Posts Tagged ‘Christoph Nissen’

We’ve Finally Seen How the Sleeping Brain Stores Memories

December 29, 2017

The title of this post is identical to the title of a post by Jessica Hamzelou in the 7 October 2017 issue of the New Scientist. To do this research needed to find volunteers who were able to sleep in an fMRI scanner. They needed to scan 50 people to find the 13 who were able to do so. These volunteers were taught to press a set of keys in a specific sequence. It took each person between 10 to 20 minutes to master this sequence.

Once they learned this sequence they each put on a cap of EEG electrodes to monitor the electrical activity of their brains, and entered an fMRI scanner, which detects which regions of the brain are active.

There was a specific pattern of brain activity when the volunteers performed the key-pressing task. Once they stopped, this pattern kept replaying in their brains as if each person was subconsciously reviewing what they had learned.

The volunteers were then asked to go to sleep, and they were monitored for two and a half hours. At first, the pattern of brain activity continued to replay in the outer region of the brain called the cortex, which is involved in higher thought.

When the volunteers entered non-REM sleep, which is known as the stage when we have relatively mundane dreams, the pattern started to fade in the cortex, but a similar pattern of activity started in the putamen, a region deep within the brain
(eLife, doi.org/cdsz). Shabbat Vahdat, the team leader at Stanford University, said that the memory trace evolved during sleep.

The researchers think that movement-related memories are transferred to deeper brain regions for long-term storage. Christoph Nissen at University Psychiatric Services in Bern Switzerland says, “this chimes with the hypothesis that the brain;’s cortex must free up space so that it can continue to learn new information.

The title of this post is identical to the title of a post by Jessica Hamzelou in the 7 October 2017 issue of the New Scientist. To do this research needed to find volunteers who were able to sleep in an fMRI scanner. They needed to scan 50 people to find the 13 who were able to do so. These volunteers were taught to press a set of keys in a specific sequence. It took each person between 10 to 20 minutes to master this sequence.

Once they learned this sequence they each put on a cap of EEG electrodes to monitor the electrical activity of their brains, and entered an fMRI scanner, which detects which regions of the brain are active.

There was a specific pattern of brain activity when the volunteers performed the key-pressing task. Once they stopped, this pattern kept replaying in their brains as if each person was subconsciously reviewing what they had learned.

The volunteers were then asked to go to sleep, and they were monitored for two and a half hours. At first, the pattern of brain activity continued to replay in the outer region of the brain called the cortex, which is involved in higher thought.

When the volunteers entered non-REM sleep, which is known as the stage when we have relatively mundane dreams, the pattern started to fade in the cortex, but a similar pattern of activity started in the putamen, a region deep within the brain
(eLife, doi.org/cdsz). Shabbat Vahdat, the team leader at Stanford University, said that the memory trace evolved during sleep.

The researchers think that movement-related memories are transferred to deeper brain regions for long-term storage. Christoph Nissen at University Psychiatric Services in Bern Switzerland says, “this chimes with the hypothesis that the brain;’s cortex must free up space so that it can continue to learn new information.

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Why Do We Sleep?

December 10, 2016

The question raised by the title of this post is highly relevant given that about one-third of our lives is spent sleeping.  A brief piece  titled “A bad night’s sleep messes with your brain’s memory connections in the In Brief Section of the August 27, 2016 Edition of the “New Scientist” provides a compelling answer.  The piece begins with the following sentence, “This is why you feel so awful after a bad night’s sleep—your brain is jammed with yesterday’s news.”

The research was done by Christoph Nissen and his team at the University Medical Center in Freiburg, Berman.  They examined the brains of 20 people after they’d slept well, and after a night of disruption.  They found that after a bad’s night sleep, people had higher levels of theta brainwaves, and it was easier to stimulate their brains using magnetic pulses (“Nature Communications.” DOI”10.1038/ncomms12455).

The findings support the theory that sleep serves to weaken memory connections, making way for new ones.  Nissan says that without this synaptic downscaling, the brain loses the capacity to for novel connections, impairing the encoding of novel memories.  The theory is that sleep evolved so that connections in the brain can be pruned down during slumber, making room for fresh memories to form the next day.

The idea that sleep is important to memory is not new.  And memory is certainly important enough that we need to devote about one-third of our lives supporting it. Of course, it is likely that memory is not the only capacity to benefit, but it is likely that other capacities that benefit are closely related to memory.

© Douglas Griffith and healthymemory.wordpress.com, 2016. Unauthorized use and/or duplication of this material without express and written permission from this blog’s author and/or owner is strictly prohibited. Excerpts and links may be used, provided that full and clear credit is given to Douglas Griffith and healthymemory.wordpress.com with appropriate and specific direction to the original content.