Home > Conscious > Chapter 10 > 10.4. Turn Feeling into Action by the Striatum

 

"Seek pleasure, avoid pain" governs the instinctual behavior of animals, including human beings. The feeling of pleasure or pain is a mental state while seeking or avoiding involves body's action. Therefore, this natural behavior represents a good example for the mind-body interaction. More importantly, the pleasure principle is not learned. It must be built into brain circuits at birth.

According to René Descartes, the mind may act on the pineal gland to trigger bodily movement. However, we know that the pineal gland is not involved in any motor functions. Instead, the striatum has been demonstrated to play a central role in action selection: Go or NoGo (Figure 10-4). Incidentally, the striatum is one of the most vulnerable areas to Tau pathology. As discussed in previous sections, electromagnetic (EM) waves could be part of the mind, responsible for the mind-body interaction. Neuronal activation by EM waves is regulated by the Tau protein. Therefore, the striatum may serve as the bridge between feeling and action.

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Figure 10-4. The neural pathways for action selection. The direct pathway (left) involves two inhibitions by the GABA neurons: striatum on GPi/SNr and GPi/SNr on the thalamus. The indirect pathway (right) involves three inhibitions: striatum on GPe, GPe on STN, and GPi/SNr on the thalamus. As a result, the direct pathway leads to the activation of the thalamus, inducing movement, whereas the indirect pathway inhibits motor activity. GPi: internal globus pallidus; GPe: external globus pallidus; SNr: substantia nigra pars reticulata; STN: subthalamic nucleus. [Adapted from OpenStax]

Activation of the striatum may induce either Go (direct pathway) or NoGo (indirect pathway). Which one will dominate depends on the level of dopamine. For this reason, the striatum has reciprocal connections with substantia nigra pars compacta (SNc) and ventral tegmental area (VTA) - the major regions that release dopamine. Further details are presented in Chapter 13.