Chapter 8: Learning and Memory

Learning is the process of acquiring new information and the outcome is memory. There are three stages of learning: (1) Encoding: process the information. There are two steps to encoding acquisition, which registers the inputs and consolidation, which strengthens the representation of the information. (2) Storage: record the information. (3) Retrieval


Short-term Memory


STM is dissociable from LTM. STM turns into LTM eventually. GE had a tumor in the left angular gyrus, affecting the inferior parietal cortex and posterior superior temporal cortex. He had deficits in STm but no in LTM.


Working Memory


Baddeley and Hitch said that there are three components for working memory. The central executive controls the phonological loop, which deals with what we hear and the visuospatial sketch pad deals with what we see. Different lesions of the brain produce different deficits in the process. Lesions to the left supramarginal gyrus produces deficits in the phonological loop. Lesions to the parieto-occipital region (mostly in the right hemisphere than the left) produces deficits in the visuospatial sketch pad.


Long-term Memory


There are two parts of LTM - declarative and nondeclarative memory. Declarative memory is our conscious memory and it plays a big role in our social interchange. It looks as if the medial temporal lobe is important to declarative memory. Declarative memory can be broken down into two different parts; episodic (events in our lives) and semantic (world knowledge) memory. Nondeclarative can be broken down to two different parts: procedural memory and perceptual representation system. Procedural memory is learning motor and cognitive skills. Perceptual representation system is the idea that the structure and form of an object or words can be primed by prior experience.


Memory and the Brain


RB had lesions in the hippocampus, more specifically the CA1 pyramidal cells. It seems as if the hippocampus is important when forming LTM. Korsakoff's Syndrome is associated with alcoholism. It causes a thiamine deficiency which leads to the degeneration of the diencephalon, especially the dorso medial nucleus of the thalamus and mammilary bodies.


Consolidation


Consolidation is the solidification of memories to LTM. Evidence from patients who have done ECT shows that memories must be consolidated. THey found that retrograde amnesia is more likely to affect items that were learned close to the time of the ECT. Semantic information is consolidated in the temporal neocortex. 


Learning New Declarative Information


KC had a loss of episodic memory but his semantic memory was intact. Semantic memories are established because of episodic memories. KC had damage to the medial temporal lobe, left dorsolateral prefrontal cortex, premotor cortex and the parietal and occipital cortices. This produced severe anterograde and retrograde amnesia.


Beth, Jon and Kate (all siblings) had hippocampal damage. They could learn semantic information but they did not know where it came from, which is called source amnesia. 


Learning New Nondeclarative Information


HM can learn new things but he could not say how he know the task. He was asked to do a mirror task and he got better every time he had to carry out the task. So his procedural memory is intact but his declarative memory is lost.


Mortimer Mishkin (1978)


He removed the hippocampus, amygdala or both in monkeys. The monkeys were tested in the delayed nonmatch-to-sample task. The card is placed over the reward (food) then the door is opened. The monkey has to pick where the reward is in order to get the food. The door is closed again and a new object is introduced. The novel card is placed over the reward and after a delay the door is reopened. The monkey has to pick the novel card in order to get the reward. After training, the monkey is able to pick the new item to get the reward. If the hippocampus and the amygdala is damaged memory was impaired.