AQA Psychology for A Level Year 2 - Student Bk

The specification says… Ways of investigating the brain Ways of studying the brain: scanning techniques, including functional magnetic resonance imaging (fMRI); electroencephalograms (EEGs) and event-related potentials (ERPs); post-mortem examinations. Advances in science and technology have brought with them ever more sophisticated and precise methods of studying the brain. Some modern scanning techniques are able to record global neural activity through the assessment of brainwave patterns whilst others are able to home in on activity in specific parts of the brain as the brain performs certain tasks and processes. Another more traditional way of investigating the brain – the post-mortem – is also considered. Key terms Functional magnetic resonance imaging (fMRI) – A method used to measure brain activity while a person is performing a task that uses MRI technology (detecting radio waves from changing magnetic fields). This enables researchers to detect which regions of the brain are rich in oxygen and thus are active. Electroencephalogram (EEG) – A record of the tiny electrical impulses produced by the brain’s activity. By measuring characteristic wave patterns, the EEG can help diagnose certain conditions of the brain. Event-related potentials (ERPs) – The brain’s electrophysiological response to a specific sensory, cognitive, or motor event can be isolated through statistical analysis of EEG data. Post-mortem examinations – The brain is analysed after death to determine whether certain observed behaviours during the patient’s lifetime can be linked to abnormalities in the brain. Concepts: Match the picture to the techniques Do the pictures (A, B, C and D) relate to fMRI, EEG, ERPs or post-mortems? @ookx hs @ookx hs Scanning and other techniques Functional magnetic resonance imaging (fMRI) fMRI works by detecting the changes in blood oxygenation and flow that occur as a result of neural (brain) activity in specific parts of the brain. When a brain area is more active it consumes more oxygen and to meet this increased demand, blood flow is directed to the active area (known as the haemodynamic response ). fMRI produces 3-dimensional images (activation maps) showing which parts of the brain are involved in a particular mental process and this has important implications for our understanding of localisation of function. Electroencephalogram (EEG) EEGs measure electrical activity within the brain via electrodes that are fixed to an individual’s scalp using a skull cap. The scan recording represents the brainwave patterns that are generated from the action of millions of neurons, providing an overall account of brain activity. EEG is often used by clinicians as a diagnostic tool as unusual arrhythmic patterns of activity (i.e. no particular rhythm) may indicate neurological abnormalities such as epilepsy, tumours or disorders of sleep. Event-related potentials (ERPs) Although EEG has many scientific and clinical applications, in its raw form it is a crude and overly general measure of brain activity. However, within EEG data are contained all the neural responses associated with specific sensory, cognitive and motor events that may be of interest to cognitive neuroscientists. As such, researchers have developed a way of teasing out and isolating these responses. Using a statistical averaging technique, all extraneous brain activity from the original EEG recording is filtered out leaving only those responses that relate to, say, the presentation of a specific stimulus or performance of a specific task. What remains are event-related potentials : types of brainwave that are triggered by particular events. Research has revealed many different forms of ERP and how, for example, these are linked to cognitive processes such as attention and perception. Post-mortem examinations A technique involving the analysis of a person’s brain following their death. In psychological research, individuals whose brains are subject to a post-mortem are likely to be those who have a rare disorder and have experienced unusual deficits in mental processes or behaviour during their lifetime. Areas of damage within the brain are examined after death as a means of establishing the likely cause of the affliction the person suffered. This may also involve comparison with a neurotypical brain in order to ascertain the extent of the difference. 0 A B C 0 150 300 450 600 +0.02mV Response to frequent stimulus A: Baseline B: N200 C: P300 Response to infrequent stimulus The term ‘event-related potential’ refers to the method used for studying the brain as well as what is examined / isolated as a result of that technique, i.e. a specific form of brainwave. In effect, the ERP technique produces the ERP! STUDY TIP C D B A Chapter 2 Biopsychology 44 •