Final answer:
The inactivation of the nucleus reuniens may lead to decreased motor activity by disrupting the inhibitory function of the indirect pathway of the basal nuclei on the thalamus, and it could also impact cognitive and memory functions.
Step-by-step explanation:
The inactivation of the nucleus reuniens a part of the thalamic midline may disrupt the normal functioning of the basal nuclei and the flow of motor information within the cerebrum. The indirect pathway, which comprises connections through the striatum, globus pallidus external segment (GPe), subthalamic nucleus (STN), and the globus pallidus internal segment/substantia nigra pars compacta, results in inhibition of the thalamus. This inhibitory effect on the thalamus subsequently decreases activity in the cerebral cortex, leading to less motor activity.
The nucleus reuniens is involved in connecting the limbic system with the prefrontal cortex and other areas of the brain, and its inactivation could potentially alter cognitive and memory functions related to these connections.