movement. The third level to evolve included areas involved in higher cortical functions, including thought. It is the task of the higher level to keep the person aware of changes in the environment.
John Hughlings Jackson
Public domain
Within this framework, Hughlings Jackson suggested principles based partly on evolutionary analysis. One important principle is hierarchical integration through inhibitory control. By this, he means that the various levels of the brain, such as the brain stem, the limbic system, and the neocortex, are able to interact with each other. Further, the type of interaction from the higher levels restricts or inhibits the lower levels.
Figure 1.11 Language Is Shown to Be Related to Different Parts of the Brain
Source: Garrett (2010).
In terms of mental illness, Hughlings Jackson (1894) suggested that symptoms such as illusions, hallucinations, and delusions are not in themselves the result of disease. Rather, it is when higher-level processes no longer inhibit the earlier evolved processes of the brain that these symptoms appear. Hughlings Jackson referred to this process as dissolutions. Dissolutions are the reversal of the normal process of evolution. Thus, the primitive experiences seen in psychosis, for example, represent the primitive parts of the brain working normally. What is missing is the relationship of these primitive areas with higher mental processes.
Charles Darwin
Public domain
A Growing Understanding of the Role of Evolution
Another big idea that emerged in the 1800s was that all of nature is in constant flow and that things, including organisms, change. This idea focused on the evolution of species and is most often associated with the work of Charles Darwin (1809–1882). Variation was to become one of the major components of Darwin’s thinking concerning evolution. In fact, he began his thinking with the assumption that heritable variations can and do occur in nature. Darwin then presented the important realization that not all plants or animals that come into existence survive. Many organisms such as sea stars, for example, produce millions of eggs of which only a limited number survive. Depending on climate conditions, food supply, predator population, and a host of other factors including disease, only a limited number of births survive to maturity.
hierarchical integration: through inhibitory control, the various levels of the brain, such as the brain stem, the limbic system, and the neocortex, are able to interact with each other, and higher levels restrict or inhibit the lower levels
variation: the assumption that heritable variations can and do occur in nature
natural selection: Darwin’s idea that if an organism has even slight variations that help it to compete successfully for survival, then over time the species will be made up more of members with these characteristics and less of individuals lacking these features
sexual selection: the manner in which males and females choose a mate
Consequently, Darwin (1859) suggested, “There is a frequently recurring struggle for existence.” Who is to survive in this struggle? Darwin suggested that if an individual has even a slight variation that helps it to compete successfully for survival, then over time the species will be made up more and more of members with these characteristics and less and less of individuals lacking these features. This process is referred to as natural selection. Darwin described this process in his 1859 book, On the Origin of Species by Means of Natural Selection.
Darwin later extended the theory of natural selection to include sexual selection, or the manner in which males and females choose a mate. This work is described in his 1871 book, The Descent of Man. Darwin noted that males and females differ not only in terms of organs of sexual reproduction but also in secondary sexual characteristics such as mammary glands for the nourishment of infants in females or facial hair in males. According to Darwin, sexual selection depends on the success of certain individuals over others of the same sex. Darwin also saw that besides same-sex competition, there is also competition to attract members of the opposite sex. As you can imagine, there has been continuous debate and research concerning what attraction means for males and females.
Darwin began the Origin work with the question of natural selection especially as it related to animals. In The Descent of Man, he expanded these ideas to humans and also examined the question of sexual selection. In other works, such as his notebooks, he extended his research to cognitive and emotional processes. The broad question is that of how psychological functions have evolved. One answer he gives is that living in social groups produces an increase in cognitive ability. Darwin also presents notes on memory and habit, imagination, language, aesthetic feelings, emotion, motivation, animal intelligence, psychopathology, and dreaming (Gruber, 1974). One important question is the manner in which self-preservation, sexual selection, and social processes are reflected in psychopathology.
A Search for Organization
One of the themes of the sciences of the 1800s was the search for organization. In understanding psychopathology, an important man associated with this search was the Paris physician Jean-Martin Charcot (1825–1893). Charcot sought to bring organization to an understanding of neurological disorders through a variety of methods such as careful observation. This observation was of both what the patient said, which we refer to today as symptoms, as well as what the clinician observed, or what we refer to as signs. The overall search was for which signs and symptoms go together to form a syndrome. An additional technique—autopsy, or examination of the body after death—further allowed for the connection of syndromes with underlying anatomy. Autopsies allowed for the determination of which tissue showed signs of pathology. Using this method, Charcot was able to show the correctness of Hughlings Jackson’s thoughts on neurological organization. Overall, Charcot showed that the human motor cortex is organized similarly to that of other animals, with the left hemisphere controlling the right side of the body and vice versa.
symptoms: features observed by the patient
signs: features observed by the clinician
syndrome: determination of which signs and symptoms go together
Charcot is best known for initially describing brain disorder relationships for a number of motor-related disorders including Parkinson’s disease and multiple sclerosis. Charcot also established Tourette’s syndrome as a separate disease when he asked his assistant Gilles de la Tourette to help him. De la Tourette wrote of cases that included a teenage boy who would show involuntary movements and scream swear words.
Charcot was also able to show that conversion reactions, in which the person shows outward signs of trouble hearing or seeing, or being unable to experience pain in the hand, were without any underlying pathology. During Charcot’s time, conversion reactions were referred to as hysteria. A young Sigmund Freud heard Charcot’s lectures on hysteria, including the observation that psychological trauma could trigger these reactions. This became the initial basis of Freud’s psychoanalytic work.
