Biopsychology Division of the Nervous System (A01) - Nervous System - Central Nervous System - Peripheral Nervous System (Somatic and Autonomic within) Nervous System (A01) - The Nervous system is a specialised network of cells and our primary communication system - Has two main functions 1: Collect, Process and respond to information from the environment 2: Co-ordinate the working of different organs and cells in the body - Divided into central nervous system and peripheral nervous system Central Nervous System (A01) - Made up of the Brain and Spinal chord - Brain is the centre of all conscious thought - Spinal cord responsible for reflex actions and passes message to and from the brain and connects nerves to the PNS Peripheral Nervous System(A01) - Transmits messages via millions of neurons to and from the nervous system - Divided into the Somatic and autonomic nervous system - Somatic system controls muscle movement and receives information from sensory receptors - Autonomic system governs vital functions in the body such as breathing, we have no control over this system it regulates itself - The ANS exerts its effects by direct neural stimulation of the body organs and stimulating the endocrine glands (release hormones to secrete Hormones) - Autonomic system broken into sympathetic and parasympathetic nervous system which control the fight or flight response - Sympathetic= Heighted sense of arousal - Parasympathetic= When relaxed brings things back to normal Voluntary and Involuntary systems - Actions that you do or do not do, as you wish are controlled by the voluntary system (somatic nervous system) Processes over which we have no control are controlled by the involuntary system (autonomic nervous system) Structure and Functions of Neurones (Sensory, Relay and Motor) (A01) Structure Cell Body Axon Function Contains the Nucleus Long fibre that transmits nerve impulses over long distance, passes messages away from the cell body to other neurons, muscles or glands Myelin Sheath Layer of fat acts as insulting layer around the axon. Means impulses carried much quicker. Produced by Schwann Cells Synaptic Found at end of the axon contains mitochondria and synaptic vesicles Terminals containing transmitter substances Dendrite Large SA to connect with other neurones. In motor neurone, they transmit nerve impulses to the cell body (receives messages from other cells) Synapse Gap between 2 neurones. Passes information across 1 neurone to another Node of Narrow gap in the myelin sheath. Action potentials jump between them Ranvier increasing speed of nervous transmission - Motor Neuron=Connects the CNS and effectors such as muscles and glands - Sensory Neuron= Carry messages to the PNS to the CNS - Relay Neuron= Connect the sensory neurons to the motor and other neurones The Synapse (A01) Neurotransmitters (only travel in one direction) (Can be excitatory or inhibitory) - The synaptic gap between neutrons is bridged by chemicals - These chemicals which are passed from one neutron to another are known as neurotransmitters - They either excite or inhibit the next nerve cell Synaptic Transmission - 1.When an action potential reaches the synaptic knob - 2.Synaptic vesicles containing neurotransmitter move to the presynaptic membranes - 3.Release the neurotransmitter into the synaptic cleft. - 4. The neurotransmitter diffuses across the synaptic cleft and binds at receptor sites on the postsynaptic membrane. - 5.This trigger an action potential in the next neurone All of nothing response - For a nerve impulse to be triggered in the nest neurone (assuming it is an excitatory synapse), enough neurotransmitter needs to be released - If insufficient neurotransmitter is released because the stimulus is too small and the threshold (level required) is not exceeded, the next neurone will not fire - However, if sufficient neurotransmitter is released and the threshold is exceeded, because the stimulus is sufficiently large, the next neurone will fire - The neurone will either fire or it won’t, this is the all of nothing response. - If it frequently fires then it is a strong stimulus - If it doesn’t fire frequently it is a weak stimulus Excitatory Synapses - Make the next nerve more likely to fire. Acetylcholine is an example of an excitatory neurotransmitter Inhibitory synapses - Make the next nerve cell less likely to fire. GABA is an example of an inhibitory neurotransmitter. Neurotransmitters (don’t need to know specfici neurotransmitters) Acetylcholine (excitatory as nerve/muscle boundary) - Found at end of motor neurone at the neuromuscular junction-where the motor neurone connects with the muscle - Involved in movement when an impulse is transmitted from the brain to the muscles. Dopamine - L Dopa is a drug given to suffered of Parkinson's to build up dopamine in the brain as its involved in movement, learning memory and arousal - Many drugs increase dopamine levels (LSD,Mushrooms) - Certain tranquillisers block dopamine receptors. Noradrenalin (neurotransmitter and hormone) - Involved in certain moods, involved in arousal Neurotransmitter of the ANS Cannabis and cocaine appear to increase noradrenaline levels in the Brian Alcohol and depressants decrees levels Serotonin (inhibitory transmitter) - Possible link with low levels of serotonin and depression - Hallucinogenic drugs appear to be picked up by serotonin receptors - Has a role in emotional arousal and sleep The Endocrine system (Also known as the hormonal system) (A01) - Made up of several glands that secrete hormones into the bloodstream - Glands= group of cells that are specialised to secrete a useful substance such as a hormone - Works alongside the nervous system to control vital functions in the body - Hormone= chemical messengers - Hormones are secreted when a gland is stimulated - Hormones trigger a response in the target cells - Stimulus -> Receptor -> Hormone -> Effectors -> Response - Hormones travel through the bloodstream and affect different organs, provides another way of communication for the nervous system. Hypothalamus - Controls the pituitary gland and the whole endocrine system Glands Pituitary gland - Located deep in the brain - Some released hormones regulate and stimulate other glands to secrete hormones - Controlled by the hypothalamus - Interaction between endocrine system and CNS happens in the hypothalamus - The hypothalamus controls the whole endocrine system Thyroid gland - Releases hormones that affect general metabolism, energy levels, growth - Produce hormones such as the thyroxine Adrenal Gland - Located immediately above the kidneys and secrete several hormones - Secretes adrenaline and responsible for the fight or flight response Pineal Gland - Responsible - to produce melatonin, plays role in controlling sleep patterns Thymus Gland - Regulates the immune system Pancreas - Releases hormones such as insulin and glucagon, which regulate blood sugar level Gonads (Ovaries and Testes) - Produce sex hormones (testosterone and oestrogen) - Testes secretes testosterone estrogen secrets estrogen Fight or Flight - Initial shock response -Hypothalamus triggers activity in the sympathetic branch of the autonomic nervous system - Stimulates the adrenal medulla within the adrenal glands which relates adrenaline and noradrenaline into the blood stream - These hormones affect the body in several ways Activation of fight or flight (Sympathetic nervous system) - Blood pressure and heart rate increase to get blood to muscles where it’s needed - Salivation decrease as digestive system isn't needed - Digestion stops so blood can go to needed place - Muscles become tenser so body is physically responsible - Breathing rate increase so more oxygen to go to muscles - Pupil size increase (Pupils Dilate) so more light can enter for clear vision - Increased breakdown of glycogen to increases glucose production (anaerobic +aerobic respiration to get from glycogen store) - Release of bladder to lighten the load so run quicker - Increased activity of sweat glands so more sweat to cool the body After fight or flight has ended the parasympathetic nervous system occurs and reverses all the effects (e.g. salivation and digestion occur) Fight or Flight measurements - Use Galvanic Skin Response(GSR) which measures the amount of sweat on the skin - Pulse meters - Blood pressure monitors - Heart rate Monitors These are all used in polygraphs (lie detector) but they are not always reliable as it is easy to beat a polygraph question Adrenaline Adrenal Glands - The adrenal gland play an important role in the psychological response of stress and fear - The adrenal medulla (inner part of the adrenal gland) is controlled directly by the sympathetic branch of the autonomic nervous system which releases adrenaline - The adrenal medulla produces both adrenaline and noradrenaline - These reactions add up to a massive and general mobilisation of bodily resources which can be achieved in a matter of seconds Anxiety, emotional tension and other mental stresses cause the hypothalamus in the brain to act upon the pituitary gland. - This releases a substance which causes the adrenal cortex (outer part of the adrenal gland) to bring about which increase blood pressure. Localisation of Function (A01) - Localisation of Function=Different parts of the brain perform different tasks and are involved with different parts of the body - Lobes of the Brain - Hemispheres of the brain - The brain is made up of the brain stem, limbic system and the cerebrum Lobes of the brain - Frontal lobe= motor area here, involved in motor processing and voluntary movement and higher thought processes such as abstract reasoning • Damage can cause impaired movement - Parietal Lobe= Somatosensory area here, deals with sensory input from skin e.g temperature, touch, pain and movement - Temporal Lobe= Has auditory area here, concerned with processing auditory information, and language Wernickes area here • Damage can cause hearing loss - Occipital Lobe= Visual are here, mainly concerned with processing visual information • Damage can cause blindness Hemispheres of the brain - The brain is split into the left and right hemisphere - They are connected by the corpus callosum - Information from the right visual field (right half of what we see) goes to the visual cortex in the left hemisphere (vice versa) - Hemispheric lateralisation of function=Each hemisphere is responsible for functions - Information passes through the corpus callosum to the side that deals with it Right Hemisphere - Associated with the left side of the body - If you are left handed this is controlled by the right side of the brain - Concerned with things like spatial comprehension, emotions and face recognition Left Hemisphere - Broca and Wernickes area are only found in the left hemisphere - It handles most of the language functions - Generally responsible for logic, analysis and problem solving Broca And Wernickes Area - Word meanings are stored in the Wernickes area(temporal lobe) - This activates the Brocas (frontal lobe) area which is responsible for speech production Damage to languages area Brocas Area - Prevents a person from producing speech - Person can still understand language - Words are not properly formed - Speech slow and slurred Wernickes Area - Loss of ability to understand language - Person speaks clearly buy words pit together make no sense Case Study= Carlson (Wada Test) and Phineas Gage (AO1+ A03) Phineas Gage - Iron bar shot through frontal part of brain, survived with no obvious handicap - Main effect=became less inhibited then before, swearing and stripping in public - Suggested that damage to parts of the brain can affect personality - Conclusion= Control of personality located in certain part of the brain Evaluation= Done to one person, as damage to another may results in different effects Carlson - Patient about to undergo surgery in speech area - Receives short acting anaesthetic in one carotid artery - Anaesthetises one cerebral hemisphere - When worn off procedure repeated with other half Results= Left hemisphere is dominant over 95% of right handed people, who lost ability to speak when left side is anaesthetised If right hemisphere is anesthetised patient talks and can hold conversation - 70% of left handed people also have left side dominance Conclusion= Supports localisation of function as it shows language is localized in the left Evaluation of Localisation of function(A03) Strength - Language area clearly seen on brains left side, using scanning techniques, shown by Carlson and Peterson et al, provides evidence that language is strongly localised Limitation - Evidence to suggest that brain shows plasticity, contradicts that parts of the brain has a function and when damaged is lost forever - Found damage in different parts of the brain may produce same disability. If localisation of function was correct only one disability should happen. - (Lashley)looked into effects of learning produced by destroying amounts of cortical tissue in rats, deficits related to amount of tissue destroyed not site of damage, suggest certain functions are related to amount of tissue no site of damage, Split Brain (A01) - - A split brain is when the corpus callouses, which connects the left and right hemisphere of the brain has been severed When a split brain occurs, an operation called commisurotomy is done to prevent the spread of epileptic seizures occurring from one hemisphere of the brain to the other. People with split brain sometimes feel like they are two people in the body of one due to the different hemispheres operating separately from one another. Even though the two hemispheres of the brain are split, some neural pathways are still connecting them and eventually the left hemisphere will be dominant over the right hemisphere. Case Study= Sperry and Turk et Al (A01+A03) Sperry - Patients had a model of a number placed in their left hand whilst they were sitting behind a screen where they wouldn't see the number - They would indicate the number by holding up their fingers. - When the patient was asked what the number was they would get the answer wrong. This was because the information from the left hand was going towards the right hemisphere and the language centres is in the left hemisphere and the right hemisphere cannot communicate with the left hemisphere, thus the left hemisphere will try and guess the answer. Sperry 2nd study - In another experiment patients were shown colours. As they could see the colour with both eyes a method had to be created in order to prevent this. - Sperry used a divided field, which was where in normal vision information travels from the left side of each eye to the left hemisphere and the right side of each eye to the right hemisphere Results = Found that if people with split brains looked straight ahead a stimulus presented on the right would only be registered by the left side of each eye and therefore the information would only be sent to the left side, and vice versa for the right side. Conclusion- This also supports the lateralisation of function because its shows that the left side is better with visual tasks. Turk Et al - Looked into face processing after split brain surgery. - They tested a 48-year-old who had a commisurotomy for epilepsy 23 years ago - The stimuli were morphed faces. One of the faces was the participants face and the others faces of researchers who he worked with for many years. - The divided field was used to present the face stimulus to one of the hemisphere - He was told to press the button if the face was his and in another trial, press the button if it was someone else face Results= Clear bias towards identifying someone who was familiar in the right hemisphere and bias in identifying himself in the left hemisphere. Conclusion= Right hemisphere is better at face professing but the left hemisphere has a role in self recognition. However, they pointed out that self-recognition requires memories and belief and self-concept therefore they believed the left hemisphere might have had a primary role in self recognition. Support=This supports lateralisation of function because it shows how the left and right hemisphere have different roles and functions. Evaluation of study= Done on one man. This therefore means we cannot trust the results as much because many split-brain patients have different severities. Evaluation of Split Brain (A03) Strengths - Split brain research has shown lateralisation of function in each hemisphere, language in the left hemisphere and right better at identifying faces and carrying out visuo-spatial tasks Limitations - Cannot be in that functionality within the two hemispheres of the brain before the - - - split-brain surgery was normal, therefore means that we cannot determine whether there is a cause and effect Sample size of split brain patients are very small, due to split brain operations used as a last option to reduce the effects of the epilepsy, many studies done only around 10 to 15 patients have been used, thus meaning the results might not be generalizable to the whole population and the results from their studies may lack reliability. Patients used in the studies were different age, gender and handedness when they developed epilepsy and when they had their split-brain research, therefore means we cannot determine if there are other factors such as age and gender which will affect them. Split brain operations varying from different surgeons and different cases, in some more neural pathways were cut while in some not as many were cut. This therefore means th at the degree of communication between the hemisphere varies differently from everyone and therefore means that the research we carry out might have to be different for each patient as each of them have a different severity of the condition. Plasticity and functional recovery of the brain after trauma - Localisation of function so if one part of the brain becomes damaged this means the function associated with it will be disrupted. - Plasticity is the idea that the brain can change and adapt because of its different experiences. - Adaption of the brain following trauma - Plasticity suggest that if a certain part of the brain is damaged, it is possible for another part of the brain to take over its function. - In the first year of life the human brain has more neurons and synapses then it will have as a mature adult brain - Spontaneous recovery Endogenous Pacemakers and exogenous zeitgebers - Endogenous pacemakers are known as internal body clocks and regulate biological rhythms such as waking and sleeping - SCN is a primary endogenous pacemaker, suprachiasmatic nucleus (SCN) are small bundles of nerve cells in the hypothalamus which helps maintain circadian rhythms, it is regulated by light from the environment - Pineal gland and melatonin are endogenous mechanisms, the SN passes info of the day length to the pineal gland which increases production of melatonin during the night, melatonin is a hormone that causes sleep and is inhibited when people are awake, Exogenous zeitgebers - Environmental cues which help to regulate the endogenous pacemakers are known as exogenous zeitgebers, they are important in maintaining the circadian rhythms so that a person is synchronised with their environment - Light and season are key exogenous zeitgebers, light is used to reset the bodies main endogenous pacemakers, when you adjust to a different time zone following travel this is known as entrainment Case Study Campbell and Murphy woke 15 P’s at various time and shone a light on the back of their knees- producing deviation in he sleep/wake cycle of up to 3 hours, they found light was a powerful exogenous zeitgeber detected by skin receptors and does not rely on the eyes to influence SCN - This therefore shows that W
