Memory And Memory

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Memory is a process of encoding, storing and retrieving knowledge and is classified by two aspects; the type of information and temporal direction. Learning on the other hand is a change in behaviour resulting from acquiring knowledge. Learning requires physical changes in neuron’s size, shape and number of connections to other neurons that may affect patterns of neural activity.
Short term and long term memory involve different neural system. The ability to store information depends on short term memory and is called working memory. Working memory manipulate multiple transient goal-relevant knowledge in mind. Long term memory on the other hand can be classified as declarative or non-declarative (procedural) (Figure 1) on the basis of how information is stored and recalled. (Kendal et al, 2012)
Declarative or explicit memory is the conscious retrieval of previous experiences and factual knowledge. The storage of knowledge in the brain is distributed among different brain regions and is accessed independently by different senses such as verbal, visual and sensory cues. Declarative memory is further divided into episodic and semantic memories (Graf and Schacter, 1985). These two forms of memories are consciously accessible.
Episodic memory is a memory for a specific auto-biological event includes information on spatial and temporal context. Episodic memory depends on interaction between medial temporal lobe and associative cortices. This phenomenon is central to memory consolidation. E.g. patient H.M who undergo removal of his bilateral medial temporal lobe due to epilepsy could remember old memories; this suggests that old memories are not stored in the medial temporal lobe, but in other cortical regions.
Semantic memory is reme...

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NMDA receptors exhibit associativity and are partly responsible in learning, memory and development as well as neuronal damage due to brain injury. Glutamate binding and membrane depolarisation causes an opening of NMDA receptors. The receptor permits a significant influx of Ca2+, and increases intracellular Ca2+ to activate a variety of processes that alter the properties of the neuron. Excess Ca2+ is neurotoxic, and hyper-activation of NMDA receptors contributes to various neurodegenerative disorders. NMDA receptor dependent long term potentiation (LTP) in the CA1 region of the hippocampus and in the cortex is essential for classical conditioning in sea snail, Aplysia. Postsynaptic glutamate receptor modulation underlies behavioural sensitization in Aplysia however Presynaptic processes seem to support only relatively brief memory in Aplysia (Berg et al, 2008).

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