The inhibitory influence of the basal ganglia is stronger than the stimulatory effect on muscle tone due to the complex network of connections within the basal ganglia and its role in motor control.
The basal ganglia are a group of structures deep within the brain that play a crucial role in motor function, including the control of movement and muscle tone. They receive input from various regions of the brain, such as the cortex, thalamus, and brainstem, and send output to the motor cortex and other motor control areas.
The main inhibitory pathway within the basal ganglia is the direct pathway, which involves the activation of the striatum (composed of the caudate nucleus and putamen) and the subsequent inhibition of the globus pallidus interna (GPi) and substantia nigra pars reticulata (SNr). The GPi and SNr are known as the output nuclei of the basal ganglia, and their inhibition leads to a disinhibition of the motor cortex and increased facilitation of movement.
On the other hand, the indirect pathway involves the activation of the striatum, which then inhibits the globus pallidus externa (GPe). The GPe inhibits the subthalamic nucleus (STN), which in turn activates the GPi and SNr, leading to an inhibitory influence on the motor cortex and a reduction in movement.
Overall, the inhibitory influence of the basal ganglia is stronger than the stimulatory effect on muscle tone because the direct pathway, which leads to disinhibition of the motor cortex and facilitation of movement, is more dominant than the indirect pathway, which inhibits movement. This balance of inhibitory and stimulatory pathways allows for precise control of muscle tone and movement.
WHY THE INHIBITORY INFLUENCE OF BASAL GANGLIA IS STRONGER THAN STIMULATORY EFFECT ON MUSCLE TONE
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