Neuroscience: Neuroscience: The last frontier of the The last frontier of the

biological sciencesbiological sciences

Understanding ourselvesUnderstanding ourselves

THE BRAINTHE BRAIN The early attention to The early attention to

brainbrain

Skull surgeries Skull surgeries Evidence: TrepanationEvidence: Trepanation Skulls show signs of healingSkulls show signs of healing

Views of ancient EgyptViews of ancient Egypt Heart: Seat of soul and memory (not the head)-the brain of Heart: Seat of soul and memory (not the head)-the brain of

the deceased was simply scooped out!the deceased was simply scooped out!

Edwin Smith Surgical papyrus (BC1700)

Men ought to know that from the brain, and from the brain Men ought to know that from the brain, and from the brain only, arise our pleasure, joys, laughter and jests, as well as only, arise our pleasure, joys, laughter and jests, as well as our sorrows, pains, griefs and tears. And by this, in an our sorrows, pains, griefs and tears. And by this, in an especial manner, we acquire wisdom and knowledge, and see especial manner, we acquire wisdom and knowledge, and see and hear and know what are foul and what are fair, what are and hear and know what are foul and what are fair, what are bad and what are good, what are sweet and what are bad and what are good, what are sweet and what are unsavory…. And by the same organ we become mad and unsavory…. And by the same organ we become mad and delirious, and fears and terrors assail us…. All these things we delirious, and fears and terrors assail us…. All these things we endure from the brain when it is not healthy…. In these ways I endure from the brain when it is not healthy…. In these ways I am of the opinion that the brain exercises the greatest power am of the opinion that the brain exercises the greatest power in the man. - Hippocratesin the man. - Hippocrates

Aristotle clung to the belief, which was still more popular then, Aristotle clung to the belief, which was still more popular then, that the heart was the center of the intellect. He proposed that the heart was the center of the intellect. He proposed that Brain was a heat radiator for the cooling of blood.that Brain was a heat radiator for the cooling of blood.

The Origins of NeuroscienceThe Origins of NeuroscienceViews of the brain in ancient GreeceViews of the brain in ancient Greece

The Origins of NeuroscienceThe Origins of Neuroscience Views of the brain during the Roman empireViews of the brain during the Roman empire

Views of Greek physician Galen (130-200 Views of Greek physician Galen (130-200 A.D.)A.D.)

: deduced from his animal dissections: deduced from his animal dissections Cerebrum: the recipient of sensationsCerebrum: the recipient of sensations Cerebellum: the commander of muscleCerebellum: the commander of muscle Ventricles: hydraulic pump of fluid for limb Ventricles: hydraulic pump of fluid for limb

controlcontrol

The Origins of NeuroscienceThe Origins of NeuroscienceViews of the Brain: The RenaissanceViews of the Brain: The Renaissance

The brain as a machine : The brain as a machine : fluid mechanical theory fluid mechanical theory prevailed and its chief prevailed and its chief advocate was Rene advocate was Rene Descartes (1596-1650)Descartes (1596-1650)

‘‘mind’, that is God-given mind’, that is God-given soul and spiritual entity, soul and spiritual entity, was proposed by him to was proposed by him to explain uniquely human explain uniquely human mental capabilitiesmental capabilities

The Origins of NeuroscienceThe Origins of Neuroscience Views of the Brain: The Seventeenth andViews of the Brain: The Seventeenth and

Eighteenth CenturiesEighteenth Centuries

Gray matter and white Gray matter and white mattermatter

White matter was correctly White matter was correctly proposed to contain fibers that bring proposed to contain fibers that bring information to and from the grey information to and from the grey matter because it was continuous matter because it was continuous with the nerves of the body with the nerves of the body

The general pattern of bumps The general pattern of bumps ((gyrigyri) and grooves () and grooves (sulcisulci) on the ) on the surface of the brain is the same ; surface of the brain is the same ; suggests that different functions suggests that different functions are localized to different bumps are localized to different bumps

The Origins of NeuroscienceThe Origins of Neuroscience Nineteenth-Century Views of the BrainNineteenth-Century Views of the Brain

Nerves As WiresNerves As Wires Luigi Galvani and Emil du Luigi Galvani and Emil du

Bois-Reymond Bois-Reymond Muscles twitch when Muscles twitch when

electrically stimulatedelectrically stimulated Brain can generate Brain can generate

electricityelectricity Charles Bell and Francois Charles Bell and Francois

MagendieMagendie Is the wire bidirectional?Is the wire bidirectional? found that dorsal and found that dorsal and

ventral roots carry ventral roots carry separate information by separate information by cutting each fibercutting each fiber

The Origins of NeuroscienceThe Origins of Neuroscience Nineteenth-Century Views of the BrainNineteenth-Century Views of the Brain

Localization of specific Functions to Different Parts of BrainLocalization of specific Functions to Different Parts of Brain Experimental ablation methodExperimental ablation method

Marie-jean-Pierre Flourens showed that the cerebellum Marie-jean-Pierre Flourens showed that the cerebellum plays a role in the coordianation of movement and plays a role in the coordianation of movement and cerebrum is involved in the sensation and perception cerebrum is involved in the sensation and perception with with solid experimental supportsolid experimental support

PhrenologyPhrenology Franz Joseph Gall proposed that the Franz Joseph Gall proposed that the

propensity for certain personal traits propensity for certain personal traits could be related to the dimensions could be related to the dimensions of the head assuming that the of the head assuming that the bumps on the head reflects the bumps on the head reflects the bumps on the surface of the brainbumps on the surface of the brain

Correlating the structure of the Correlating the structure of the head with personality traitshead with personality traits

Right assumption but wrong Right assumption but wrong approach!!approach!!

The Origins of NeuroscienceThe Origins of Neuroscience Nineteenth-Century Views of the BrainNineteenth-Century Views of the Brain

Localization of specific Functions to Localization of specific Functions to Different Parts of BrainDifferent Parts of Brain Paul Broca (1820-1880) proposed Paul Broca (1820-1880) proposed

that the production of speech can be that the production of speech can be localized to a region of human localized to a region of human cerebrum cerebrum

His patients could not speak while His patients could not speak while they could understand languagethey could understand language

All had a lesion in the frontal lobe of All had a lesion in the frontal lobe of left hemisphereleft hemisphere

““Nous parlons avec l’hemisphere Nous parlons avec l’hemisphere guache!”guache!”

Karl Wernicke described another type Karl Wernicke described another type of aphasiaof aphasia

His patients could speak but could not His patients could speak but could not understand languageunderstand language

Localized to posterior part of temporal Localized to posterior part of temporal lobe lobe

The Origins of NeuroscienceThe Origins of Neuroscience Nineteenth-Century Views of the BrainNineteenth-Century Views of the Brain

The Evolution of Nervous systemsThe Evolution of Nervous systems Charles Darwin included behavior among the heritable traits Charles Darwin included behavior among the heritable traits

that could evolvethat could evolve Because behavior reflects the activity of the nervous system, Because behavior reflects the activity of the nervous system,

we can infer that the brain mechanisms that underlie a we can infer that the brain mechanisms that underlie a behavioral reaction may be similar, if not identical, across the behavioral reaction may be similar, if not identical, across the speciesspecies Adaptations Adaptations

Many behavioral traits are Many behavioral traits are highly specialized for the highly specialized for the environment (niche) environment (niche)

Reflected in the structure Reflected in the structure and function of the brain and function of the brain of every speciesof every species

The Origins of NeuroscienceThe Origins of Neuroscience Nineteenth-CenturyNineteenth-Century Views of the Brain Views of the Brain

The Neuron: The Basic The Neuron: The Basic Functional Unit of the BrainFunctional Unit of the Brain Theodor Schwann proposed Theodor Schwann proposed

the ‘cell theory’the ‘cell theory’ All tissues are composed of All tissues are composed of

microscopic units called microscopic units called cellscells