Cortex (anatomy) in the context of "Cerebral cortex"

The cerebellum (pl.: cerebella or cerebellums; Latin for 'little brain') is a major feature of the hindbrain of all vertebrates. Although usually smaller than the cerebrum, in some animals such as the mormyrid fishes it may be as large as it or even larger. In humans, the cerebellum plays an important role in motor control and cognitive functions such as attention and language as well as emotional control such as regulating fear and pleasure responses, but its movement-related functions are the most solidly established. The human cerebellum does not initiate movement, but contributes to coordination, precision, and accurate timing: it receives input from sensory systems of the spinal cord and from other parts of the brain, and integrates these inputs to fine-tune motor activity. Cerebellar damage produces disorders in fine movement, equilibrium, posture, and motor learning in humans.

Anatomically, the human cerebellum has the appearance of a separate structure attached to the bottom of the brain, tucked underneath the cerebral hemispheres. Its cortical surface is covered with finely spaced parallel grooves, in striking contrast to the broad irregular convolutions of the cerebral cortex. These parallel grooves conceal the fact that the cerebellar cortex is actually a thin, continuous layer of tissue tightly folded in the style of an accordion. Within this thin layer are several types of neurons with a highly regular arrangement, the most important being Purkinje cells and granule cells. This complex neural organization gives rise to a massive signal-processing capability, but almost all of the output from the cerebellar cortex passes through a set of small deep nuclei lying in the white matter interior of the cerebellum.

Purkinje cells or Purkinje neurons, named for Czech physiologist Jan Evangelista Purkyně who identified them in 1837, are a unique type of prominent, large neuron located in the cerebellar cortex of the brain. With their flask-shaped cell bodies, many branching dendrites, and a single long axon, these cells are essential for controlling motor activity. Purkinje cells mainly release GABA (gamma-aminobutyric acid) neurotransmitter, which inhibits some neurons to reduce nerve impulse transmission. Purkinje cells efficiently control and coordinate the body's motor motions through these inhibitory actions.

Evolutionary explanations for the existence of discrete emotions such as fear and joy are one of many theoretical approaches to understanding the ontological nature of emotions. Historically, evolutionary theoretical approaches to emotions, including basic emotion theory, have postulated that certain so-called basic emotions (usually fear, joy, anger, disgust, and sadness) have evolved over human phylogeny to serve specific functions (for example, fear alerts a human mind of imminent danger). So-called basic emotions are often linked causally to subcortical structures of the brain, including the amygdala (pronounced uh-MIG-duh-luh). In other words, subcortical structures have historically been considered the causes of emotions, while neocortical (neo- meaning new, recent and cortical meaning relating to cortex) structures, especially the prefrontal cortex, are almost invariably understood as the cause of reason. Those ideas about the brain are old; they're traceable at least to Aristotle and were later incorporated into Paul MacLean's mistaken model of brain organization, the "triune brain." These ideas have led to the widespread, erroneous belief that animal brains, including human brains, evolve in a linear fashion, such that, along the course of evolution, new layers of brain tissue are stacked upon older layers of brain tissue, much like the formation of sedimentary rocks. Brain evolution is a lot more complicated than that.

Evolution and natural selection has been applied to the study of human communication, mainly by Charles Darwin in his 1872 work, The Expression of the Emotions in Man and Animals. Darwin researched the expression of emotions in an effort to support his materialist theory of unguided evolution. He proposed that much like other traits found in animals, emotions apparently also evolved and were adapted over time. His work looked at not only facial expressions in animals and specifically humans, but attempted to point out parallels between behaviors in humans and other animals.