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Old 05-01-2014, 04:20 PM
brujaja is offline
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What is the neurochemical necessary for memory formation?


I'm recalling a TV show of some kind where they deprived test animals of this chemical (blocked it or whatever) and the animals could not remember a maze.

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Old 05-01-2014, 06:15 PM
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Glutamate in parts of the hippocampus, probably, disrupting long term potentiation. You can't really deprive animals of that without killing them, but chemicals can block it in some way.

Morris et al. 1982 Nature is one cite but with lesions in a Morris water maze.

ETA: lidocaine seems to have been used, but it's not a glutamate antagonist AFAIK.

Last edited by thelurkinghorror; 05-01-2014 at 06:16 PM.
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Old 05-01-2014, 06:20 PM
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They might possibly have done this with some drug that, very temporarily, blocked protein synthesis. However, protein synthesis is very basic to all processes of life, so if any animal was on such a drug for more than a very short time, it would die.

There is no single chemical, or even group of chemicals, that is necessary for memory formation and which you could otherwise do without. (Protein, incidentally, is not a single chemical but a huge class of chemicals with vastly varying properties that play many, many different vital roles in living organisms.) Furthermore, the point is not just that we do not know very much about how memory formation works yet (although that is true); we do know enough to know that it is not going to be anything like that simple.

ETA: Also, @thelurkinghorror, memory formation does not happen in the hippocampus.

Last edited by njtt; 05-01-2014 at 06:24 PM.
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Old 05-01-2014, 06:47 PM
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Quote:
Originally Posted by njtt View Post
ETA: Also, @thelurkinghorror, memory formation does not happen in the hippocampus.
Consolidation does, and I interpret the OP as saying that treated animals were put through a maze, and could not remember it once the drug wore off.
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Old 05-01-2014, 07:42 PM
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Originally Posted by thelurkinghorror View Post
Consolidation does, and I interpret the OP as saying that treated animals were put through a maze, and could not remember it once the drug wore off.
I meant to say "does not all happen in the hippocampus."

Where do hippos go to school?
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Old 05-01-2014, 07:57 PM
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I'm pretty sure it was glutamate I was thinking of. Is this pathway something that could ever become blocked in humans by diet, dysfunction, or behavior?
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Old 05-01-2014, 09:02 PM
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Right. If you ask "where does LTM memory occur?" the answer is "take your pick." No specific part of your brain holds it all.

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Originally Posted by brujaja View Post
I'm pretty sure it was glutamate I was thinking of. Is this pathway something that could ever become blocked in humans by diet, dysfunction, or behavior?
The main problem is that glutamate is the most common excitatory neurotransmitter, and possibly the neurotransmitter we have the most of period (citation needed). It's used all over the brain so it's hard to pinpoint directly. And biosynthesis is from glutamine, among others. I have no idea if it's possible to severely limit your intake but it's in a lot of things.

Glutamate receptors come in different varieties. All respond to glutamate, but some respond to chemicals that other receptors don't. NMDA and AMPA receptors are the most involved in memory, IIRC.

Too much glutamate can affect you with excitotoxicity or a loss of glutamate:
Olney's lesions. See caveats and all.

They use some drugs to affect memory. PCP, ketamine, DXM are glutamate are antagonists. It's debatable whether they can permanently damage your brain. But sometimes they might help: MDMA/ecstasy could be used to treat PTSD (increases monoamines like serotonin).

Last edited by thelurkinghorror; 05-01-2014 at 09:03 PM.
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Old 05-02-2014, 09:50 AM
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I'm pretty sure it was glutamate I was thinking of. Is this pathway something that could ever become blocked in humans by diet, dysfunction, or behavior?
No. Glutamate is ubiquitous in the body, not just the brain, and plays a vital role in the biochemistry of, essentially, all living things. Although it may be possible for scientists to interfere with limited aspects of glutamate metabolism in a very temporary and localized way so as to affect memory formation without any other very serious ill effects, any more general interference with glutamate metabolism sufficient to affect memory, with blunt instruments like diet, etc., would very quickly prove fatal.

Last edited by njtt; 05-02-2014 at 09:53 AM.
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Old 05-02-2014, 03:52 PM
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Quote:
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I'm recalling a TV show of some kind where they deprived test animals of this chemical (blocked it or whatever) and the animals could not remember a maze.
Could you be thinking of cAMP Response Element-binding Protein? CREB is highly involved in memory formation and other cognitive processes, and while its production isn't governed by nutritional inputs directly but gene expression can (and has) been altered in Drosophila melanogaster, various members of Cephalaspidea, rats, mice, and other creatures to cause them to produce the inactive (non-binding) form of CREB which prevents the formation of long term memories.

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