Introducing the enlarging brain: human cerebellum different (Introduction)

by David Turell , Sunday, June 14, 2020, 23:36 (1621 days ago) @ David Turell

I have tried to clarify why our cerebellum is different according to recent research:

https://www.sciencealert.com/a-hidden-region-of-the-human-brain-was-revealed-while-maki...

"A previously unknown brain structure was identified while scientists carefully imaged parts of the human brain for an upcoming atlas on brain anatomy.

"Neuroscientist George Paxinos and his team at Neuroscience Research Australia (NeuRA) have named their discovery the the endorestiform nucleus. This landmark study suggests that the way our brains plan our movements takes into account not only the muscles we think we might need to flex, but also whether we believe the outcome of this movement will be rewarding. As we currently understand it, the cerebellum receives two basic types of information: what we plan to do when we make a movement, and the actual result of that movement (as seen by our eyes and felt by our skin/muscles). For example, let’s say we try to hold up two fingers on our right hand, but instead we extend all five. In that case, the cerebellum would detect a significant difference in our motor plan and our motor outcome. This discrepancy would be impossible to avoid in the future without the cerebellum, which is believed to correct such motor errors by sending highly-specific “teaching” signals to the other areas of the brain’s motor system8, 9. But if we believe a movement will result in a positive, rewarding experience, and then it turns out that it actually doesn’t, isn’t this also a form of error? Wagner and Kim’s work suggests that our brains might very well perceive it this way. More importantly, though, they have shown that this “motivation error” is processed, at least in part, in the same way that a motor error is: using the powerful circuits within the cerebellum. - because it is located within (endo) the inferior cerebellar peduncle (also called the restiform body). It's found at the base of the brain, near where the brain meets the spinal cord.

"This area is involved in receiving sensory and motor information from our bodies to refine our posture, balance and movements.

**"

"The location of this elusive brain bit leads Paxinos to suspect it may be involved in fine motor control - something also backed up by the fact that this structure has yet to be identified in other animals, including marmosets or rhesus monkeys.

"I cannot imagine a chimpanzee playing the guitar as dexterously as us, even if they liked to make music," Paxinos pointed out. (my bold)

"Humans have brains at least twice as big as chimpanzees (1,300 grams vs 600 grams, or 2.9 lbs vs 1.3 lbs), and a larger percentage of our brain neuronal pathways that signal for movement make direct contact with motor neurons - 20 percent compared to 5 percent in other primates.
So, the endorestiform nucleus may be another unique feature in our nervous system, although it's too soon to tell just yet. Paxinos is set to do some work in chimpanzees soon.

Additional related functions:

https://scasource.net/2018/10/26/accidental-discovery-reveals-possible-link-between-cer...

"Recently, though, there have been some hints that there is more to this part of the brain than we might have thought: brain imaging studies of patients suffering from bipolar disorder, for instance, have sometimes shown abnormalities in the cerebellum. Cerebellar abnormalities have been implicated in a variety of other diseases, as well, including autism spectrum disorders, schizophrenia, Alzheimer’s disease, and multiple sclerosis. Now, thanks to the hard work of scientists at Stanford University7 – as well as a bit of luck – we know that the cerebellum is not only involved in how we move, but why.

"This landmark study suggests that the way our brains plan our movements takes into account not only the muscles we think we might need to flex, but also whether we believe the outcome of this movement will be rewarding. As we currently understand it, the cerebellum receives two basic types of information: what we plan to do when we make a movement, and the actual result of that movement (as seen by our eyes and felt by our skin/muscles). For example, let’s say we try to hold up two fingers on our right hand, but instead we extend all five. In that case, the cerebellum would detect a significant difference in our motor plan and our motor outcome. This discrepancy would be impossible to avoid in the future without the cerebellum, which is believed to correct such motor errors by sending highly-specific “teaching” signals to the other areas of the brain’s motor system. But if we believe a movement will result in a positive, rewarding experience, and then it turns out that it actually doesn’t, isn’t this also a form of error? Wagner and Kim’s work suggests that our brains might very well perceive it this way. More importantly, though, they have shown that this “motivation error” is processed, at least in part, in the same way that a motor error is: using the powerful circuits within the cerebellum."

Comment: Our larger cerebellum is more involved with our larger cerebrum than in animal brains. Note the bold. The endorestiform nucleus means we can do a whole lot more with our fingers than apes can. Looks certainly like the sapiens brain made for future functions, anticipated by a designer, but no cell committees would hav e thought of them.