The corollary discharge signal, as I understand it, seems to be an internal signal that "informs" a neuron of its neighbors' actions and thus allows coordination of various behavioral patterns. In other words, it allows different bhavioral patterns to arrange themselves in what can be seen as an acceptable motor symphony, rather than a discordant jumble of "notes". Earlier in the course, you mentioned that the corollary discharge signal was not a sensory signal. In the case of stretch receptors, however, the sensory neuron directly contacts the motor neuron. Here, the motor neuron is "informed" of an action affecting its neighbor (the sensory neuron) and it goes on to act in a coordinated manner. Wouldn't the signal it receives from the sensory neuron be an example of corollary discharge also, and if so, couldn't it be termed a sensory signal as it is coming from a sensory neuron?

CD most typically a signal from one GROUP of neurons to another GROUP of neurons, but yes, you've got the important idea. Yes, sensory neuron to motoneuron is, in a sense, one neuron telling another what it is doing. One tends to use CD for signals which originate inside the nervous system, rather than in sensory pathways, to try and emphasize the extent to which internal organization/coordination can be independent of sensory input. Hence, one wouldn't normally call the sensory to motor signal a CD (but there is indeed some fuzziness in definition there, as is always the case when terms have arisen in different contexts for different purposes). PG