- Types of Memory
- Short term memory: lasts seconds to hours. Due to synapses.
- Long term memory: Days or can last for lifetime. long term memory involves formation of new synaptic connection and synthesis of new proteins"
- Recruitment of neurons is called Cortical plasticity and is a established mechanism of Memory & learning
- Recent memory: Short-term memory. Also called working memory.
- Working memory is a form of short-term memory that keeps information available, usually for very short periods, while the individual plans action based on it.
Capacity: About 7 plus or minus 2 "chunks" of information (Miller, 1956)
Duration: About 18 to 20 seconds (Peterson & Peterson, 1959)
- Long-term memory is the relatively permanent memory store. Also called remote memory. Duration: Up to a lifetime.
- Delayed memory This term is used to describe the experience of an individual who recalls a memory for which he or she was previously amnestic. The recollection may occur spontaneously or in the context of therapy.
- Memory function includes:
1. Registration (acquisition)
2. Conversion of Short-term memory to Long term memory
3. Retention (storage or consolidation)
5. Retrieval (decoding or recall)
- The process of Conversion of Short-term memory to Long term memory occurs in hippocampal cortex while the process of retreival requires the frontal lobe. When the subject recalls words there is increased activity in their right frontal lobe and para hippocampal cortex on both sides.
- The encoding process for short-term explicit memory involves the hippocampus; long-term memory is stored in various part of neocortex.
- The dominant source of input to the hippocampus is the entorhinal cortex (EC). Within the hippocampus, the flow of information is largely unidirectional, with signals propagating through a series of tightly packed cell layers, first to the dentate gyrus, which projects to the CA3 layer, which projects to the CA1 layer, which projects to the subiculum, which projects out of the hippocampus to the EC. Theta rhythm is produced by Hippocampus. long-term potentiation (LTP) is produced here which involves NDMA receptors.
Note: Acc. to current views information from the senses is temporarily stored in various parts as working memory which is relayed to the medial temporal lobe, and specifically to the parahippocampal gyrus From there, it enters the hippocampus. Output from the hippocampus leaves via subiculum and the entorhinal cortex and somehow binds together and strengthens the circuit in neocortex forming over time the stable remote memories.'
Learning: By Reinforcement (reward & punishment mechanism) & conditioned reflex
Conditioned reflex is a example of associative learning.eg Pavlov's classic experiments.
1. meat in front of dog : unconditioned stimulus (US)
2. Innate response : salivation with food
3. The conditioned stimulus (CS) : bell ringing
4. Conditioned Reflex : Salivation on ringing of bell alone
Mirror neuron is a neuron which fires both when an animal acts and when the animal observes the same action performed by another animal (especially by another animal of the same species). Thus, the neuron "mirrors" the behavior of another animal, as though the observer were itself acting. These neurons have been directly observed in primates, and are believed to exist in humans and other species including birds. In humans, brain
activity consistent with mirror neurons has been found in the premotor cortex and the inferior parietal cortex. Mirror neurons might be very important in imitation and language acquisition.