Biopsychology Flashcards
Evaluations for final topic not included. (41 cards)
What are the key features of the nervous system?
A specialised network of cells which transport electrical and chemical signals.
1) Collect, process and respond to information in the environment.
2) Co-ordinate working of different organs and cells.
Describe the CNS
Central Nervous System (CNS)
- Made up of brain and spinal cord.
The brain is centre of conscious awareness, a highly developed cerebral cortex is what separates humans from other primates and has two hemispheres.
The spinal cord is an extension of the brain and responsible for reflex action. Passes messages to and from the brain and connects nerves to PNS.
Describe the PNS
Peripheral Nervous System (PNS)
- Transmits messages via millions of neurons to and from the nervous system.
It divides into:
1) Autonomic Nervous System
- Governs vital (automatic) function of the body.
- Divides into Sympathetic and Parasympathetic.
2) Somatic Nervous System
- Receives information from sensory receptors to govern muscle movement.
Describe the endocrine system.
Works alongside the nervous system to control vital functions using hormones. Works slower than electrical signals (seconds instead of milliseconds.
Glands:
- Organs which produce hormones. Pituitary gland is the “master gland” as it controls all other endocrine glands.
Hormones:
- Secreted in the bloodstream and affect any cell that has a receptor for it (lock and key model). E.g thyroxine affects cells in the heart.
How do endocrine system and ANS work together?
Example: fight or flight response
- Stressor perceived by hypothalamus which activates pituitary.
- SNS (Sympathetic) is now aroused.
- Adrenaline released to deliver the arousal state which causes symptoms such as increased heart and breathing rate, plus dilated pupils.
- Immediate and automatic response when threat is perceived.
- PNS (Parasympathetic = the rest system) takes over once threat has passed.
What are neurons and the 3 types of neuron?
Cells which transmit signals chemically and electrically to provide nervous system with communication. 100 billion neurons 80% located in the brain.
1) Sensory
- Carry messages from PNS to CNS. Long dendrites and short axons. Located in PNS.
2) Relay
- Connect between neurons (e.g sensory to motor). Have short dendrites and short axons. 97% located in brain and visual system.
3) Motor
- Connect CNS to muscles and glands. Short dendrites and long axons. Cell bodies in CNS but long axons in PNS.
What is the structure of a neuron?
Cell body:
- Includes nucleus and genetic material.
Dendrites:
- Branch like structure which protrudes from the cell body. Carry nerve impulses from neighbouring cell to neuron.
Axon:
- Carries the electrical signal away from cell body. Covered in fatty myelin sheath for protection. Gaps called “nodes of Ranvier” speed up transmission impulse.
Terminal buttons:
- End of axon communicates with the next neuron across the synapse.
What happens when a neuron is activated by a stimulus?
The inside of the cell becomes positively charged for a split second, causing an action potential to occur which creates an electrical impulse that moves down the axon.
Describe the basic prosses of synaptic transmission.
Signals within the neuron are always electrical, between neurons they are always chemical.
When electrical impulse is at end of neuron (presynaptic terminal) it triggers the release of neurotransmitter from synaptic vesicles.
Neurotransmitter crosses gap and is taken up by postsynaptic receptor site meaning the signal only ever goes one way.
What are neurotransmitters?
Chemicals that diffuse across the synapse and each has its own specific molecular structure it fits into on the receptor site, lock and key model.
Examples:
- Serotonin affects mood and social behaviour.
- Acetylcholine causes muscles to contract.
What is inhibition and exhibition?
Neurotransmitters create either an inhibitory or exhibitory effect.
Inhibition:
- Increases the negative charge of the postsynaptic neuron, making it less likely the neuron will fire.
- e.g. Serotonin
Exhibition:
- Increases the positive charge of the postsynaptic neuron, making it more more likely the neuron will fire.
- e.g. Adrenaline.
Impulses are added up and must reach a certain threshold for an action potential to occur. Either the add up is exhibitory or inhibitory.
Outline the localisation of function in the brain.
Holistic theory (all parts of brain involved in thought and action) replaced by localisation theory in the 19th century.
The brain is divided into two hemispheres and lateralised (certain functions mainly controlled by one side e.g left controls right side of body).
Outer layer of the brain is the cerebral cortex, its 3mm thick and humans is far more developed than all others. Its also called grey matter.
Cerebral cortex of both hemispheres is divided into four lobes:
1) Frontal lobe = motor area
2) Parietal lobe = Somatosensory area
3) Occipital lobe = visual area
4) Temporal lobe = Auditory area
Describe the language centres of the brain.
Broca’s area:
- Speech production, in frontal lobe.
- Broca’s aphasia causes slow, laborious speech which lacks fluency.
Wernicke’s area:
- Language understanding, in temporal lobe.
- Wernicke’s aphasia produce language with ease but is mostly nonsense words with no meaning.
Give two positive evaluations of localisation of function in the brain.
1) Brain scan evidence:
Peterson et al.
- Showed Wernicke’s area was active during a listening task, and Broca’s area active during a reading task.
Tulving et al.
- Showed semantic and episodic memories are located in different parts of the frontal cortex.
2) Supported by neurosurgery:
Dougherty et al.
- Neurosurgery is used to treat mental disorders.
- Studied 44 people with OCD who had a cingulotomy. At follow-up, 30% met he criteria for successful response and 14% for partial response. Success of such procedures suggest behaviours associated with serious mental disorders may be localised.
Give two negative evaluation of localisation of function in the brain.
1) Language localisation model questioned:
Dick and Tremblay
- Very few researchers still believed language is restricted to B and W areas. Advanced techniques also reveal areas in right hemisphere and the thalamus. Suggests language may be organised more holistically.
2) Case study evidence:
- Yes there is Phineas Cage and patient KM, but it is hard to make generalisations based on single individuals.
Outline hemispheric lateralisation
The brain is lateralised (two hemispheres) with some functions being localised.
Localised and lateralised:
- Some functions are both localised and lateralised.
Contralateral:
- One side of brain controls function on opposite side of body.
Contralateral and ipsilateral:
- Left visual field (LVF) of both eyes is connected to RH and LH, same with the RVF.
- Same arrangement for auditory functions.
Describe a procedure and findings into split-brain research.
Sperry
Procedure:
- Corpus callosum can be severe (separates the Hs) for those with sever epilepsy.
- 11 split-brain participants were studied. Shown image or word projected to RVF (LH) or LFV (RH). Presenting image to one hemisphere only meant information could not be shared across the two.
Findings:
- Object shown to RVF could be described (language is LH).
- Object shown to LVF could not be described or named, but participants could select a matching or closely associated object.
- Demonstrates how certain functions are lateralised.
Give one positive and negative evaluation of hemispheric lateralisation.
1) Evidence of lateralised brain function in “normal” brains.
- PET scans show when “normal” participants attend to general image elements, RH is more active. With focus of finer detail, LH is more active. Suggests lateralisation is a feature of “normal” brain.
2) Idea of analyser versus synthesiser brain may be wrong.
Nielsen et al.
- Research suggests people do not have a dominant side. Analysis of 1000 brain scans, showed lateralisation but not dominance.
- Idea of left or right brain people is wrong.
Give one positive and negative evaluation of split brain research.
1) Support from more recent split-brain studies:
Luck et al.
- Demonstrated split-brain participants twice as fast at identifying the odd one out of similar objects. In neurotypical brain, LH’s superior processing abilities watered down by RH. Supports Sperry’s findings of left and right brain having distinct functions and abilities.
2) Causal relationships hard to establish:
- Sperry’s research compared split brains against neurotypicals. But none of the controls had epilepsy. Was the difference due to split-brain or epilepsy?
Outline plasticity
The brain is “plastic” with synaptic connection form and are pruned.
- Growth of synaptic connections peak at 2-3 years of age, at around 15,000.
- Rarely used connections are deleted, frequently used ones are strengthened.
- Neural connections can be formed at any time during your life (learning).
Which two studies support plasticity?
1) Taxi driver study:
Maguire et al.
- London cabbies had more matter in the posterior hippocampus than control group. This part of the brain is linked to development of spatial and navigational skills, those who had been in the job longest had a more developed PH.
2) Images of medical students:
Draganski et al.
- Images three months before and after finals. Physical development was visible in areas linked with learning.
Give one strength and one limitation of plasticity.
1) Plasticity may not decline sharply with age:
Ladina Bezzola et al.
- 40 hours of golf training produced changes in the neural representations in participants aged 40-60. Using fMRI, motor cortex activity in the novice golfers was reduced compared to a control group. Suggests greater efficiency after training. Neural plasticity can continue throughout life.
2) Plasticity has possible negative behavioural consequences.
Medina et al.
- Brain’s adaption to prolonged drug abuse led to poorer cognitive function later on in life.
- 60-80% of amputees have phantom limb syndrome.
- Brains ability to adapt is not always beneficial and my lead to physiological and psychological problems.
NOTE
2) Is not really a negative evaluation of research, just a downside of plasticity. The evaluation DOES NOT reduce validity.
Outline functional recovery of the brain after trauma.
Following trauma, unaffected areas of the brain take over “lost functions”.
The brain “rewires” itself by forming new synaptic connections. Secondary neural pathways (like a backup power generator) carry out “lost” functions.
Structural changes in the brain occur:
1) Axonal sprouting:
Nerve ending growth connects with undamaged areas to form new “pathways”.
2) Denervation super-sensitivity:
- Axons that do a similar job are put on higher levels of arousal to compensate for ones that are lost.
3) Recruitment of homologous area:
- Opposite side of brain takes over different tasks.
Give one positive and one negative evaluation of functional recovery of the brain after trauma.
1) Real-world application:
- Understanding plasticity has led to neuro-habilitation. Understanding axonal growth encourages new therapies.
2) Neural plasticity may be related to cognitive reserve:
Schneider et al.
- Compared how long patients spent in education (indicated cognitive reserve) and chances of disability free recovery. 40% of patients with 16 plus years in education had DFR, compared to 10% who had less than 12 years. Suggests that cognitive reserve is a crucial factor in determining how well brain recovers.
