Wednesday, November 29, 2006

Stuff I forgot to mention about memory

And speaking of memory here and here, there's recent research I forgot to mention. Oh, the irony. (Damn! I sure hope someone comes up with a memory pill, and fast.)

First up is a gene named Kibra. It's expressed in the hippocampus, and has been found to be associated with memory performance.

Research Team Identifies Human 'Memory Gene'
The impact of the study is that it gives the research community a new and important handhold into truly understanding the process of memory. The ramifications of this report are ultimately developing new and effective medicines that can combat memory loss, and that might also help improve memory in people with memory disorders like Alzheimer's disease.

The team has already begun working on new drugs to restore memory function in age-related memory loss and diseases that have a memory loss component.

What this press release doesn't make clear is that discovering exactly what the protein corresponding to this gene does in neurons of the hippocampus will help us understand memory better. And that in turn may help find ways to augment memory even in people who don't have memory disorders.

In the meantime, while we're awaiting such a breakthrough, research has found ways to make the best use of the memory we have. First:

Asleep at the Memory Wheel
Going a night without sleep may cause your hippocampus to go on strike. A new study has caught this crucial memory-encoding brain region slacking off in college students the day after they've pulled an all-nighter. The study is one of the first to investigate how sleep deprivation interferes with memory mechanisms in the human brain.

Unfortunately, you need a subscription to Science in order to see the full article, but the key point is this:
To find out which part of the brain was responsible for this forgetfulness, the researchers repeated the experiment with a different group of undergrads, but this time used functional magnetic resonance imaging (fMRI) to monitor brain activity while the students viewed a set of emotionally neutral photographs. The fMRI scans revealed lower activity in the hippocampus of sleep-deprived students than in well-rested students. This suggests that just as sleep is important for consolidating new memories after they're learned, as other studies have shown, it's equally important for preparing the brain to learn new things the following day.

This work was done by Matthew Walker and his colleagues at Harvard. Here are several reports of releated work they've done previously.

One last item – if you want a good memory, lay off the weed:

Marijuana wreaks havoc on brain's memory cells
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.

See also: Marijuana's High Times Not Memorable with Neurons Out of Sync

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