FIGURE 1.

Pathways involved in Huntington’s disease (HD). Impacted striatal neurons, leading to atrophy of the cerebral cortex, subsequently the caudate and putamen, as well as the globus pallidus (internal and external). The external globus pallidus will receive fewer neurotransmitters, causing false signals that allow more neurotransmitters to be released to the subthalamic nuclei. Additionally, neurons can also be disintegrated in the regions of the hypothalamus, thalamus, and zona reticulata of the substantia nigra. Substance P, enkephalin, and dynorphin are found in susceptible striatal neurons, which mainly innervate the substantia nigra and globus pallidus. The upregulation and modulatory effects may cause a sequence of neurodegenerative events, including overstimulation of the motor cortex, thus showing the progression of the disease. Abbreviations: VA, ventral anterior nucleus; VL, ventral lateral nucleus.