Most dogs will exhibit a scratch reflex when they are stimulated in the saddle region, which consists of the belly, sides, flanks, and back.
[1] Researchers focused predominantly on investigating spinal cord neural circuitry responsible for the generation of the scratch reflex, limiting the system of study.
In preparations without movement-related sensory input, one of three strategies is used: Electromyographic (EMG) and electroneurographic (ENG) techniques are used to monitor and record from animals during experiments.
Recordings indicate that feedback modulates the timing and intensity of scratching, in the form of phase and amplitude changes in nerve firing.
Research on hybrid and switch movements at transition zones indicates that the CPGs responsible for scratch generation are modular and share interneurons.
[8] This research further supports the findings on the switch and hybrid movements, which suggest a modular organization of unit generator CPGs used in combination to achieve a task.
Initial experiments on the scratch reflex in dogs revealed that the spinal cord has circuits capable of summing inputs.
This allows the spinal CPGs to generate a scratch response targeted to the site of the stimulus independent of supraspinal structures.
[7] More recent research suggests that form selection is accomplished using the summed activities of populations of broadly tuned interneurons shared by various unit CPGs.
[10] Additionally, intracellular recordings have illustrated that motor neurons receive at least two types of inputs from spinal CPGs.
Very recent research suggests that the scratch reflex shares interneurons and CPGs with other locomotor tasks such as walking and swimming.
[10] The findings from these studies also suggests that mutual inhibition between networks may play a role in behavioral choice in the spinal cord.
[3] Stimulation of pyramidal tract neurons has been found to modulate the timing and intensity of scratch reflex.
Furthermore, extensive research has identified the involvement of supraspinal structures in the modulation of the rhythmic elements of the scratch reflex.