A simple reflex like the myotactic reflex is produced via
single synapses between sensory axons and motor
neurons. The required circuitry for this reflex is confined
to the spinal cord, as shown in Figure HN-1-1 on page
HN-1-1. Sensory information also ascends to higher
centers, but the brain is not necessary or required to
perform the reflex. More complex reflexes usually
involve additional (inter-) neurons and more than one
population of motor neurons. Thus, more neurons and
synapses are involved, which usually results in a longer
delay between stimulus and response and often a more
complex response. One example of such a complex
response is the flexion withdrawal reflex, where a
noxious stimulus to one leg causes withdrawal of the
stimulated leg and extension of the other.
In this lab you will study the time taken between a
stimulus and the response. These reaction time
measurements will be made from an individual subjected
to harmless visual and sound stimuli. In addition, the
effect of priming and prediction will be examined.