Tag Archives: Memory
Skull electrodes give memory a boost
Scientists find link in humans between nerve cell production & memory
The researchers studied how stem cells in a memory-related region of the brain, called the hippocampus, proliferate and change into different types of nerve cells. Scientists have been unsure of the significance of that process in humans.
“The findings suggest that if we can increase the regeneration of nerve cells in the hippocampus we can alleviate or prevent memory loss in humans,” said Florian Siebzehnrubl, Ph.D., a postdoctoral researcher in neuroscience in the UF College of Medicine, and co-first author of the study. “This process gives us what pharmacologists call a ‘druggable target.’”
Over the past two decades, several studies have shown that new nerve cells are generated in the hippocampus. In animal studies, disrupting nerve cell generation resulted in the loss of memory function, while increasing the production of new nerve cells led to improved memory.
To investigate whether the same is true in humans, the UF researchers, in collaboration with colleagues in Germany, studied 23 patients who had epilepsy and varying degrees of associated memory loss. They analyzed stem cells from brain tissue removed during epilepsy surgery, and evaluated the patients’ pre-surgery memory function.
In patients with low memory test scores, stem cells could not generate new nerve cells in laboratory cultures, but in patients with normal memory scores, stem cells were able to proliferate. That showed, for the first time, a clear correlation between patient’s memory and the ability of their stem cells to generate new nerve cells.
Seeing the Brain Hear Reveals Surprises About How Sound Is Processed
New research shows our brains are a lot more chaotic than previously thought, and that this might be a good thing. Neurobiologists at the University of Maryland have discovered information about how the brain processes sound that challenges previous understandings of the auditory cortex that suggested an organization based on precise neuronal maps.
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Kanold and colleagues were able to look at the activity of all the neurons in a large region of the auditory cortex simultaneously. To get the highest resolution picture to date of how auditory cortex neurons are organized, the researchers used a technique to fill neurons in living mice with a dye that glows brightly when calcium levels rise, a key signal that neurons are firing. They then selectively illuminated specific regions of the cortex with a laser and measured the neuronal activity of hundreds of neurons in response to stimulation by simple tones of different frequencies.
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“We discovered that the organization of the cortex does not look as pretty as it does in the textbooks, which surprised us,” explains Kanold. “Things are a lot messier than expected.” And we don’t see evidence of the maps previously proposed using less precise techniques.” But the disorder they found could indicate that the brain is far more adaptable than previously thought. “These results may rewrite our classical views of how cortical circuits are organized and what functions they serve,” suggests Dr. Shihab Shamma, whose previous research has involved mapping responses in the auditory cortex using traditional microelectrodes.
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This suggests that there is very little redundancy in the function of cells in the auditory cortex, which differs notably from the visual cortex, in which neighboring neurons perform the same function as one another. This could be because our acoustic environment, such as the speech we hear, changes much faster than our visual environment, so we have to constantly adapt to new situations.
