Development of Physiological Influences The brain Nerve function Visual perception Brain...

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, 1848 - 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)