History of Neuroscience

 

Introduction

 The history of Neuroscience has been shaped by three major debates:

Timeline

Picture

Person/Period

Issue/Debate

Explanation

Egyptians
1700 bc

 [Mind-Brain]

First written account of the "brain," its anatomy, the meninges (covering of the brain) and CSF (Cerebrospinal fluid) on a payrus called the Edwin Smith Surgical papyrus. It may have been written by Imhotep (did anyone see the movie, "The Mummy?"). But they did not think much of this organ given that unlike the other organs, it was discarded, not preserved after death. Picture is Egyptian hieroglyph writing for "brain."

Plato
427-347 bc

 [Mind-Brain]

Created near Athens the Academy, which was the most influential school in the ancient world. He taught there until his death, and Aristotle was his most famous student. He believed the brain was the seat of mental processes.

Aristotle
384-322 bc

 [Mind-Brain]

Believed the mind was located in the heart, which contained all emotions and thinking. The brain was instead a radiator used to cool the heart. He experimented by dissecting animals (human dissection was forbidden).

Galen
130-200 ad

[Neural Communication]

Hailed as a great surgeon. Believed the brain receives sensory information and is responsible for motor control, using the mechanism of fluid energies. (Picture shows surgical procedures described by Galen.)

René Descartes
1596-1650

[Mind-Brain]
[Neural Communication]

Believed nerves contain fluids, or "animal spirits," which are responsible for the flow of sensory and motor information in the body. He believed in the "Balloonist Theory" which asserted that little balloons expanding would cause motion. He was a dualist, believing that the mind and body are separate, communicating via the pineal gland.

Age of Enlightenment
1700's

[Neural Communication]

From the beginning of the 18th century, known as the Age of Enlightenment, it was discovered that the nervous system is electrical in nature. The previous Ballonist Theory was disproved using the technique of water displacement. (Win a prize if you can guess whose picture that is!)

Johannes Müller
1801-1858

[Neural Communication]

Doctrine of specific nerve energies. Different sensations are caused by different energies in nerves. Today we know this is not true, different receptors interpret the same action potentials.

Franz Joseph Gall
1758-1828

[Localist/Holist Debate]

Advocate of cerebral localization. One of the founders of phrenology, but used it more as a spectacle than as a scientist. With Spurzheim, divided the brain in 35 separate functions, ranging from concrete concepts like language and color to abstract ones like hope or self-esteem. (Gall was jealous of a friend who was very good with language and memory. Because this friend had big bulging eyes, he though the brain was bigger behind it, hence those brain functions must be behind the eyes!)

Johann Spurzheim
1776-1832

[Localist/Holist Debate]

Worked with Franz Gall in the study of brain injuries using phrenology. He became the leading phrenologist in the world. Both he and Gall believed you could go a long way in determining a person's personality traits by analyzing the cranial surface, revealing areas where the brain "pushes out" more (and hence is more or less developed).

Johannes Pukinje
1787-1869

[Neural Communication]

He was first to describe a nerve cell. Contributed heavily to the field of experimental psychology. Explored sensory and visual experience after stimulation, by applying pressure and electrical current to the eyeball, etc. Discovered large nerve cells ("Pukinje Cells) with many branching extensions in the cerebral cortex.

Pierre Flourens
1794-1867

[Localist/Holist Debate]

Flourens ablated the cortical tissue of dogs, rabbits and birds, showing that the eventual recovery was due to the brain's aggregate field, where the entire brain participated in behavior. He was a strong opponent of the localization theory, virtually disproving phrenologists, and advocated a holistic view of the brain, where other parts of the brain could take over the function of damaged ones.

J. Hughlings Jackson
1835-1911

[Localist/Holist Debate]

Showed how seizures in epileptic patients appeared to progress from one part of the body to the next, apparently stimulated from a brain map. This topographic organization theory helped swing the pendulum back toward the localizationist view.

Pierre Paul Broca
1824-1880

[Localist/Holist Debate]

Advocated functional localization by cerebral convolution. In 1862, showing brain lesions in a stroke patient who could understand language but could not speak (could only say "tan"), he demonstrated that the left frontal lobe was responsible for articular speech. Demonstrated this in several patients. This region has since been named Broca’s area.

Carl Wernicke
1848-1904

[Localist/Holist Debate]

Like Broca, Wernicke showed a similar stroke victim. But this time the patient could speak but made no sense. The damaged area was around where the temporal and parietal lobes meet in the posterior part of the left hemisphere. His findings further revived the localizationist view.

Gustav Fritsch
1838-1907

[Neural Communication] [Localist/Holist Debate]

Further supported localization of function, stimulating the brain surfaces of live dogs and frogs using electricity. This resulted in characteristic movements in the neck and hind legs.

Eduard Hitzig
1838-1927

[Neural Communication] [Localist/Holist Debate]

Working with Fritsch, Hitzig showed how electric current applied to brain regions in dogs caused specific muscular contractions.

Korbinian Brodmann
1868-1918

[Localist/Holist Debate]

Categorized the brain into 52 distinct areas based on the cellular organization of the cortex in the respective regions, and therefore helped to support the localist view, which was already very strong. This was accomplished through tissue stains (i.e., histology), in order to visualize the different cell types. The difference between individual cell regions is called cytoarchitectonics, or cellular architecture.

Camillo Golgi
1843-1956

[Neural Communication]

Developed a silver stain that would permit the full visualization of a single neuron. He believed the brain was a continuous mass of tissue that shares a single cytoplasm. Though this theory was disproved by Cajal, they both shared the Nobel Prize in 1906.

Santiago Ramón Y Cajal
1852-1934

[Neural Communication]

Discovered that neurons were discrete unitary entities, and that they conducted electrical signals in only one direction. He established the Neuron Doctrine, which is the fundamental organizational and functional principle of the nervous system, stating that the neuron is the anatomical, physiological, genetic and metabolic unit of the nervous system. He won the Nobel Prize in 1906. The Neuron Doctrine proposes that the neuron is the anatomical, physiological, genetic and metabolic unit of the nervous system:

  1. Neurons are discrete and autonomous cells that can interact
  2. Synapses are gaps that separate neurons
  3. Information is transmitted in one direction from dendrites (input) to the axon (output)

K. S. Lashley
1890-1958

[Localist/Holist Debate]

Worked extensively with rats to discover where memory lies. He searched for the neural components of memory, which he called engrams. He systematically lesioned different percentages of rats' brains and then tested them in mazes they had known well. This resulted in a gradual but consistent degradation in performance. Hence the engram is not a specific connection, but rather the sum of many connections. This supported the holistic view.

Wilder Penfield
1891-1976

[Localist/Holist Debate]

One of the great neurosurgeons of all times, and a leading authority on epilepsy. While stimulating different sections of the cortex of epileptic patients during neurosurgery, he found that activating multiple cells would produce specific results (e.g., a patient would speak out "Grandma" -- hence the "Grandmother cell"), and on their connected regions. His localizationist views profoundly affected modern neurology and other scientific fields.

Modern Day
2000-

[Neural Communication]

The communication of discrete neurons (brain cells) using electrical and chemical signals (neurotransmitters) is well established and accepted (Neuron Doctrine).

   

[Localist/Holist Debate]

Extreme localism and holism have both been replaced by "connectionism." This view contends that lower level or primary sensory/motor functions are strongly localized but higher-level functions, like object recognition, memory, and language are the result of interconnections between brain areas. In addition, even within areas that seem to be localized for a particular function, that function is distributed among many neurons. There appears to be no "grandmother cell."

   

[Mind/Brain]

Although most cognitive neuroscientists must believe that the mind and brain are related to each other in some way (or else their work would be meaningless!), many also believe in a soul. How can we reconcile these views? It is necessary to reconcile them?