4000BC – Sumerian records show first writing on the brain – An anonymous report on sensations after ingesting poppy seed plant.

450BC – Alcmaeon, an early Greek physician, is the first to use anatomic dissection of animals as a basis for his theories.
He concludes from his studies that the brain, not the heart, is the central organ of sensation and thought. This idea directly contradicts the accepted theory of his time which holds that the heart is the true seat of intelligence. Alcmaeon also suggests that the optic nerves are light-bearing paths to the brain and that the eye itself contains light. This fanciful theory of the eye as a container of light is believed by many neuroscientists until the middle of the 18th century.

335BC – Aristotle states that the organ of thought and sensation is the heart and that the brain is merely a radiator designed to cool it. 
He claims, however, that the organ of thought is not the same as the basis for thought. The basis for thought, which he calls the rational soul, is immaterial and can not be found anywhere within the body. Aristotle’s theories about memory ultimately prove to be more successful. He correctly surmises that the processes involved in short term memory (immediate recall) differ distinctly from those involved in long-term memory.

1664 – Thomas Willis, a professor at Oxford, writes the first monograph on brain anatomy and physiology – ‘Cerebri Anatome’.  
In his book, he states that the cerebral hemispheres, which constitute 70% of the human brain, determine thought and action and are completely separate from the part of the brain that controls basic motor functions like walking. He also locates specific mental functions within the corpus callosum, corpus striatum and the cerebellum and introduces the words; ‘neurology,’ ‘hemisphere,’ ‘lobe,’ ‘pyramid,’ ‘corpus striatum,’ and ‘penduncle’ into the modern vocabulary. His work is influential in leading future neuroscientists to study the functional contributions of individual brain parts.

1848 – Phineas Gage, a railroad worker, survives a bizarre accident in which the frontal lobe of his brain is pierced by an iron rod during an explosion.
Although he eventually recovers, he experiences profound mood and behavior changes. By all accounts, a quiet, industrious worker before the accident, Gage becomes a surly, combative man who can not hold down a job. This famous case, now found in countless neuroscience textbooks, was an important milestone in the study of the brain’s anatomy because it suggested that key parts of the personality resided in the frontal lobe. These findings indirectly lead to the development of the procedure called lobotomy, which was based on the theory that removing portions of the frontal lobe could cure mental derangement and depression.

1869 – Sir Francis Galton publishes his work – ‘Hereditary Genius’, which claims that intelligence is an inherited trait and that high levels of intellectual achievement follow genealogical lines. 
Galton also makes the first scientific attempt to measure intelligence. In 1888, he sets up an “anthropometric laboratory” in which he uses the rather dubious measures of visual acuity, auditory accuracy, and breathing capacity to assess levels of intelligence.

1875 – Wilhelm Wundt, in Leipzig, Germany, sets up the first lab devoted to study in human behaviour and suggests that psychology should be regarded as a complementary scientific discipline to anatomy and physiology.
Wundt is deeply interested in philosophy as well, and many of his students at the lab, known as the Institute for Experimental Psychology, are men who have studied philosophy at other German universities. At the Institute, students are taught a wide range of philosophic and psychologic subjects including the study of attention and sensory processes. Wundt’s Institute becomes the model for most of the psychological laboratories established in Europe in subsequent year.

1905 – Alfred Binet, a leading French psychologist, disputes Galton’s use of sensory discrimination as a measure of intelligence.
He claims that individual differences in intelligence can be detected only through measures of complex processes such as memory, imagination, attention and comprehension. In 1904, Binet is appointed to a commission concerned with how to integrate retarded children into the public school system in Paris. The committee decides that special education programs should be provided for them and proposes that a system be designed for identifying retarded children entering school. Binet sets out to develop a scale that can differentiate children who are slow learners from children who are learning at a normal rate. He collaborates with Theodore Simon, a young physician who has worked with retarded children in the past. The result is a scale designed to measure a variety of higher mental processes such as memory and imagination. To test their scale, Binet and Simon draw samples of children from schools, hospitals, orphanages, and asylums. They use these samples to try out the various cognitive tests they have designed with the goal of selecting those tests that clearly discriminate between the slightly retarded and the normal school population. In 1905, Binet and Simon introduce their intelligence scale and provide guidelines for its administration. They stress that the scale is appropriate only for assessing whether or not a child is of normal or inferior intelligence and is not designed to uncover the psychologically unstable or insane.

1911 – Henry Head, a British neuroscientist, publishes ‘Studies in Neurology’.
In it, he disputes the prevailing theories about aphasia and argues that speech is not a localized function. He also conducts important studies with the Irish neurologist, Sir Gordon Holmes, on the neurophysiology of sensory perception in the cerebral cortex, focusing particularly on patients’ spatial perceptions of their own bodies.

1921 – Hermann Rorschach, a Swiss psychiatrist, develops the ink blot test.
The Rorschach test, as it is now called, consists of ten standardized ink blots. Half of the ink blots are in black and white and the other half are in color. A subject is asked to describe what he sees in the visually ambiguous pictures and then his responses are analysed or “scored” by the test giver. The test contains three scoring areas — location, determinants and content. Location refers to how much and which part of the ink blot is described. Determinants refers to the patient’s description of the blot’s shape or colour. Content, the most straightforward of the categories, refers to the types of objects described. Many psychiatrists have found animal and human sightings to be particularly useful clues to patients’ psyches. The Rorschach test, once widely used as an “open-ended” test for personality traits and disorders, has fallen out of favor in recent years because it is so difficult to independently validate the results.

1949 – Walter Rudolph Hess wins the Nobel Prize for his work on the interbrain, which includes the hypothalamus, subthalamus and parts of the thalamus.
His research shows that the interbrain is responsible for coordinating the activities of the body’s internal organs.

1974 – M.E.Phelps, E.J.Hoffman and M.M.Ter Pogossian develop the first Positron Emission Topgraphy (or PET) scanner, a machine that provides visual information about the activity of the brain.
A patient undergoing a PET scan is administered a substance that includes radioactive atoms that emit positively charged particles known as positrons. The gamma radiation that results from this process is sensed by detectors and converted into computer-generated images of the brain as it would appear in cross-section. Doctors use PET scans to monitor such things as blood flow and oxygen utilization in the brain.

1990 – U.S President George Bush declares the decade starting in 1990 the “Decade of the Brain”.

1997 – Stanley B. Prusiner wins the Nobel Prize for his discovery of a new genre of infectious agents known as prions.
Normally, prions exist as harmless cellular proteins. However, they possess an innate capacity to convert their structures into highly stable configurations that can lead to the formation of harmful particles. Prusiner’s research implicated prions as infectious agents in several brain diseases that cause dementia in humans and animals. Prusiner’s discovery of this new principle of biological infection has also helped to provide important insights into the mechanisms underlying other types of dementia-related diseases, such as Alzheimer’s.

2000 – Arvid Carlsson, Paul Greengard and Eric Kandel share the Nobel Prize for their discoveries concerning signal transduction in the nervous system.
Signal transduction occurs when a message from one nerve cell is transmitted to another through a chemical transmitter. It takes place at special points of contact, called synapses. Each nerve cell can have thousands of such contacts with other nerve cells. Carlsson, Greengard, and Kandel’s research focuses on one type of signal transduction between nerve cells, known as slow synaptic transmission. Their discoveries have contributed to a greater understanding of the normal function of the brain as well as how disturbances in this signal transduction can give rise to neurologic and psychiatric diseases.

The above information was sourced from: http://www.pbs.org/wnet/brain/history