NOTICE: Posting schedule is irregular. I hope to get back to a regular schedule as the day-job allows.

Sunday, February 6, 2011

We call them "Nuclei", not "Brainzzzz!"

Again, many thanks to Sotarr for the link to Pinky and the Brain's guide to the brain. It's almost as good as a LabRat's Guide.

So, continuing with the structure of the brain – at right is an image showing the deeper structure. To give credit where credit is due, this image comes from, by S.N. Koch, another scientist-writer although focused more on human behavior. There are some interesting descriptions on the site, and I refer you to it as further reading.

The thalamus is the major relay for sensory information – particularly feedback from the rest of the body that is used to assess the results of movements. The primary function is one of switching or routing the inputs to the appropriate cortical (surface) areas (vision, hearing, touch, etc.). There are also connections between cortical areas that are routed through thalamus, and it is essential at directing information that needs to be combined – i.e. vision plus muscle movement for visual tracking, hearing plus vision for speech. The lentiform nucleus – also called "corpus striatum" (striped body) or "striatum" – manages movement. Parkinson's Disease affects neurons in this part of the brain. Striatum also serves as an essential component of learned behaviors, by providing information about reward and motivation. It is the neurons in this region that are involved in the behaviors leading to drug abuse, as well as positive/negative reinforcement training.

Hypothalamus is not well labeled in this diagram, but is the yellow area under ("hypo") the thalamus. This region is involved in all of the hormonal and "autonomic" (think of it as "automatic") functions of the body – hunger, satiety, temperature regulation, metabolism, menstrual cycle…

Pons and medulla are relay points in the nerve and muscle connections between brain and body (via the spinal cord). They also form the muscle control equivalent of the hypothalamus: heart rate, respiration rate, eyeblink. Some of the "reflex" actions such as control of muscles that push vs. pull at the same joint are handled here as well as deeper within the spinal cord.

I saved amygdala and hippocampus for last, largely because they figure prominently in future blogs. I will go into *much* more detail about hippocampus in discussion of memory. Amygdala is commonly called the center of emotion. While this is not strictly true, amygdale – in fact the whole "limbic system" – mammillary bodies, fornix amygdale and hippocampus (yes, they form a loop – when viewed from the side, it forms almost a complete cycle of a spiral) are involved in processing emotion. More appropriately, amygdala is involved in processing the emotional content or context of information. To do so requires reference to memory – and that requires hippocampus, and the temporal and frontal cortex.

Next blog, I'll talk about the brain cells themselves, and then bring on the dancing rats for some more generalized discussions!

1 comment:

  1. Hmmmm. So, for we folk steeped in Gymnastics, from a very early age, the links in the parts, above, work together when "Total Spatial Awareness", by the gymnast's body/brain collaboration, is working? In my case it is alla time - I just notice it after bod is already deep into emergency response to slippin whilst walking, or after bod/vehicle combo is already deep into coping with sudden sideways-on-black-ice at 2am, onna Alaska Highway, going _uphill_. Thinkings Control Centre has to set down Beverage, and close book, ere starting to direct traffic, as it were... Putting on Skates, putting on Skiis, and putting on Snoshoes, alerts an extra set of Spatial Awareness subroutines, as best as I can explain the goings-on, in there...
    Neil Frandsen


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