Biopsychology Flashcards
Discuss localisation of brain function in the brain
A01
The term localisation refers to the principle that specific functions originate in certain regions in the brain. Research has been carried out since the 19th century to determine the functions of these different areas of the brain.
Firstly, the visual cortex, located in the occipital lobe, is responsible for processing visual information. Nerve impulses are transferred form the retina to the visual cortex via the optic nerves. Secondly, the auditory cortex, located in the temporal lobe, is responsible for auditory processes. The process starts at the cochlea which directs sound and then transports the message to the brain stem for basic processing, and then onto the auditory cortex. Thirdly, the motor cortex, located in the frontal lobe, is responsible for co-ordinating movement. Finally the somatosensory cortex in the parietal lobe processes information relating to touch, pressure, pain and temperature etc.
Other important areas of the brain are the language centres, located in the left hemisphere. The Wernicke area is responsible for speech perception, and the Broca area is responsible for speech production. The Wernicke area receives sound impulses and processes its meaning. These messages travel to the Broca’s area where sounds are assembled, then to the motor cortex which sends signals to the speech muscles.
Discuss localisation of brain function in the brain
A03
Some psychologists argue that the idea of localisation fails to take into account individual differences. Herasty (1997) found that women have proportionally larger Broca’s and Wernicke’s areas than men, which can perhaps explain the greater ease of language use amongst women. This however, suggests a level of beta bias in the theory; the differences between men and women are ignored and variations in the pattern of activation and the size of areas observed during various language activities are not considered. Therefore we are unable to generalise research examining localisation of function to both men and women equally, as the different brain structures/sizes suggest that different considerations are required when considering the different sexes.
The claim that functions are localised to certain areas of the brain has been criticised. Lashley proposed the equipotentiality theory, which suggests that the basic motor and sensory functions are localised, but that higher mental functions are not. He claimed that intact areas of the cortex could take over responsibility for specific cognitive functions following brain injury. Critics like Lashley argue that theories of localisation are biologically reductionist in nature and try to reduce very complex human behaviours and cognitive processes to one specific brain region. Such critics suggest that a more thorough understanding of the brain is required to truly understand complex cognitive processes like language. This therefore casts doubts on theories about the localisation of functions, suggesting that functions are not localised to just one region, as other regions can take over specific functions following brain injury.
There area wealth of case studies on patients with damage to Broca’s (e.g. Tan) and Wernickes’s areas that have demonstrated their functions. For example, Broca’s aphasia is an impaired ability to produce language; in most cases, this is caused by brain damage in Broca’s area. Wernicke’s aphasia is an impairment of language perception, demonstrating the important role played by this brain region in the comprehension of language. Case studies provide evidence to support the idea that certain elements of language production and comprehension are localised in the Broca and Wernicke regions.
What is localisation of function?
Localisation of function is the idea that certain functions (e.g. language, memory, etc.) have certain locations within the brain.
Describe the three methods used for investigating the brain
Post-mortem studies look at the physical structure of the brain. The brain is examined physically after a person’s death. Features can be linked with what was known about them whilst alive. Broca found brain damage in the left frontal lobe in a patient who was unable to speak, Broca’s area, responsible for speech production.
An EEG looks at electrical activity. Electrical activity from groups of neurons is recorded as a trace on paper. When the retina is exposed to a flash of light, the EEG trace in the visual cortex changes in response.
A PET scan looks at glucose consumption. More glucose is consumed in areas where the brain is more active. The scanner shows relative activity levels as different colours. Wernicke’s areas ‘light up’ when people listen to speech.
Name and outline the 4 main lobes of the brain
Frontal lobe - a portion of the cerebral cortex lying just behind the forehead; involved in speaking and muscle movements and in making plans and judgements.
Temporal lobe - portion of the cerebral cortex lying roughly above the ears; includes the auditory areas, each receiving information primarily from the opposite ear.
Parietal lobe - portion of the cerebral cortex lying at the top of the head and towards the rear; receives sensory input for touch and body position.
Occipital lobe - portion of the cerebral cortex lying at the back of the head; includes areas that receive information from the visual fields.
Hemispheres
Left hemisphere - The left brain is the logical brain responsible for words, logic, numbers, analysis, lists, linearity and sequence. It controls the right side of the body.
Right hemisphere - The right brain is the creative brain and is responsible for rhythm, spatial awareness, colour, imagination, daydreaming, holistic awareness and dimension. It controls the left side of the body.
Outline the role of the CNS
This is made up of the brain and spinal cord. It receives information from the senses and controls the body’s responses.
Outline the spinal cord
This passes information to and from the brain and connects the nerves to the PNS.
Outline the brain
This co-ordinates the functioning of the body and higher level processes.
Outline the PNS
This consists of the ANS and SNS, it transmits messages to and from the CNS.
Outline the Somatic NS
This system controls voluntary movements and has sensory and motor pathways. It transfers information from receptor cells in the sense organs to the CNS and receives information from the CNS that directs muscles to act.
Outline the Autonomic NS
This system operates involuntary, its pathways are purely motor. It transfers information to and from bodily organs, it has two main divisions the sympathetic NS and the parasympathetic NS.
Outline the Sympathetic NS
This activates internal organs in response to stressful events, it increases heart rate and breathing.
Outline the Parasympathetic NS
This generally maintains, slows down the activity of the body, aim is to conserve energy, it decreases heart rate and breathing.
Explain the structure and function of sensory neurons
Transmit impulses from sensory receptors toward the CNS. They have long dendrites and short axons.
Explain the function of relay neurons
Transmit impulses between sensory and motor neurons.
Explain the function of motor neurons
Transmit impulses away from the CNS to effectors, muscles or glands. They have short dendrites and long axons.
What are dendrites?
Extensions of neurons that receive signals and conduct them towards the cell body.
What are axons?
Axons are extensions of neurons that conduct signals away from the cell body to other cells.
Explain two ways in which neurons are adapted for their function
Myelin sheath - a fatty layer that protects the axon and speeds up electrical transmission
Nodes of Ranvier - gaps between the myelin sheath which also speed up transmission as the impulse jumps between the gaps, if it was continuous it would slow down.
Reflex actions - what happens?
1) receptor detects a stimulus - change in the environment
2) sensory neurone sends signal to relay neurone
3) motor neurone sends signal to effector
4) effector produces a response
Outline the structures and functions involved in synaptic transmission
When the electrical impulses reach the end of the neuron it triggers the release of neurotransmitters from tiny sacs called presynaptic vesicles. These neurotransmitters chemically diffuse across the synapse. The neurotransmitters are taken up by the post-synaptic receptors of the neighbouring neuron. The excitatory and inhibitory influences of the neurotransmitters are summed. If the net effect of the post synaptic neuron is inhibitory, the neuron will be less likely to fire. If the net effect is excitatory, the neuron will be more likely to fire.
What is the endocrine system?
The endocrine system secretes hormones into the bloodstream from glands throughout the body. Hormones travel in the blood stream to specific target organs, where they have an effect.
What are hormones?
A hormone is a chemical substance, produced by a gland and carried in the bloodstream, which alters the activity of specific target organs. An example of this is the release of the hormone adrenaline, which is released by the adrenal glands. One of its target organs is the heart, where it increases the heart rate.
Once a hormone has been used, it is destroyed by the liver.
Like the nervous system, hormones can control the body. The effects are much slower than the nervous system, but they last for longer.
