Below you'll find a review of the topics we've covered for Motor Control (corresponding to Chapter 5 in Purves - Introduction to Cognitive Neuroscience and the accompanying lectures in NE202/PS339).
We discussed experiments using several different techniques during this chapter:
Here is an article than talks about different ways the motor system can code movements. The population vector would be an example of a neuronal "democracy."
This animation has a bit more detail than we covered in class, but I found it really helpful for describing the stretch reflex. Muscle spindles and alpha motor neurons are also discussed. Wikipedia gives the definition of a stretch reflex as:
a muscle contraction in response to stretching within the muscle.
Here is a resource on neural circuits in general, with information on the knee jerk reflex. There are some flash animations that are kind of nice, but it looks like if you don't have flash installed in your browser, you'll have to download the animations.
Definition from Marder & Bucher, 2001
Central pattern generators are neuronal circuits that when activated can produce rhythmic motor patterns such as walking, breathing, flying, and swimming in the absence of sensory or descending inputs that carry specific timing information.It's a closed circuit that doesn't require conscious control. The circuit will get started due to some external input, like the stretching of a muscle as a treadmill moves it, and once that muscle gets stretched, somatosensory signals get sent into the spinal chord and activate the motor neurons of the opposing muscles. Once the cycle gets going, it can keep going. The most famous demonstration of a central pattern generator is the experiment with the decerebrate (cerebrum cut and separated from the rest of the nervous system) cat. There is a video; it's kind of sad but also hard to forget, on youtube (this link).
Here is a description of what the basal ganglia are, and their role in movement. And here's a super short video on the basal ganglia:
We talked about the basal ganglia as being the source of a "go signal." The “go signal” we talked about means that the basal ganglia don’t actually contain a movement command, but they help to release a movement. The basal ganglia tell the cortex that movement that was planned in the cortex can “go”.
The case of the "frozen addicts" describes a case where a group of people were poisoned by MPTP, a accidental byproduct of the synthesized opiod, MPPP. MPTP causes a total obliteration of the dopamine producing neurons in the brain, and induced symptoms very similar to Parkinson's disease. This led researchers to make the connection between dopamine and Parkinson's.
A nice explanation is here:
Given what was said in the above video about stimulation actually "shutting down" part of the brain and what we know about the causes of Parkinson's Disease, which brain regions do you think are normally targeted for deep brain stimulation in Parkinson's?
Here's a video of a man with a deep brain stimulator demonstrating how much it improves his condition.
HowStuffWorks.com has a comprehensive article describing the current state of BCI.
Here's a link to the video of the brain machine interface we saw in lecture.
This video shows the implementation of a human-machine interface. The woman in the video controls a prosthetic arm using control of the spared nerves that she feels as her "phantom limb." The video is kind of long, but interesting.
Hemiplegia is paralysis on one side of the body, often caused by stroke or other trauma to the motor cortex. More info here.