Introduction and basics: Motor Unit: Motor unit is an alpha motor neuron and the muscle fibers it supplies. Motor units vary in size, smaller motor units supply few muscle fibers and larger motor units supply many muscle fibers. The motor units follow ‘All-or-None’ law. When a motor unit fires, it stimulates all the muscle fibers simultaneously. For [...]
Archive for the ‘Motor Control’ Category
Recruitment and rate coding
Posted in Motor Control on November 13, 2009 | Leave a Comment »
Validity and Reliability – Motor Control
Posted in Motor Control on November 5, 2009 | Leave a Comment »
When we use a measuring device in the lab to measure something, we need to make sure that our test is valid and reliable. So what do they mean? Validity: Validity means our device measures what we want to measure in a fairly accurate way. How do we know that our device measures precisely? We [...]
Generalized Motor Program – Schmidt
Posted in Motor Control on April 11, 2008 | Leave a Comment »
Motor program concept says that our movements are pre-programmed in an open-loop fashion. Imagine a seed which has a blueprint of what it wants to become in its core. Especially this motor program concept is applied to explain fast movements that are around 100-150 ms. If such were the case, would it then be possible [...]
Measurements of Error
Posted in Motor Control on March 5, 2008 | Leave a Comment »
Imagine a target where archer A and archer B are trying their luck for a good shot. The following figure is the outcome. Now let us try to figure out who has done the best. Again it depends on what you want to see. The common error measurements are as follows: [...]
Speed Accuracy (Temporal) Trade Off
Posted in Motor Control on March 5, 2008 | Leave a Comment »
Again this is a continuation of the previous blogs. So far we have seen the ability to precisely tap the target as one of the variables. This comes under spatial domain. What about temporal domain? Meaning, could we be able to precisely monitor our timing? For example, take a stopwatch. Try to measure ½ sec [...]
Linear Speed (Spatial) Accuracy Trade Off – Schmidt
Posted in Motor Control on March 5, 2008 | Leave a Comment »
This is the continuation of the previous blog. What if we vary the distance between targets (D) and the movement time (MT) and keep the width (W) of the target constant? The variability that arises (due to be within the target) is linearly proportional to D and MT. D/MT (distance/time) is nothing but velocity, therefore [...]
Speed Accuracy (Spatial) Trade Off: Fitts Law
Posted in Motor Control on March 3, 2008 | Leave a Comment »
One of the important concepts to understand in motor control is about Fitts Law. What is it primarily about? Fitts, in his experiment, asked the participants to tap as fast as they could on two targets that had a width of W (in inch) and separated by a distance of D (inch). Both W [...]
