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The Biological Approach: Influential Research - Coggle Diagram
The Biological Approach: Influential Research
Robert Whytt (1714-1766)
Studied reflex actions
Decapitated frogs show reflexes - Brain not needed for reflex response
Distinguished between voluntary + involuntary actions
Habit formation
Studied conditioned reflexes + conditioned response (e.g. salivating when hungry)
Led to:
Learning Theory
Behaviourism
Bell-Magendie Law (Francois Magendie, 1783-1855)
Knee jerk reaction
Hammer hits below knee.
Sensory neuron sends electrical message to spinal cord (along posterior spinal root).
Interneuron sends message to motor neuron from spinal cord.
Motor neuron sends message to target muscle (via anterior spinal root)
Muscle moves - Knee jerks
Motor fibres always come from anterior spinal root
Sensory fibres always come from posterior spinal root
Basic arrangement of nervous system - Nerve function based on electrical function + connections between nerves form simple reflexes
Nerve conduction research (Magendie, Hemholtz) led to:
Cognitive Psychology
Johannes Muller (1801-1858):
Law of specific energies
Stimulation of a nerve depends on the type of nerve it is rather than the mode of stimulation (e.g. stimulated by heat/light)
Herman Helmholtz (1821-1894)
Measured speed of nerve impulses
Studied vision = Depth perception, colour vision
Studied hearing = Resonance theory (cochlea identifies different pitches)
Research of the senses led to:
Physiological Psychology
Perception
Heinrich Von Waldeyer-Hartz (1836-1921)
Created Neurone Doctrine - Nervous system made up of individual + discrete cells (neurones)
Camillo Golgi (1843-1926)
Developed stain for brain tissue
Produced first clear pictures of neurons (supported neurone doctrine)
Proposed 'nerve network theory' - brain functions by nerves contacting other cells
NNT rejected by Cajal (1852-1934) - Claimed there was a gap between neurons
Sir Charles Sherrington (1857-1952)
Studied reflex actions on 'spinal dogs' (exposed spinal cord)
Found contradictory evidence to nerve network theory
Found reaction time too slow - stimulate spinal cord, motor response slower than expected
Temporal summation - If spinal cord stimulated with enough successive signals, reflex occurs
Spatial summation - If spinal cord stimulated with enough signals from various areas, reflex occurs
Supported Cajal's gap theory - 'synapse'
Predicted existence of neurotransmitters - Chemical change rather than electrical
Led to:
Pharmacological treatment for disorders
Franz-Joseph Gall (1758-1828)
Phrenology
Believed brain is organ of the mind
Mind is composed of 'faculties' (cognitive + emotional)
Each faculty is associated with specific brain location
Larger brain area = greater ability
Surface of scalp = surface of brain
Jean Pierre Flourens (1794-1867)
Rejected phrenology as a science
Ablation (removing tissue) via in vivo experiments on animals
Found removing cerebellum affects motor coordination, not sexual behaviour (cerebellum not faculty of amativeness)
Found the more brain regions ablated, the worse the outcome
Paul Broca (1824-1880)
Localisation of language (1861)
Tan - Expressive aphasia (couldn't speak)
Post-mortem of Tan - large lesion in left-frontal region (Broca's area)
Arcuate fasciculus - Bundle of white matter connecting Broca's + Wernicke's areas
Carl Wernicke (1848-1905)
Wernicke's area - language comprehension (1874)
Receptive aphasia (inability to understand language) - Lesion in left posterior region of superior temporal gyrus
Wernicke-Lichtheim Model:
Functional model based on clinical observation + a priori reasoning (knowledge gained without experience)
5 types of aphasia:
Broca's aphasia - Motor word representations area damaged
Wernicke's aphasia - Auditory word representation area damaged
Sensory Transcortical aphasia - Connection between elaborated concepts area + auditory word representations area damaged
Motor Transcortical aphasia - Connection between elaborated concepts area + motor word representations area damaged
Conduction aphasia - Inability to repeat words, understand + speak (model predicted this type of aphasia)
Phineas Gage (1823-1860)
Tamping iron passed through head
Damaged frontal lobe - Personality changed (more horrible, fitful, "no longer Gage")
Led to:
Cognitive Psychology
Clinical neuropsychology
Karl Lashley (1890-1958)
Taught rats to complete complex maze task
Systematically lesioned area so rat unable to remember how to complete task
Found larger lesion = greater deficit
2 laws:
Law of mass action - Speed of learning depends on mass of cortex (more mass in cortex = more learning)
Equipotentiality - All parts of cortex are equal in terms of its contribution to learning
Lorber (1980)
Documented over 600 scans of people with hydrocephalus (surface spinal fluid build up + causes skull to get bigger + brain to get smaller)
Found ventricles are bigger in brain with hydrocephalus than normal brain
Brain is plastic organ - Development pressures affect the way brain is structured/organised, adaptive
Donald Hebb
Memories stored in networks across large areas of cortex
Destroying any part won't destroy entire memory
Wilder Penfield (1891-1976)
Cortical stimulation - different areas of brain stimulated on over 1000 patients + asked for their experiences, mapped out cortex
Body represented in a systematic way across cortex - larger areas = more important parts of body
E.g. tongue = large area in cortex
Memory only in temporal lobes
Involved in surgery in epilepsy - remove brain tissue causing seizures (invasive)
Led to:
Modern mapping of brain
Localisation of function
Scanning techniques (e.g. fMRI, PET, MEG etc)