ways of studying the brain

• post-mortem examinations: they are used to establish the underlying neurobiology of a particular behaviour e.g. researchers may study a person who displays behaviours while they are alive but suggests possible underlying brain damage
• post-mortem examinations: when the person dies the researchers can examine their brains to look for abnormalities that might explain that behaviour and which are not found in control individuals
• post-mortem examinations: an early example of this technique was Broca's work w/ his patient Tan who displayed speech problems when alive and was subsequently found to have a lesion in the area of the brain that is now known as the Broca's area - an area important for speech production
• post-mortem examinations: post-mortem studies have also made it possible to identify some of the brain structures involved in memory, Jacopo Annese's post mortem of Henry Molalison (HM) confirmed that HM's inability to store new memories was linked to lesions in the hippocampus
• post-mortem examinations: the use of post-mortem studies has also been used to to establish a link between psychiatric disorders such as schizophrenia and depression and underlying brain abnormalities
• post-mortem examinations: e.g. post-mortem studies have found evidence of reduced numbers of glial cells in the frontal cortex of patients w/ depression
• post-mortem examinations: post-mortem examinations help to establish the underlying neurobiology of a particular behaviour
• fMRI: is a technique for measuring changes in the brain activity is a technique for measuring changes in brain activity while a person performs a task
• fMRI: it does this by measuring changes in the blood flow in particular areas of the brain which indicated increased neural activity in those areas
• fMRI: if a particular area of the brain becomes more active there is an increased demand for oxygen in that area the brain responds to this extra demand by increasing blood flow delivering oxygen in the red blood cells
• fMRI: as a result of these changes in blood flow researchers are able to produce maps showing which areas of the brain are involved in a particular mental activity
• fMRI: e.g. a participant might be asked to alternate between periods of doing a particular task (e.g. looking at a visual stimulus for 30 seconds) and a control state e.g. (30 seconds w/ their eyes closed) the resulting fMRI data can then be used to identify the brains areas where there is a matching pattern of change
• fMRI: as a result of this data it can be conducted that these areas have been activated by the stimulus in question
• EEG: an EEG measures electrical activity in the brain, electrodes placed on the scalp detect small electrical charges resulting from the activity of brain cells
• EEG: when electrical signals from the different electrodes are graphed over a period of time the resulting representation is called an EEG
• EEG: EEG data can be used to detect various types of brain disorder such as epilepsy or to diagnose other disorders that influence brain activity such as Alzheimer's disease
• EEG: e.g. EEG readings of patients w/ epilepsy show spikes of electrical activity, EEG patterns in patients w/ brain disease and brain injury show overall slowing of electrical activity
• EEG: the 4 basic EEG patterns are alpha waves, beta waves, delta waves and theta waves, when a person is awake but relaxed, rhythmical alpha waves are recorded, when the person is physiologically aroused their EEG pattern shows low amplitude and fast frequency beta waves
• EEG: beta waves are also found in REM sleep when the eyes move rapidly back and forth, delta and theta waves occur during sleep as the person moves from light to deep sleep the occurrence of alpha waves decreases and are replaced first by lower frequency theta waves and then by delta waves
• ERPs: are very small voltage changes in the brain that are triggered by specific events or stimuli such as cognitive processing of a specific stimulus
• ERPs: ERPs are difficult to pick out from all the other electrical activity being generated within the brain at a given time
• ERPs: to establish a specific response to a target stimulus requires many presentations of the stimulus and these responses are then averages together, any extraneous neural activity that is not related to the specific stimulus will not occur consistently whereas activity linked to the stimulus will
• ERPs: this has the effect of cancelling out the background neural 'noise' making the specific response to the stimulus in question stand out more clearly
• ERPs: ERPs can be divided into 2 categories, waves occurring within the 1st 100 milliseconds after presentation of the stimulus are termed 'sensory' ERPs as they reflect an initial response to the physical characteristics of the stimulus
• ERPs: ERPs generated after the 1st 100 milliseconds reflect the manner in which the subject evaluates the stimulus and are termed 'cognitive' ERPs as they demonstrate information processing
• fMRI S: fMRI is noninvasive (i.e. it does not involve the insertion of instruments into the body) nor does it expose the brain to potentially harmful radiation as is the case w/ some other scanning techniques used in the study of the brain
• fMRI S: fMRI offers a more objective and reliable measure of psychological processes than in possible w/ verbal reports, it is useful as a way of investigating psychological phenomena that people would not be capable of providing in verbal reports
• EEG S: it provides a recording of the brain's activity in real time rather than a still image of the passive brain, this means that the researcher can accurately measure a particular task or activity with the brain activity associated w/ it
• EEG S: an EEG is useful in clinical diagnosis e.g. by recording the abnormal neural activity associated w/ epilepsy, epileptic seizures are caused by disturbed brain activity which means that the normal EEG reading suddenly changes, this helps diagnose whether someone experiencing seizures had epilepsy
• ERP S: because ERPs provide a continuous measure of processing in response to a particular stimulus, it makes it possible to determine how processing is affected by a specific experimental manipulation e.g. during presentation of different visual stimuli
• ERP S: an ERP can measure the processing of stimuli even in the absence of a behavioural response, ERP recordings make it possible to monitor 'covertly' the processing of a particular stimulus w/o requiring the person to respond to them
• post-mortem examinations S: post-mortem studies allow for a more detailed examination of anatomical and neurochemical aspects of the brain than would be possible w/ the sole use of non-invasive scanning techniques such as fMRI and EEG e.g. it enables researchers to examine deeper regions of the brain such as the hypothalamus + hippocampus
• post-mortem examinations S: Harrison (2000) claims that post-mortem studies have played a central part in our understanding of the origins of schizophrenia, he suggests that as a direct result of post-mortem examinations, researcher have discovered structural abnormalities of the brain and found evidence of changes in neurotransmitter systems, both of which are associated w/ the disorder
• fMRI L: because fMRI measures changes in blood flow in the brain then it is not a direct measure of neural activity in particular brain areas, this means it is not a truly quantitative measure of mental activity in these brain areas
• fMRI L: critics argue that fMRI overlooks the networked nature of brain activity as it focuses only on localised activity in the brain, they claim that it is communication among the different regions that is most critical to mental function
• EEG L: because an EEG can only detect the activity in superficial regions of the brain, it can't reveal what is going on in the deeper regions such as the hypothalamus or hippocampus, electrodes can be implanted in non-humans to achieve this but it is not ethically permissible to do this w/ humans because this would be too invasive
• EEG L: electrical activity can be picked up by several neighbouring electrodes therefore the EEG signal is not useful for pinpointing the exact source of an activity, as a result it does not allow researchers to distinguish between activities originating in different but closely adjacent locations in the brain
• ERP L: because ERPs are so small and difficult to pick out from other electrical activity in the brain, it requires a large number of trials to gain meaningful data, this places limitations on the types of question that ERP readings can realistically answer
• ERP L: a limitation of the ERP technique is that only sufficiently strong voltage changes generates across the scalp are recordable, important electrical activities occurring deep in the brain are not recorded meaning that the generation of ERPs tend to be restricted to the neocortex
• post-mortem examinations L: because people die in a variety or circumstances and at varying stages of disease these factors can influence the post-mortem brain, similarly the length of time between death and the post-mortem (post-mortem delay), drug treatments and age at death are possible confounding influences of any difference between cases and controls