History of Neuropsychology

Psychology: the study of the description, explanation, modification and prediction of human and animal behavior.

The study of how the complex properties of the brain allow for the behavior to occur is Neuropsychology.


  • the study of the relationships between brain function and behavior
  • observation of changes in thoughts and behaviors that relate to the structural or cognitive integrity of the brain
  • a method of studying the brain by examining its behavioral product

Evidence of Early Neuropsychology: Trephanation
Trephanation is the ancient surgical procedure of operating on the human skull by scraping, chiseling, or cutting bone from the skull.

  • discovered by archaeologists
  • many who underwent trephanations survived - evidence of healing
  • many died - no healing; many multiple trephanations
  • at times, on damaged skulls - perhaps TBI following hand-to-hand fighting
  • at times on intact skulls - perhaps psychiatric disorders
  • perhaps a religious rite - to release evil spirits

Verona & Williams (1992) examinied 750 skulls from Peru and measured trepahaned skulls for technique, location, size, healing, and presence of fractures. Results suggest that most trephanations were performed in the frontal and upper parietal regions following injury to the skull from clubs and other weapons of the pre-Columbian era. Scraping and circular grooving had the highest success rates as opposed to straight cutting and drilling. Techniques used were similar to modern-day methods of drilling "burr holes" to relieve pressure and release trapped blood.

This image on the left depicts the drilling method. Here, the practitioner has produced ring of small holes. The next step in the procedure was to cut the bone betwen each hole and pry off the bone piece in the center. This patient probably died before the trephination was completed. There is no evidence of healing. There is also a large linear skull fracture beside the trephination opening. It is clear that this trephination was used to treat the associated skull fracture. Perhaps the practitioner believed that a blood clot was underneath the skull, near the fracture. Such blood clots are a frequent result of this type of traumatic skull injury.

This skull on the right shows evidence of multiple head injuries and trephinations. There is a well-healed trephination and a fresh one. The patient probably died soon after receiving this recent head injury and fresh trephination. This one demostrates the great survival rate associateed with the procedure. This person lived for many years after the first trephination. There is considerable healing. This trephination was done with the scraping method.

Here is a fresh trephination done in series,using the straight cutting method. The practitioner began with cuts that surround the central area. He began cutting the outer perimeter in order to create a larger opening, but stopped, presumably because the patient died. This trephination shows no signs of healing. You can even see numerous fresh cuts and scrapes produced by the trephining tool.




Ancient Egyptians:
The Edwin Smith Papyrus (2500-3000 BC). This papyrus represents the earliest written record of medical treatment. Among the 48 cases described, are included references to head and brain injury. These descriptions suggest, for the first time, that brain functions are localized in specific parts of the brain. Here is an excerpt (courtesy of Dr. Leitner):

These are references to weakness on one side of the body (hemiplegia) and the build-up of pressure, probably a blood-clot in this case. The Egyptian physician was unclear about the side of the hemiplegia. Of course, hemiplegia occurs on the side opposite to the lesion. The Egyption physician may have been confused by the presence of a contra-coup injury, in which a brain lesion occurs on the opposite side of the brain from the initial impact. (Williams, 1998)

Ancient Greeks:
Unfortunately, the knowledge of brain function at that time was limited by the strong aversion to dissecting the brain. They had a number of mistaken beliefs, including Aristotle's localization of mental functions in the heart. This theory explained that people with heavy upper bodies were intellectualy dull due to the extra weight bearing on the heart. The view that the heart is the organ of the human mind or consciousness is called the "cardiac or cardiocentric hypothesis". Aristotle identified the heart as "the most important organ of the body," and the first to form according to his observations of chick embryos. It was the seat of intelligence, motion, and sensation - a hot, dry organ. Aristotle described it as a three-chambered organ that was the center of vitality in the body. Other organs surrounding it (e.g. brain and lungs) simply existed to cool the heart.

Why? Importance: After death, the heart was weighed to see if one would enter into eternal afterlife, but the brain was usually discarded. Aristotle believed in "dualism" which divides the world into two spheres: mind and matter. The mind (or soul) is a nonphysical entity, which somehow interacts with the material body. In particular, mind-body dualism claims that neither the mind nor matter can be reduced to each other in any way, and is sometimes referred to as "mind and body" and stands in contrast to philosophical monism, which views mind and matter as being ultimately the same kind of thing. (see Wiki). According to Aristotle, the mind and body interacted through a "point of interaction" which he identified as the heart. To this day, we continue to perpetuate this belief by giving cards with hearts on Valentine's day, and by using terms such as "heartbroken" or "cold-blooded."

Pythagoras (circa 550 BC, best known for the Pythagorean theorem) was one of the first to propose that the thought processes and the soul were located in the brain and not the heart. This belief is the "brain or cephalocentric hypothesis", stating that the brain is the source of reasoning and all human behavior. Pytharoras also claimed to have lived four lives that he could remember in detail, and heard the cry of his dead friend in the bark of a dog.

Hippocrates (circa 400 BC, influenced by Socrates) was considered one of the most outstanding figures in the history of medicine, is referred to as the "father of medicine", and was the founder of the Hippocratic school of medicine. The Hippocratic school held that all illness was the result of an imbalance in the body of the four humours, fluids which in health were naturally equal in proportion (pepsis). When the four humours, blood, black bile, yellow bile and phlegm, were not in balance (dyscrasia, meaning "bad mixture"), a person would become sick and remain that way until the balance was somehow restored. Hippocratic therapy was directed towards restoring this balance. (Wiki)

However, Hippocrates also believed the brain to be the seat of intelligence, and the controller of the senses, emotions, and movement, and was the first to recognize that paralysis occurred on the side of the body opposite the side of a head injury.

The Cell Doctrine:
This theory postulated that mental and spiritual processes/functions were localized in the ventricles (called Cells) of the brain. The theory was proposed by Nemesius and Saint Augustine in approximatley 130-200 A.D. It was strongly influenced by the anatomical studies of Galen in the second century, in which he described the ventricles in detail and developed his own theory of "psychic gases and humours", that flowed through the body and ventricles (thus, the "ventricular localization hypothesis"), giving rise to mental functions. (He also characterized the brain as a "large clot of phlegm".) The idea that the veltricles were merely a sewer system through which passed bodily fluids, led to the theory of the importance of "humors" which has persisted for 1000 years. Mental functions derived from the descriptions of Aristotle, such as memory, attention, fantasy and reason, were assigned locations within the ventricles. These images depict the connections between the senses (vision, hearing etc.) and the "Common Sense", located in the first ventricle. Cognitive functions were then arrayed from front to back in the ventricles. This Doctrine was proven to be totally false, as we now know that the ventricles are the site through which cerebrospinal fluid passes.

From this period, many important discoveries and theories were noted. Dissections of condemned criminals (who, at that time, were at the disposal of scientists and physicians) led to the knowledge that specific parts of the brain control specific behaviors (discussed later as localization). As well, the discovery of ascending (sensory) and descending (motor) nerves occurred.

Galen (circa 200 BC) was a prominent ancient Greek physician, who also served as a physician in a gladiator school. During this time he gained much experience with treating trauma and especially wounds, which he later called "windows into the body". He performed many operations, including brain and eye surgeries, and also "vivisections" of numerous animals to study the function of the kidneys and the spinal cord. From these studies, Galen hyppthesized that the mind controlled fluids known as pneuma (animal spirits): the brain was the reservoir of pneuma, which were stored in the ventricles.

Pneuma traveled through nerves, which Galen believed were tubes, throughout the body - sent out from the brain to the muscles (i.e., controlled by the mind, causing the body to move) and sent back to the brain due to sensory stimulation. Physical functioning was dictated by the balance of four bodily fluids or humors: Blood, Mucus, Yellow bile, Black bile, which were related to the four elements - air, water, fire, and earth. Galen also showed that pressing on the heart in human subjects did not lead to loss of consciousness or loss of sensation but severing the spinal cord in animals abolished sensory responses after brain stimulation.

The First Anatomical Studies:
Vesalius (1514-1564) was the first to conduct careful observations of brain antomy and qualify the teachings of the cell doctrine in which he was trained. He represents the beginning of a period in which careful observations and empirical science began to triumph over the ideas that had been handed down since the time of Aristotle and Galen. Vesalius introduced the anatomical theater in which students and doctors could watch dissections from above. Vealius made careful diagrams of human anatomy.

Mind-Body Dualism:
Descartes (1596-1650) introduced the concept of a separate mind and body. He believed that all mental functions were located in the pineal gland, a small centrally-located brain structure which is now believed to play a role in sleep/wake and dark/light cycles. The dualist philosophy suggested a complete split between mental and bodily processed, and explained automatic bodily reflexes (body) while purposeful behaviors were a product of free-will (mind).

Descartes did subscribe to some of Galen's theories (that the brain was a reservoirr of fluid), as demonstrated by one of his illustrations, in which the fire displaces the skin, which pulls a tiny thread, which opens a pore in the ventricle (F) allowing the "animal spirit" to flow through a hollow tube, which inflates the muscle of the leg, causing the foot to withdraw. This would now be described as a reflex, for which Descartes is credited. Popular culture has many references to dualism.


Gall (1758-1828) introduced the idea that the brain was comprised of separate organs, each localized and responsible for a basic psychological trait. These traits controlled complex mental faculties, such as Cautiousness, Combativeness and Agreeableness, and simpler functions, such as Memory, Calculation Ability and Color Perception. Phrenology correlated the mental faculties described by philosophers with the development of specific brain areas. The development of these brain areas, called cerebral organs, resulted in skull prominences. These bumps could be analyzed and a Phrenology practitioner could determine the subject's personality and intelligence from analysis of the skull, called cranioscopy.

Followers of phrenology categorized individuals on the basis of skull, and thus, brain size. Men were believed to have larger "social regions" with more "pride, energy, and self-reliance", as compared to female skulls which were thought to possess more "inhabitivness (love of home), a lack of firmness and self esteem." Many studies have refuted the notion that skulls of different races reflect superiority, and it is impossible to distinguise between murderes and geniuses on the basis of skull size or shape.

So, there is no relationship between the bumps on the skull and the underlying brain tissue, nor is there a relationship between the size of an area of brain and the size of the function that it supports (skulls are hard, brains are not). Although he was almost completely incorrect, Gall's Phrenology represents the beginning of the strong modern-day localizationist doctrine.

19th Century Localization:
Broca (1824-1880) described most famous case, "Tan", a patient who suffered a stroke of the left hemisphere who could only utter the phrase "Tan". The patient could accurately comprehend language. Broca then used this case and a number of others to show that the expression of language was localized to the left frontal lobe. If you look carefully at the brain, you can detect a soft, fluid-filled area in the frontal lobe. This represents the empty space, or infarction that is caused by the drop in blood supply to that brain area (stroke). The third convolution of the inferior posterior frontal lobe has since become known as "Broca's area", and patients with damage to Broca's area are referred to as having "Broca's aphasia".

Several years after Broca presented his cases of frontal lobe lesions, Wernicke (1848-1904) presented cases in which patients had lesions of the superior posterior part of the left hemisphere and had trouble comprehending language. This resulted in the idea that component processes of language were localized. On the basis of Wernicke's observations, the modern doctrine of component process localization and disconnection syndromes was begun. This doctrine states that complex mental functions, such as language, represent the combined processing of a number of subcomponent processes represented in widely different areas of the brain. A mental faculty like "Combativeness" described by the Phrenologists was not discreetly localized in the brain. Such faculties, if they have validity at all, are the result of a number of primary cognitive operations.

Responses to Localization:
Freud described several types of language disorders wich could not be explained by lesions to Broca's or Wernike's areas. He postulated that lesions in the subcortical areas ould produce similar behavioral disorders. Similar anti-localization concepts were presented by Flourens (1794-1867). He asserted that while sensory input was localized, to an extent, at an elementary level, the more comples process of perception was dependent on the entire brain (Luria later explained this in terms of primary, secondary and tertiary zones). Based on ablation studies of hens and pigeons, he concluded that loss of function is more a product of the amount of damage rather than the location of that damage. Flourens also offered the notion of equipotentiality of brain tissue, or that if there is enough intact tissue following brain damage, the remaining tissue will compensate and take over the function of the missing area. By utilizing dependent measures such as wing-flapping and eating behaviors in pigeons, Flourens erroneously suggested that only 10 percent of brain tissue of used.

Munk (1839-1912) produced temporary "mind-blindness" in dogs following lesions in their association cortex. This notion that an animal will recognize an object (i.e., see the object) but fail to recall the conditioned significance is similar to the concept of "anosognosia." Following lesions to the association cortex of the right hemisphere, Babinski (1857-1932) described a similar unawareness of deficit.

Lashley supported Flourens' notion of equipotentiality based on his own research on rats. While the specific area of the lesion had no effect on subsequent performance, Lashley found that the amount of brain tissue removed from rat brains effected the ability to negotiate previously learned mazes. From his studies, Lashley offered the theories of "mass action" and "multipotentiality"; the amount of damaged brain tissue influences subsequent behavior and each part of the brain participates in multiple functions.

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