ischemic stroke
due to blockage of blood vessels, dies from insufficient nutrients and oxygen
hemorrhagic stroke
rupture of blood vessels, blood
... [Show More] leaves and other parts are insufficient of oxygen
Brainpower
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stroke
one of the most common causes of severe brain injury
lack of proper blood flow to the affected areas
tumors
mass of new tissue growing independently of its surroundings
nearly 40,000 people diagnosed/year
meningitis
tissues surrounding the brain and spinal cord become inflamed; often bacterial _____ spread to the brain, causing encephalitis
neuropsychology
goal: to understand the relationship between brain function and behavior
clinical perspective (of neuropsychology)
focus on the effects of brain damage or disease on psychological processes, interested in damages to the hardware
cognitive perspective (of neuropsychology)
understand impairments of psychological processes in terms of disruption of information processing systems; interested in particular symptoms, damage to the software
brain hypothesis vs. heart hypothesis
-the brain vs. heart as the source of behavior
-heart was long believed to be the organ of thinking and mental processes, and these processes were regarded as "immaterial", i.e., not physical
Aristotle (384-322 BC)
-earliest study of formal logic
-favored the heart hypothesis over brain hypothesis
-believed the mind is mental, i.e., not physical
-in ancient times, the predominant belief was that the heart was the enter of the "soul" and of "thought" and "mind", thought the heart was warmer than the brain
Galen of Pergamum (129-210)
-Roman physician presented some of the most compelling early arguments against the "heart hypothesis"
-challenged it by describing changes in behavior from gladiator head wounds
-when you touched the brain, body parts would move
-found nerves and traced them back to the brain, not heart
Rene Decartes (1596-1650)
-"cogito ergo sum" --> "I think, therefore I am"
-"mind-body problem"
contributions:
-used a MODEL to explain how the world works, it was wrong but could be proved wrong empirically
-emphasized NERVES, made it important and interesting again to examine nerve function; suggested sensory nerves worked differently from motor nerves
-split between PHILOSOPHY and PSYCHOLOGY: rationalism vs. empiricism, argue about how the world works or examine it?
mind-body problem
A fundamental psychological issue: Are mind and body separate and distinct, or is the mind simply the physical brain's subjective experience?
--> mentalism was still present: the idea that the mind was immaterial, yet the brain is very material
--> said the pineal gland picks up the vibrations and transducer the mind into physical signals controlled in the body
-->suggesting localization of function by saying that it was that region doing that particular function
Decartes' Model
automation vs. human
tubes = nerves
ballons & springs = muscles & tendons
water = animal spirits
Descartes' notion of how nerves work
sensory nerves: act like strings
motor nerves: act hydraulically
trap doors in pineal gland and CSF flows and causes muscles to move
Luigi Galvani (1737-1798)
-first to disprove Descartes' theory of (motor) nerve action
-electrical action of nerves
-used frogs as his animal model (frog legs)
--> isolated frog legs from the rest of the body (cut them off)
--> by cutting the nerves open, there could be no hydraulic pressure in them. then he hooked up electrodes to the nerves and stimulated them
--> had developed one of the first batteries
-experiment showing that nerves could be stimulated by "static" electricity from an electrical storm
--> he attached dozens of frog legs to a mental trellis during an electrical storm
Franz Joseph Gall (1758-1828)
-German anatomist, phrenologist
-first general theory to propose that different parts of the brain have different functions developed in the early 1800s
-proposed that the cortex was the functioning part of the brain, not just a covering for pineal gland
-first to distinguish gray matter (neurons) from white matter (axons)
phrenology
mental faculty (personality traits) can be located through particular parts of the cortex; look for bumps on the skull
-done by Franz Joseph Gall
Pierre Flourens (1794-1867)
developed techniques of cutting or removing parts of the brain to systematically study effects of brain damage on behavior
-greatly changed the validity of phrenology
-used pigeons as an animal model:
-->loss of behavioral function was more related to amount of tissue damage than to location of tissue damage
Paul Broca (1824-1880)
-worked with a patient who had suffered damage to the Broca's area of the brain impairing his speech, gave insight into lateralization
-introduced lateralization - that one cerebral hemisphere can perform a function not shared by the other
-famous case of 'Monsieur Tan' - left frontal lobe affected by stroke, could not speak or get words out
Broca's aphasia
lack of speech
Carl Wernicke (1848-1905)
-German numerologist and psychiatrist who discovered that damage to an area on the left temporal lobe caused deficits in language comprehension
-created the first model of how brain produces language in 1874
-was aware that part of the cortex into which the sensory pathway from the ear projects (auditory cortex) is located in the temporal lobe behind Broca's area; suspected a relation between hearing and speech functions, and he described cases in which aphasic patients had lesions in this auditory area of the temporal lobe
Wernicke's aphasia
people often speak in "word salad"; patients could speak fluently, but what they said was confused and made little sense
Wernicke's model
1) sounds enter the brain through the auditory pathway
2) sound images are stored in Wernicke's area...
3) .. are sent to Broca's area...
4) ... for articulation over the motor pathway
this makes a new prediction: damage to the pathways between the areas should result in impairments even though the areas themselves are not damaged
alexia
loss of ability to read following damage to the angular gyrus or disconnection of angular gyrus and Wernicke's area; "word blindness"
Gustav Fritsch (1838-1929) & Eduard Hitzig (1838-1907)
-used electrical stimulation of cerebral cortex to establish topographic organization of motor strip
--> parts of the cortex that are adjacent to each other control parts of the body that are adjacent to each other
-established the motor cortex - showed it was electrically excitable with electricity using a rabid then a dog
-helped establish right hemisphere controls left body, vice-versa
topographic organization
seen in the motor homunculus which depicts the parts of the body controlled by specific areas of the motor cortex
Karl Lashley (1890-1950)
mass action: the entire cortex is involved in all function
equipotentiality: each area of cortex can assume control for any particular behavior
-he searched for the memory "engram", the physical, anatomical location of memory in the brain
-trained rats to solve a maze, then cut different parts of the cortex
--> no cut significantly imparted the rat's performance, related to amount removed not location removed
-concludes: the entire Cortex was involved because big parts of the cortex removed impacted functions
neuron hypothesis
the unit of brain structure and function is the neuron
1) neurons are discrete, autonomous cells that interact with each other but are not physically connected
2) neurons send electrical signals that have a chemical basis
3) neurons use chemical signals to communicate with one another
Camillo Golgi (1843-1926)
nerve net hypothesis: all neurons are connected together in a neural net, allowing the brain to act as a single, holistic organ
-first to develop best technique
-used silver nitrate to stain entire neuron; sometimes saw "fields" of neurons
Santiago Ramon y Cajal (1852-1934)
neuron hypothesis: cells connected in pathways do different functions
-used Golgi's techniques to produce beautiful drawings of neurons in different areas of the brain that looked very different from each other
-never saw connections from cell to cell, concluded each cell was thus distinct
-examined chick neurons at different stages of development
Hodgkins and Huxley (Nobel Prize, 1963)
-axons isolated from the squid mantle nerve were used to show electrical conduction along the length of the axon
-evidence that neurons send chemically-based signals was shown by Hodgkins and Huxley using the "giant axon" of the squid mantle nerve
showed that neurons generate brief electrical charges that are conveyed along the axon by way of chemical ion movement
Otto Loewi
Experiment:
-donor heart and recipient frog heart
-stimulating Vagus nerve, making the heart slow down
-collects fluid and dribbles it onto recipient heart
-recipient's heart slows down
Conclusion: the fluid has a chemical in it released from the neurons, which goes across the gap from one neuron to the next
-stimulating the nerve attached to the frog heart released something into the fluid around the heart - a chemical
connectionism
the modeling of mental or behavioral phenomena as the emergent processes of interconnected networks of simple units
-with the emergence, or re-emergence of neuropsychology in the 1950s and 1960s came increased understanding of the importance of this between brain areas an an interest in this of the parts to explain functions and impairments in function in damaged brains
Jerry Fodor (1935-2017) [Show Less]