Biopsych Evaluation Flashcards
The fight or flight response evaluation
The tend or befriend response
Taylor et al suggests that for females behavioural responses to stress are more characterised by a pattern of tend and befriend then fight or flight. This involves protecting themselves and their young through nurturing behaviour (tending) and may form protective alliances with other women (befriending). Women may have a completely different system for coping with stress because fleeing too readily at any sign of danger may put the females offspring at risk. Research has shown that there may be a physiological response to stress that inhibits flight – the release of the hormone oxytocin. This increases relaxation and decreases the stress response characteristic of the F or F response.
Another limitation of the fight or flight response is that it may have negative consequences. Although it may be adapted for a stress response that requires energetic behavioural responses, the stresses of modern life rarely require such levels of physical activity. The problem for modern humans arises when the stress response is repeatedly activated. For example, the increased blood pressure that is characteristic of SNS activation can lead to physical damage and blood vessels and eventually to heart disease.
Gray argues that the first phase of reaction to a threat is not to fight or flee but to avoid confrontation. He suggests that prior to responding with attacking or running away most animals typically display the freeze response. This initial freeze response is essentially a stop look and listen response where the animal is hyper vigilant and alert to the slightest sign of danger. This matters because fight or flight may not tell the whole story, and may be best called the fight, flight or freeze response.
Localisation of function evaluation
Challenges to localisation – Equipotentiality. Not all researchers agreed with the view that cognitive functions are localised in the brain. And influential conflicting view is the Equipotentiality theory by Lashley. Supporters of this very believe that motor and sensory functions were localised but that higher mental functions were not. Lashley claimed that intact areas of the cortex could take over responsibility for specific cognitive functions following injury to the area normally responsible for this function. Therefore according to this view the affects of damage to the brain will be determined by the extent rather than the location. This is been supported by some case studies.
There is evidence of the different functions of Broca’s and Wernicke’s areas in language production and understanding comes from the discovery that damage to these different areas results in different types of aphasia. Expressive aphasia (broca’s aphasia) is an impaired ability to produce language. In most cases this is caused by damage in the Broca’s area. Receptive aphasia (Wernicke’s aphasia) is an impaired ability to understand language and to extract meaning from spoken or written words, but they can still speak even though it makes little sense. These two different forms of aphasia demonstrate the different areas of the brain are responsible for different functions – production of language and comprehension of language.
Another limitation of localisation of function is that there are individual differences in language areas. The pattern of activation observed in response to various language activities can vary from individual to individual. For example, in a study of silent reading, Bavelier et al. found A large variability in individual patterns of activation across different individuals. Other studies have found significant gender differences in the size of the brain areas associated with language. For example, Harasty et al, found that women have proportionately larger Broca’s and Wernicke’s areas then men, the result of women is greater use of language.
Lateralisation and split brain research evaluation
One limitation of using split brain research is that the number of patients who have had this procedure are rarely encountered in sufficient numbers to be useful for research. Andrewes argues that many studies are presented with as few as 3 ppts or even just one single ppt. Therefore, he claims, conclusions have been drawn from individuals who either have a confounding physical disorder that made the split brain procedure necessary or have had a less complete sectioning of the two hemispheres then was originally believed.
There are advantages of hemispheric lateralisation. It is generally assume that the main advantage is that it increases normal processing capacity. As by only using one hemisphere to engage in a particular task it would leave the other hemisphere free to engage in another function. However, despite this assumption very little empirical evidence has been provided to show that lateralisation confers any advantage to the functioning of the brain. Rogers et al found that in a domestic chicken, brain lateralisation is associated with an enhanced ability to perform two tasks simultaneously – finding food and being vigilant for predators. This finding does provide some evidence that brain lateralisation enhances brain efficiency.
There are a number of advantages and disadvantages associated with hemispheric lateralisation. For example, architects and mathematically gifted people tend to have superior right hemispheric skills better but they are also more likely to be left-handed and to suffer at higher rates of allergies and problems with the immune system. For example, Morfit and Weekes found support to this suggestion, as they found that left-handers had a high incidence of immune disorders in their immediate family then did right-handers.
Plasticity and functional recovery of the brain evaluation
PLASTICITY
There is research support from animal studies of the brains ability to change as a result of experience. Kempermann et al investigated whether any enriched environment could alter the number of neurons in the brain. They found evidence of an increased number of new neurons in the brain is of rats housing complex environments compare to rats housed in Laboratory cages. In particular, the rats housed in the complex environment showed an increase in neurons in the hippocampus, a part of the brain associated with the formation of new memories.
There is also research support from human studies. Maguire et al (2000) studied London taxi drivers to discover whether changes in the brain could be detected as a result of their extensive experience of spatial navigation. Using an MRI scanner The researchers calculated the amount of grey matter in the brains of taxidrivers and a set of control participants. The posterior hippocampi if taxidrivers were significantly larger then those of the control participants. And the volume of their posterior hippocampi was positively correlated with the amount of time they had spent as a taxi driver.
FUNCTIONAL RECOVERY
There is also research support from animal studies for functional recovery after trauma. Tajiri et al (2013) provided evidence for this. They randomly assigned rats with traumatic brain injury to one of two groups. One group received a transplant of stem cells into the region of the brain affected by traumatic injury. The control group received a solution infuse into the brain containing no stem cells. Three months after the brain injury, the brains of the stem cell rats showed a clear development of neuron like cells in the injury area. This was accompanied by a solid stream of stem cells migrating to the brains site of injury.
It is a commonly accepted view that functional recovery reduces with age. However studies have suggested that even abilities commonly thought to be fixed in childhood can still be modified in adults with intense retraining. Despite these indications of adult plasticity, Elbert et al conclude that the capacity for neural reorganisation is much greater in children than adults, as demonstrated by the extended practice that adults require in order to produce changes.
Schneider et al found a link between educational attainment and functional recovery. He found that patients with the equivalent of a college education are seven times more likely than those who didn’t finish high school to be disability free one year after a moderate to severe traumatic brain injury.
Circadian rhythms evaluation
There is research support for the importance of light. Hughes tested the circadian hormone release in four participants stationed at the British Antarctic station. After three months of continuous darkness, their cortisol level patterns changed, with the peak levels being at noon rather than when they awoke. This suggests that the extremes of daylight found in polar regions of the world may be responsible for variations in circadian hormone release. However, other research using scientific communities in the Arctic he would be subject to similar prolonged winter darkness found no such disruption of cortisol release patterns.
There are two important types of individual differences in circadian rhythms. One is the cycle length, which can vary from 13 to 65 hours. And the other type relates to cycle onset. This is where individuals appear to be innately different in terms of when their circadian rhythm is reach their peak. Duffy et al found that morning people prefer to rise early and go to bed early whereas evening people prefer to wait and go to bed later.
One real world application of circadian rhythm is chronotherapeutics. This is the study of how timing affects drug treatments. The specific time that patients take their medication is very important as it can have a significant impact on treatment success. It is essential that the right concentration of a drug is released in the target area of the body at the time that the drug is most needed. Therefore, chronotherapeutic medications have been developed with a novel drug delivery system. These medications can be administered before the person goes to sleep at 10 PM but the actual drug is not released until the vulnerable period of 6 AM to noon.
Ultradian and infradian rhythms evaluation
There is some support for the importance of the BRAC from studies of elite performers. Ericsson et al studied a group of elite violinists and found that, among this group, practice sessions were usually limited to a duration of no more than 90 minutes at a time, with practice systematically distributed during the day in these 90 minutes segments. Consistent with Kleitman’s claim that fatigue was a characteristic at the end of the BRAC cycle. Ericssons analysis also indicated that the violinists frequently napped to recover from practice. He found the same pattern among other musicians, athletes, chess players and writers.
Research by Penton-Voak et al suggests that human mate choice varies across the menstrual cycle, with different preferences at different stages of the cycle. In their research, they found that women generally expressed a preference for slightly feminised male faces when picking a partner for long-term relationship. However, when in the ovulatory phase of the menstrual cycle women showed a preference for more masculinised faces. This preference is believed to represent a preference for kindness and cooperation in parental care in long-term mates, but a preference for male with good genes for short-term liaison so that these genes might be passed on to their offspring.
There is also research to show that the menstrual cycle can be controlled by exogenous cues as well as the endogenous system. Russell et al collected daily samples of sweat from one group of women and rubbed it on to the upper lips of women in the second group. The group were kept separate yet the menstrual cycles became synchronised with the ‘odour donor’. This suggests that the synchronisation of menstrual cycles can be affected by pheromones. These act in a similar way to hormones but have an affect on the bodies of people close by rather than the body of the person producing them.
Individual differences in sleep stages. Differences in the sleep pattern of individuals are usually attributed to different nonbiological factors e.g. room temperature. However a study by Tucker et al suggest that these differences are in large part biologically determined and may even be genetic in origin. Ppts were studied over 11 consecutive days and nights in a strictly controlled lab environment. They assessed sleep duration, time to fall asleep and the amount of time in each sleep stage. They found large individual differences in each of these characteristics which showed up consistently across the eight nights. For deep sleep The differences were particularly significant. This meant the differences between participants were not driven by circumstance, but were at least partially biologically determined.
Endogenous pacemakers and exogenous zeitgebers evaluation.
ENDOGENOUS PACEMAKERS
The importance of the SCN as an in endogenous pacemaker has been demonstrated an animal studies. Morgan bred a strain of hamsters so that they had abnormal circadian rhythms of 20 hours rather than 24 hours. SCN neurons from these abnormal hamsters within transplanted into the brains of normal hamsters. These normal hamsters then displayed the same abnormal circadian rhythm of 20 hours showing that the transplanted SCN had imposed it pattern onto the recipients brain. The same was found for the reverse of this experiment.
Separate rhythms. Under normal conditions the SCN coordinate all of the bodily rhythms. However in some circumstances these rhythms come to come out of step with each other. Folkard studied a university student who volunteered to spend 25 days in the controlled environment of a laboratory. During her time in the laboratory she had no access to daylight or other zeitgebers that may have reset the SCN . At the end of the 25 days her Core temperature rhythm was still at 24 hours. However, the sleep wake cycle had been extended to 30 hours with periods of sleep as long as 16 hours being recorded.
EXOGENOUS ZEITGEBERS
Burgess et al found that exposure to bright light prior to an east-west flight decreased the time needed to re-adjust to local time on arrival. Volunteers participated in one of three treatments – continuous bright light, intermittent bright light, or dim light. Ppts exposed to continue with bright light shifted their circadian rhythm by 2.1 hours over the course of the study. Those that are exposed to intermittent bright light shifted their rhythm by 1.5 hours and a third group exposed to dim light shifted theirs by just 0.6 hours. As a result they woke closer to the local time they travelled to.
Support for the role of melanopsin in setting the circadian rhythm comes from the studies of blind people. Some blind ppl are still able to reliably entrain their circadian rhythm in response to light despite a total lack of image forming visual perception. A lot of this evidence comes from Skene and Ardent. As further evidence for the importance of this pathway in setting the biological clock, people without light perception show abnormal circadian entrainment.
