Biopsychology Flashcards
The two main functions of the nervous system
- To collect, process and respond to information in the environment
- To co-ordinate the working of different organs and cells in the body
The nervous system
Our primary communication system/a network of cells.
What is the central nervous system made up of?
The brain and the spinal cord.
What is the nervous system separated into?
The central nervous system (CNS) and the peripheral nervous system (PNS)
Parts of the peripheral nervous system
Somatic nervous system and autonomic nervous system
Parts of the somatic nervous system
Sensory neurons and motor neurons
Parts of the autonomic nervous system
Sympathetic division and parasympathetic division
Brain
- Centre of consciousness
- Made up of billions of interconnected neurons
- Bilateral (two-sided)
- Separated into distinct lobes each associated with certain types of functions
- All areas of the brain interact with one another
Spinal cord
- An extension of the brain
- Responsible for reflex actions
- Routes messages to and from the brain
- Cord is organised into 30 segments which correspond to the vertebrae
- Each segment is connected to a specific part of the body through the PNS.
Peripheral nervous system (PNS)
Connects the CNS to the rest of the body.
Somatic nervous system
Controls muscle movement and receives information from sensory receptors. Associated with conscious and voluntary behaviours. Involved in the relay of sensory and motor information to and from the CNS.
Autonomic nervous system
Governs vital functions such as breathing, heart, digestion, sexual arousal and stress response. It is involuntary.
Sensory neurons
- Carry information from sensory receptors (vision,taste,touch etc.) to the CNS
- They convert information from these sensory receptors into neural impulses
Motor neurons
- Takes information from the CNS to muscles and glands in the body.
- Form synapses with muscles and control their contractions
- Release neurotransmitters that bind to receptors on the muscle and trigger a response, leading to muscle movement
Sympathetic division
- Ready for action/fight or flight response
- Involved in preparing the body for stress-related activities e.g. increasing heart rate and blood pressure
- Slows down body responses less important in emergencies such as digestion
- Responds to a perceived threat
Parasympathetic division
Sometimes referred to as rest and digest. Restores natural order in the body and returning it back to routine.
Homeostasis
A state of equilibrium in which biological conditions are maintained at optimal levels. The sympathetic and parasympathetic have complementary functions and work in tandem to maintain the body’s homeostasis.
Reflexes
Reactions to stimuli that are rapid and automatic as sensory input is immediately acted upon by the spinal cord without input from the brain.
Neurons
The main building blocks of the nervous system. They have a structure which is specialised to their function.
The structure of neurons
- Nucleus located in the soma (cell body)
- The soma has branching extensions known as dendrites
- Dendrites act as input sites where signals are received from other neurons
Axon
A major extension from the soma
Terminal buttons
Contain synaptic vesicles that house neurotransmitters and release them into the synapse.
The action potential from an electrical impulse moves rapidly down the axon to the terminal buttons.
Synapse
A very small place between two neurons. An important site where communication between neurons happens.
Synaptic cleft
The space between two neurons.
Synaptic knob
The bulb shaped end of a neuron where it meets another neuron.
Synaptic vesicles
In the synaptic knob and are where neurotransmitters are stored before release into the synaptic cleft.
Neurotransmitter
A chemical messenger that carries information from one neuron to another.
Neurotransmitters can be divided into those that perform an excitatory function and those that perform an inhibitory function.
Receptors
Proteins on the cell surface where neurotransmitters attach.
Specific neurotransmitters fit specific receptors (lock and key relationship)
Relay neurons
Allow sensory and motor neurons to communicate with each other. They lie wholly within the spinal cord.
Inhibitory neurotransmitters
The nervous system’s “off switches” and are generally responsible for calming the mind and body including sleep and filtering out unnecessary excitatory signals.
They decrease the likelihood of a new action potential forming in the postsynaptic cell
Excitatory neurotransmitters
The nervous system’s “on switches”. They cause excitation of the post synaptic neuron by increasing its positive charge and making it more likely to fire (increasing the likelihood of a new action potential forming in the postsynaptic cell)
Dopamine
- Can be both an excitatory or inhibitory neurotransmitter depending on the receptor it binds to
- Associated with rewards as the brain releases it in response to pleasure
- Responsible for movement co-ordination and is implicated in Parkinson’s disease
- Excess dopamine in certain regions of the brain is associated with positive symptoms of schizophrenia
Serotonin
- Inhibitory neurotransmitter
- Regulates sleep, mood and appetite
- SSRIs relieve the symptoms of depression by increasing levels of serotonin in the brain
Dendrites in sensory neurons are…
Long
Axons in sensory neurons are…
Short
Dendrites in relay neurons are…
Short
Axons in relay neurons are…
Short
Dendrites in motor neurons are…
Short
Axons in motor neurons are…
Long
Myelin sheath
- An insulating layer around axons
- Made of protein and fatty substances
- Allows electrical impulses to transmit quickly and efficiently along the nerve cells
- Sensory neurons and relay neurons have a myelin sheath
Nodes of Ranvier
Gaps in the myelin sheath coating on the axon.
The endocrine system
Made up of a series of glands that produce hormones
Hormones
- Chemical messengers that must bind to a receptor in order to send their signal
- Secreted into the bloodstream and travel around the body
- Slower to take effect than neurotransmitters
Pituitary gland
- Descends from the hypothalamus at the base of the brain
- “Master glad” - its messenger hormones control all the other glands in the endocrine system
- Secretes growth hormone, endorphins for pain relief and hormones that regulate fluid levels in the body
The thyroid gland
- Located in the neck
- Releases hormones that regulate growth, metabolism and appetite
Examples of thyroid disorders
Hyperthyroidism
Grave’s disease
What causes hyperthyroidism or Grave’s disease/What are the symptoms
- When the thyroid secretes too much of the hormone thyroxine
- Symptoms include weight loss and agitation
Adrenal glands
- Located on top of the kidneys
- Secrete hormones involved in the stress response such as adrenaline and noradrenaline
The pancreas
Secretes hormones that regulate blood sugar (insulin and glucagon)
Insulin
Lowers blood sugar levels
Glucagon
Raises blood sugar levels
Gonads
- Secrete sexual hormones
- Mediate sexual motivation and sexual behaviour
Ovaries
- The female gonads
- Secrete oestrogen and progesterone
Testes
- The male gonads
- Secrete androgens such as testosterone
Pineal gland
- Small pea shaped gland in the brain
- Production and regulation of melatonin which is important for regulating sleep
Parathyroid glands
- Lie behind the thyroid glands
- Produce and regulate the parathyroid hormone
- Parathyroid hormone regulates the body’s levels of the minerals calcium and phosphorus
Thymus glands
- In the centre of the chest
- Produce progenitor cells which mature into T-cells
- Important for the immune system
Hypothyroidism symptoms
- Reduced hormone levels cause tiredness
- Sufferers often complain of feeling cold
Excitation
When a neurotransmitter such as adrenaline increases the negative charge of the post synaptic neuron. This increases the likelihood that the neuron will fire and pass on the electrical impulse.
Inhibition
When a neurotransmitter such as serotonin increases the negative charge of the postsynaptic neuron. This decreases the likelihood that the neuron will fire and pass on the electrical impulse.
Synaptic transmission
The process by which neighbouring neurons communicate with each other by sending chemical messages across the gap (synapse) which separates them.
Which two systems work together as part of the stress response?
The nervous system and the endocrine system
Limitations of fight or flight
- Evolutionary aspect - fight or flight may not be as useful for understanding modern day stressors
- Gender bias - research based on males. Females can show “tend and befriend” response. Release of oxytocin in females in response to stress
- Ignores the freeze response
Which part of the nervous system is activated when we are faced with stressful or high-arousal situations?
The sympathetic nervous system
Changes in the body when fight or flight response is activated
- Pupils dilate
- Heart rate and blood pressure increase
- Bladder relaxes
- Liver releases glucose
- Adrenaline surges into the bloodstream
What do the physiological changes that occur due to the fight or flight response allow?
They allow the body to access energy reserves and heightened sensory capacity so that it might fight off a threat or run away to safety.
Which part of the nervous system is activated once threat has been resolved?
Parasympathetic
HPA axis
- Becomes especially active when the sympathetic nervous system becomes active
- Works more slowly
- Mainly endocrine in nature
Cortisol
- Stress hormone
- Help to provide that boost of energy when we first encounter a stressor
- Sustained elevated levels of cortisol weaken the immune system
Localisation of function
The idea that certain functions (e.g. language, memory, etc.) have certain locations or areas within the brain
Lobes in the brain (Starting from the front and going round clockwise)
- Frontal lobe
- Parietal lobe
- Occipital lobe
- Temporal lobe
Areas of the brain (starting from the front and going round clockwise)
- Broca’s area
- Motor area
- Somatosensory area
- Visual area
- Wernicke’s area
- Auditory area
Which lobe is the Broca’s area in?
Frontal lobe
Which lobe is the motor area in?
Frontal lobe
Which lobe is the somatosensory area in?
Parietal lobe
Which lobe is the visual area in?
Occipital lobe
Which lobe is the Wernicke’s area in?
Temporal lobe
Which lobe is the auditory area in?
Temporal lobe
Broca’s area
Located in the left hemisphere and is responsible for speech production.
Motor area
Regulates movement
Somatosensory area
Processes sensory information such as touch
Visual area
Receives and processes visual information
Wernicke’s area
Located in the left hemisphere and responsible for language understanding.
Auditory area
Concerned with speech analysis
Evidence from brain scans
FMRI scans show that the Broca’s area is active when people read a poem and the Wernicke’s area is active when they listen to a poem.
Case study evidence
- Phineas Gage
- Metal rod destroyed parts of his frontal lobe and he experienced personality changes
- Supports the idea that the frontal lobe regulates mood
- Case studies cannot be generalised
Evidence from neurosurgery
- Areas of the brain can be destroyed to control/change aspects of behaviour
- 33% success rate in psychosurgery for depression and OCD - suggesting emotions are localised
The concept of plasticity
- The brain is not fixed
- Following injury or surgery the brain can reorganise itself e.g. the left hemisphere can take over functions from the right hemisphere
Counter evidence from Lashley
- Higher cognitive functions such as learning are not localised but distributed over the whole cortex
- Rats with up to 50% of their cortex removed were no slower at learning a maze
Which side of the body does the left hemisphere control?
Right
Which side of the body does the right hemisphere control?
Left
Corpus callosum
- Connects to two brain hemispheres
- Allows the two hemispheres to communicate with each other
Cerebral cortex
- The outer surface of the brain
- Associated with higher level processes e.g. emotion, language and memory
What is the limbic system involved in?
Processing emotion and memory
Lesion studies
Examine the changes in the behaviour and ability of people who have had damage to the brain
Four main principles of plasticity
- Impulses travel along neurons and travel to the next neuron via a synapse
- Neural pathways are created as new information is passed from one neuron to another
- The more these neural pathways are used, the stronger the pathway becomes
- If the pathway is not used regularly, the connection weakens
Who Investigated the effects of split-brain surgery?
Sperry (1968)
Method of Sperry’s experiment
- Participants had already had their corpus callosum severed due to severe epilepsy
- 11 participants (10 men and 1 woman)
- In the visual tests, images were flashed into their left or right visual fields for 1/10 of a second and they were asked to name, describe or draw the objects
- In the tactile test, objects were placed in either their left or right hand behind a screen
Findings of Sperry’s experiment
- Information presented to the right visual field could be described in speech and writing but if the same information was presented to the left visual field, the participant could not remember seeing anything and could not describe it
- Objects placed in the right hand could be described in speech or writing. If the same objects were placed in the left hand, participants guessed and sometimes seemed unaware they were holding anything
Strength of Sperry’s experiment
Controlled and standardised - reliable
Limitations of Sperry’s experiment
- Small sample
- Individual differences
- Lack of ecological validity
Maguire (2000) Evidence for plasticity
- A natural experiment
- Using an MRI scanner, the researchers calculated the amount of grey matter in the brains of London taxi drivers and a set of control patients
- The posterior hippocampi of the taxi drivers were significantly bigger than those in the control group
- Posterior hippocampi volume had a positive correlation with the amount of time they had spent taxi driving
- The structure of the brain can change in response to the demands placed upon it
Strengths of split brain research
- Sperry’s research uses standardised procedures so variables were highly controlled. This means the results are valid and the experiment can be easily replicated
- Tonnessan et al (1993) research suggests there are advantages to hemispheric lateralisation. He found in domestic chickens, lateralisation is associated with an enhanced ability to perform tasks simultaneously which suggests that lateralisation aids brain efficiency in cognitive tasks and therefore is an evolutionary advantage for survival
Weaknesses of split brain research
- The findings of Sperry’s research can’t be generalised as it was only based on 11 patients with epilepsy so results may not apply to a healthy patient
- The differences between the hemispheres have been exaggerated as modern neuroscientists would contend that the brain is much less clear cut than suggested by Sperry’s study. Brain plasticity and recruitment of homologous areas suggests the theory is inaccurate
- Sperry’s research and a few subsequent repeats are the only evidence for the theory of lateralisation limiting the validity of the study
- Recent evidence has challenged the claim that language is restricted to the left hemisphere. Gazzinga (1998) patient case study with the capacity to speak out of the right hemisphere could then speak about information presented to the left or right of the brain despite one sided brain damage. Suggests the theory is too simplistic.
Plasticity
The brain’s ability to change, reorganize, or grow neural networks
Functional recovery
Functional recovery is the transfer of functions from a damaged area of the brain after trauma, to other undamaged areas.
Elbert et al (1985)
- A professional violinist relies on extraordinary finger dexterity in their left hand
- Brain scans of the somatosensory cortex in violinists reveal an unusually large region devoted to the fingers in the left hand (much more than for finger movement in the right hand)
- Suggests the brain adapts by recruiting neurons to help support finger control in the left hand
May (2004)
- Divided a group of 24 non-jugglers into two groups
- 12 participants were to learn how to juggle and the other 12 were used as a control group
- After 3 months all participants in the experimental group could juggle for at least 60 seconds
- Brain scans showed changes in regions specific to visualisation in the temporal lobes
- Total volume of those areas increased by an average of 3% and there was no difference in the brains of the control group
- A brain scan 3 months later (during which time no participants juggled) showed the the structural changes had reversed
- The human brain’s macrostructure can change in direct response to training
Strength of plasticity
- Contributed to the field of neurorehabilitation (practical applications)
- Shows that the brain has the capacity to fix itself
Weakness of plasticity
- The brain’s ability to retire itself can sometimes have maladaptive behavioural consequences e.g. prolonged drug use has been shown to result in poorer cognitive functions as well as increased risk of dementia later in life (medina, 2007)
- 60-80% of amputees have been known to develop phantom limb syndrome (thought to be due to cortical reorganisation in the somatosensory cortex that occurs as a result of limb loss)
- Individual difference - Mathias (2015) meta analysis demonstrated in and educational background are positively correlated with better outcomes after traumatic brain injury
What factors make it easier to recover from brain injury?
Age - the younger you are the easier the recovery but you can recover at any age
Education - The more educated you are, the better the recovery
Recruitment of homologous areas
Other areas of the brain taking over so that specific tasks can still be performed.
Axonal sprouting
Growth of new nerve endings which connect with other undamaged cells to form new neuronal pathways
Reformation of blood vessels
Damaged blood vessels are reformed to ensure the brain functions in affected areas
fMRIs
- Using radio waves and magnetic fields, fMRIs detect changes in the levels of oxygen in the blood
- Areas of the brain that are more active require more oxygenated blood and therefore can be identified buy the fMRI
- Creates a dynamic 3D map of the brain
Strengths of fMRIs
- Good spatial resolution (within 1-2mm) meaning it can detect differences in structure and function in different areas of the brain - provides a clear picture of
- Risk-free, non-invasive and straightforward to use
Weaknesses of fMRIs
- Poor temporal resolution (1-4 seconds delayed) meaning it cannot detect changes in brain activity over time
- High running cost/expensive
- Patients have to sit still for a long time in an enclosed space so it is quite claustrophobic and may not be suitable for children
- Do not provide a direct measure of neural activity. They just measure changes in blood flow
Electroencephalogram (EEG)
- A patient is hooked up to an EEG
- Electrodes are placed on the scalp of the patient and this records brain activity
- Wave patterns are generated
- Different patterns are going to result from different stimuli
- Often used in sleep studies to compare brain activity during the different stages of sleep. Wave patterns are usually different depending on the sleep stage
Synchronised patterns
Recognisable patterns
Desynchronised patterns
No pattern at all
Amplitude
The intensity or size of the activity
Frequency
The speed or quantity of activity
Strengths of EEGs
- High temporal resolution meaning they show changes in brain activity over time well
- Subtle differences across seconds can be recorded and provide valuable information
- Can be used to diagnose Alzheimer’s and detect epilepsy and sleep disorders
- Useful in studies of sleep stages
- Non-invasive
Weaknesses of EEGs
- Poor spatial resolution meaning they do not show brain activity of specific areas, only overall brain wave activity
- Electrical activity is often detected in several regions so it can be difficult to pinpoint the exact region of activity
Event-Related Potential (ERP)
- Electrical activity in the brain generated as a result of stimuli
- EEGs are used to study the wave patterns
- Normal wave patterns can be compared to the patterns that are caused by external stimuli
- Different wave patterns are generated in response to different stimuli
- Use electrodes attached to the scalp
Strengths of ERPs
- Non-invasive
- Enable the determination of how processing is affected by a specific experimental manipulation
- High temporal resolution
Weaknesses of ERPs
- Superficial general regions only
- Lack of standardisation in methodology so difficult to confirm findings
- Background noise and extraneous material must be completely eliminated
Post-mortem examinations
- Used to establish the underlying neurobiology of a particular behaviour
- Researchers may study a person who displays behaviour while they’re alive that suggests possible underlying brain damage
- When the person dies, the researchers can examine their brain to look for abnormalities that might explain that behaviour and which are not found in control individuals
Strengths of post-mortem examinations
- Provides an insight into brain structure
- Generates hypotheses for further study
- Increases medical knowledge
Weaknesses of post-mortem examinations
- Causation - observed deficits maybe linked to trauma or decay rather than the issue being studied
- Ethics - consent of person before death
What is the name of the electrical impulse that moves down the axon to the terminal buttons?
Action potential
Direct effects of adrenaline
- Constricts blood vessels, increasing rate of blood flow, raising blood pressure
- Diverts blood away from the skin, kidneys and digestive system
- Sweating
- Increases blood to the brain and skeletal muscle
- Increased heart rate and breathing
General effects of adrenaline
- Prepares body for fight or flight
- Increase blood supply/oxygen to skeletal muscle for physical action
- Increase oxygen to the brain for rapid response planning
Depolarisation
When detected by receptors in the postsynaptic cell, excitatory neurotransmitters make the electrical charge inside more positive and more likely to fire.
Positively charged sodium ions enter the postsynaptic cell.
Hyperpolarisation
When detected by receptors in the postsynaptic cell, inhibitory neurotransmitters make the electrical charge insides more negative and less likely to fire.
Positively charged potassium ions leave the postsynaptic cell.
Summation
The combined effect of all the excitatory and inhibitory neurotransmitter influences on the postsynaptic neuron. If a threshold is reached then a new action potential will form in the post synaptic cell.
Outline one difference between the EEG and ERPs (2)
EEG is a recording of general brain activity usually linked to stages of sleep whereas ERPs are elicited by specific stimuli presented to the participant.
Outline the role of adrenaline in the fight or flight response (4)
- Adrenaline is released from the adrenal medulla in response to activation of the sympathomedullary pathway
- Adrenaline has a range of effects on the body
- Direct effects of adrenaline such as increased heart rate, diverts blood away from digestive system, increases respiration and sweating
- General effects of adrenaline such as preparing the body for action and increasing oxygen to skeletal muscle for physical action
The actions of the autonomic nervous system
- The sympathetic division responds to perceived threat/ prepares the body for fight or flight
- The other section is the parasympathetic nervous system which restores homeostasis in the body once the threat has passed.
- Sympathetic activity - breathing quickens, mouth dries, heart pounds
- Parasympathetic- breathing slows
Danelli et al (2013) - Supporting evidence for plasticity and functional recovery
- Case study of 14-year-old EB. At the age of two and a half EB had a hemispherectomy of the left side of his brain to remove a tumour.
-This removed the language centres of Broca’s and Wernicke’s areas. - Immediately after surgery EB had lost all language ability (aphasia).
- However, after two years of recovery EB had recovered his language ability. Even without his left hemisphere EB developed normally as he aged asides from some dyslexia like symptoms. - Researchers noted FMRI scans showed the right hemisphere followed a “left-like blueprint” for language.
- This research suggests that the brain can adapt and recover after significant damage, especially early in life, with the right hemisphere taking roles usually performed by the left.
Right
