Suetaz

Researchers have identified the mechanism by which Marijuana may affect learning and memory

News-Medical | Sept. 29, 2004

Marijuana use has long been known to cause problems with learning and memory. Now, researchers at the Albert Einstein College of Medicine of Yeshiva University have identified the mechanism by which Marijuana may affect activity in the hippocampus, the portion of the brain responsible for learning and memory. They reported their findings in the September 16 issue of the journal Neuron.

The active chemical in Marijuana, THC, is also present in Marijuana-like molecules called endocannabinoids that occur naturally in our brains, explains Dr. Pablo Castillo, associate professor of neuroscience at Einstein. These naturally occurring endocannabinoids are neurotransmitters that send signals between neurons in the brain, permitting the intake and storage of information that is critical for effective learning and memory. This communication process between neurons is referred to as synaptic plasticity. (Synapses are the gaps between nerve cells into which one nerve cell secretes a neurotransmitter that stimulates the adjacent nerve cell; and synaptic plasticity refers to the ability of these impulses to pass between neurons.)

But Dr. Castillo notes that when cannabinoids are introduced from outside the body through Marijuana use, they serve to short circuit the internal system and impair synaptic plasticity in particular, thereby interfering with the way neurons signal one another, gather information, and store it.

“When a person smokes Marijuana, an outside signal triggered by the THC is received in the brain,” he says. “But at the same time, the brain’s naturally occurring cannabinoids are also sending messages via neuronal synapses. These conflicting cannabinoid-triggered signals create confusion, interfering with normal brain function, synaptic plasticity and, ultimately, with the ability to learn.”

[Suetaznote: I don't know if they've got this right. It may effect some people's ability to learn, but most people find that using Marijauna enhances their learning, or at the very least it doesn't deter their learning. I wonder if it has more to do with dosage than anything. Maybe all the people they have studied were too stoned and inexperienced with weed. Concentration effects memory. If we can't concentrate enough on something, we won't be able to remember it. I know if I am too stoned, I can't concentrate on anything. If I am stoned 'just right', you can't break my concentration. My concentration and the ability to learn and retain what I learn depends on how stoned I am. I don't learn or retain as much when I am sober as I do when I am stoned just the right amount.]

The researchers were surprised to find that endocannabinoid signaling could be confined to a local region of neurons. "Edocannabinoids did not operate in as diffuse a manner as we had imagined,” says Dr. Castillo. “Instead, they're released into specific synapses in the hippocampus, where endocannabinoid signaling plays a complex and important role in the storage of memories.

Through further study of the internal system, Dr. Castillo and his colleagues hope to gain understanding of how activation of the endogenous system occurs. “By learning how the naturally occurring cannabinoid system is activated,” says Dr. Castillo, “we can begin to develop a strategy for understanding the effects that the cannabinoids from Marijuana smoking have on it. Only then can we think about developing agents for blocking their adverse effects.”

[Suetaznote: Yeshiva University is in the Bronx, NY for those that have never heard of it. It's good to hear of more Marijuana research being done in the US, even if it isn't Federally funded or approved.]

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cassiusclay

“When a person smokes Marijuana, an outside signal triggered by the THC is received in the brain,” he says. “But at the same time, the brain’s naturally occurring cannabinoids are also sending messages via neuronal synapses. These conflicting cannabinoid-triggered signals create confusion, interfering with normal brain function, synaptic plasticity and, ultimately, with the ability to learn.”


Why does he assume that there is a conflict between endo-cannabs and smoked ones? At the end he says he needs to study more even to begin to understand what he assumes is true. blah.

If you think you're supposed to be stupid when you get high, you'll feel stupid. What's actually happening is your brain is being freed to work in ways you can't achieve by just eating your wheaties. The potential to learn is still there, its just that you may no longer be interested in what you thought you wanted to learn before smoking.

I had a 3.0 (all I really wanted actually) gpa in engineering school and smoked all the time. It was hard to concentrate at first, kinda like getting used to a clutch on a new sports car, but after a short time I was able to focus much better. I became interested in why everything worked instead of just trying to memorize stuff to pass. Short term memory took practice but during that practice, I believe long term memory became greatly enhanced.

PotShot

While I agree that it takes a little bit of practice to get used to memory and learning while being stoned, I in no way think that it is permanent. My first 10 or so experiences with cannabis are VASTLY different than my smoke sessions now. Be it physical tolerance, or just my adaption to my "stoned perception", cannabis does not affect my concentration, learning ability, or memory like it used to(unless as Suetez noted, I am REALLY stoned ).

At the very least this is research, and I fully support any research into the workings of the human mind(as long as its not used for nefarious purposes i.e. MIND CONTROL). Go Science!

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Carl Sagan Goodness Richard Dawkins Goodness

Suetaz

Who moved my worm? Bird-food study by Cornell biologists shows role of brain's cannabinoid chemicals in dealing with change

Cornell News
FOR RELEASE: Sept. 29, 2004
Contact: Roger Segelken
Office: 607-255-9736
E-Mail: hrs2@cornell.edu

ITHACA, N.Y. --Some birds' already-amazing memories -- for the thousands of different spots where they cached their food -- can be further improved by blocking natural brain chemicals called cannabinoids, which resemble the active ingredient THC in Marijuana.

But improved memory can be a liability for cannabinoid-free birds, Cornell University researchers have discovered: When their food is moved, birds without benefit of cannabinoids have trouble imagining where else the food might be.

The discovery is reported in the British journal, Proceedings of the Royal Society: Biological Sciences (Vol. 271, No. 1552, Oct. 7, 2004) under the title, "Cannabinoid Inhibition Improves Memory in Food-storing Birds."

Timothy J. DeVoogd, the Cornell professor of psychology and of neurobiology and behavior who led the study, comments: "Since Marijuana is known to impair formation of new memories in people, perhaps an anti-cannabinoid drug like the one we used in this research might improve the retention of a new memory in people, just as it does in birds. However, this research suggests that enhanced memory retention might come with a cost -- the loss of the ability to change the memory. Perhaps the reason cannabinoid sensitivity exists in the brain is to provide a balance in memory, between accuracy and flexibility."

The Cornell biologists' study focused on food storage by black-capped chickadees (Poecile atricapilla ) and examined the function of a cannabinoid receptor called CB1-R in the bird's hippocampus, the same area of the brain used by humans for storing memories. CB1-R receptors react to changing levels of so-called endogenous cannabinoids, the natural hormones such as anadamide, circulating inside animals' bodies.

Cannabinoids were named for cannabis plants where the hormones were first identified. Since then, studies in other laboratories have suggested a variety of roles for the body's endogenous cannabinoid system -- ranging from pain control, reproduction, vision and immune function to learning, memory formation and retention. In the Cornell study, endogenous cannabinoids were blocked from reaching the birds' CB1-R receptors with a cannabinoid-antagonist drug called SR141716A.
For chickadees treated with anti-cannabinoid drugs and for "control" birds receiving a placebo treatment that allowed endogenous cannabinoids to reach their brain receptors, the assigned task was a simpler form of a food-storage exercise wild birds perform thousands of times each season -- remembering where bits of food were hidden. First the chickadees were allowed to find a mealworm that scientists had placed in one of 19 identical feeding holes. Then the lights went out and the birds returned to their nests. Seventy-two hours later, when the birds were released to visit the feeders, knotted string had been stuffed in all 19 feeding holes to conceal the worm.

Birds that had learned while on cannabinoid blockers were more successful at finding the hidden worm on the first try, while birds with endogenous cannabinoids reaching their brain receptors made more errors -- they pulled out several knotted strings before finding the food cache.

Then the scientists changed the game plan. They placed a worm in a different feeding hole, allowed all the birds to find the new location, and repeated the exercise. This time it was the cannabinoid-blocked birds that made more mistakes. They returned again and again to the hole where the first worm had been hidden. They frantically tugged on nearby knots to look for worms. But they couldn't seem to erase the memory of the first feeding hole and comprehend that the worm had been moved.

However, birds with free-flowing cannabinoids took the change in stride. They wasted little time searching for worms in the first location and easily moved on to the next site. They were better able to do what food-storing birds outside the laboratory do naturally -- "extinguish the previous memory trace and avoid revisiting emptied cache sites," as the biologists explained in their Proceedings report.

Cannabinoid signaling was allowing the control birds to overcome the source of errors made by the cannabinoid-blocked birds, the so-called proactive interference in which an old memory interferes with a new one, such that the birds cannot shift attention to new sites.

"It may be that both states of cannabinoid exposure, which we manipulated separately in our experiments, normally alternate in the same birds with such prodigious memories for food-storage sites," DeVoogd said. "Perhaps the endogenous cannabinoid system switches on and off, briefly reducing exposure to the chemical to help memories form, then increasing cannabinoid levels when the memory is no longer needed."

Also conducting the study, which was funded by the National Institutes of Health, were Alexander Z. Rankin, a Cornell undergraduate who is now in medical school at Loyola University; Michelle L. Tomaszycki, , a research associate at Cornell; and Michael W. Shiflett, who is now a researcher at the University of Pittsburgh.

Mamabudz

So basically cannabinoid-triggered signals from THC and endogenous cannabinoids interfering with normal brain function in the synapeses.

I believe the correct term for this condition is STONED

As for effecting learning functions, memory and behaviour -- this is old news. Cannabis effect all three. That is why people smoke it.

Is the effect long term? So far studies have shown NO long term effect.

Is the effect negative? That depends on with whom you speak.

Having a didactic memory can be an excellent tool however, it is not all it's cracked up to be, being able to put breakers on it is quite helpful -- especially when you wish to sleep.

Being able to sublimate recurring thoughts of traumatic events is a blessing for those suffering the effects of post traumatic stress.

Mood elevation to a severly depressed person is simply put: life saving.

That's my opinion...but you know I've been known to smoke pot...

...have a cookie

Mama Budz