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Biopsychology - Coggle Diagram
Biopsychology
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Localisation of Functon
the idea that certain functions (e.g. language, memory, etc.) have certain locations or areas within the brain
- brain is divided into two halves
- lateralisation - idea that the two halves of the brain are functionally different e.g. the left is dominant for language, and the right excels at visual motor tasks
- left side of body controlled by right hemisphere, right side controlled by left hemisphere
+ - brain scan evidence to support
Petersen et al (1988) used brain scans to show activity in Wernickes area during listening task and in Brocas area during a reading task, suggesting these areas have different functions
Objective methods - inc scientific credibility
+ - support from case studies
Phineas Gage received serious brain damage, affected his personality, suggests the frontal lobe may be responsible for regulating mood
— - existence of contradictory research
Lashley (1950) removed between 10% and 50% of the cortex in rats
no one area was more important than other - involves whole brain
— - neural plasticity is a challenge to localisation theory
when the brain has become damaged and a function has become compromised, the rest of the brain is able to reorganise to recover the function
- motor area - at the back of the frontal lobe (both hemispheres). controls voluntarymovement
- somatosensory area - at the front of the parietal lobe. processes sensory information from the skin
- visual area - in the occipital lobe at the back of the brain. each eye sends information to the RVF to the left visual cortex, and from the LVF to right visual cortex
- auditory area - in the temporal lobe. analyses speech-based information
- Brocas area
- speech production
- left frontal lobe
- damage causes brocas aphasias - speech is slow and lacking in fluency
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- Wernickes area
- language comprehension
- back of the temporal lobe
- wernickes aphasia patients can produce language but struggle understanding it
Biological Rhythms
- internal biological ‘clocks’ (endogenous pacemakers)
- external changes in the environment (exogenous zeitgebers)
- ultradian rhythms - occur many times a day
- circadian rhythms - 24 hour cycle
- Infradian rhythms - take more than a day
- circannual rhythms - yearly
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The Nevous System
- to collect, process and respond to information
- to coordinate the working of different cells
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Neurons
Types:
- Motor Neurons - connect the CNS to effectors (muscles and glands)
- Sensory Neurons - carry messages from the PNS to CNS
- Relay Neurons - connect sensory to motor or other relay neurons
Structure:
- cell body - includes genetic material
- dendrites - carry nerve impulses from neighbouring neurons towards the cell body
- axon - carries electrical impulse away from cell body
- myelin sheath - fatty layer protects axon
- nodes of Ranvier - gaps in axon speeds up transmission of impulse
- terminal buttons - end of the axon communicate with next neuron across the synapse
Electric Transmission:
- When a neuron is in a resting state inside of the cell is negatively charged compared to the outside
- When a neuron is activated, the inside of cell = positively charged for a split second causing an action potential to occur
- Creates an electrical impulse that travels down the axon towards the end of the neuron
Synaptic Transmission
- signals within neurons are transmitted electrically, signals between neurons transmitt chemically across synapse
- when the electrical impulse reaches the presynaptic terminal it triggers the release of neurotransmitters from synaptic vesicles
- once it crosses the gap, it is taken up by the postsynaptic receptor site on the next neuron
- chemical message is converted back to electrical impulse
- Neurotransmitters are chemicals that diffuse across the synapse
Neurotransmitters either have an excitatory or inhibitory effect on neighbouring neuron
- Adrenaline - generally excitatory, inc +’ve charge of the postsynaptic neuron, making it more likely the neuron will fire
- Serotonin - generally inihibitory, inc -‘ve charge of the postsynaptic neuron, making it less likely the neuron will fire
- Dopamine - equaly likely to have excitory or inhibitory effect
Summation
- Excitatory and inhibitory are summed and must reach a certrain threshold in order for the action potential of the postsynaptic neuron to be triggered
- more likely to fire = net effect is excitatory
Brain Plasticity
- a process that involves adaptive structural and functional changes to the brain
- synaptic pruning - rarely used connections are deleted and frequently used ones are strengthened
Maguire et al (2000)
- found significantly more volume of grey matter in the posterior hippocampus in London taxi drivers than in a matched control group
- this part of the brain is linked with the development of spatial and navigational skills
- learning experience has altered the structure of the taxi drivers brain
Draganski et al (2006)
- Imaged the brains of medical students three months before and after final exams
- Learning-induced changes were seen in the posterior hippocampus and the parietal cortex
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The Endocrine System
- control vital functions through hormones
- slower than nervous system
- Glands
- organs in the body that produce hormones
- main = pituitary gland located in brain - controls the release of hormones for all other glands
Hormones
- secreted into the bloodstream and affect any cell in the body that has a receptor for that particular hormone
- e.g Throxine produced by the thyroid gland affects cells in the heart and also cells throughout the body which inc metabolic rates, affecting growth rates
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Split Brain Research
- Hemispheric lateralisation - concerns behaviours controlled by just one hemisphere
e.g Language is lateralised to the left
Sperry (1968)
- demonstrate that the two hemispheres were specialised for certain functions and could perform tasks independently of one another
- the hemispheres are connected by the corpus callosum
- may be surgically removed to control epileptic seizures
- Sperry studied a group of epileptics who had the operation
Method
- an image or word is projected to a patients RVF (processed by LH) and another image to the LVF
- normally, corpus callosum ‘shares’ information between both hemispheres - in split brain information cannot be shared
Results
- Object shown to:
- RVF - patient can easily describe what is seen
- LVF - patient says ‘theres nothing there’
- cant describe objects in LVF because RH usually lacks language centres
- messages recieved by RH are normally relayed via the corpus callisum to language centres in LH
- however could select matching objects
Findings
- LH dominated the verbal description
- RH dominated the selection of a matching picture
+ - shows lateralised brain functions
LH is analytical and verbal and the RH is adapt at spatial tasks
+ - standardised procedure in Sperrys research
ensured only one hemisphere received info at a time - well controlled procedure
an image was flashed up for 0.1 seconds, so pps had no time to move their eyes over
Inc internal validity and reliability
— - generalisation
split brain patients are unusual sample of patients
only 11 paients took part and they had a history of seizures - may have caused other issues
reduces validity
— - Sperrys research may be too simplistic
many behaviours that are typically associated with one hemisphere can be peformed by the other when situations require
flexibility of the brain limits Sperrys condition
+ - practical application
understanding plasticity has contributed to the field of neurorehabilitation
+ - support from animal studies
Hubel and Wiesel (1963) sewed one eye of a kitten shut - visual cortex continued to process information from the open eye
— - potential negative consequences
prolonged drug use can result in poorer cognitive functioning and increased risk of dementia
Also - 60%-80% of amputees develop phantom limb syndrome - due to the reorganisation in the somatosensory cortex
— - neural plasticity may be related to cognitive reserve
Schneider et al (2014) found the more time brain injury patients spent in education, the greater their chance of disability-free recovery
— - Functional plasticity tends to reduce with age