PAPER 2- TOPIC 2 BIOPSYCHOLOGY ✅ Flashcards
define the nervous system
- specialised network of cells in body, that is our primary internal communication system
- based on electrical and chemical signals
role of nervous system
- collect, process and respond to information in the environment
- communicates with and co-ordinates the different organs and cells
two sections of the nervous system
central nervous system
peripheral nervous system
Describe what makes up the Central Nervous System
•brain
- centre of conscious awareness (makes all decisions)
- controls every process (e.g. thoughts, emotion hunger)
- cerebral cortex wraps around whole brain
•spinal cord - passes messages to and from brain - connects nerves from brain to the peripheral nervous system - responsible for reflex arc (effectively an extension of the brain)
role of central nervous system
controls all complex demands and decisions
define the peripheral nervous system
- connects CNS to organs, limbs and sensory receptors
- transmit messages from the outside world to the CNS
- transmit messages from the CNS to the effector cells
describe the two sections of the peripheral nervous systems
•somatic nervous system -transfers info from receptors to CNS ----> and CNS to effectors ......????? -controls voluntary muscle movement
•autonomic nervous system
- important in homeostasis (vital involuntary processes)
- transmits info from CNS to organs (and from organs to CNS) automatically
- –> allows automatic responses and vital functions to occur
- splits into parasympathetic and sympathetic
describe the two sections of the autonomic nervous system
and examples of what occurs
•sympathetic
- prepares the body for a fight or flight response during stressful events
e. g. ——increases heart and breathing rate
•parasympathetic
- restores body to normal resting state after stressful event
- works as an antagonist to the sympathetic nervous system (opposite)
e. g. ——-slows heart rate, resumes digestion
way to remember sympathetic and parasympathetic
S sympathetic = S cared
P arasympathetic = P revent
define a neuron
an specialised nerve cell that carries neural information around the body through electrical and chemical impulses
describe the route that each neurone takes
sensory- info from stimuli in receptor cells in PNS to the CNS
relay- connect sensory and motor neurons, or between other relay neurons, form part of reflex arc (mostly in brain and spinal cord)
motor- from the CNS to effector cells (muscles and glands)
outline the role of the different structures in a neuron
nucleus- control centre for activity and contains genetic material
cell body- contains information being carried, contains nucleus
axon- carry impulse away from cell body across the neuron
dendrite- carries message from other neurones towards cell body
axon terminal (terminal buttons)- where axons communicate with other neurons across a synapse - releases neurotransmitters into synaptic cleft
myelin sheath- insulates and protects axon, to speed up transmission
nodes of ranvier- small gaps in the myelin sheath that speed up transmission (as impulse must “jump”)
describe the structure of a sensory, relay and motor neuron
sensory: long dendrites . cell body . short axons
relay : short dendrites . cell body (majority of neuron) . short axons . (no myelin sheath)
motor: short dendrites . cell body . long axons
define neurotransmitters
2 features
chemicals which diffuse across synapses to relay impulses to the next neuron
—-> electrical impulses trigger their release from synaptic vesicles
- every NT has its own specific structure and so fits into specific receptor sites like a lock and key
- either have an excitatory effect or inhibitory effect on neighbouring neurons
define a synapse
extremely small gap between neurons that allow them to communicate through chemical impulses
define synaptic transmission
how neurons communicate with other neurons (& rest of body) by sending chemical impulses across a synapse
describe the process of synaptic transmission of neurons
- electrical impulse is converted to a chemical impulse (neurotransmitters)
- neurotransmitters are released from synaptic vesicles in the pre- synaptic terminal , diffuse into the synaptic cleft
- they are absorbed by the specific post synaptic receptor sites in the dendrites of the next neurone
- and converted back to electrical impulse
describe the stages of electrical transmission of neurons
- when a neuron is at a resting state, the cell body is negatively charged
- when the neuron is activated by a stimulus, the cell body becomes positively charged for a split second
- causes action potential
- which causes an electrical impulse to travels down axon towards end of neuron (neuron is fired)
describe the idea of summation
• decides whether post-synaptic neurone fires or not
- post synaptic neurons can receive both excitatory and inhibitory neurotransmitters simultaneously
- these influences are summed and the net effect is what charge the post synaptic neuron will have
• if reaches positive threshold, the action potential is triggered, the cell body is momentarily positively charged, causing an electrical impulse to travel down the neuron’s dendrites
describe the excitatory effect a neurotransmitter can have on a neuron
example
- increases the neuron’s positive charge and makes it more likely to fire
- e.g adrenaline makes the neuron and more positively charged and more likely to fire
describe the inhibitory effect a neurotransmitter can have on a neuron
example
- increases the neuron’s negative charge and makes it less likely to fire
- e.g serotonin makes the more neuron negatively charged and less likely to fire
define localisation of function in the brain
idea that specific areas of the brain are responsible for certain tasks, behaviours or processes
- if a certain part of the brain gets damaged then the associated area and the function of this area will also be affected
what was the historic view of the brain
- holistic theory that all parts of brain were responsible for all thoughts and actions
describe the research that changed the view of the brain as holistic to localised
• Phineas Gage
- metal pole was projected through his eye and through his frontal lobe and out his skull
- survived, but friends said he now was more quick tempered and rude
- his change in personality then led to suggestions that the frontal lobe is associated with mood regulation
• Broca
-responsible for speech production, and damage to this area causes Broca’s aphasia (laborious speech)
• Wernicke
-responsbile for speech comprehension, damage to this area causes Werncike’s aphasia (unmeaningful speech)
describe language centres research
• Broca’s area
- located in frontal lobe, in left hemisphere
- responsible for speech production
- damage to this area causes Broca’s aphasia: slow, laborious, unfluent speech
- case study “Tan” - (he could only say Tan)
• Wernicke’s area
- located in temporal lobe, in left hemisphere
- responsbile for speech comprehension
- damage to this area causes Werncike’s aphasia: fluent but meaningless speech, often add nonsense words
describe the structure of the brain
- cerebrum divided into two hemispheres
- two hemispheres separated by corpus callosum (bundles of nerve fibres that allow communication between the two hemispheres)
- most functions are lateralised (LH controls right side of body, RH controls left side of body)
- 4 lobes
4 lobes and their associated function
•the cortex is the outer layer of both hemisphere and its split into 4 lobes
==frontal lobe (top left of brain)
- decision making and mood regulation
==parietal lobe (top right of brain)
- processing sensory information
==temporal lobe (bottom of brain)
- auditory info
==occipital lobe (back of brain)
- visual info
describe the 4 parts of the cortex
•motor cortex (1) - frontal lobe
- controls voluntary movement in opposite side of body
- damage leads to loss of fine motor skills
•somatosensory cortex (2) - parietal lobe
- processes sensory information and is represented in the brain
- the amount of somatosensory area devoted to a body part denotes its sensitivity
- damage leads to numbness, sometimes paraesthesia (tingling sensations)
•auditory centres (2) - temporal lobe
- analyse speech based information
- damage may lead to hearing loss, damage to wernickes lead to speech comprehension damage.
•visual centres (2) - occipital lobe
- received and processes visual information
- RVF to LH
- LVF to RH
- therefore damage to LH can produce blindness of the RVF in both eyes
define lateralisation of function in the brain
- the idea that the two hemispheres of the brain are functionally different
- some behaviours and processes are controlled by one specific hemisphere
example of lateralisation of function in the bran
- language centres
- Broca’s and Wernicke’s area in the left hemisphere
- RH provides the context and emotion to what is being said (synthesiser)
- LH can produce and comprehend the speech (analyser)
-in RH, controls spatial tasks
Examples of unlateralised functions in the brain
small detail
•motor areas
-contralateral (RH controls movement on left side of body)
•visual centres
- contralateral and ipsilateral
- –> contralateral (left hemisphere receives info from right eye)
- –> ipsilateral (left hemisphere receives small info from the small bit of RVF in the left eye)
describe the contralateral processing of visual information
contralateral (cross-wired) and ipsilateral (same sided)
- each eye receives information from the LVF and RVF
- LVF of both eyes is connected to RH
- left hemisphere receives RVF (from right eye) and bit of RVF (from left eye)
why does the visual processing occur from both hemispheres, contralaterally and ipsilaterally
- helps aids depth perception, though comparing the slightly different perspectives
generally describe split brain research
studies on people who have had severe epilepsy and had their corpus callosum severed to try and control it, to investigate lateralisation of function
- the severing meant the hemisphere could not communicate between one another, allowing researchers to see the function of individual hemispheres
describe method of Sperry’s split brain research
- told 11 P’s, with epilepsy history and cut corpus callosum, to stare at dot in centre of screen
- flashed up an image for a split second on the left and right side, with other eye blindfolded
- asked them to say what they saw
findings of Sperry’s research + conclusion
- if word flashed up on RVF, LH would process it and be able to say it
- if word flashed up on LVF, RH would process it but not be able to say it (and couldn’t communicate it to LH- the language centres) so would say nothing was shown
- however, when showed to LVF, they could draw it if pen is in left hand as motor skills are contralateral
- also, they could select the exact or a similar object, out of sight, using their left hand
e.g. if shown funny pic in LVF, may giggle but say saw nothing
CONCLUSION
- show how certain functions (language) can be lateralalised
- support LH as verbal and RH as ‘silent’ but emotional
define plasticity
the brain’s tendency to change and adapt (functionally and physically) as a result of learning or experience
define synaptic connection
the communication and relay of info of two neurons across a synapse
- creates a network pathway for certain behaviours
define synaptic pruning
synaptic connections that aren’t often used are deleted and those connections frequently used are strengthened
describe plasticity in more detail
- the brains ability to change throughout life, is strongest during infancy
- —> the no. of synaptic connections grow rapidly
- Gopnick said that it peaks at 2-3 years old with 15,000 connections per neuron
- synaptic pruning deletes unused and strengthens used connections
- reduces no. of connections in adults but allows lifelong plasticity (shows new neural connections can be formed)
describe research into plasticity
+++ • london cab drivers (Maguire)
- brain scan found more grey matter in posterior hippocampus than control
- area associated with navigation and spatial skills
- —> suggested because of the ‘Knowledge Test’ they have to take (knowledge of Londons roads)
- also found longer in the job the more structural difference
• medical students (Draganski)
- scanned 3 months before and 3 months after final exam
- found changes in posterior hippocampus in all, must be due to learning
• billingual people (Mechelli)
- found bilinguals have larger parietal cortex than control
define functional recovery
when undamaged areas of brain adapt and compensate for the function of damaged areas.
- damage through trauma or illness
- form of plasticity
define spontaneous recovery
when there is quick recovery shortly after the trauma but this recovery slows down several weeks or months after
- means rehabilitation is required to recover further
describe the brain processes during functional recovery
- brain rewires and reorganises itself by forming new synaptic connections close to damaged area
- secondary neural pathways, not typically used for that function, are ‘unmasked’ and activated to allow function to continue (Doidge)
- –> this process is supported by changes in brain structure
structural changes in brain that support unmasking/activation of secondary neural pathways
- axonal sprouting - new nerve endings grow and connect to other undamaged nerve cells to form new neural pathways around damaged areas
- reformation of blood vessels - blood vessels reform to ensure brain functions on damaged areas
- recruitment of homologous areas - similar areas in opposite hemisphere carry out the function of the damaged area
- denervation supersensitivity - axons that do similar jobs to the damaged area become more aroused to compensate for lost function
ways of studying the brain
- functional magnetic resonance imaging (fMRI)
- event related potentials (ERP)
- electroencephalogram (EEG)
- post mortem examination (PME)
describe functional magnetic resonance imaging
fMRI
- produces 3D images showing which parts of the brain are involved in particular processes/behaviours
- detects radio waves from changing magnetic fields
- allow the measure of change in blood oxygenation that results from brain activity
- can find more active parts of brain as they consume/require more oxygen
- in response, more blood flows to these areas (haemodynamic response)
describe electroencephalogram
EEG
• measures electrical activity in the brain
- —> recording represents brain wave patterns made by millions of neurons, through fixed electrodes on a skull cap
- the scan gives overall account for brain activity during general activities (e.g. sleeping, sitting)
- useful for identifying unusual arrhythmic patterns, and whether they link to neurological abnormalities (e.g. epilepsy, tumours & sleep disorders)
describe event related potentials
ERP
• researchers isolate neural responses of brain to sensory, cognitive or motor events through statical analysis of EEG data
- focus on one event related potential (types of brain waves triggered by individual events)
- using statistics, researchers can identify an average response to what they are investigating (e.g. a stimulus or task being performed)
- use average from hundreds of scans as ERPs are difficult to separate from the background EEG data
describe post mortem examination
PME
•analysing a person’s brain following their death
- can look at tissue level under a microscope
- usually compare brains with rare disorders & unusual cognitive processes to neurotypical brains (can see whether certain disorders are linked to structural abnormalities or damage)
strengths and weaknesses of fMRI
••• strengths
- high spatial resolution (pinpoint localisation down to mm’s)
- doesn’t rely on radiation
- uninvasive
••• weaknesses
- don’t understand what neurons are doing, just blood flow
- poor temporal resolution (5 second time lag)
- very expensive equipment
strengths and weaknesses of EEG
••• strengths
- useful in diagnosing epilepsy (random bursts of electrical activity can be detected) and sleeping conditions
- very high temporal resolution (can measure changes in real time-1 millisecond)
••• weaknesses
- low spatial resolution (hard to determine where each electrical activity in different but adjacent locations, originated)
- generalised information received (receive info from thousands of neurons)
strengths and weaknesses of ERP
••• strengths
- much more specific data on individual neural processes than the raw EEG data
- high temporal resolution, as come from EEG
useful for measuring cognitive function during specific tasks (e.g. helped identify aspects of WWM)
••• weaknesses
- not always possible to remove all extraneous variables and “background noise”, so data may not be pure and valid
- lack of standardisation- different researchers use different methodology to generate event related potentials
strengths and weaknesses of PME
••• strengths
- very high spatial resolution
- historically led to breakthroughs for Broca and Wernicke, & HM
- useful for examining brains with rare disorders and seeing if they correlate to structural abnormalities or damage
••• weaknesses
- very invasive so rely on donated brains
- can’t link certain areas to behaviours or mental processes (no temporal resolution)
- can’t tell if observed damage is be linked to disorders or in fact trauma/decay
