MT1 Flashcards
why do we have brains?
1. Daniel Wolpert
2. mentalism and cardiac hypothesis
3. brain hypothesis
4. dualism
5. phrenology
- brains responsible for movement and all behaviour is gov by movement since it is only way to influence with environment around us
- Aristotle proposed that every person has an independent non-material mind which governs behaviour through the heart which makes people unique
- As physician Galen noticed through open wounds that many vessels lead to the brain, thus brain must be where the mind is
- Rene Descarte proposed that immaterial mind located in the pineal gland and physical body are separte entities but each can interact with another
- brain is tissue governing the body with specific parts cobtrolling diff behaviours, the size of each part of the brain correlated with dev of behaviour which can be measured by palpating bumps of the skull; change behaviour by changing size of brain region
case study on language
1. case studies in neuropsychology
2. localization and lateralization of function
3. Broca’s area
4. Wernicke’s area
5. Wernicke’s model
- in-depth investigations of a phenomenon, often small sample size; reveal how the brain works through the dysfunction of a part and its affect on behaviour
- functions are located in one part of the brain and can be lateralized to one side of the brain
- part of left frontal lobe responsible for motor control of speech; dysfunction of Broca’s area is Broca’s aphasia where speech movements are lost but sound rep is not, therefore have trouble producing right sounds or finding right words but can understand speech
- Wernicke’s area is part of the left temporal lobe responsible for the organization of language; Wernicke’s aphasia where sound rep damaged, therefore can speak fluently but it will not make sense, typically have trouble understanding language
- auditory info travels from ears to temporal lobe, sounds are processed into auditory representations and stored in Wernicke’s area, sent to through arcuate fasciculus bending around lat fissure to Broca’s area, sound representations turn into speech movements and stored, area representations of speech movements in Broca’s area are sent to muscles involved in speech to produce appropriate sounds
disconnection
1. conduction aphasia
2. neuroplasticity
3. hierarchical org
- if arcuate fasciculus was dmged then speech sounds and movement retained but speech still impaired since signal cannot be conducted between regions
- Goltz challenged idea of localization by removing entire cortex of dog, no change in specific function, dog behaved like a normal dog, except with shorter sleep wake cycle and duller senses, though impaired abilities recovered suggesting brainstem can substitute for cortex indicating a lvl of neuroplasticity
- since removal of cortex did not eliminate function but only reduced all functions suggests information is processed in sequence and organized in a functional hierarchy, higher level areas control more complex aspects of behaviour via lower levels, dmg to higher levels produce dissolution (reverse evolution where behaviours are simpler like in animals that did not dev missing brain struc)
- Brain mapping
- Neuropsychology
- Neuron hypothesis
- Nervous system overview
- Korbinian Brodman used golgi staining techniques to observe nerve tissue using a microscope, discovered six layers of nerve cells with different characteristics (different functions), different parts of cells, and mapped the parts of the brain
- Study of the connection between human behaviour and brain, influenced by variety of disciplines
- Neuron is major unit of brain structure and function
- Split into CNS comp brain and spinal cord, PNS comp ANS and SNS (sensory and motor)
Wilder Penfield
- Work with epilepsy patient, reduce seizures caused by abnormal electrical activity by removing parts of the brain suspected to be the cause
- Stimulating different parts of the brain cause sensations in different parts of the body, somatosensory cortex (S1) localizes sensation of parts of the body to a representation in the brain, the more sensory neurons in a an area the larger the representation in the brain
Patient H.M.
- When he was eight or nine got into a cyclist accident and began experiencing seizures which got progressively worse to point he would exp multiple a day, negatively impacting all aspects of his life
- Lobotomy removing large part of his hippocampus treated his seizures but lost the ability to convert short term memories to long term memories, could only remember 20 seconds but could acquire new motor skills therefore different parts of memory are encoded differently
Distributed sys
1. Binding problem
2. Streams of processing
3. Ventral v. Dorsal stream in vision
- How different aspects of experiences are processed by different parts of the brain and are put together seamlessly
- different parts of the brain put experiences together to produce a modaility (memory, vision, sound, etc); dorsal stream involves parietal lobe, ventral stream involes temporal lobe
- ventral stream responsible for object recognition during concious perception; dorsal responsible for localization during unconcious perception; both work together to bind info together to produce sensation and ability to interact with environment
brain damage: traumatic brain injuries
1. head injury
2. concussions
- TBI is dmg or injury to brain caused by external force or recurring pressure on skull occurring after birth, disrupts brain function, not hereditary, congenital, degen, or induced by birth trauma; can be open (skull penetration) or closed
- closed head injury that can’t be seen by neuro imaging tech which affects the way people think and remember and causes variety of symptoms; coup is site of blow, countercoup is the second area of damage produced by compression of the brain against the skull opposite to the coup; severe (counter)coup can be accompanied by bleeding or subdural hematoma; can occur without blow
dementia pugillistica
1. overview
2. p-tau proteins
3. risk of brian injuries
4. prolonged brain rest and recovery period
4. sport concussion stats
- boxer’s syndrome or chronic traumatic encephalopathy (CTE) is progressive degen brain disease caused by repeated head trauma which cause accumulation of p(phosphorylated)-tau proteins in neurons and glial cells,
- tau proteins are responsible for stabilizing microtubules in brain for transport of nutrients in nerve cells, phosphorylation of tau proteins destabilize microtubules leading to clumping which breaks down brain cells leading to declining cog ability, short term memory less, tremours, loss of coordination, difficult speech, and emotional disturbance
- athletes with E4 variant of apolipoprotein (APOE) gene have increased risk of dev brain injuries
- when told too ill, take on sick role psychologically and can worsen symptoms; after initial 1-2 days of rest, try to return to daily life until symptoms show, stop, rest, repeat; axonal health (myelination) makes it easier to recover from concussion, recovery also lengthed by mental health (post and pre concussion anxiety)
- concussions in sport are public health issue due to frequency and consequences; most prevalent in youths 10-20 since they are more likely to be active in sports and not follow safe practices, more in males and high in sports such as ice hockey, rugby, and ringette
neuron theory
1. overview
2. electrical activity in neurons and behaviour
3. TMS
4. learning
- neurons are autonomous ceells that interact but are not physically connected, neurons send electrical signals with a chem basis, neurons use chem signal to communicate
- Fritsch and Hitzig showed that electrically stimulating the parts of cortex via an electrode produces selective movement in certain parts of the body on the opposite side, suggests that cortex forms topographic neural-spatial reps of body
- non-invasively stimulate different parts of the brain by inducing electrical activation via magnetized coil on surface of skull to study how different parts of the brain produces different behaviour
- Sherrington theorized that neurons separated by junctions called synapses, Loewi discover that synapses release chemicals to influence adj cells; based on this Hebb proposed that when individual cells activated at same time, synapses are est or strengthen to form basis of memory, families of neurons form cell assemblies to rep units of behaviour underlying conciousness
contributions to neuropsych from allied fields
1. neurosurgery
2. psychometrics
3. brain imaging
- long history of neurosurgery; Hippocrates gave directions for trephining (cutting hole in skull) to reduce pressure from swelling brain from TBI; modern era with intro of antisepsis, anesthesia allowing patients to remain conscious and contribute by providing info about effects of localized stim, and principle functional localization
- Binet and Simon produced a test to id children with learning disabilities with a mental lvl based on score of 80-90% typical children of a certain age; Terman revised the test so that the mental age rep by IQ was set at average to be 100; when Hebb gave IQ tests brain dmged people, those with frontal lobe lesions did not have decreased scores
- early neuropsych relations between brain and behaviour could only be made at autopsy such as Charcot discovering MS (degen disease characterized by hardening of nerves in the spinal cord leading to loss of sensory and motor func); brain imaging allows for quick localization of symptoms for diagnosis
brain imaging techniques
1. CT
2. PET
3. MRI
4. Diffusion tensor imaging
- produces 3D image by passes X rays through head, bone absorbs more x-rays than brain cells which absorb more than water, dead brain cells with more water, produces darker images than healthy cell, quick, cheap but low quality
- radiotracer injected and decays, releasing photons which are used to create reconstruction of brain activity based on use of radiotracer
- calculate location of moving molecules using electrical charge generated by their movement to produce high quality image
- MRI method using direction of water molecules to gen images of brain’s nerve pathways
brain damage: tumors
1. overview
2. assessment
3. types
4. symptoms
- majority arise in glial (gliomas) and meninges cells (meningiomas, often benign and easy to remove at surface of brain); caused by old cells that do not die normally, insides of cells leaking, or abnormal multiplying which increases mass in area
- req symptomatology from patient, neuroimaging, and neuropsychological testing to fully assess the extent and type of tumor
- malignant tumors lack defined cell membrane and are likely to recur following removal, can metastasize when cells are shed and travel to other sites, increasing probability that tumors will occur; benign tumors are contained within own membrane, not shedding cells or relasing chem therefore have a low chance of recurring after removal
- pressure in skull, specific disruptions related to location
degree and treatment of tumors
1. grades of tumors WHO
2. treatment
- benign, slow growing, respond well to surgery
- malignant, slow growing, increased chance of recurrence
- malignant, high change of recurrence, req aggressive treatment
- rapidly fatal
- best treatment depends on size, type, grade, location, metastasis, and patient capacity to tolerate treatment; radiation therapy uses internal or external high E rad to target and destroy cancer cells but may dmg healthy cells; chemotherapy meds target rapidly div cells such as cancer but also some healthy cells; targeted therapy uses drugs that selectively interfere with specific molecules contributing to growth and survival of cancer cells
multiple sclerosis
1. overview
2. risk factors
3. symptoms
4. prevalence
- chronic autoimmune disorder affecting CNS which damages oligodendrocytes (glial cells forming myelin in CNS) and attacks myelin, forming scar tissue which hardens the white matter leading to inflammation and disruption of signals
- increased risk with higher estrogen, twice more common in females, female immune sys more susceptible to MS dev, and low levels of vitamin D (more common in women), modest heritability and environmental factors
- often appears first between ages of 20-40 y/o, common symptoms are numbness and tingling, fatigue, pain, muscle spasms, and difficulty walking
- Canada has one of the highest rates, more prevalent in countries closer to the poles