research into form selection has revealed that form selection is also intrinsic to the spinal cord. more recent research suggests that form selection is accomplished using the summed activities of populations of broadly tuned interneurons shared by various unit cpgs. additionally, intracellular recordings have illustrated that motor neurons receive at least two types of inputs from spinal cpgs. these inputs include inhibitory postsynaptic potentials (ipsps) and excitatory postsynaptic potentials (epsps), meaning that scratch cpgs are responsible for both the activation and deactivation of muscles during the scratch response.