Biopsychology Flashcards
What is the biological approach?
Suggests that everything psychological is first biological, so to fully understand human behaviour we must look at biological structures and processes within the body.
What is the nervous system?
Highly specialised set of cells and the primary internal communication system. Made up of billions of neurons.
What are the two main functions of the brain?
To collect, process and respond to information in the environment.
To co-ordinate and direct the working of different organs and cells within the body.
What is the central nervous system made up of?
The brain and spinal cord
What is the peripheral nervous system made up of?
The semantic nervous system and the autonomic nervous system
What is the autonomic nervous system made up of?
The sympathetic branch and para sympathetic branch
What does the brain do?
Centre of all consciousness that controls all behaviours. Involved in all psychological processes. Primitive parts involved in breathing and heartbeat. Higher order thinking such as planning and problem solving.
What is the spinal cord?
Contains a series of neurons and nerve circuitry. Carries messages from the brain to the peripheral nervous system. Allows the brain to monitor bodily processes like breathing and digestion.
What is meant by an arc reflex?
Do not involve conscious part of the brain. The stimulus is picked up by the receptor. An impulse is then transmitted down the sensory neuron to the CNS. The relay neuron takes it through the CNS. The impulse then moves from the CNS to the effector through the motor neuron. The effector then causes a proactive response against the stimulus. The effector can be a muscle or gland.
What is the peripheral nervous system?
All the nerves outside the brain and spinal cord. Main function is to relay nerve impulses from the CNS to the rest of the body and back.
What is the somatic nervous system?
Contains both motor and sensory neurons so transmit info to and from the senses and the CNS. Sensory neuron to CNS
Motor neurons from CNS.
Controls voluntary movements, skeletal muscles and bones. The control centre is the motor cortex. Also involved in arc reflex actions.
What is the autonomic nervous system?
Only contains motor neurons. Contains internal organs and glands that we do not need to be consciously aware of. Transmits to and from internal organs to sustain life processes. The control centre is the brain stem. The two parts of the ANS are responsible for functions that keep the body in a stable state (homeostasis)
What does the somatic nervous system do?
Transmit and receive information about the senses such as visual or auditory - sensory pathways
Motor pathways - direct voluntary movement of skeletal muscles and orchestrates all of our movements from the brain
What is the parasympathetic nervous system?
Maintains and conserves body energy and functions. Returns the body to a state of relaxation and decreases bodily activities after activation from the sympathetic branch.
What is the sympathetic nervous system?
It prepares the body to expend energy for fight or flight. This involves physiological changes which prepare the body for activity and slows down other non-essential activities.
What dies the parasympathetic nervous system do?
Increases digestion
Increases saliva production
Decreases heart rate
Stimulates bile production
Contracts the bladder
Constricts pupil dilation
Constricts bronchi
What does the sympathetic nervous system do?
Slows digestion
Inhibits saliva production
Increases heart rate
Stimulates glucose production
Relaxes the bladder
Dilate pupils
Dilates bronchi
Neuron - cell body
Contains nucleus, which contains all genetic material of the cell
Neuron - dendrites
Branch like structures that project from the cell body. Carry impulses from other neurons towards the cell body.
Neuron - axons
Carry impulses away from the cell body down the length of the neuron
Neuron - myelin sheath
A layer that covers the axon and speeds up the electrical impulse
Neuron - Nodes of Ranvier
Segments the myelin sheath. They speed up transmission of the impulse by forcing it to ‘jump’ across gaps along the axon
Neuron - terminal buttons
At the end of the axon and communicate with the next neuron in the chain across the synaptic gap by using neurotransmitters
What is a sensory neuron?
Found in receptors and carry nerve impulses to the spinal cord and brain. When the impulses reach the brain, they are translated into sensations such as vision, hearing, taste or touch to give information about the environment. Some neurons stop at the spinal cord, allowing for quick research actions.
What is the structure of the sensory neuron?
Long dendrites and short axons
What is a relay neuron?
Found in the brain and spinal cord, and allow sensory and motor neurons to communicate. They are found between sensory input and motor output.
What is the structure of a relay neuron?
Short dendrites, and long or short axons
What is a motor neuron?
Found in the CNS and control muscle movement. When they are stimulated, they release neurotransmitters that bind to the receptors on the muscles to trigger a response.
What is the structure of a motor neuron?
Short dendrites and long axons
What is the first stage of synaptic transmission?
Dendrite picks up NTs and sends an action potential through the cell body and along the axon to the terminal button.
What is the second stage of synaptic transmission?
Once the action potential has reached the terminal button, it needs to be transferred to another neuron. To achieve this it must cross the synaptic gap between pre and post synaptic neuron.
What is the third stage of synaptic transmission?
Synaptic vesicles store NTs - chemical messengers that convert the impulse to a chemical message
What is the fourth stage of synaptic transmission?
As the impulse reaches the synaptic vesicle, they release the NTs that cross the synaptic gap
What is the fifth stage of synaptic transmission?
The NT diffuses across the synaptic gap then binds to the specialist receptors on the surface of the next cell that recognise it and match that particular cell - eg dopamine receptors recognise dopamine
What is the sixth stage of synaptic transmission?
Once the next cell is activated the receptor molecules produce either an excitatory effect or an inhibitory effect depending on the summation of activity at a post synaptic level.
What is the seventh stage of synaptic transmission?
It is completed by a process called reuptake. This is where the NT is taken back up/recycled by the pre-synaptic neuron
What are the key areas of synaptic transmission?
Synaptic vesicle
Terminal button
Synaptic gap
Receptor
Neurotransmitters
Post synaptic neuron
What is a neurotransmitter?
Chemicals that are released from the end of brain cells that allow them to communicate with each other and relay messages to different areas of the brain. As one neuron releases an NT, receptors on other neurons pick up this message and relay it to the next neuron. Neurotransmitters affect the transfer of an impulse to another neuron or muscle.
What is an excitatory effect?
They create a positive charge, making the neuron more likely to fire. This rise in action potential will increase activity.
What is an inhibitory effect?
They create a negative charge, making the neuron less likely to fire. This fall in action potential will decrease activity.
What is the first function of the endocrine system?
Functions to secrete hormones into the bloodstream to regulate many of our bodily functions. Together with the nervous system, they work closely together to regulate and coordinate physiological processes in the body.
What is the second function of the endocrine system?
To provide a chemical system of communication via the bloodstream. It’s a network of glands throughout the body that secrete chemical messengers and deliver them to target sites throughout the body.
What are hormones?
Chemicals released from glands that circulate in the bloodstream and are carried to target structures around the body.
What hormones are released by the pituitary gland?
ACTH, growth hormone and prolactin
What does ATCH do?
It targets the adrenal cortex and stimulates the release of glucocorticoids, which is a key component in the stress response.
What does the growth hormone do?
Produced by the anterior pituitary for the general promotion of cell growth and multiplication.
What does prolactin do?
Produced in the anterior pituitary gland, and it is involved in the production of milk for infants. It regulates the immune system and behaviour.
What does the adrenal gland do?
Produces adrenaline which prepares the body for emergencies, increases heart rate and breathing, raises blood sugar level and diverts blood from the gut to the limbs.
What does the pineal gland do?
It produces melatonin, which affects reproductive development and daily physiologic cycles. More melatonin increases sleep.
What does the pancreas do?
Secretes insulin which converts excess glucose into glycogen in the liver. It then produces glucagon which converts glycogen back into glucose in the liver.
What does the thyroid do?
It secretes thyroxine which controls the rate of metabolism and rate that glucose is used up in respiration and promotes growth.
What is the appraisal of the stressor?
The body appraises the situation using its sensory systems and stored memories. The hippocampus and amygdala to recognise emotional reactions to stimuli and access stored memories for potential danger. The hypothalamus is then alerted which controls the systems that have central roles in the stress response.
What is the sympathomedullary pathway?
Situation is perceived as stressful due to memories, emotions or instincts. The hypothalamus is alerted. This recognises the stress as acute so the SAM pathway is activated. This stimulates the adrenal gland which is situated just above the kidneys. The adrenal medulla secretes the hormones adrenaline and corticosteroids.. These hormones prepare the body for fight or flight.
How does adrenaline affect the body?
Increases perspiration because it regulates body temperature
Dilates pupils because it improves vision
Increases rate of respiration because it increases oxygen intake
Increases heart rate and raises blood pressure because it increases blood flow to organs and spreads adrenaline around the body.
Increases blood flow to muscles for muscular tension because it reduces reaction time.
What happens when we experience a stressor?
Our body activates the autonomic nervous system, specifically the sympathetic branch. This arouses the body and activates the SAM pathway. After a few minutes the parasympathetic branch will be activated, which will reduce the fight or flight response.
What is spatial resolution?
The capacity a technique has to tell you exactly which area of the brain is active
What is temporal resolution?
The ability to tell you exactly when the activation happened
What are post mortem examinations?
When a person’s physical brain is examined who displayed a particular behaviour that suggested possible brain damage. They try to correlate structural abnormalities with behavioural changes. In modern examinations, the brain can be sliced into sections and studied on a microscope.
What are the strengths of post mortem examinations?
Allows detailed observation of anatomical structure and neurochemical aspects of the brain that is not possible with non-invasive techniques.
Provides insight into deeper regions of the brain like the hypothalamus and hippocampus which other techniques cannot access.
What are the weaknesses of post mortem examinations?
Retrospective method so it may be hard to make comparisons with functioning before death.
Need for special permission leads to small sample size
Ethical issues as there are debates on whether patient would need to give consent before death, though patients with severe psychological deficits would be unable to give consent.
What is functional Magnetic Resonance Imaging?
An fMRI uses a strong magnetic field and radio waves to detect changes in blood oxygenation and flow in the brain as a result of neural activity. It takes repeated scans to form a dynamic image of concentration of blood in the brain at one time. Areas of high activity will have a high amount of blood concentration. This allows active sections of the brain to be identified.
What is a strength of fMRIs?
Provides moving picture of brain activity which is highly valuable when trying to link brain activity to key behaviours.
It is considered to be more ethical due to it being a non invasive scanning method.
It has a good spatial resolution of 1-2 mm, which allows scientists to discriminate between different areas of the brain.
What are the weaknesses of fMRIs?
Scans simply measure blood flow, so scientists are unable to conclude whether the brain region is associated with a particular function - we cannot establish cause and effect.
Poor temporal resolution of 1-4 seconds, meaning scientists are unable to predict with a high degree of accuracy the onset of brain activity.
What are Electroencephalograms?
EEGs work on the premise that information is processed in the brain as electrical activity in the form of action potentials. It uses electrodes fixed to a pts scalp which detect neuronal activity directly below where they are placed. It measures the amplitude and frequency of electrical activity and identifies patterns in activity that may be associated with certain states. Small electrical changes are graphed over a period of time.
What are the strengths of EEGs?
Can be used effectively in clinical practise to study sleep disorders, identify disturbed brain activity and help with diagnosis.
Good temporal resolution (1-10 ms) meaning it can record the brain’s activity in real time as opposed to looking at a passive brain
What are the weaknesses of EEGs?
Electrical activity can be picked up by neighbouring electrodes therefore it is not useful for pinpointing the exact source of activity.
Poor spatial resolution so it is unable to provide information on what is happening in deeper regions of the brain.
What are event related potentials?
Uses electrodes attached to the scalp and a stimulus is presented to the pt and the researcher looks for neuronal activity in response to that stimulus. It is necessary to take recordings from numerous presentations then average out the response. Often used when investigating fast responses that may not be detected by other investigative techniques.
What is a strength of ERPs?
Useful to measure the reliability of self reported techniques especially when the topic being investigated is sensitive and is affected by social desirability.
Good temporal resolution (1-10 ms) meaning it can look at the brain’s activity in real time rather than looking at a passive brain
What are the weaknesses of ERPs?
It only detects strong voltage changes across the scalp. Important electrical activity deep in the brain is not recorded, hence this method is limited to just the neocortex.
Poor spatial resolution so it is unable to provide information on what is happening in the deeper regions of the brain.
What are the similarities between fMRIs and EEGs?
Both are able to give fully informed consent.
Both are non invasive
Both are based on interpretation
Causation is not clear
What are the differences between fMRIs and EEGs?
fMRIs have good spatial resolution whereas EEGs do not
fMRIs have poor temporal resolution whereas EEGs have good temporal resolution
fMRIs based on stimulus presentation whereas EEGs are not
fMRIs have a high cost whereas EEG cost is low
What are the similarities between fMRIs and ERPs?
Both able to give fully informed consent
Both are non invasive
Both are based on interpretation
Both are based on stimulus presentation
What are the differences between fMRIs and ERPs?
fMRIs have good spatial resolution whereas ERPs do not
fMRIs have poor temporal resolution whereas ERPs are good
Causation is clear in ERPs but not in fMRIs
Cost of fMRI is high whereas cost of ERPs are low
What are similarities between EEGs and ERPs?
Both able to give fully informed consent
Both have low cost
Both have poor spatial resolution
Both have good temporal resolution
Both are non invasive
Both are based on interpretation
What are the differences between EEGs and ERPs?
Causation is clear in ERPs but not in EEGs
ERPs are based on stimulus presentation whereas EEGs are not
What are the similarities between post mortem examinations and scanning techniques?
All rely on interpretation
Causation is not clear in post mortems, fMRIs and EEGs
Post mortems and fMRIs both have high costs
What are the differences between post mortem examinations and scanning techniques?
Post mortems may not have consent whereas others do
Spatial resolution does not apply to post mortems, neither does temporal resolution.
Invasive whilst the rest are non invasive
What is localisation?
The theory that specific areas of the brain are associated with particular physical and psychological functions
What are the two hemispheres connected by?
The corpus callosum
What is each hemisphere divided into?
The frontal lobe
The parietal lobe
The temporal lobe
The occipital lobe
What is hemispheric lateralisation?
The dominance of one hemisphere of the brain for particular physical and psychological functions. Lateralisation is the fact that the two halves of the brain are functionally different and that each hemisphere has functional specialisations.
What is the primary motor cortex?
Responsible for the generation of voluntary motor movements and is located in the frontal lobe. Motor movements are contralateral meaning the right lobe controls movement on the left side of the body and vice versa. It is somatotopically organised, meaning it is the point for correspondence of an area of the body to a specific point on the CNS. Areas which are finely controlled have larger portions of the cortex whereas coarsely controlled areas have smaller portions.
What is the somatosensory cortex?
The primary somatosensory cortex detects sensory events arising from receptors in the different areas of the body. It is located in the parietal lobe. Using sensory information from the skin, the cortex produces sensations of touch, pressure, pain and temperature, which it then localises to specific body regions. It is contralateral. It is somatotopically organised meaning a specific part of the body is associated with a distinct location in the CNS.
What is the visual cortex?
The primary visual centre is located in the visual cortex. It is located in the occipital lobe. Visual processing actually occurs in the retina where light enters and strikes the photoreceptors. Nerve impulses from the retina are then transmitted to the brain via the optic nerve. It is largely contralateral. It contains several different areas which process different types of information, such as colour, shape or movement. Damage to the cortex can lead to loss of vision but visual perception requires additional input from neighbouring cortical areas and damage to these can lead to loss of specific areas of visual perception, such as prosopagnosia.
What is prosoprognosia?
Loss of ability to recognise familiar faces or identify faces at all.
What is the auditory cortex?
Auditory centre in the brain is concerned with hearing. Most of this area lies in the auditory cortex within the temporal lobes of both hemispheres of the brain. It is contralateral. Auditory areas begin in the cochlea in the inner ear, where sound waves are converted to nerve impulses. These travel to the brain stem where a basic decoding takes place before moving onto the thalamus and then finally the auditory cortex where sound is recognised and interpreted. Damage to the auditory cortex produces difficulties in processing and understanding sounds rather than total deafness.
Is there research to suggest that vision is localised?
Horovitz et al in 1999 found that damage to area VI (a specific area within the visual cortex) leads to a complete loss of all vision including visual images in dreams. When this was damaged, vision was completely lost, suggesting that vision is localised.
Is there research to question the idea of localisation of brain function?
Lashley made lesions into different areas of the brains of rats who were put into a maze. Found large lesions on visual areas impaired maze learning but smaller covering the same brain areas had no effect. Concluded that functions such as learning were spread widely across brain areas. He called this the law of mass action.
Are there case studies to support localisation of brain function?
Phineas Gauge - railroad worker in 1848. He was preparing to blast a section of rock with explosive but accidently hit his tamping iron on the rock causing an explosion to ignite and send a metre length pole through his left cheek, passing behind his left eye and exiting out of his skull, taking most of his pre frontal lobe matter with it. He survived, but the damage to the pre frontal lobe left him with a major change in personality. He turned from calm and polite into bad tempered and rude. The frontal lobe has been linked to regulating mood, which seems to correlate with his change in personality.
Do other factors question localisation of brain function?
Lashley proposed the law of equipotentiality. When the brain is damaged and a particular function is affected, the rest of the brain seems to reorganise itself to recover the lost function (plasticity). Surviving brain circuits chip in so the same neural action can be achieved. This has been shown in documented cases of stroke victims who have recovered abilities originally lost. We should look at the brain in a more holistic way.
Are there case studies that demonstrate localisation of language comprehension and production?
Case study of patient Tan who had damaged his Broca’s area. Broca’s aphasia is the impaired ability to produce language, which is in most cases, caused by damage to the Broca’s area. Wernicke’s aphasia is an impairment of language perception, demonstrating the important role played by this area in the comprehension of language.
Is there contradictory research into the Broca’s and Wernicke’s areas?
Dronkers conducted an MRI scan into two patients with similar brains to Tan to try and confirm Broca’s findings. Although there was a lesion found in Broca’s area, they also found evidence to suggest that other areas may have contributed to the failure of speech production. These results suggest that Broca’s area may not be the only region responsible for speech production and the deficits found in patients with Broca’s aphasia could be the result of damage to neighbouring regions.
What does the left hemisphere control?
Right side of the body
Number skills
Logic and reasoning
Is language always in the left hemisphere?
96% of right handers and 70% of left handers have left hemispheric dominance for language
What does the right hemisphere control?
Left side of body
Creativity
Emotion
Spatial
What is the Broca’s area?
Posterior portion of the frontal lobe of the left hemisphere which is critical for speech production. Broca found patients with deficits who could understand language but could not speak or write had lesions in their left frontal hemisphere whereas patients with damage in these areas on the right hemisphere did not have the same language problems. Not all words are affected - nouns and verbs seem to be fine but conjunctions and prepositions have major problems.`
What is Wernicke’s area?
Posterior portion of the left temporal lobe. People with Wernicke’s aphasia could speak but were unable to understand language. Wernicke proposed that language involves separate sensory and motor regions located in different cortical regions. The motor region, located in Broca’s area controls the mouth, tongue and vocal cords, hence involved in speech production.Sensory region, which is located in Wernicke’s area in close to regions of the brain responsible for auditory and visual input. In the Wernicke’s area it is recognised with language and associated with meaning.
Is there case study evidence to support Broca’s and Wernicke’s areas?
Demonstrated functions being lateralised to the left hemisphere. Tan could not produce language due to damage in the left hemisphere. Caused by damage to the Broca’s area.
Is there problems for using case study evidence to support hemispheric lateralisation?
Only specific to individuals concerned so may not be generalisable to others.
Is there support from human clinical case studies to support hemispheric lateralisation?
Receptive aphasia (difficulty understanding spoken language) following damage to the Wernicke’s area is seen in many cases, suggesting functions in the brain are localised and lateralised
Is the theory of lateralisation biologically reductionist?
Cannot reduce complex brain function into one specific area. No evidence for 100% left hemisphere dominance as it is 96% for right handers and 70% for left handers. Need to use a more holistic approach.
Problems using post mortem examinations to explain hemispheric lateralisation?
Could pinpoint different areas of the brain involved with particular functions, it is not possible to then refine the understanding of these functions by getting participants to do further tasks.
What are split brain patients?
Those who have had their connections between the right and left hemisphere (corpus callosum) severed. Normally the two hemispheres share information. When eyes visual fields are restricted, the differences between the left and right hemisphere functioning can be seen.
What processes are involved in split brain research?
It uses a split visual field experiment. Pts are sat in front of a screen and asked to gaze at a fixed point in the centre of the screen. Visual stimuli are projected onto a screen either to the right or left visual field at a very high speed so the pt has no choice but to move their head and is only able to process the image in the visual field where it is placed.
What was found from the verbal responses to language in split brain research?
Words were projected to the LVF, so going to the right hemisphere. The words did not seem to be registered, which suggests that the left hemisphere is responsible for language.
What was found from the physical responses to language in split brain research?
A word was presented to the LVF so goes to the right hemisphere. The left hand was placed behind a screen and then had to select the object from a number of items. Pts could select the correct object despite being unable to verbally report having seen it. This indicates that the right hemisphere does have the same language ability for understanding words if bot for speech.
What was found from the matching abilities in split brain research?
A different face was presented to each hemisphere at the same time. Pts were then given a set of faces to look at and asked to select those they had seen earlier. Pts chose the one presented to the right hemisphere indicating its role and identifying faces and shapes. This indicates that the right hemisphere is responsible for visuospatial tasks.
Does split brain research have practical applications?
Enables a greater understanding of different functions in hemispheres. We now know that language is largely processed in the left hemisphere so we can now target this area for therapy when there are problems of aphasia.
Does the split brain research lack generalisability?
Limited number of participants - 11 went through all tasks. Pts varied in age, gender and handedness as well as the age at which they developed epilepsy, plus the degree of drug therapy they have experienced before the operation.
Can we establish cause and effect with split brain research?
It could be that epilepsy causes changes in the brain that influences the findings. Some pts experienced more disconnection of the two hemispheres.
Does split brain have methodological strength?
Experiments were highly specialised used standardised procedures. Presenting visual info to one hemisphere at a time could be controlled so could easily vary aspects whilst still maintaining control.
Is there research to contradict the findings of split brain research?
Kim Peek was born without a corpus callosum but she could read out loud from a book from the right and left pages at the same time. If language was lateralised to the left hemisphere she would only be able to read words from the right page.
Who did split brain research?
Sperry
What is brain plasticity?
The brain’s ability to change and adapt (functionally and physically) as a result of or in reaction to the environment, experience and new learning.
What is experience expectant plasticity?
The idea that changes in the brain take place during infancy and childhood.
What is experience dependent plasticity?
The idea that the brain continues to create new neural pathways and alter existing ones as a result of learning and life experience
What are the three ways plasticity can happen?
Synaptogenesis
Neurogenesis
Synaptic pruning
What is synaptogenesis?
When new synapses are formed. This can occur throughout life but during infancy there is an explosion of Synaptic formation.
What is Neurogenesis?
This refers to when neurons are grown. In infancy this is responsible for populating the growing brain with neurons but it also occurs in adulthood.
What Synaptic pruning?
The process of synapse elimination that typically happens between early childhood and the onset of puberty
This has also been shown to occur to a lesser extent in adulthood.
What has infancy shown about brain plasticity?
During infancy, the brain experiences a rapid growth in the number of Synaptic connections it has, peaking at approximately 15,000 by the age of 2-3. This is twice as many as there are in the adult brain. This shows that as we age, rarely used connections are deleted and frequently used connections are strengthened in a process known as cognitive pruning.
Has does computer gaming show plasticity?
Kuhn illustrated the potential benefits of playing SuperMario for 2 months playing at least 30 minutes per day. They found significant increases in areas of the brain responsible for key behaviours such as working memory, planning and motor performance. Video games could be argued to have caused synaptogenesis.
How has taxi drivers shown plasticity?
Maguire studied the brain’s of London taxi drivers using an MRI and found significantly more grey matter in the hippocampus than in a matched control group. Cabbies must take a complex test called the knowledge which assess their recall of city streets and possible routes. This is the part of the brain that is associated with the development of spatial and navigational skills. The longer they had the job, the more pronounced was the structural difference.
How have astronauts shown plasticity?
Koppelmans studied the effect of no gravity in space and how this affects the brain. 27 astronauts were brain scanned before a space mission, then again upon their return. Between 2 weeks to 6 months in space, the cerebellum shrunk and the motor and somatosensory regions were swollen.
What might happen to the brain following injury or other forms of trauma?
Individual may experience loss of brain function such as paralysis, aphasia etc. In these cases, unaffected areas sometimes adapt or compensate for those areas that are damaged. Functional recovery can happen quickly after trauma and then slows down after several weeks.
What are the different types of functional recovery?
Neural regeneration
Neuronal unmasking
Neural reorganisation
What is neural regeneration?
This is known as axon sprouting and it occurs when new nerve endings grow and connect with undamaged areas. This can compensate for damaged areas and enable the recovery of previously lost functions. This can be seen as a type of synaptogenesis
What is Neuronal unmasking?
This occurs when dormant synapses in the brain are opened and become functional. This can occur when the surrounding brain area become damaged as the rate of input of these dormant synapses would increase opening connections of the brain that are not normally active and allowing the gradual development of new structures. This is a type of synaptogenesis or Neurogenesis
What is neural reorganisation?
This occurs when the brain transfers functions from the damaged area to undamaged sections of the brain. In extreme cases whole areas of the brain me can take over the functions of damaged sections.
Is there case study evidence to support plasticity?
Danelli investigated the case of an Italian boy who had most of his left hemisphere removed aged 2.5 to remove a tumour. With intensive therapy his right hemisphere was able to take over almost all of the functioning that would normally have been done by the left.
Does the case study for functional recovery lack population validity?
Male Italian patient so the findings could be considered androcentric and does not represent people of different ages or cultures.
Is there research into age for functional recovery?
Teubar found a negative correlation with age and recovery as when investigating soldier’s recovery from brain injury, 60% under 20 years made huge improvement whereas only 20% over 26 made similar improvement
Is there refuting evidence for age and plasticity?
Boyke found even 60 year old could regain abilities thought to be fixed in childhood with intense retraining. Elbert concluded that capacity for neural reorganisation is much greater in children than in adults.
Does research into plasticity have practical applications?
Stem cells planted into damaged areas of the brain have the potential to grow into neurons and make functional Synaptic connections. Tajiri found that stem cells provided to rats after trauma found a clear development of neuron like cells in the area of injury.
What is a biological rhythm?
Any change in physiological activity that repeats periodically in a set cyclical pattern
What is a circadian rhythm?
A cycle that takes approximately 24 hours. Examples include the sleep wake cycle, body temperature, metabolic activity and hormones.
What is an infradian rhythm?
One cycle takes longer than 24 hours. Examples include menstruation, hibernation and SAD
What is an ultradian rhythm?
One cycle takes less than 24 hours. Examples include feeding, stages of sleep and alertness.
How does the menstruation cycle work as an infradian rhythm?
The follicular phase - 10 - 14 days. Low levels of oestrogen and progesterone during menstruation. When the bleeding stops the endometrium grows and thickens. FSH levels rise. This signals ovaries to produce oestrogen which stimulates LH levels to rise. Eggs is released into one of fallopian tubes. LH causes progesterone after ovulation which stimulates the endometrium to prepare a thick blanket of blood vessels to support a fertilised egg.
What is body temperature as a circadian rhythm?
Human body temperature is at its lowest in the early hours of the morning and at its highest during early evening. Sleep typically occurs when core temperature starts to drop and body temperature starts to rise towards the end of the sleep cycle, promoting feelings of alertness influenced by muscular activity, digestion and heat loss.
What is an endogenous pacemaker?
Internal mechanisms that influence the patterns of our biological rhythms. These may be genetic mechanisms. They help maintain regular rhythms in absence of zeitgebers but they are not perfect and need zeitgebers to synchronise the rhythms to our original behaviours.
What is the role of endogenous pacemakers in controlling the sleep wake cycle?
Internal body clock inside the hypothalamus is called the SCN. The SCN receives light through the eyes. When light levels drop, this information is received by the SCN causing it to fire impulses to the pineal gland which secretes melatonin which causes sleepiness. When light increases, melatonin levels fall making us more alert. Without light as a zeitgeber, the process free runs into a 25 hour cycle.
Case study to support the role of endogenous peacemakers?
Siffre spent six months in an underground cave. He found that his body was able to free run to a regular pattern of 25 - 30 hours. The internal body clock regulated even without external cues.
Problem with using case studies to evaluate endogenous pacemakers?
Siffre was a one off study so results may not be representative. Individual differences make it difficult to generalise findings.
Scientific evidence to support the role of endogenous pacemakers?
Ralph took the SNC from a mutant hamster who had a circadian rhythm which mutated to 20 hours. Mutant SNC was transplanted into brains of normal adult hamsters. The normal hamsters took on the circadian rhythm of the mutant hamsters.
Is the use of animal studies problematic when evaluating endogenous pacemakers?
Results cannot be extrapolated to explain human brains as many animals are nocturnal. Humans are more adaptable than animals.
What are exogenous zeitgebers?
External stimuli/environmental cues that are responsible for resetting the biological clock which provide information about elapsed time and prompt changes in bodily activity and the patterns of our biological rhythms.
Is there evidence to support the role of exogenous zeitgebers?
Vetter changed light in the workplace. 4000 kelvin was natural warm light and 8000 kelvin was blue enriched light. Results suggest that blue enriched light and natural light complete as a zeitgeber. Pts working under warmer light tended to synchronise to natural dawn whereas pts exposed to blue enriched light synchronised to office hours.
Problem with using artificial tasks as evidence for exogenous zeitgebers?
Vetter’s study used a task with artificial light which could affect the way that the body clock would naturally work so study lacks ecological validity
Is there contradictory evidence of light as an exogenous zeitgeber?
Luce and Segal study arctic circle. People still maintain a reasonable constant sleep pattern averaging 7 hours a night despite 6 months of light and 6 months of dark. Appears that social factors reset endogenous rhythms.
Do individual differences need to be taken into account when exploring the role of exogenous zeitgebers?
Some people are more alert early in the day and others later. This could be due to lifestyle or age, or the speed at which they adapt to disruptions. Look more holistically.
What is jet lag?
The effects we experience when crossing into a different time zone. Estimated that SCN takes several cycles to entrain to a new environment. Winter estimated that it takes 1 day to adjust to each hour of time change. Symptoms include fatigue, insomnia, anxiety, constipation or diarrhoea.
What is phase delay?
Travelling from east to west extends your day
What is phase advance?
Travelling from west to east shortens your day
Is it easier to adjust to phase delay or phase advance?
Phase delay because it is lengthening our day. Our internal rhythm is greater than 24 hours. Phase delay therefore brings external factors closer in line with internal whereas phase advance moves them further away.
What is shift lag?
It is caused by rotating shift. Working at night requires you to be alert at times when you are used to being asleep and vice versa. This means that natural rhythms will be out of synchronisation with most of the available cues from external zeitgebers. Symptoms include fatigue, sleep disturbance, digestive problems, lack of concentration, memory loss and mood swings.
What are the effects of shift work?
Knutsson found that individuals who worked shifts for 15yrs were three times more likely to develop heart disease. One main effect is difficulty sleeping during the day. Chernobyl occurred at night and it was down to human error.
Should you rotate shifts slowly or fast?
Czeisler recommended a slow rotation, for example spending three weeks on each shift. Bambra preferred a fast rotation of just 3 - 4 days on each shift so the body never has time to adjust to the new cycle.
