Topic Tuesday Biopsychology

Split brain patients show unusual behaviour when tested in experiments   Split brain patients show unusual behaviour when tested in experiments. Briefly explain how unusual behaviour in split brain patients could be tested in an experiment. (2) plausible experimental situation/set-up – eg split visual field plausible stimulus – visual, faces, words, auditory, digits, music etc plausible task for patient – verbal or visuospatial response, eg drawing, matching etc

Support: Evaluation of Sperry’s Split Brain Patients Study The method was a quasi experiment using controlled conditions. The use of a T- scope and the displaying of the same visual stimuli to all participants meant that the experiment had high internal validity as all procedures were standardised for each participants. For example, the fast presentation of the visual stimuli meant that the stimuli flashed up very quickly (1/10th of a second) preventing the participant chance to move their eye across to process the image with the other eye. However, although standardised, the procedure is not applicable to real life where a patient can adjust their visual position so information can enter into both hemispheres meaning that the study lacks ecological validity. Furthermore, another criticism of the research is to do with the small sample meaning that the experiment lacks population validity. The sample consisted of 11 patients. It could be argued that this may not be a large enough sample to generalise. Also it may be inappropriate to make generalisations about non- epileptic brain patterns from these patients. The epileptic seizures could have made changes to the brains that could have affected the findings.

Unfortunately, much of the research into lateralisation is flawed because the split-brain procedure is rarely carried out now, meaning patients are difficult to come by. Such studies often include very few participants (Sperry used 11 participants) and often the research takes an idiographic approach meaning that it is difficult to draw general laws of behaviour. Therefore, any conclusions drawn are representative only of those individuals who had a confounding physical disorder that made the procedure necessary. This is problematic as such results cannot be generalised to the wider population

Gazzaniga (1998) suggests that some of the early discoveries from split-brain research have been disconfirmed by more recent discoveries. E.g. split brain research had suggested that the right hemisphere was unable to handle even the most rudimentary language. However, case studies have demonstrated that this was not necessarily the case. One patient (J.W.) developed the capacity to speak out of the right hemisphere, with the result that J.W. can now speak about info presented to the left or to the right brain. This suggests that Language may not be exclusively limited to the left hemisphere. It also supports brain Plasticity as before his surgery he had language dominant left hemisphere so it shows the brain can recover functions. Split brain patients who are initially unable to produce speech in their right hemispheres sometimes develop the ability to do so. Patient J. W., the subject of this report, is such a patient. At the time of his callosotomy, J.W. had a language dominant left hemisphere; his right hemisphere could understand both spoken and written language, but he was unable to speak. Fourteen years after his surgery, we found that J. W. was capable of naming 25% of the stimuli presented to his left visual field (LVF). Now, 1 year later, we find that he can name about 60% of such stimuli. This latedeveloping speech ability appears to be the consequence of long-term neural plasticity. However, the subject's extended verbal responses to LVF stimuli seem to result from a collaboration between the hemispheres and to involve the left hemisphere interpreter.

Area in the brain (a)     A (b)     C (c)     D (d)     E (e)     B

Define plasticity and functional recovery? Brain plasticity refers to the fact that the brain has the ability to change and adapt as a result of learning and experience (1 mark). This includes the ability to adapt, following damage through trauma (2 marks), where functions may be redistributed to other areas of the brain (3 marks) The recovery of abilities and mental processes that have been affected as a result of brain injury or disease.

Lotta’s grandmother suffered a stroke to the left hemisphere, damaging Broca’s area and the motor cortex. (a)Using your knowledge of the functions of Broca’s area and the motor cortex, describe the problems that Lotta’s grandmother is likely to experience. (4) As a consequence of damage to Broca’s area, Lotta’s grandmother is likely to suffer from language/speech problems (Broca’s aphasia). It will affect her language production (but not her understanding). Lotta’s grandmother will only be able to talk in short meaningful sentences which take great effort. Her speech will lacks fluency or she will have difficulty with certain words which help sentences function (e.g. ‘it’ and ‘the’). As consequence of damage to the motor cortex, Lotta’s grandmother is likely to suffer from loss of muscle function/paralysis

Lotta worries that because of her grandmother’s age she will not be able to make any recovery. Using your knowledge of plasticity and functional recovery of the brain after trauma, explain why Lotta might be wrong. (4) Lotta’s grandmother might still be capable of functional reorganisation/plasticity/functional compensation by other undamaged areas. Although she is older her brain might still be able to form new connections (axons and dendrites) between neurons. The fact that Lotta grandmother is a women means that she might recover quicker than a man.Neuronal loss may be compensated for by regeneration (axon sprouting). Denervation supersensitivity to reduce the severity/extent of Lotta’s grandmother’s impairment. Plasticity allows the brain to cope better with ‘indirect’ effects of brain damage resulting from inadequate blood supply following a stroke.

Josie is twelve. Last year she was involved in a serious road accident and suffered head injuries that caused problems with speech and understanding language. Now, a year later, Josie has recovered most of her language abilities. Using your knowledge of plasticity and functional recovery of the brain after trauma, explain Josie’s recovery. (5) When the brain is still maturing recovery from trauma is more likely. Josie is young. Transfer of functions to undamaged areas (‘neural reorganisation’) which can explain her recovery. Growth of new neurons and/or connections to compensate for damaged areas (‘neural regeneration’) which can explain her recovery. Plasticity allows the brain to cope better with ‘indirect’ effects of brain damage eg swelling, haemorrhage following road accident.

Discuss what research has shown about localisation of function in the brain. (8) Some functions are more localised than others eg somatosensory and motor functions are highly localised to particular areas of cortex. Other functions seem more widely distributed eg the language system (though some components may be localised eg speech comprehension). Localisation can involve restricted areas of cortex eg motor control, or broader aspects eg right hemisphere visuo-spatial functions

Discuss Use of research evidence eg Lashley’s classic work on equipotentiality of the cortex; Hubel and Wiesel’s work on distributed functions of the visual system Human clinical case studies of loss of specific abilities after restricted brain damage eg aphasia, amnesia Simpler functions are likely to be more localised in the brain, eg motor control as compared with eg personality, consciousness The brain is so complex that no one part acts independently of the rest, so strict localisation is impossible General commentary on whether localisation or “holistic” approaches are more appropriate Limitations of methods/scanning techniques used to investigate localisation

Essay Plan- The Extent to which brain functions are localised Ao1 Outline- (6 marks = 6 points) Localisation vs holistic theory - define Hemispheres of brain (two) and Cerebral Cortex (subdivided into 4 lobes- frontal, parietal, occipital, temporal) Frontal= motor which controls movement Parietal= somatosensory which represents sensory info Occipital= visual cortex sent information from the eye Temporal= auditory analysing speech- Broca and Wernickes areas A03 Evaluate (potential content) (10 marks) Remember- 3 good elaborative points are better than 5 weaker points Supportive research- Case studies (Phineas Gage/ Clive Wearing) Supportive research- Neurological studies (Peterson et al) Evaluation of research- Case study methods   or lab experiments   Challenging research- Lashey/ Phineas Gage? Challenging theory- Plasticity Application- Mental health disorders/ Memory

Topic Tuesday Biopsychology 2

Biopsychology AS check Lesson 1

Recap: complete the following questions Draw the nervous system Answer the exam question ‘outline the division of the nervous system’ (6) Draw the three different neurons (label the dendrites, cell body, axon) and describe the differences between the sensory and motor neuron Describe the process of synaptic transmission (4 marks) Briefly outline how excitation and inhibition are involved in synaptic transmission (4) Draw a torso. Label 3 glands. Identify two hormones and briefly outline their effect (4)

The major sub-divisions of the human nervous system

Outline the division of the nervous system (6) The nervous system is split into the central nervous system (CNS) and the peripheral nervous system (PNS). The central nervous system is divided into the brain, which contains billions of nerve cells and the spinal cord which links the brain to the peripheral nervous system. The PNS is split into the somatic nervous system (SNS) and the autonomic nervous system (ANS). The somatic nervous system consists of sensory neurons which transmit information from the sensory receptors in the body to the CNS. Motor neurons transmit information from the CNS to voluntary muscles for movement. The ANS works automatically and is not under voluntary control. It is split into the sympathetic nervous system, which is responsible for the fight or flight response and the parasympathetic nervous system which returns our body back to calm after the stress response, otherwise known as rest and digest.

Synaptic Transmission Synaptic transmission begins at the dendrite and an action potential goes across the cell body to the axon. It travels down the axon to the axon terminal. Vesicles in the axon terminal store neurotransmitters and the electrical impulse causes these to release neurotransitters into the synaptic cleft, which is the gap between neurons. These neurotransmitters bind to to the receptors in the post synaptic neuron and. stimulation of postsynaptic receptors by neurotransmitters result in either excitation or inhibition of the postsynaptic membrane. If they are in sufficient quantities, will cause this post synaptic neuron to fire.  

Briefly outline how excitation and inhibition are involved in synaptic transmission (4) Neurotransmitters can be excitatory or inhibitory and many can be both. If a neurotransmitter is excitatory it will be more likely to cause the post synaptic neuron to fire and if it is inhibitory the post synaptic neuron is less likely to fire. When a neuron receives inhibitory and/or excitatory neurotransmitters is will ‘add’ up the inputs together. If there are more excitatory than inhibitory the Post synaptic neuron will fire but if there are more inhibitory messages it will not.

Identify two hormones and briefly outline their effect (4) Adrenaline is released by the adrenal gland (medulla)and causes increase in heart rate, blood pressure and inhibits digestion. Oestrogen is released from the ovaries and helps to regulate the female reproductive cycle

Biological rhythms: chart

Outline one example of a circadian rhythm. (4) Circadian rhythms have a 24 hour periodicity, and include the sleep / waking cycle and body temperature. Candidates are likely to outline the sleep-waking cycle. Besides correctly identifying the rhythm, an outline might include reference to the role of endogenous body clocks and external zeitgebers such as light. However any material relevant to the sleep-waking cycle would be credit-worthy. This section should be marked bearing in mind time constraints.

Outline one or more examples of ultradian rhythms. (4) Candidates need to outline an example of one or more examples of ultradian biological rhythms ie rhythms that have a cycle length of more than one cycle every 24 hours. The most accessible example is the alternation between REM and NREM sleep during the night. For marks in the top band candidates should provide some details of this alternation, such as the number of REM episodes per night, the link with stage 2 NREM, or the distinctive characteristics of each sleep type. Other examples of ultradian rhythms include meal patterns in humans and other animals and variations in locomotor activity in rats. Again, for marks in the top band detail beyond a simple outline is necessary. Description of the stages of sleep without reference to the ultradian rhythm can gain a maximum of 1 mark. Straightforward definitions are not credit-worthy. However, candidates who provide an incorrect definition of an ultradian rhythm but present an appropriate outline may earn marks across the scale.