OCR Psychology A Level Book 2 sample

Cognitive neuroscience explanation of major depression Helen Mayberg and her colleagues (1999) were among the first researchers to identify two major differences in activity in the brains of depressed people compared with people who were not depressed. They found that depressed people had increased activity in some of the structures of the limbic system (e.g. hippocampus , amygdala ) and decreased activity in the prefrontal cortex . Mayberg (2003) has since built on this observation in her corticolimbic dysregulation model of depression. Role of the corticolimbic circuit A complex disorder like depression is very unlikely to be the result of one or two dysfunctional brain areas or neurotransmitter systems. Instead, it appears that the cause could be an impaired neural circuit that connects the prefrontal cortex and the limbic system—the corticolimbic circuit . An impairment of this mood-regulating circuit means that the ‘higher’ areas of cognitive processing in the cortex cannot perform their normal function of regulating the emotionally responsive limbic structures. Depression is one possible consequence of this dysregulation. Research evidence Amit Anand et al . (2005) compared the fMRI scans of 15 people diagnosed with depression and 15 non-depressed participants matched for age, gender and ethnicity. The participants were all shown three types of image during fMRI scanning—emotionally negative, emotionally positive and emotionally neutral. To measure connectivity between the cortex and the limbic system, the researchers measured the correlation in activity between these areas. A higher correlation implies greater connectivity (and vice versa). The researchers found that cortex–limbic correlations were lower in depressed participants than in non-depressed participants. This was true for all types of image. This result shows that corticolimbic connectivity is reduced in depression, so that cortical areas cannot regulate limbic structures, as predicted by Mayberg’s model. Background Alternatives to the medical model Topic 3 Cognitive neuroscience principles Cognitive neuroscience is concerned with neurotransmitters (see page 22) and brain localisation (see page 26), but the most fundamental issue is about how neurons combine to determine cognitive functions such as thinking and perception. Neural circuits The basic unit of the nervous system is the neuron (nerve cell) but cognitive neuroscience is more concerned with how vast numbers of neurons work together in organised groupings called neural circuits . A single neuron in the cerebral cortex may receive inputs from thousands of other neurons and send outputs to thousands more. Some of these connections are excitatory (increasing the likelihood of a signal being passed on) and some are inhibitory (reducing it). To add to this complexity, the connections in a neural circuit are usually two- way. So neuron A can influence the activity of neuron B, but neuron B can also influence neuron A. When neurons repeatedly trigger each other in a circuit, their activity can eventually become stable. This means that when one neuron fires, so do all the others. The end result of such activity in neural circuits is cognitive processing— thinking, memories being stored, perception and so on. The specification requires that you study explanations of mental illness that are alternatives to the medical model. Five alternative explanations are identified. You are required to know the behaviourist and cognitive explanations plus one other (humanistic, psychodynamic or cognitive neuroscience). On this spread we look at the cognitive neuroscience explanation of mental illness. This spread covers the essential information you will need on background for the exam but you also need to link the background to issues and debates and to the key research. We will look at these links on page 46. The cognitive neuroscience perspective Cognitive neuroscience is a relatively recent field in psychology interested in the biological processes that underlie thought processes (cognitions). In other words, cognitive neuroscience considers how biological factors (for example, a part of the brain) can have an impact on cognitive processes (for example, memory or perception). Cognitive neuroscience overlaps considerably with two of the medical model explanations covered earlier in this chapter—the biochemical explanation (page 22) and brain abnormality (page 26). Find the ‘GoCognitive’ website at tinyurl.com/5txfxrb On this website you can watch videos and interviews about cognitive neuroscience. For example, there are interviews with experts discussing how language is processed in the brain, the neural basis for attention and the fascinating phenomenon of mirror neurons. You can also take part in lots of memory, attention and perception tests at tinyurl.com/354eq For example, as a class you could test whether there is a correlation between score on a personality test and ability to spot a fake smile, or if there is a difference in ability to spot emotion between students who take arts subjects or science subjects. You could then conduct a statistical analysis of your class results. Dorsolateral prefrontal cortex Motivation and executive function Hippocampus Learning and memory Amygdala Processing of emotions Anterior cingulate cortex Reward anticipation, decision-making, empathy, emotion, and impulse control The cognitive neuroscience explanation of mental illness Chapter 1: Issues in mental health 42