A-Level Psychology > Biopsychology > Flashcards
Biopsychology Flashcards
The nervous system
A system that consists of two parts that work together to collect information from inside the bosy and the environment around it
Nerve
A bundle of fibres made up of neurons that carry sensory and motor information throughout the body through electrical impulses
Central Nervous System
Made up of the brain and the spinal cord
Brain
A part of the central nervous system that aids conscious awareness, controls behaviour and regulates the body’s psychological processes
Spinal cord
A part of the central nervous system that runs the length of the spinal column and relays information to the brain and the body
Paralysis
A break in the spinal cord
Psychological Process
Bodily functions that include breathing and sleeping
Sensory information
Information from the senses i.e sight, smell, taste, touch and hearing
Muscle
Tissues that aid movement
Gland
Secretes Hormones
Hormones
Chemical messengers secreted by glands
Nerve impulse
An electrical signal that is transmitted along an axon in response to a stimulus to relay information
Peripheral Nervous System
Receives sensory information and sends it to the CNS via sensory neurons and transmits information from the CNS to the muscles and the body
Somatic Nervous System
Facilitates communication between t he CNS and the outside world through the use of sensory neurons and a motor Pathway
Autonomic Nervous System
Responsible for the vital functions such as heartbeat, breathing and digestion. It operates automatically and involuntarily, sending information to the internal body organs
Sympathetic Nervous System
Stimulates bodily functions, such as heart rate, preparing the body for a fight-or-flight response
Parasympathetic Nervous System
Slows bodily functions, such as heart rate, recovering the body from a fight-or-flight reponse
Antagonistic
Working in opposition to each other
Homeostasis
Optimal functioning in response to internal and external
SAM Pathway
Sympathomedullary pathway; the route through w which the brain directs the sympathetic branch of the autonomic Nervous system to activate in response to short term stress
Amygdala
Part of the limbic system, deep in the brain that alerts the hypothalamus to threats
Adrenal Medulla
Part of the Adrenal gland, on top of the kidneys, which directs the Adrenal glands to produce adrenaline
Hormone
A chemical messenger
Endocrine System
A system made up of glands that works alongside the nervous system to control the vital functions of the body and maintain Homeostasis
Gland
Organs that produce and secrete hormones that regulate the activity of cells and other organs
Pituitary gland
Also referred to as the master gland because it releases the activating hormone which stimulates other glands to secrete hormones
Hypothalamus
A structure in the brain that releases the releasing hormone which stimulates the pituitary gland
Negative feedback loop
Restores systems to their original level by responding to changes in the system and returning them to their optimum level
Adrenaline
A hormone secreted by the Adrenal medulla and triggers the body’s fight-or-flight response
Neuron
Cells of the nervous system that transmit signals electrically and chemically, providing the nervous system with a means of communication
Axon
An extension of the neuron that carries impulses away from the cell body
Dendrites
These extend from the cell body to transmit impulses to other neurons
Myelin sheath
A fatty substance which increases the speed at which electrical impulses travel
Nodes of Ranvier
Breaks of between 0.2mm and 2mm in the wyelin sheath through which the action potentials jump to speed up the transmission
Nucleus
Carries the genetic information of the neuron
Soma
The cell body of the neuron which ensures the synthesis of many components required for the structure and function of a neuron
Sensory neuron
Carries information from the senses to the central nervous system
Relay Neuron
Carries information from the sensory to the motor neuron
Reflex Arc
A special type of neural circuit that begins with a sensory neuron at a receptor and ends at an effector, involving the spinal cord as a part of the CNS instead of the brain
Synaptic Transmission
This is the passage of action potentials from the presynaptic to the post-synaptic neuron through the synapse
Inhibitory Neurotransmitters
Makes the postsynaptic cell more likely to carry an inhibitory postsynaptic potential and not fire
Excitatory neurotransmitters
Makes the postsynaptic cell more likely to carry an excitatory postsynaptic potential and fire
Synaptic Gap
A gap between tw neurons through which action potentials
Receptor sites
Receptors on the postsynaptic neuron that receive the chemical neurotransmitters
Diffusion
Movement of particles from an area of high concentration to an area of low concentration until equilibrium is reached
Synaptic re-uptake site
The site reabsorption of a chemical neurotransmitter on the presynaptic neuron when it does not attach to the receptor site
Motor cortex
The cortex in the frontal lobe that controls voluntary movement
Somatosensory cortex
The cortex in the parietal lobe that controls the haptic sense
Visual cortex
The cortex in the occipital lobe that receives, integrates and processes visual information the retinas
Auditory cortex
A part of the tempura love that is the most highly recognised unit of sound in the brain
Broca’s area
A part of the motor lobe that is involved with speech production
Wernicke’s area
A part of the temporal lobe that is involved in speech comprehension
Localisation of function
The idea that certain functions such as language and memory have certain locations in the brain
Lateralisation
The idea that the two halves of the brain are functionally different and that each hemisphere has cognitive and physiological specialisations, e.g left for language while the right is dominant for visual motor tasks
Hemisphere
The symmetrical halves of the brain
Hemispheric lateralisation
The odea that the left hemisphere controls functions such as language, logic and mathematics while the right hemisphere controls functions such as creativity and feelings
Contralateralisation
The idea of opposite control, i.e left hemisphere controls the right side while right hemisphere controls left side
Fixation Point
The point in space on which the eyes are focus
Plasticity
The brain’s tendency to change and adapt functionally and structurally as a result of experience and new learning
Synaptic pruning
The process by which rarely used connections formed at infancy are eliminated an frequently used connections are strengthened
Posterior hippocampus
The part of the brain associated with the development of spatial and navigational skills
Equipotentiality
The notion that all areas of the brain are equally able to perform a task
Neurorehabilitation
The use of motor therapy and electrical stimulation of the brain to counter the negative effects and deficits in motor and cognitive functions following accidents, injuries or strokes
Functional Recovery
The brain’s ability to compensate or adapt for damaged areas using unaffected areas following physical injury or other forms of truama such as infection or strokes
Spontaneous Recovery
Recovery that happens quickly after trauma and that slows down after several weeks
TBI
Traumatic Brain Injury; one that causes severe damage to the brain and usually has lasting damage
Axon sprouting
New nerve endings grow and connect with damaged areas of the brain
Reformation of blood vessels
The blood vessels are reformed to ensure the brain functions in unaffected areas
Recruitment of homologous areas
The recruitment of the same areas in the opposite hemisphere to do specific tasks
Stem cells
Cells with the potential to develop into many different types of cells in the body
fMRI
A technique for measuring changes in brain activity while a person does a task
EEGs (Electroencephalogram)
A measure of electrical activity in the brain using electrodes to detect small changes in the activity of brain cells
Event Related Potential
Small voltage changed in the brain triggered by specific events or stimuli
Post-mortem examinations
Examinations of dead participants used to establish underlying neurobiology of a particular behaviour
Spatial resolution
The ability of the brain to distinguish different locations in the brain or smallest feature or measurement that a scanner can detect
Temporal resolution
The accuracy of the scanner in relation of time; how quickly to scanner can detect changed in brain activity
Non-invasive
Not involving the introduction of instruments into the body
Biological rhythms
Distinct patterns of change in body activity or behaviour that conforms to cyclical time periods
Circadian Rhythms
Rhythms lasting 24 hours; set and reset by light such as sleep/wake cycle
Endogenous pacemakers
Body’s internal clock or internal factors that affect biological Rhythms
Exogenous zeitgebers
External changes in the environment that regulate biological rhythms
Infradian rhythms
Rhythms that last longer than a day such as the menstrual cycle
Ultradian Rhythms
Rhythms that last less than a day, such as the cycle of brain activity during sleep
Oestrogen
A hormone involved in the menstrual cycle tha causes the ovary to develop and release an egg
Progesterone
A hormone involved in the menstrual cycle that thickens womb lining
Suprachiamsatic nuclei
An endogenous pacemaker which innervates or stops innervating the Pineal Gland to suppress to increase melatonin production
Sleep-wake cycle
A circadian rhythm that regulates the cycles of alertness and sleepiness by responding to light changed in our environment
Jet lag
A disruption of the sleep-wake cycle after a long flight across different time zones displayed by extreme tiredness
Melapnosin
A hormone that innervates the SCN as a part of the sleep-wake cycle
Melatonin
A hormone that increases or decreases in response to the SCN as a part of the sleep-wake cycle
Innervates
To stimulate
Pineal Gland
A gland in the brain that secretes melatonin
Social Cues
Cues in the environment that affect behaviour such as the sleep-wake cycle
What does the nervous system consist of and what does it do?
The Nervous system consists of two systems which work together to collect information from inside the body and the environment around it, processing the information and then dispatching instructions to the rest of the body, facilitating an appropriate response.
It is divided into two parts: the Central Nervous System and the Peripheral Nervous System
What does the Central Nervous System consist of and what do they do?
The Central Nervous System is divided into the brain and spinal cord.
The brain provides conscious awareness, controls behaviour and regulation of the body’s physiological processes (bodily functions such as sleeping).
This includes receiving sensory information from around the body and sending information to the muscles and glands of the body.
The spinal cord which runs the length of the spinal column and relays information to the brain and body.
What does the Peripheral Nervous System do and consist of?
The Peripheral Nervous System receives information from the senses (or the environment) and sends it to the Central Nervous System via the sensory neurons and transmits information from there to the effectors via motor neurons.
It consists of The Somatic Nervous System and The Autonomic Nervous System.
What does the Somatic Nervous System do?
The Somatic Nervous System facilitates sensory communication between the CNS and the outside world as it is made up of sensory receptors that carry information to the spinal cord and the brain and the motor pathways allow the brain to control movement, providing muscle responses.
What is the Autonomic Nervous System and what does it do?
The Autonomic Nervous System operates automatically and involuntarily, sending information from and to the internal body organs such as the liver and the lungs. It is responsible for vital internal functions such as heartbeat.
It is made up of The Sympathetic Nervous System (which stimulates biological function for ‘fight-or-flight’) and The Parasympathetic Nervous System (which slows functions to recover from ‘fight-or-flight’). Their actions are antagonistic, working in opposition to create Homeostasis (optimal functioning in response to stimuli).
Name some antagonistic actions involved in the fight or flight response
Heart: increases the heart rate vs decreases heart rate (more blood for more energy)
Eye: dilates pupils vs constricts pupils (let more light in to see where going)
Gut: slows digestion vs speeds up digestion (more energy somewhere else)
Lungs: dilates bronchi vs constrict bronchi (more oxygen so no run out of breath)
How are the effects of the endocrine system different to those of the nervous system?
It acts more slowly than the nervous system but has very widespread and powerful effects.
Endocrine glands
Endocrine glands are organs that produce and secrete hormones, chemical substances that regulate the activities of cells and other organs. Hormones are released into the bloodstream where they communicate with the body by heading toward their target organs to bring about a particular change.
What are some Endocrine glands
The Pituitary gland: Activating/Stimulating Hormone which stimulates hormones of other glands.
Hypothalamus: Releasing Hormone which stimulates the pituitary gland.
Thyroid gland: Thyroxine which controls metabolism rate.
Adrenal gland: Adrenaline which triggers the fight or flight response.
Ovaries: Oestrogen which causes changes at puberty, bone strength and regulation of the female reproductive system; Progesterone which stimulates glandular development and development of red blood cells in preparation for pregnancy.
Testes: Testosterone which causes development of male, sex characteristics during puberty while also increasing muscle growth and also links to aggression.
Why are the endocrine glands important?
The glands that do not constantly secrete hormones rely on the presence or absence of hormones in the blood to turn on and off their secretions. If there isn’t enough hormone circulating in the blood, the hypothalamus secretes the releasing hormone which stimulates the secretion of the stimulating hormone in the pituitary gland which stimulates the target gland to secrete some more hormones. If there is too much hormone, the target gland inhibits the hypothalamus which inhibits the pituitary gland. This is called the negative feedback loop.
Explain the fight or flight response
The fight or flight response starts when a person enters a stressful situation and the amygdala is activated which sends a distress signal to the hypothalamus. This activates the SAM Pathway which is the route through which the brain directs the sympathetic branch of the autonomic nervous system. This stimulates the adrenal medulla, part of the adrenal gland, which secretes the hormone adrenaline and the neurotransmitters noradrenaline into the bloodstream. Adrenaline breaks down glycogen into accessible glucose for energy and causes a number of physiological changes such as dilation of the bronchi, to prepare the body for fight or flight.
Evaluate the fight or flight response
Previous research on the fight or flight response may be gender biased.
Taylor et al suggests that for females, behavioral responses to stress are more characterised by a pattern of tend (through nurturing behaviors) and befriend (form protective alliances with other women). This may because females evolved in the context of being the primary caregiver in addition to their higher levels of oestrogen and oxytocin. Fleeing would put the offspring at risk.
Lee and Harley found a genetic basis for gender differences in fight or flight responses. Evidence found that the SRY gene, one that females do not carry, directs aggression in males and may be responsible for males’ response to stress including producing adrenalin and heart and muscle change.
This is a weakness of research into the fight or flight response as evidence suggests that both genders respond with some differences in stressful situations and this needs to be considered for a complete understanding of the process.
The fight or flight response can have negative consequences due to high numbers of modern day stressors.
For example, the increased blood pressure caused by the release of adrenalin can lead to damaged blood vessels and heart disease. Similarly, the release of high levels of cortisol, a stress hormone, can weaken the immune system.
When considering the stress involved in employment, study and social life in modern societies, it becomes apparent that the fight or flight response (as it is activated more frequently) may have a negative effect on human health and wellbeing.
It is important to recognise that the fight or flight response might not be adaptive in modern societies.
There may be more reactions to stress than the fight or flight response.
Gray argues that the first stage of stress response is to freeze. The initial reason for this is to avoid confrontation. It is also a state of hyper vigilance where information is collected in order to make the optimal decision to avoid a particular threat.
Von Dawans et al challenges the view that fight or flight and the tend and befriend responses are the only reactions to stress. The study found that stress increased cooperative and friendly behaviors, even in men. This suggests that humans can respond socially and collectively, perhaps reflecting our social evolution.
This is a weakness of previous research into the fight or flight response as these studies suggest that the human response may be complex and varied than proposed.
Percentage of neurons in the brain
80%
Parts of the nucleus
The cell body contains the nucleus.
The dendrites extend from the body, carrying electrical impulses from other neurons toward the cell body.
The axon is an extension of the neuron which carries impulses away from the cell body, specifically at the axon terminal. It is covered by a sheath of myelin, a fatty substance, which increases the speed at which the electrical impulses travel.
Nodes of Ranvier are breaks in the myelin sheath of about 0.2mm and 2mm between which action potentials jump to travel down the axon to speech up the transmission.
Types of neurons
Sensory Neurons: they have long dendrites which carry information from senses to the CNS.
Relay Neuron: many dendrites to pass information from neuron to neuron and are only found in the CNS.
Motor Neuron: particularly long axon movement signals to the muscles from the CNS
Chemicals can either be…
Excitatory or inhibitory
Explain synaptic transmission
Information is passed down the axon in an electrical impulse known as action potentials.
Once the action potential reaches the end of the neuron it needs to be carried to another neuron by crossing the synaptic cleft between the presynaptic and postsynaptic neurons.
At the end of the neuron, vesicles contain the chemical messages known as neurotransmitters.
When the vesicles reach the neuron membrane, they release their contents of neurotransmitters into the synapse.
Neurotransmitters diffuse across the gap. Some bind to receptor sites on the postsynaptic cell that then becomes activated. Some that do not reach the receptor sites are sucked back into the re-uptake site. Once the receptors have been transmitted, they either produce positive or negative effects on the postsynaptic cell, depending on whether they are excitatory or inhibitory. This will make the neuron more or less likely to fire, depending on the summation of these effects.
How do Reflexes work?
They begins at the sensory neuron which sends information to the relay neuron, specifically the spinal cord. This sends a response through the motor neuron which causes a muscle to contract. This is an automatic response that does not require a decision from the CNS.
Holistic theory
The idea that all parts of the brain are equally and simultaneously involved in processing thoughts and actions
The brain is divided into…and how does that link to lateralisation?
The brain is divided into 2 symmetrical halves. Localisation also supports lateralisation, the idea that some of our physical and psychological functions are controlled or dominated by a particular hemisphere. As a general rule, activity on the left side is controlled by the right hemisphere and vice versa.
What does the cerebellum do?
It controls involuntary movement and balance and the brain stem which sends signals to and from the brain.
What is on the outer layer of the brain?
On the outer layer of the brain lies the cerebral cortex which, on each hemisphere, is divided into two lobes named after the four bones which they lie: the parietal lobe, occipital lobe, frontal lobe and temporal lobe
What does the parietal lobe control?
In the parietal lobe, which controls sensory information, lies the Somatosensory cortex, which receives sensory information from the touch receptors e.g about the temperature.
What does the occipital lobe control?
In the occipital lobe, which controls visual information, lies the visual cortex which receives and processes visual information.In the occipital lobe, which controls visual information, lies the visual cortex which receives and processes visual information.
What does the frontal lobe control and who investigated it?
In the frontal lobe, the site for decision making and conscious making, lies the motor cortex which is responsible for voluntary movement and Broca’s Area which controls speech production. Broca investigated the difficulties of a stroke victim named Tan, who could only say the word ‘Tan’ and found during an autopsy a lesion in Broca’s Area which was found responsible for fluent coherent speech. Damage to this area causes slow and laborious speech which is referred to as Broca’s aphasia.
What does the temporal lobe control and who investigated it?
In the temporal lobe, which controls auditory information and memory acquisition, lies Wernicke’s Area which is responsible for speech comprehension. Wernicke discovered that patients with lesions were unable to comprehend language, often producing meaningless but fluent language. This is referred to as Wernicke’s aphasia.
Evaluate Localisation of Function
It has been argued that language is not localised because language production may not be confined to Broca’s area alone.
Although there is evidence from case studies to support the function of Broca’s area and Wernicke’s areas, more recent research has provided contradictory evidence.
Dronker’s et al conducted an MRI scan on Tan’s brain, to try to confirm Broca’s findings and also found evidence to suggest that other areas as well as Broca’s areas may have contributed to the failure in speech production,
These results suggest that the 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 other neighboring regions. This also suggests that cognitive functions may involve a wider neural network than being simply localised to specific areas.
There are many brain scans studies that support localisation,
Tulving found that Semantic long term memory to be link to the activity in the left prefrontal cortex, the episodic long term memory to be linked to activity in the right prefrontal cortex and Procedural long term memory to be linked to activity in the cerebellum.
Peterson also found Broca’s area to be active during a speech task and Wernicke’s area to be active during a listening task, supporting that specific brain areas have specific cognitive functions.
However, activity does not equal function as active parts could simply be relay stations.
This is a weakness as it provides empirical and reliable evidence to support the claims of localisation theory.
Numerous case studies also support localisation theory.
CW, whose hippocampus faced severe damage after an brain infection, lost most of his episodic long term memory, but his Semantic and Procedural LTMs remained intact. Furthermore, Tan suffered from Broca’s aphasia and could only say Tan due to damage to his left frontal lobe, where Broca’s area is said to be located.
This is clinical evidence that specific areas of the brain are responsible for particular cognitive functions.
As these are special cases, they may be affected by confounding variables such as stress or trauma to other parts of the brain.
This is a strength as there is evidence taken from real-life cases.
Lateralisation vs Contralateralisation
Lateralisation is the idea that the two halves of the brain are functionally different and that each hemisphere has cognitive and physiological specialisations, i.e the left hemisphere is for language while the right hemisphere is dominant for visual motor tasks. Some left-hemisphere functions are language logic, linear thinking and mathematics while some right-hemisphere functions include holistic thinking, intuition and feelings.
Contralateralization is the idea of opposite control of the hemispheres; i.e the right hemisphere controls the left hand side and vice versa.
Who investigated Contralateralization and how?
Sperry and Gazzaniga investigated the extent to which the two hemispheres are specialised for certain functions. They acquired a sample of 11 right-handed split-brain patients. They were asked to focus on a Fixation point and a stimulus (either a word or image) was projected to the patients left visual field (which is processed by the right hemisphere) or the right visual field (which is processed by the left hemisphere).
Ppts were asked to describe and draw what they say in each visual field. The researchers found that the stimulus presented in the right visual field, the participants were able to verbally describe it. However, the stimulus presented in the left visual field could not be described but could be drawn with the left hand.
In conclusion, split-brain patients cannot share information between hemispheres. The left hemisphere has language ability and right has spatial/visual ability.
Evaluate Lateralisation of function
Research has suggested that lateralisation changes with age.
Szaflarski et al found that language became more lateralized to the left hemisphere with increasing age in children and adolescents, but after the age of 25, lateralisation decreased with each decade of life.
Lateralisation of function appears not to stay exactly the same throughout an individual’s lifetime, but changes with normal ageing. Across many types of tasks and many brain areas, lateralised patterns found in younger individuals tend to switch to bilateral patterns in healthy older adults.
It is difficult to know why this is the case. One possibility is that using the extra processing resources of the other hemisphere may in some way compensate for age-related declines in function, suggesting that lateralisation is not a fixed process and that the theory is incomplete.
More recent research contradicts Sperry’s original claim that the right hemisphere could not process even basic language.
For example, Turk et al’s case study of JW found that after damage to the left hemisphere he developed the ability to speak out of his right hemisphere which means that can speak information presented to either his left or his right visual field.
This suggests that perhaps lateralisation is not fixed and that the brain can adapt following damage to certain areas, further presenting the argument that language may not be restricted solely to the left hemisphere and contradicting the theory of hemispheric lateralisation.
The main limitation of split-brain research is that the procedure is rarely carried out these days.
Therefore, patients who have had this procedure are rarely encountered in sufficient numbers to be useful for research and often research takes an idiographic approach.
Andrewes argues that many studies have only 3 (sometimes only 1 ppt). Therefore, he claims conclusions have been drawn from a small sample of individuals who also has a confounding physical disorder that made the procedure necessary.
This is a weakness as such results cannot be generalised to the wider population and as Andrewes claims that these rogue cases are often only identifies when the results of a study have failed to be replicated.
How does Neuroplasticity affect us as we age?
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 years old. This equates to twice as many as there are in the adult brain.
As we age, rarely used connections are eliminated and frequently used connections are strengthened in a process called synaptic pruning. This shows that the brain is in a continual state of change from growth in early years to change and refinement in adulthood as we learn and experience. In recent years, it’s become clear not only that neural organisation is changed as a result of experience, but also there are many different types of experience, such as meditation and video games, which can do this.
How can Neuroplasticity be negative?
Examples of this include strengthening addictions by strengthening dopamine pathways, prolonged drug use leading to poorer cognitive functioning and old age being associated with dementia.
Evaluate Neuroplasticity
There is research support for neural Plasticity.
Maguire et al studied the brains of London taxi drivers using an MRI and found significantly more grey matter in the posterior hippocampus than in the matched control group. This part of the brain is associated with the development of spatial and navigation skills in humans and other animals.
As part of their training, London Cabbies must take a complex test called the ‘the knowledge’ which assesses their recall of the city streets and possible routes. It is also noteworthy that the longer they has been doing the job, the more pronounced the structural differences were.
Because this is a correlational study, it is difficult to assert cause and effect as to where this structural difference was as a result of the knowledge.
This is an overall strength as it provides scientific, objective measurements, supporting the theory of plasticity.
Animal Studies support the brains’ activity to change as a result of experience.
Kempermann et al found evidence of an increased number of neurons in the brains of rats housed in complex environments compared to rats in lab cages.
The rats housed in complex environments showed an increase in neurons in the hippocampus, the area of the brain associated with formation of new memories.
However, this cannot be generalised to humans.
This is a strength as this reliable, controlled and empirical evidence suggests that new neural networks were created from the experience of needing to navigate from one area to another supporting the view of neural plasticity.
A strength of research examining plasticity and Functional Recovery is the real-life applications of the findings to the field of neurorehabilitation.
Neurorehabilitation uses motor therapy and electrical stimulation of the brain to counter the negative effects and deficits in motor and cognitive functions following accidents, injuries and/or strokes, especially after periods of spontaneous recovery have reduced.
This demonstrates the positive application of research in this area to help improve the quality of life of people suffering from brain injuries.
What is functional recovery and why is studying it important?
The ability of the brain to adapt or compensate for damage areas using unaffected areas following physical injury or other forms of trauma. The functional recovery that occurs in these cases is an example of neural plasticity.
Neuroscientists suggest that this can happen quickly after trauma as spontaneous recovery and then slow down after several weeks or months where therapy may then be needed.
The brain is able to rewire and reorganise itself by forming new synaptic connections close to the affected area. Secondary neural pathways that would not be typically used to carry out certain functions are unmasked and enabled to continue functioning.
Steps involved in plasticity and Functional recovery
Axon sprouting: when new nerve endings grow and connect with undamaged areas
Reformation of blood vessels: to allow more blood to get to the brain for energy
Recruitment of homologous areas on the opposite hemisphere to do specific tasks.
This process may also involve stem cells which replace or repair damaged cells. `
Who investigated Functional Recovery and what was found?
Tajir et al provided evidence for the role of stem cells in recovery from brain injury. They randomly assigned rats with traumatic brain injury to one of two groups; one received transplants of stem cells into the region of the brain affected by traumatic brain injury while the other received an infusion into the brain containing no stem cells. Unlike the control group, the brains of stem cell rats showed clear development of neuron-like cells in the affected area, accompanied by a solid stream of stem cells migrating to the brains site of injury.
Evaluate functional recovery
Human echolocation may support functional recovery. This is the learned ability for humans to sense their environment from echos.
This ability is used by some blind people to navigate their environment and sense their surroundings in detail. Some studies using fMRIs have shown that parts of the brain associated with visual processing are adapted for this new skill.
Studies with blind patients, for example, suggest that the click-echos heard by these patients were processed by the brain regions devoted to vision rather than audition.
Human evidence is restricted due to small scale studies of people who already have issues but it is unclear whether what we are seeing is due to recovery or individual differences.
However, this is a strength as it may be evidence of real-life functional recovery.
Functional Recovery may be linked to age differences.
According to this view, the only option following traumatic brain injury beyond childhood is to develop compensatory behavioural strategies to work around the deficit (such as seeking social support or to develop strategies to deal with cognitive deficits).
However, studies have suggested that abilities commonly thought to be fixed in childhood can still be modified in adults with intense training. Despite these indication of adult plasticity, ELbert et al conclude that the capacity for neural reorganisation is much greater in children than in adults.
Therefore, age differences need to be considered when discussing functional recovery.
Functional Recovery may be linked to educational attainment.
Schneider et al found that patients with the equivalent of a college education are seven times more likely than those who didn’t high school to be disability-free one year after a moderate to severe traumatic brain injury.
They carries out a retrospective study based on data from the US Traumatic Brain Injury Systems Database and found that of the 40% patients with 16 or more years of education had received DFR, and just 10% of those with less than 12 years of education achieved DFR after just one year. The researchers concluded that cognitive reserve could be a factor in neural adaptation during recovery from traumatic brain injury.
Therefore, educational attainment may affect an individual’s ability to functionally recover.
Why do we study the brain
As the main focus of neuroscience, studying the brain gives important insight into the underlying foundations of our behaviour and mental processes. A variety of methods is used by researchers to study the functions and areas of the brain.
fMRIs facts
It is used for measuring changes in brain activity while a person performs a task by measuring changes in blood flow in particular areas of the brain, indicating increased neural activity.
More activity in a certain area increases the demand for oxygen in that area thereby increasing the blood flow delivering oxygen in the red blood cells.
This change in blood flow aids researchers to produce maps showing which areas of the brain are involved in a particular mental activity.
Examples: in recall of a previously learnt list to inform psychologists about the areas of the brain used in memory recall and localise LTMs.
Evaluate fMRIs
They are praised for being Non-invasive as they do not inversion of any instruments or exposure to potentially harmful radiation. This is a strength as it means that an individual’s behaviour can be investigated without their physical, mental or psychological health being placed at risk.
They offer a more objective and reliable measure than possible with verbal reports as blood volume can be measured accurately and empirically. This makes it superior to reliance on observations of behaviour. This is a strength as fMRIs are useful for investigating phenomena which would not have been possible through verbal reports and removing bias.
fMRIs produce images with very high spatial resolution, depicting activity by the millimetre, providing a more detailed analysis of the location of neural activity to be conducted.
fMRIs have poor temporal resolution, meaning it takes approximately five seconds for the image to appear since the actual neural activity took place.
The sample sizes are often unrepresentative. Research usually has a limited amount of funding and using fMRIs scans often require lots of money. This is a weakness because this makes the research difficult to generalise.
They are not a direct measure of neural activity in particular brain areas. It only measures change in blood flow which makes their interpretation complex. This is a weakness as it is not truly an accurate measure of mental activity at an individual neuronal level
EEGs facts
It measures electrical activity in the brain using electrodes placed on the scalp to detect small electrical charges from the activity of the brain cells.
Electrical signals from these electrodes are graphed over time resulting in EEGs.
They can be used to diagnose brain disorders that can influence brain activity.
The four basic EEG patterns are alpha, beta, delta and theta which vary from when a person is awake but relaxed, to physically aroused to awake respectively. Moving from light sleep to deep sleep changed from alpha to theta and delta waves.
More frequency means more brain activity while more amplitude means a stronger signal.
Evaluate EEGs
It has high temporal resolution, creating a measure of brain functioning in real time. It also takes a reading of an active brain, rather than a passive one so a task can be accurately associated with the brain activity.
They are useful for clinical diagnosis; e.g epilepsy causes a change in brain activity meaning the normal reading changes. This is a strength as it points out brain abnormalities.
They only detect activity in the superficial regions of the brain, preventing it from revealing activity in the deeper regions of the brain such as the hippocampus. This is a weakness as it limits the information gained unless more invasive procedures are used.
It is not useful for pinpointing the exact source of brain activity as electrical activity can be picked up by several neighbouring electrodes. Weakness because researchers cannot distinguish between activities originating from different but closely adjacent regions of the brain.
ERP facts
They are small voltage changes that are triggered by specific events or stimuli.
They are difficult to detect from other electrical activity going on in the brain so to establish a specific response to a target stimulus, they are compared to EEG reading to find a change or difference.
Activity linked to the specific stimulus will occur consistently while extraneous stimuli will not, cancelling out neutral background noise and highlighting a specific response.
They can be divided into two categories; waves occurring in the first 100 milliseconds which are called sensory ERPs which reflect the initial response to physical characteristics of the stimulus and waves after which are called cognitive ERPs and evaluate the stimulus.
Evaluate ERPs
They produce a measure of processing in response to a particular stimulus as it is possible to see what neural activity is associated with the processing of different visual stimuli, giving it high temporal resolution. Strength as researchers are able to determine how processing is affected by different stimuli and insight can be gained into the functioning of the brain.
It measures the processing of stimuli even in the absence of a behavioural response as it monitors processing without a response which helps psychologists gain a better understanding of the brain.
They are useful for pinpointing the exact source of brain activity as it can be picked up by several neighbouring electrodes. The inner brain is also difficult to measure sso studying the cortex is often the most common use. Weakness as researchers are unable to distinguish activities in the brain.
The output can only be interpreted by a trained professional.they require intense and expensive training in order to fully appreciate the activity measured which can increase the cost of research.
Post mortem exams facts
They are used to establish an underlying neurobiology of a particular behaviour. Researchers might study a person who behaved strangely to discover what caused the brain damage.
They examine the brain of these individuals to look for abnormalities which may explain behaviour.
An early example would be Broca’s work with his patient Tan who discovered speech lesions may be as a result of lesions in the area now known as Broca’s area—the site for speech production.
They can also be used to find areas of the brain responsible for memory e.g Annesse found that HM’s inability to store new memories may have been due to lesions in the hippocampus.
They could also be used to establish a link between abnormalities and psychiatric disorders such as schizophrenia.
Evaluate post mortem
They allow a more detailed examination of anatomical and neurochemical aspects of the brain than would be possible through fMRIs as they enable an examination of deeper regions of the brain such as the hippocampus. Strength as it allows psychologists to understand the role of the brain in human development, abnormality and behaviour.
They have played a central role in the development of early understandings of brain functions. Broca and Wernicke relied on them to establish a link between language, brain and behaviour decades before neuroimaging ever became a possibility. Strength as it improved medical knowledge and the further proposition of hypotheses.
They can sometimes lead to inaccurate data and findings as the length of time between death and post mortem, drugs and age of death could all be confounding influences of any difference between case and controls. Weakness as it may lack internal validity and make it difficult to make conclusions on cause and effect.
It is retrospective as the individual is dead so the researcher cannot follow up on anything that arises concerning a possible relationship between brain abnormality and cognitive functioning. Weaknesses as conclusions are often limited.
Core temperature in relation to circadian rhythms
The core body temperature is an indicator of circadian rhythms. It is at its lowest at 4:30 am at about 36 degrees and its highest at 6pm at about 38 degrees. During a normal circadian rhythm, core temperature begins to drop when sleep occurs and it begins to rise during the last hour of sleep, causing a feeling of alertness in the morning. A small drop in body temperature also occurs between 2 and 4pm, explaining why people may feel sleepy in the afternoon
How does Circadian rhythm affect the sleep cycle?
Circadian rhythms also determine when we sleep and wake up, making us feel drowsy at night and alert in the day. The SCN in the hypothalamus synchronises the The internal body clock with the outside world to coordinate the activity of the entire circadian system. Light, specifically blue light and darkness are external signals which determine this, acting as exogenous zeitgebers and keeping us awake as long as there is sunlight. Homeostatic control, an endogenous pacemaker, also determines sleep by alerting the body of a need to sleep because of the amount of energy used up during wakefulness. This homeostatic drive increases gradually during the day and peaks at night. However, it leads to drowsiness throughout the waking period regardless of if it’s day or night because the internal circadian clock is free running and intolerant of major alterations in sleep which may cause the internal physiological system to become completely out of balance referred to as desynchronisation.
Who investigated biological rhythms
Siffre investigated circadian rhythms without effects of exogenous zeitgebers by spending approximately 6 months in a cave without daylight so his sleep/wake cycle would only be regulated by internal body clock. He found that he eventually settled into a 25 hour cycle and believed the date was a month earlier, suggesting we have a free-running cycle which is naturally 25 hours.
Evaluate circadian rhythms
Research has been conducted to investigate circadian rhythms and the effect of external cues like blue light on this system.
Siffre found that the absence of external cues significantly altered his circadian rhythm as he believed when he returned from his underground stay with no clocks or light that the date was an hour earlier than it was.
This suggests that his 24-hour sleep/wake cycle was increased due to a lack of external cues such as light, clocks and so on, making him believe that a day was longer than it was, leading him to think fewer days had passed.
This is a strength as this study provides evidence for the effect of endogenous pacemakers and the importance of the role of exogenous zeitgebers in training the sleep/wake cycle.
It is important to note the individual differences when it comes to circadian cycles.
Duffy et al found that morning people called ‘larks’ prefer to rise and go to bed early between 6am and 10pm while evening people called ‘owls’ prefer to wake and go to bed later between 10am and 1am.
This demonstrates that there may be innate individual differences in circadian rhythms, suggesting that researchers should focus on these differences during investigations.
Knowledge of circadian rhythms can have real life applications in the fields of shift work.
For example, night shift workers will be expected to work despite numerous external zeitgebers influencing their circadian rhythm to sleep such as reduced light. This can lead to irregularities in the body’s sleep/wake cycle known as desynchronisation which can have negative effects on safety.
Boivin et al found that concentration dips at around 6am meaning mistakes are more likely. Knutsson also found a link between night-shift work and ill health, suggesting a risk posed to workers’ health, such as tripled risk of health disease.
Employing practices that seek to mitigate these potential negative effects of night-shift work could have benefits for the economy and raise the quality of life of workers.
The menstrual cycle in relation to Infradian Rhythms
This cycle refers to the time between the first day of a period and the day before the start of the next period. This is an entirely endogenous system as it is regulated by hormone levels (endogenous pacemakers).
During each cycle, rising levels of oestrogen causes the ovary to develop and release eggs into the uterus for fertilisation (ovulation phase). After this is the luteal phase, progesterone thickens womb lining, preparing the womb for pregnancy and the ova to be fertilised and implanted. Finally, during the follicular phase, which is the first day of pregnancy, the egg is absorbed in the womb lining and the menstrual flow begins.
Evaluate Infradian Rhythms
There is evidence supporting the effect of exogenous zeitgebers on the menstrual cycle.
Russell et al found that the female menstrual cycle became synchronised with other females due to odour exposure. In one study, sweat samples from one group of women were rubbed onto the upper lip of another group and despite the fact that the groups were separate, their menstrual cycles synchronised.
This suggests that the synchronisation of menstrual cycles can be affected by pheromones, which have an effect on people nearby rather than on the person producing them. Evolutionary psychologists claim that this external factor provides an advantage for groups of women as synchronised pregnancies means childcare can be shared among multiple mothers who have children at the same time.
These findings indicate that external factors must be taken into consideration when investigating Infradian Rhythms and that perhaps a more holistic approach should be taken as opposed to a reductionist approach which only considers endogenous influences.
Research suggests that the menstrual cycle is, to some extent, governed by exogenous zeitgebers.
Reinberg examined a woman who spent three months in a cave with only a small lamp to provide light. He noted that her menstrual cycle shortened from the usual 18 days to 25.7 days.
This result suggests that the lack of blue light, an exogenous zeitgeber, in the cave affected her menstrual cycle and therefore this demonstrates the effect of external factors of Infradian rhythms.
This is further evidence to suggest that exogenous zeitgebers can affect infradian rhythms.
The sleep cycles in Ultradian Rhythms
This rhythm found in human sleep follows a pattern of alternating REM (rapid eye movement) and NREM (non-rapid eye movement) sleep, consisting of stages 1 through 4. This cycle repeats itself about every 90 minutes throughout the night with different stages having different durations.
A complete cycle consists of a progression through the four stages of NREM sleep before entering a final stage of REM sleep, and then the whole cycle repeats again.
Knowledge from different stages of sleep come from recording the electrical activities of the brain, with each stage showing a distinct EEG pattern.
In the first stage (where alpha waves are present) and the second stage (where theta waves are present), a person is in light sleep and in each stage there is a decrease in muscle activity and body temperature respectively. In the third and fourth stage of deep sleep, the brain generates delta waves, breathing is rhythmic and it is difficult to awaken
As a person enters deep sleep, their brain waves slow and their breathing and heart rate decreases. During the fifth stage of REM sleep, the EEG pattern resembles that of an awake person, and it is in this stage that most of the dressing occurs.
Evaluate Ultradian Rhythms
An issue with studying sleep cycles is individual differences.
Tucker et al found significant differences between participants in terms of the duration of each stage, particularly stages 3 and 4 (just before REM sleep).
This demonstrates that there may be innate individual differences in Ultradian differences which means that it is worth focusing on these differences during investigations into sleep cycle as these findings cannot be generalised.
There is some evidence of support for elite performers.
Ericsson et al studied elite violinists who chose to limit their practice sessions to multiple 90 mins blocks with short breaks in-between, even including naps. He used EEGs to study electrical currents of their brains ad found that sleep pattern continues during the day; i.e 90 mins of activity and 20 mins break.
Similar results have been found for chess players, athletes and writers.
This is real life evidence that gives external validity to Kleitman’s ABC theory as it is able to explain real-life behaviours.
What is the most important endogenous pacemaker?
The most important endogenous pacemaker is the suprachiasmatic nucleus (SCN), which is closely linked to the Pineal gland, both of which are influential in maintaining the circadian sleep-wake cycle.
Exogenous zeitgebers and social Cues
Exogenous zeitgebers are environmental events that are responsible for resetting the biological clock of an organism, including daylight (which is responsible for resetting the sleep-wake cycle each day, keeping it on a 24 hour cycle). It also includes social cues such as mealtimes which compensate for a lack of natural light.
How endogenous pacemakers affect the sleep wake cycle
When blue-light reaches Melanopsin receptors, a neural signal is sent via the optic nerve to the SCN which lies in the hypothalamus. The SCN stops innervation of the pineal gland to suppress melatonin production as light levels increase in the morning including the feeling of alertness.
At night, the SCN innervates the Pineal Gland to increase melatonin production and secretion to help induce sleep and feeling of drowsiness.
Both the SCN and the pineal gland are responsive to the external cue of light to entrain the cycle of 24 hours.
Who investigated endogenous pacemakers and circadian rhythms?
Klein and Wegmann found that the circadian rhythm of air travellers adjusted more quickly if they went outside more at their destination as they were exposed to social cues in their new time zones. Likewise, the circadian rhythm of blind people were thought to be no different to sighted people due to exposure to the same social cues. In terms of light exposure, despite having no visual perception, connections between the eye and the SCN do not involve those parts of the visual system so they are still influenced by light during the day.
Evaluate endogenous pacemakers
Many researchers argue that an interactionist system is most appropriate when studying endogenous and Exogenous pacemakers.
This is because only in extreme circumstances are exogenous zeitgebers not present in individuals’ lives. For example, the Siffre cave case study did not reflect real-life situations.
As such, endogenous and Exogenous factors will likely be present simultaneously in most people’s real lives.
Therefore, perhaps it does not make sense to separate them out for the purposes of research and instead study how they interact to regulate the sleep/wake cycle.
There is further research support for the role of exogenous zeitgebers.
When Siffre returned from and underground stay with no clocks or light, he believed the date to be a month earlier than it was.
This suggests that his 24 hour sleep-wake cycle was increased by the lack of external cues, making him believe one day was longer than it was.
However, this is a small sample and not reflective of everyday life where exogenous cues are present so it lacks external validity.
This is a strength as it highlights the impact of external factors on bodily rhythms.
There is also research supporting the role of melapnosis.
Skene and Arendt claimed that the majority of blind people who still have some light perception have normal circadian rhythms whereas those without any light perception are more likely to show abnormal circadian rhythms.
This demonstrates the importance of exogenous zeitgebers as a biological mechanism and their impact on biological circadian rhythms
