'intelligence' .. i mean, i know ppl with a high IQ and some people would call them retarded basically, when you look at their situation in terms of the bigger picture....there are different forms of intelligence, and then a general well-rounded intelligence that you get from ppl who aren't particularly 'gifted' or whatever words you want to use.... emotional intelligence, spiritual intelligence, artistic intelligence, mechanical intelligence, logical intelligence, intuitive intelligence.... people with the high IQ's are often the most able to 'fool' themselves into believing whatever is convenient for them to believe, to maintain their own delusion...it's not an intelligence that necessarily leads to physical, emotional, or spiritual wellbeing -- so really, how does that help? -- high IQ is not an especially "intelligent" trait in my eyes

Edited November 24, 2006 by coin

[spiders]

Most of he people I have known who claimed to have high IQs were socially retarded...

[naja naja]

I am socially retarded.

[coin]

yep...and then there are those who are "intelligent" enough to successfully navigate themselves through social situations but only in a 'logical' way -- i.e. they are essentially faking it

[dqd]

yep...and then there are those who are "intelligent" enough to successfully navigate themselves through social situations but only in a 'logical' way -- i.e. they are essentially faking it

Sometimes this can be necessary for the emotional 'comfort' of others; when you're at a party who would make you feel more comfortable; the person who 'fakes it' or the 'wierdo' (just an example of common terms ) who smiles at the floor laughing but never taking part in the conversation? It is entirely possible to be intelligent and completely socially inept, especially if you don't drink . Personally I think that social factors and upbringing also play a part; I can think of three people off the top of my head in this situation, one lost a parent to suicide at a young age, one was sexually abused and one was school-bashed from year 2 onwards; all three are intelligent and have skills to offer to society, and all three are ostricised by society as a whole because socially they just don't 'fit in'. I can guarantee the 'wierdo' is made to feel far more uncomfortable than you .

...just an aside, but how much is the IQ test out of now? I did a 'Tickle' online test a couple of years ago and that was out of 140... but as a kid I remember it being more than this?

Just my 2cents worth , have a good day all

[Green Osiris]

I wonder if long-term cookie usage (ie totally void of smoking Mary Jane) makes for a varied long term detriment ?

[gomaos]

for a start I'd like to say Mr. Robbe is a bastard using animals for experiments.

i'd like to shove a few 100 grams of cannabis down his throat I would (but what a waste)

Those researches go to any lenght to prove their points, it's just like pro-religion-people trying to proove their point by stupid, ill-fitting examples that prove nothing.

Why does one take cannabis? Many reason, but a primary one: To forget!!!

To forget everyday's problems and annoyances, to have some peace from it, some relaxation.

To me it's the one true anti-depressant, the only one that works.

And if cannabis works by stuffing up the "in-line-firing" of neorons, great. At least it doesn't damage and destroy anything like alcohol does. Great that it has found a way to interrupt the non-sensical rationality of the brain

. Ok the brain needs to be rational for everyday functions, but boy, at days end, when we're tired, DO we want the brain to have a rest, to stop functioning properly, boy do we want to forget all that everyday-crap that makes our lives miserable.

or maybe it's just me. don't know. I'd def say Mr Robbe should have a smoke so he would understand things.

What a dork!(for torturing rats)

I wonder if long-term cookie usage (ie totally void of smoking Mary Jane) makes for a varied long term detriment ?

so do I. my guess; it's no different.

Edited November 25, 2006 by gomaos

[faustus]

i think most people understand that IQ does not have much to do with overall 'intelligence'

i disagree. IQ is associated with intelligent behaviour, but whether or not it's a true measure of intelligence is a different matter. IQ is strongly correlated with positive outcomes in life: SES, education, job performance, likelihood of imprisonment, even happiness in marriage, publishing more papers, books, getting more things patented, etc, etc.

emotional intelligence

EI offers little to no predictive validity over and above IQ scores. if EI is something that can be taught i.e. is an ability, then individuals with a high IQ have a greater capacity to learn it. if EI can't be taught (is a trait), then it's normally distributed, and people with a high IQ are just as likely to have a high EI as someone with a low IQ: we're no closer to an egalitarian approach to intelligence.

artistic intelligence,

i mentioned this before, but those typically regarded as creative geniuses by their peers commonly have an IQ of 130+, but obviously having an IQ of 130 alone doesn't guarantee that you're a creative genius.

mechanical intelligence, logical intelligence

current IQ tests accomodate these abilities.

people with the high IQ's are often the most able to 'fool' themselves into believing whatever is convenient for them to believe, to maintain their own delusion

ok, so you're saying that IQ is positively correlated with 'delusional' beliefs? this is quite a strong claim, have you ever spoken to people that are absolutely dumb as dog shit?

...just an aside, but how much is the IQ test out of now?

in theory, it's unlimited, but usually it's ~200. mean is always 100, with a standard deviation of 15. extreme scores (mentally retarded and genius) are more unreliable to measure.

for a start I'd like to say Mr. Robbe is a bastard using animals for experiments.

next year i'll be doing animal experiments. either with DMT or with meth addiction. guess i'm a bastard (to be) too. but what's the deal with all this anti animal experimentation rhetoric on these forums? animals experimentation is subject to ethics committee review, the little buggers are treated with a modicum of respect. moreover, what's the difference between eating meat (which only benefits you) and experimenting on an animal (which hopefully benefits all)? is it that lab rats suffer more? methinks you're grossly mistaken... besides, people don't gnaw rats, they eat cattle, which would arguably have a greater capacity to experience pain. animal research probably accounts for .001% of all animal deaths, yet people are quite willing to criticise this while chewing on one of the colonel's finest.

*sigh*

I'd def say Mr Robbe should have a smoke so he would understand things.

trust me, the field of psychopharmacology is one where drug usage is a professional qualification. you really think that someone who dedicates their life's work to understanding the effects of cannabis has never tried it once?

[spiders]

'yep...and then there are those who are "intelligent" enough to successfully navigate themselves through social situations but only in a 'logical' way -- i.e. they are essentially faking it'

yeah - also know as Aspergers Syndrome.

[naja naja]

Aspergers

Hehehehe u said Aspergers