Chapter 1 Neuroscience: Past, Present, and Future

Introduction Virtually all aspects of human nature & behavior are governed by the nervous system: –Curiosity, –Pain, –Pleasure –Movement –Reasoning –Learning –Memory –Emotion Neuroscience –The formalized study of the nervous system and how it develops, how it is organized, and how it functions. The Society for Neuroscience

It is presumed that this individual received this surgery to combat some sort of psychosis, although other causes could be explanations as well. Trepanation is the purposeful cutting of a hole into the skull.

SfN's Mission: 1.Advance the understanding of the brain and the nervous system by bringing together scientists of diverse backgrounds, by facilitating the integration of research directed at all levels of biological organization, and by encouraging translational research and the application of new scientific knowledge to develop improved disease treatments and cures. 2. Provide professional development activities, information, and educational resources for neuroscientists at all stages of their careers, including undergraduates, graduates, and postdoctoral fellows, and increase participation of scientists from a diversity of cultural and ethnic backgrounds. 3. Promote public information and general education about the nature of scientific discovery and the results and implications of the latest neuroscience research. Support active and continuing discussions on ethical issues relating to the conduct and outcomes of neuroscience research. 4. Inform legislators and other policymakers about new scientific knowledge and recent developments in neuroscience research and their implications for public policy, societal benefit, and continued scientific progress. The Society for Neruoscience (SfN):

Brief History of the Origins of Neuroscience : Ancient Egypt - symptoms of brain injuries were noted, but the heart was considered the seat of emotions and the “soul”. Ancient Greece - Hippocrates & Aristotle were the primary philosopher/scholars that defined the view of the brain during this period. Roman Empire - Galen’s writings and work defined the view of the role of the brain during this period. Renaissance Period – 1700’s – Vesalius and Descartes shaped the changes in understanding of the brain during this period. 1800’s -

Hippocrates ( B.C.E.) – first ascribed to the brain the role of the organ of sensation and the seat of intelligence.

Aristotle ( B.C.E.) – felt the heart was the center of intellect and believed the brain was more akin to a “radiator” to cool the body.

Galen ( A.D.) – Greek physician who tried to deduce function of the brain from structure of the cerebrum and cerebellum. He put forth a model for brain function that was the start of the fluid-mechanical theory. Galen was one of the earliest scientists to perform significant animal dissection leading to the field of comparative anatomy.

In Galen’s dissection work with sheep, he could feel physical differences in the texture of the cerebrum and the cerebellum. The cerebrum was softer, and more “spongy” than the firmer cerebellum. With this discovery, he proposed that the cerebrum was the area receiving sensations because it needed to be pliable and flexible, whereas the rigid cerebellum controlled the musculature.

Views of the Brain: The Roman Empire –Views of Greek physician Galen Cerebrum Cerebellum Ventricles

In the period of time from the Middle Ages into the early Reniasance, few changes or advancement in our understanding of the brain occurred. Most historians attribute the lack of growth in understanding of the brain during that time to the significant taboo on exploring the internal workings of the human body via dissection during that age. Annonymous painting from the 1300’s (Middle Ages) showing a surgeon and monk suggesting the prohibition on dissection.

Andreas Vesalius – publishes On the Workings of the Human Body in 1543… an enormously influential work during a period where it was still considered very taboo to engage in exploration of the internal workings of the human body.

Another example of one of his drawings. Notice the very precise drawing style and the quality of the drawings.

Rene’ Descartes – ( ) considered one of the most significant of the Western Philosophers and Scientists during his time. He promoted the idea of the brain function occurring via the fluid-mechanical theory…. especially for NON-HUMAN animals. He believed that a human’s soul necessitated other methods to explain human neural function and behavior.

Descartes ascribed special fluid moving powers to the pineal gland (letter “H”).

From Galen’s time through Descartes, the major emphasis on study of the brain focused on the ventricles, and tended to ignore or diminish potential roles for the tissue of the brain itself.

Grey & White Matter: When the tissue portion of the brain began to be more closely examined during the Renaissance, the focus shifted to examining tissue from the standpoint of the two visible color differences seen in the brain. These colors were readily observable in both fresh and preserved specimens. We use the same terms to name these different portions to this day…. grey and white matter. The hypothesis of that age on the function of these two distinctly different areas was that: a.White Matter, because it is similar in color and appears contiguous with the nerves in the peripherial body, serves to connect the brain and spinal cord to the nerves. b.Grey Matter, lying outside on the surface regions of the brain and spinal cord, is going to receive information from the periphery directly through interaction with the White Matter. These ideas are reasonably aligned with our current understanding of how these tissue areas function.

Overall views of the Brain During The Renaissance –The brain as a machine – Vesalius –Fluid-mechanical theory of brain function - Descartes –Philosophical mind-brain problem – Descartes (How do you meld the physical, observable tissues of the brain/nervous system with the philosohpical/religious ideas about the soul? BUT, by the mid to late 1700’s there was a well known and well respected body of knowledge in the dissected anatomy of the brain including gyri, sulci, and fissures.

Gyrus – “hill”-like area of tissue Sulcus – “valley’-like area of tissue Fissure – an especially deep sulcus

CNS – central nervous system…. brain & spinal cord PNS – peripheral nervous system… basically everything else

Benjamin Franklin publishes Experiments and Observations on Electricity in His notions on electricity paved the way for a new theory of neural function that prevailed in the 1800s.

Luigi Galvani Emil du Bois-Reymond These two researchers were responsible for determining the interaction between electricity and the brain.

Du Bois – Reymond later in life. Using electricity, Du Bois-Reyond was able to demonstrate a clear link between the contraction of muscle tissue and electricity. He proposed that this was the way in which nerves functioned in the body.

Du Bois – Reymond’s work generated worry and fear in the general population at many levels.

Charles Bell Francois Magendie These two conducted experiments that answered the question on whether the movement in a nerve was bidirectional or unidirectional. They saw that the nerves of the PNS will divide into two branches (ROOTS) just before merging with the CNS.

Overview of the Brain: The Nineteenth Century –Nerve as wires, understanding of electrical phenomena, nervous system can generate electricity –Bell and Magendie: Dorsal and ventral roots carry information in opposite directions These two roots (dorsal and ventral) carry information in different directions. Basically the ventral roots carry information out to the PNS to engage motor function. The dorsal roots transmit PNS sensory information into the spinal cord.

Franz Joseph Gall ( ) was the founder of phrenology.

Phrenology is a pseudoscience primarily focused on measurements of the human skull, based on the concept that the brain is the organ of the mind, and that certain brain areas have localized, specific functions or modules Phrenology was especially popular from about 1810 until 1840.

Marie-Jean-Pierre Flourens Famous for the development of the experimental ablation method. Ablation – a technique to eliminate or destroy tissue. In neuroscience, the origins of this technique occurred in bird studies, whereas today rodent studies are the most prevelant.

Franz Joseph GallPaul Broca Gall described the concept of phrenology – looked at the external skull (now discredited) Broca first identified a region of the cerebrum being associated with function – focused on the internal gyri and sulci of the cerebrum.

This left frontal lobe lesion (non experimental ablation) resulted in the inability to speak, showing a specific localized function for a region of the brain.

Charles Darwin – his theory of natural selection helped to explain the growth and development of the brain. What is especially valuable with Darwin’s work relative to neuroscience is his inclusion of BEHAVIOR among the heritable traits shaped through evolution. The very notion that many animals display a similar behavioral response to a similar stimulus suggests further a common ancestor. This is a very basic tenet of the current state of research in neuroscience and exemplifies why animal experimentation is so valuable.

However, it must also be understood that there can be unique specializations that can evolve in species relative to behavior. Specialized visual center in the monkey is show compared to a specialized region for smell in the rat.

So, for the evolution of the nervous system: –Natural selection –Nervous systems of different species may share common mechanisms –Rationale for “animal models”

The emergence of the CELLULAR study of the nervous system: The 1800s also heralded in the age of a cellular look at the nervous system. The cellular approach significantly contributed to further understanding of the system and complemented prior and continuing pathways of research into the function of the brain.

Theodor Schwann proposed the cell theory…. ALL TISSUES ARE COMPOSED OF CELLS This laid the groundwork for the tremendous molecular advances in neuroscience occurring today.

Otto Deiters (1865) – identified the major parts of the neuron and predicted the communication and interaction between the axon and dendrites.

An example of Otto Deiters drawing of a neuron.

Neuroscience Today We, like most all of science follows a reductionist approach: Reductionism can mean an approach to understanding the nature of complex things by reducing them to the interactions of their parts, or to simpler or more fundamental things or a philosophical position that a complex system is nothing but the sum of its parts, and that an account of it can be reduced to accounts of individual constituents. This can be said of objects, phenomena, explanations, theories, and meanings. Reductionism strongly reflects a certain perspective on causality. –Levels of analysis Molecular Cellular Systems Behavioral Cognitive

Levels of Analysis can be applied to Neuroscience

The Use of Animals in Neuroscience Research: Examples (from simple to more complex) - nematodes, insects, snails, squid, rodents, monkeys, etc. Animal rights Philosophy Abolition of animal use Animal rights activists

The Neuroscientist -Education, Training, Research experience -Clinical vs. Experimental research

The Cost of Ignorance: Nervous System Disorders