Changes in the Number of Neurons in the Rat Motor Cortex and Movement Activity with Age

A programmable Laboras apparatus, consisting of an automated behavioral reaction recording system, was used to record movement activity in male rats aged one, eight, and 16 months studied in groups of 12, with subsequent determination of the numbers of neuron bodies in layer V of the motor cortex in preparations stained by the Nissl method. Different age groups were found to have different numbers of neurons in the motor cortex. The greatest number was seen in animals aged eight months. Movement activity correlated with the number of neurons.