Quantification of responses from proprioceptive neurons in the limbs of the crab, Cancer magister

In the limbs of crustaceans, proprioception is monitored by chordotonal organs. One in particular, MC1, is arranged in a manner that is accessible for single unit recording of primary sensory neurons while simulating joint movement. The movement-sensitive cells are of two types, those sensitive to relaxation or to elongation of the chordotonal strand which corresponds to flexion or extension of the meropodite-carpopodite joint, respectively. A statistical method for the quantification of these movement-sensitive proprioceptive neuronal responses was implemented. This statistical index, eta², should allow neuronal responses recorded in different laboratories to be easily and quantitatively compared. In addition, an eta² value can be assigned to individual cells which represents a cell's consistency and degree to which the response is related to the stimulus. We found some cells to have a high eta² and to be consistent in their activity while other cells had a high degree of variability with low eta² values.