Please enable JavaScript.
Coggle requires JavaScript to display documents.
Neuroscience: Historical Perspectives (Early Theories: Mind/soul -…
Neuroscience: Historical Perspectives
Early Theories: Mind/soul - Body/Brain
Plato
no difference between sense in the brain, more central functions (Sensation + knowledge)
Encephalicentric
3 species of soul
Logos (head/divine)
Thymos (chest/feelings)
Epithemtikon (liver/hunger, passion, unconsious)
Earliest = Egyptians
Cases of head/neck injuries
Brain controlling behaviour
Heart is most important (mummification)
Homer
- Psyche: non-localised soul, individual life/identity, NOT specific body part, dreams (prior to Freud), life vs body soul
Natural Philosophers
Explain constitution of matter in substances (elements)
Rejected supernatural
Addressed problem of nature of soul
Brain or heart?
Encephalocentrism: brain is seat of human consciousness, sensation and knowledge
Cardiocentrism: attributed all these faculties to the heart
Anatomical dissections
Cognitive sig. of brain - channel like structure
Seat of consciousness and sensation
Distinguished bewteen sensation and understanding (build on)
Western Medicine
Human brain similar to animals (2 hemispheres)
Lateralisation of effects of brain injury
Epilepsy not scared
Brain = seat of intellect, causing neurological disorders
Aristotle
- Cardiocentric, different soul faculties, reside in heart
Galen
Against cardio-centric
Brain received sensations, produces images and understands thoughts
Rigorous anatomical testing
Brain + spine = nerves (connections)
Ventricular Hypothesis
Pig = kept breathing, not squealing, after throat nerves cut - voice from brain not heart
Brain = reciprocal for the soul - communication
Localise Mind without Brain: Neuroanatomy
Mind brain
- related but separate, Magnus: brain = centre of mental activity, mental brain and function = linked but mind is immaterial
Neuroanatomy rebirth
Da Vinci
- relating structure to mental function
Anatomical detail
Wax cast of ventricle
Ventricularist
- responsible for major brain functions, soul in brain rather than surrounding
Vesalius =
Non-ventricularist
Rejected ventricular localisation
Mammals = same brain but not intelligence
Cartesian Legacy
Mediated by fluid dynamics
Tech as metaphor
"Balloonist Theory": brain controlled body mechanically via fluids
Mind in
pineal gland
(endocrine gland) - between two hemispheres
Cartesian Dualism = immaterial and material interaction
Gap = how can they interact?
Cortex
= seat of psychological functions
Still cartesian - so still problem with gap
contact and causal interaction is cortex not pineal gland
Neuron Doctrine: Modern Neuroscience
Understanding nervous system
Microscopy > understanding of nervous system organisation
Histological methods > detail
Dendrites, cell bodies, axons
Reticularists vs. Cell theories
R = NS is large network of tissue, fused processes. Network not individual cells
CT = cells are separate but communicate as NS
Both = same methods but different conc. about structure
Limit = low mag + poor resolution
Organisation of NS
Purkinje Cells
Early microscopes = distortions, Newer = clearer
Discovering cerebellar cells (largest invertebrate)
Microscopic image of nerve
Golgi Staining
Rete Nervosa Diffusa
Nervous tissue = continuous, not discrete
Connections with infinite others
Holistic approach: NS as reticulum
Silver nitrate method
Thought observation confirmed hyp that NS = continuous network
Modern Neuroscience
Santiago, Ramon and Cajal
Acceptance of Neuron Doctrine
Tenets
Fundamental structural and functional unit of NS is neuron
Neurons = discrete not continuous cells
3 Parts - dendrites, cell body, axon
Info flows in one direction
Reasons for delay
Technical: histological preparation and optic quality microscope need to be improved
Area of study: nerve cells = extraordinary complex + variable structure
Theoretical: Belief that cell continuity necessary for interaction
Neuron = anatomical/functional unit of NS
Relationship is not continuity but contiguity
Staining Improved
- Cajal
Immersing tissues in fixative and silver nitrate 2nd, deep
Axon endings = consistent with location of dendrites
No evidence for reticulum - abandoned
Neuron
Constituted by numerous neuron units
Nerve cell, nerve fibre, terminal arborizations
Synapse = direction (polarised)
Theory supported by electron microscope techniques
Localisation and Brain Mapping: Phrenology to Cortical Topography
Early Observation
Effects of Brain Damage
- Diseases of the brain, not paralysed tongue but can't speak > memory
Localisation
Brain equipotentiality theory: brain functions as whole
Localisation: specialisation in the brain
Phrenology
Brain composed of many organs, dedicated to particular skill
Size of organ = measure of power
Shape = determined by development of organs
Skull takes shape from brain > surface = accurate index
*Greater use = increased
Analysis = insight into personality
Phrenometer = measure bumps on skulls
Functional specialisation = not empirically derived/constrained by theories
Against Localization
Animal lesions did not cause specific deficits
Aggregate field: whole brain in behaviour
One faculty, one seat in organs
Brain Mapping + Lesions
Cortical specialisation for uniquely human capacity for speech
Lost speech 20yrs before
Post-mortem
Lesion in L inferior frontal cortex
Specific area and specific dysfunction
Wernicke's Aphasia
Language understanding
Problems after damage to posterior part of L hemisphere
Nothing to do with speaking but understanding
Brain Mapping
First
Dogs stimulated with electric current
Surface = muscles contractions face and neck on opposite side
Unilateral ablation of forepaw did not affect sensation but impaired motor
Motor Cortex
Epilepsy: disease on one side of brain = convulsions on the other
Speculation: motor cortex = somatopically
W/ Anatomy
Brodmann
Systematic investigation of variation of cortex cellular properties
Somatosensory map = organised adjacent to body surface
Motor map = musculature represented in adjacent parts
Contribution
Empirical approach explaining
Dualism > materialism
Reductionism