Structure and Operation of the Human Brain – Week 8

This week we had a lecture on the motor system; it started with a recap of the somatotopic map of the body surface onto primary somatosensory cortex, also known as the homunculus. It’s a visual representation which illustrates a cross section of the postcentral gyrus and represents which neurons are most responsive to parts of the body. This provided a good segue to start talking about the spinal control of movement.

To understand the somatic motor system (the skeletal muscle and the parts of the nervous system that controls them) we need to understand the motor units (a motor neuron and the skeletal muscle fibers that are innervated by the motor neuron’s axons) work- that is, to understand the muscles and the motor neuron’s innervations.

The muscle fibers only contract, and to cause extension or flexion of a joint we have different muscles which are extensors or flexors respectively. There are three types of motor units that contract: Fast fatigable, fast fatigue-resistant and slow, the type of motor unit is controlled by the type of alpha neuron.

We also reviewed the mechanism for this contraction at a molecular level.

In the last part we talked about the pathways from the brain to the muscles, which are how the brain controls the movements.

The function of the mirror neurons was also discussed.

I’m deeply interested in these topics especially in its applications, like the neural oscillators (model CPGs) that can be used for robot’s locomotion control so I’ve had already studied some of them before but it’s always good to go back to the basics and study such interesting topics again.

Posted by Salvador Gutierrez Medina

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