Saturday, May 05, 2018
Irresistible image
This week I'm working on a courseware chapter about the cerebellum. Making animations forces me to (partly!) learn what's going on. In the brainstem and cortex, we have a fairly good sense of how things work, partly because the cortex is divided into visible sections with specific functions. The cerebellum is more mysterious, partly because it's not neatly modular and partly because its function seems to depend on waves and resonance.
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The cortex has folds on its surface that correspond closely to areas of function. You can see the sensory strip, the motor strip, the speech reception area, and so on, as hills or bumps.
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The cerebellum just has uniform unmarked folds, called folia or pages. One folium is lined in green.
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Here's a super-simplified piece of one folium:
The main players are the granule cells (blue) and the Purkinje cells (purple).
Granule cells (blue) are small, simple and NUMEROUS, making up 80% of ALL the neurons in the WHOLE brain. They are scattered densely through the interior of the cerebellum. Each granule cell picks up signals from the input mossy fibers (green). Most of the input is from the body via the spine; some is from eyes, ears, balance mechanisms, and cortex. The output of each granule cell splits into a T-shaped parallel fiber, which runs along the length of the folium. These parallel fibers are densely packed along the surface of the cerebellum.
Purkinje cells (purple) are the receivers. They're BIG and relatively sparse, and gridded in a tight layer underneath the parallel fibers. They pick up signals from the parallel fibers, do something with the signals, and send the processed or sorted signals back down to the spine to drive muscles.
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Given that the granules are known to be resonant senders of modulated pulses, this image is irresistible:
Here the resonant dipole sending antenna (parallel fibers) is producing a tuned signal, and Polistra (Purkinje) is tuning her receiver to pick up this particular sender. In the real world, as in the real cerebellum, there are many sending antennas and many receivers, each seeking out its desired signal.
Pulling the metaphor to the breaking point: Since the transmitting parallel fibers are along the surface of the cerebellum, are they also transmitting externally to other brains? And past the breaking point, power of prayer? These neurons do a whole lot of monostable and astable multivibrator activity. When internal sync is gone, can external input resync?
= = = = =
The cerebellum just has uniform unmarked folds, called folia or pages. One folium is lined in green.
= = = = =
Here's a super-simplified piece of one folium:
The main players are the granule cells (blue) and the Purkinje cells (purple).
Granule cells (blue) are small, simple and NUMEROUS, making up 80% of ALL the neurons in the WHOLE brain. They are scattered densely through the interior of the cerebellum. Each granule cell picks up signals from the input mossy fibers (green). Most of the input is from the body via the spine; some is from eyes, ears, balance mechanisms, and cortex. The output of each granule cell splits into a T-shaped parallel fiber, which runs along the length of the folium. These parallel fibers are densely packed along the surface of the cerebellum.
Purkinje cells (purple) are the receivers. They're BIG and relatively sparse, and gridded in a tight layer underneath the parallel fibers. They pick up signals from the parallel fibers, do something with the signals, and send the processed or sorted signals back down to the spine to drive muscles.
= = = = =
Given that the granules are known to be resonant senders of modulated pulses, this image is irresistible:
Here the resonant dipole sending antenna (parallel fibers) is producing a tuned signal, and Polistra (Purkinje) is tuning her receiver to pick up this particular sender. In the real world, as in the real cerebellum, there are many sending antennas and many receivers, each seeking out its desired signal.
Pulling the metaphor to the breaking point: Since the transmitting parallel fibers are along the surface of the cerebellum, are they also transmitting externally to other brains? And past the breaking point, power of prayer? These neurons do a whole lot of monostable and astable multivibrator activity. When internal sync is gone, can external input resync?
Labels: Asked and unanswered, Grand Blueprint
¶ 7:47 AM
