Neuroscience: The last frontier of the biological sciences

1. Neuroscience: The last frontier of the biological sciences Understanding ourselves

2. THE BRAIN • The early attention to brain • Skull surgeries • Evidence: Trepanation • Skulls show signs of healing • Views of ancient Egypt • Heart: Seat of soul and memory (not the head)-the brain of the deceased was simply scooped out! Edwin Smith Surgical papyrus (BC1700)

3. The Origins of NeuroscienceViews of the brain in ancient Greece • Men ought to know that from the brain, and from the brain only, arise our pleasure, joys, laughter and jests, as well as our sorrows, pains, griefs and tears. And by this, in an especial manner, we acquire wisdom and knowledge, and see and hear and know what are foul and what are fair, what are bad and what are good, what are sweet and what are unsavory…. And by the same organ we become mad and delirious, and fears and terrors assail us…. All these things we endure from the brain when it is not healthy…. In these ways I am of the opinion that the brain exercises the greatest power in the man. - Hippocrates • Aristotle clung to the belief, which was still more popular then, that the heart was the center of the intellect. He proposed that Brain was a heat radiator for the cooling of blood.

4. The Origins of NeuroscienceViews of the brain during the Roman empire • Views of Greek physician Galen (130-200 A.D.) : deduced from his animal dissections • Cerebrum: the recipient of sensations • Cerebellum: the commander of muscle • Ventricles: hydraulic pump of fluid for limb control

5. The Origins of NeuroscienceViews of the Brain: The Renaissance • The brain as a machine : fluid mechanical theory prevailed and its chief advocate was Rene Descartes (1596-1650) • ‘mind’, that is God-given soul and spiritual entity, was proposed by him to explain uniquely human mental capabilities

6. The Origins of NeuroscienceViews of the Brain: The Seventeenth andEighteenth Centuries • Gray matter and white matter • White matter was correctly proposed to contain fibers that bring information to and from the grey matter because it was continuous with the nerves of the body • The general pattern of bumps (gyri) and grooves (sulci) on the surface of the brain is the same ; suggests that different functions are localized to different bumps

7. The Origins of NeuroscienceNineteenth-Century Views of the Brain • Nerves As Wires • Luigi Galvani and Emil du Bois-Reymond • Muscles twitch when electrically stimulated • Brain can generate electricity • Charles Bell and Francois Magendie • Is the wire bidirectional? • found that dorsal and ventral roots carry separate information by cutting each fiber

8. The Origins of NeuroscienceNineteenth-Century Views of the Brain • Localization of specific Functions to Different Parts of Brain • Experimental ablation method • Marie-jean-Pierre Flourens showed that the cerebellum plays a role in the coordianation of movement and cerebrum is involved in the sensation and perception with solid experimental support • Phrenology • Franz Joseph Gall proposed that the propensity for certain personal traits could be related to the dimensions of the head assuming that the bumps on the head reflects the bumps on the surface of the brain • Correlating the structure of the head with personality traits • Right assumption but wrong approach!!

9. The Origins of NeuroscienceNineteenth-Century Views of the Brain • Localization of specific Functions to Different Parts of Brain • Paul Broca (1820-1880) proposed that the production of speech can be localized to a region of human cerebrum • His patients could not speak while they could understand language • All had a lesion in the frontal lobe of left hemisphere • “Nous parlons avec l’hemisphere guache!” • Karl Wernicke described another type of aphasia • His patients could speak but could not understand language • Localized to posterior part of temporal lobe

10. The Origins of NeuroscienceNineteenth-Century Views of the Brain • The Evolution of Nervous systems • Charles Darwin included behavior among the heritable traits that could evolve • Because behavior reflects the activity of the nervous system, we can infer that the brain mechanisms that underlie a behavioral reaction may be similar, if not identical, across the species • Adaptations • Many behavioral traits are highly specialized for the environment (niche) • Reflected in the structure and function of the brain of every species

11. The Origins of NeuroscienceNineteenth-Century Views of the Brain • The Neuron: The Basic Functional Unit of the Brain • Theodor Schwann proposed the ‘cell theory’ • All tissues are composed of microscopic units called cells