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Chapter nine psych oxford

Terms in this set (38)

Patients with damage to their hippocampus have enabled researchers to realise that there were two types of long-term memory: long- term declarative memory (a form of explicit memory) and long-term procedural memory (a form of implicit memory). They found that the hippocampus was active for explicit memory tasks but other parts of the brain were active for procedural memory tasks - for example, the cerebellum was, in part, responsible for remembering motor skill tasks. People with hippocampal damage are still able to learn and remember non- declarative (i.e. procedural) information such as motor skills or habits. If asked, however, these people cannot remember actually performing the skill because their memory of it is declarative (episodic) memory. Bechara and colleagues (1995) demonstrated the important role of the amygdala for non-declarative emotional memory. This research included one participant with damage to both amygdala and another participant whose hippocampus was damaged on both sides of the brain. The researchers tried to link responses in the participants by making a loud unpleasant noise when a blue slide was shown to them, but no noise when a slide of a different colour was shown. The participant with the damaged amygdala reacted emotionally to the loud noise and was able to tell the researchers which slide was followed by the unpleasant noise; however, when the same blue slide was presented without the loud noise, he did not react emotionally. In other words, he had no emotional memory (reflex response) associated with the blue slide and so did not react to it when it was not accompanied by the unpleasant noise. In contrast, the participant with damaged hippocampi showed an emotional response to the noise and also to the blue slide (the conditioned stimulus) but, when asked later, could not remember which colour slide was associated with the loud noise. In other words, his brain had not consolidated declarative memory for the colour that was associated with the noise
This study indicated that people with a damaged amygdala are incapable of fear conditioning, indicating that this part of the brain is important for the formation of this type of memory.
This neurodegenerative disease, which is most common in old age, involves gradual, severe memory loss, confusion, impaired attention, disordered thinking and depression. It involves both anterograde and retrograde amnesia because the disease affects both the hippocampus and the prefrontal cortex. The earliest symptom is usually impaired declarative memory, where the patient has difficulty remembering events from the day before, forgets names and has difficulty finding the right word when speaking. Next, the patient might repeat stories or questions, and eventually will fail to recognise familiar people and family members. Amyloid plaques (proteins that form among axon terminals and interfere with communication between neurons) typify Alzheimer's disease. In addition, patients' brains have neurofibrillary tangles (an abnormal build-up of protein inside neurons) and these are associated with the death of brain cells. Alzheimer's patients also have lower levels of important memory neurotransmitters, especially acetylcholine. One of the first brain structures to be affected by this disease is the hippocampus. When the cells are lost here, it causes the brain to atrophy (shrink) and the damage to the temporal lobes means that the hippocampus becomes isolated. This is probably why there is early memory loss. Plaques and tangles in the frontal lobes cause more memory problems and difficulty in attention and motor coordination. In the occipital lobes, the disrupted link between the primary visual cortex and the visual association areas in the parietal and temporal lobes can cause reading and other visual problems for the patient. Altogether, the nature of the brain damage caused by Alzheimer's disease means that declarative memory in particular is impaired.