Development of Physiological Influences The brain Nerve function Visual perception Brain localization Psychophysics

The Brain Australopithecus africanus Trephining

Egyptians Threw away brain when mummifying

Greek Doctors: Are there Animal Spirits in there? Dissected brains and optic nerves; brain is organ of thought The soul is in the fourth ventricle and the "animal spirits" (intellectual, motor system) are in the brain itself (cerebrum)

Galen’s Cell Doctrine Galen localized the mind to the ventricular system of the brain First cell: imaginativa and fantasia Second cell: aestimativa, cognitativa, and ratio Third cell: memorativa

Pre-Renaissance “Animal Spirits”

Renaissance - da Vinci da Vinci’s system: Anterior ventricle: intelletto and imprensiva Middle ventricle: volonta and senso comune Posterior ventricle: memoria

Renaissance - Descartes Agreed with Galen about ventricles Hydraulic theory of nerves

Nerve Function (electricity view)

Whytt's (b. 1714) Reflex Reflexive contraction of pupil to light Reflexes were involuntary and depended on spinal cord

Galvani-Volta Debate

Luigi Galvani (b. 1737) claimed that he discovered animal electricity Count Alessandro Volta (b. 1745) did not agree

Galvani will become known for…?

Volta will become known for…?

Giovanni Aldini provided basis for a novel written by a famous writer…

HINT:

du Bois-Reymond (b. 1818) Discovered the action potential He or Galvani the "Father of Electrophysiology“?

Sir Charles Bell (b. 1774) Experiments with rabbits Francois Magendie – experiments with puppies 

Bell-Magendie Law Dorsal roots of spinal nerves bring in sensory information Ventral roots carry motor fibers down to the muscles

Johannes Muller (b. 1801) Directly aware only of the activity in our nerves, not external reality Doctrine of specific nerve energies

Research on Visual Perception

Hermann von Helmholtz (b. 1821) Medicine, physics, math, psychology, music, philosophy Metabolism Determined wavelength of ultraviolet light Optics Theory of velocity of air in open tubes (acoustics) Thermodynamics (Law of conservation of energy)

Contributions to Psychology Measuring the speed of the nerve impulse (REACTION TIME) Young-Helmholtz trichromatic color theory Place theory of pitch perception

Ewald Hering (b. 1834) Opponent-process theory of color perception

Hering Illusions

Hering bow

Jan Purkinje (b. 1787) Shift from cone to rod vision in twilight The “Purkinje Effect” or “Red Shift”

Brain Localization

Phrenology

Franz Gall (b. 1758); his pupil Spurzheim The mysterious “Miss Leisler” "Neither sin nor friends will ever leave me."

Gall’s Work on Nervous System Nervous system is like a tree Distinction between gray matter (neurons) and white matter (axons) CNS fibers terminate in the cortex, not the medulla Identified origins of cranial nerves I-VIII Pyramidal tracts crossing brain hemispheres

Gall’s Claim Mental activities localized in the cortex Wanted to develop a functional anatomy and physiology of the brain, as well as a revised psychology of personality Led to theories concerning localization and cranioscopy

The System of Organology Brain is organ of the mind Brain is a collection of organs representing various propensities, sentiments, faculties Size of each organ indicates its power Skull conforms to brain's shape Mind's functions located in different places in the brain

How Many Faculties of Mind? Gall sez 27 Spurzheim sez 37

Napoleon’s & Descartes’ Heads

Phrenology taken over by Quacks Employment Marriage prospects Children's prospects 1920's - “The Psychograph” Problems?

Contributions of Phrenology Established brain as the source of mind Mental functions localized in the brain

Pierre Flourens (b. 1794) "An Examination of Phrenology" 1824 Ablation technique- removal of one of six separate areas of brain

6 Different Brain Functions Cerebral hemispheres - willing, judging, memory, seeing, hearing Cerebellum - motor coordination Medulla oblongata - mediation of sensory/motor functions Corpora quadrigemina (inferior/superior colliculi) - vision Spinal cord - conduction Nerves - excitation

Flourens vs. Gall Flourens’ approach reflected localization, but he stressed the common action of the various parts Emphasis on the common unity of the entire system

Recovery of Function Also observed recovery of mental function over time - forerunner of "neural plasticity"

Brain Localization: The Story of Phineas Gage

Sept. 13, Vermont - a deadly day for Phineas Iron rod entered under left cheek, exited through top of head, landed 30 yards away. Dr. John Harlow MRI analysis by Damasio shows damage in ventromedial region on left side of brain

Off Off Off Theatre Boo Hoo Ramblers

Language Localization in Brain

Paul Broca (b. 1824) Patient named Mr. Leborgne Autopsy showed lesion to 3rd convolution of left frontal lobe Concluded this area important for speech articulation

Broca’s Brain!

Karl Wernicke (b. 1848) Damage in top left temporal lobe causes poor language comprehension (Receptive aphasia)

Psychophysics – the Beginning of Psychology?

Ernst Weber (b. 1795) Investigated 2-point thresholds for touch Jnd's investigated for various stimuli Jnd's vary by a constant ratio called “Weber Fraction” First to quantitatively measure the mind?

Gustav Fechner (b. 1801) "Elements of Psychophysics" 1860 The term “Psychophysics” coined Fechner's Law Developed method of limits, method of constant stimuli, method of average error (adjustment)