Introducing the brain: our amazing cerebellum (Introduction)

by David Turell , Wednesday, October 16, 2024, 21:25 (36 days ago) @ David Turell

Really helps our movements:

https://www.sciencedaily.com/releases/2024/10/241015141324.htm

"More than half a century ago, neuroscientists discovered that damage to a brain region called the medial temporal lobe (MTL) caused a severe impairment to long-term declarative memory -- memories for explicit facts such as names and dates -- but left very short-term memory intact. Patients with damage to the MTL could keep up with and carry on a short conversation but, just a minute or two later, couldn't remember that the conversation even took place.

"Surprisingly, though, those patients could learn new motor skills and retain them for days, months, or even longer, indicating that MTL damage had little effect on memories for motor skills.

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"Now, researchers from the Harvard John A. Paulson School of Engineering and Applied Sciences (SEAS) have shown that, just like declarative memories, short-term and long-term memories for motor skills form in different regions of the brain, with the cerebellum being critical for the formation of long-term skill memories.

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"Researchers have long known that the cerebellum is critical for motor learning, but the role it plays in forming short- and longer-term skill memory was unclear. To understand the connection between the cerebellum and these memories, Smith and first author Alkis Hadjiosif, a postdoctoral fellow at SEAS and Massachusetts General Hospital, took inspiration from a seemingly messy set of previous results on motor learning in patients with cerebellar damage.

"While these previous studies all found evidence for impaired sensorimotor learning in individuals with cerebellar damage, the size of this impairment varied widely among them.

"'While this discrepancy might have been due to differences in the amount or precise location of the damage or to differences in the types of motor learning tasks employed, we had a different idea," said Smith.

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"The researchers found that both studies had rather short intertrial intervals overall and reported only small impairments in learning for patients with severe cerebellar disease compared to healthy individuals. This meant that when participants were asked to perform the same task, say, five times, with only a few seconds between each repetition, the patients with cerebellar degeneration performed only slightly worse than healthy individuals.

"But by diving deeper into the data, Smith and Hadjiosif found something interesting. Between trials, there was sometimes more time to allow the research team to reset or the participant to take a short break.

"'When we examined these trial-to-trial differences, we found that the same patients who displayed near-normal performance on their short-interval practice trials were dramatically impaired on long-interval trials within the same session. And this was the case in the data from both studies," said Hadjiosif.

"The team then looked at more than a dozen additional studies in which individuals with cerebellar degeneration performed motor tasks and found that the studies that used a larger number of movement directions in the task -- which would increase the time between same-direction trials that would share sensorimotor memory -- had dramatically increased memory impairment compared to those with fewer movement directions."

Comment: this clearly shows how important the cerebellum is to all of our possible movements and the fact that it has a past memory of coordinated movements.