Big brain evolution: early research on cerebellum (Evolution)

by David Turell , Tuesday, January 22, 2019, 21:29 (2130 days ago) @ David Turell

Not much research has been done on humans and not much is known about apes:

https://www.scientificamerican.com/article/the-cerebellum-is-your-little-brain-mdash-an...

"For the longest time the cerebellum, a dense, fist-size formation located at the base of the brain, never got much respect from neuroscientists.

"For about two centuries the scientific community believed the cerebellum (Latin for “little brain”), which contains approximately half of the brain’s neurons, was dedicated solely to the control of movement. In recent decades, however, the tide has started to turn, as researchers have revealed details of the structure’s role in cognition, emotional processing and social behavior.

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"One of the strongest pieces of evidence for the cerebellum’s broader repertoire emerged around two decades ago, when Jeremy Schmahmann, a neurologist at Massachusetts General Hospital, described cerebellar cognitive affective syndrome after discovering behavioral changes such as impairments in abstract reasoning and regulating emotion in individuals whose cerebella had been damaged. Since then this line of study has expanded. There has been human neuroimaging work showing the cerebellum is involved in cognitive processing and emotional control—and investigations in animals have revealed, among other things, that the structure is important for the normal development of social and cognitive capacities. Researchers have also linked altered cerebellar function to addiction, autism and schizophrenia.

"Although many of these findings suggested the cerebellum played an important part both in reward-related and social behavior, a clear neural mechanism to explain this link was lacking. New research, published this week in Science, demonstrates that a pathway directly tying the cerebellum to the ventral tegmental area (VTA)—one of the brain’s key pleasure centers—can control these two processes.

"Earlier investigations in his lab had hinted there might be unexpected connections between the cerebellum and other parts of the brain. Specifically, while examining the brain circuits underlying dystonia—a movement disorder that causes uncontrollable muscle contractions—in mice, Khodakhah’s team discovered the cerebellum directly communicated with the basal ganglia (involved in movement, motivation and reward functions) to control complex movements. It was previously thought that to coordinate such actions, the two brain areas communicated via the cortex, the region responsible for higher-order tasks such as planning and decision-making.

"Earlier investigations in his lab had hinted there might be unexpected connections between the cerebellum and other parts of the brain. Specifically, while examining the brain circuits underlying dystonia—a movement disorder that causes uncontrollable muscle contractions—in mice, Khodakhah’s team discovered the cerebellum directly communicated with the basal ganglia (involved in movement, motivation and reward functions) to control complex movements. It was previously thought that to coordinate such actions, the two brain areas communicated via the cortex, the region responsible for higher-order tasks such as planning and decision-making.

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“'This [study] is one of the most clear and interesting demonstrations that the cerebellum is indeed involved in the control of high-level, nonmotor functions,” says Egidio D’Angelo, a neurophysiologist at the University of Pavia in Italy who was not part of the work."

Comment: Most of the human brain enlargement has not been in the cerebellum but in the frontal and pre-frontal lobes, and so my guess is that the ape cerebellums will be found to be quite similar to the human.