Episodic and Semantic memory
|Females consistently perform better than males on episodic long-term memory tasks, especially those involving delayed recall and recognition.
However, males and females do not differ significantly on working memory and semantic memory tasks.
There is also evidence for a negative recall bias in women, which means that females in general are more likely than males to recall their mistakes.
Episodic memory represents our memory of experiences and specific events in time in a serial form, from which we can reconstruct the actual events that took place at any given point in our lives. It is the memory of autobiographical events (times, places, associated emotions and other contextual knowledge) that can be explicitly stated. Individuals tend to see themselves as actors in these events, and the emotional charge and the entire context surrounding an event is usually part of the memory, not just the bare facts of the event itself.
Semantic memory, on the other hand, is a more structured record of facts, meanings, concepts and knowledge about the external world that we have acquired. It refers to general factual knowledge, shared with others and independent of personal experience and of the spatial/temporal context in which it was acquired. Semantic memories may once have had a personal context, but now stand alone as simple knowledge. It therefore includes such things as types of food, capital cities, social customs, functions of objects, vocabulary, understanding of mathematics, etc. Much of semantic memory is abstract and relational and is associated with the meaning of verbal symbols.
The semantic memory is generally derived from the episodic memory, in that we learn new facts or concepts from our experiences, and the episodic memory is considered to support and underpin semantic memory. A gradual transition from episodic to semantic memory can take place, in which episodic memory reduces its sensitivity and association to particular events, so that the information can be generalized as semantic memory.
|Experiments on rats in the 1970s showed that there are over a million place cells in a rats hippocampus, each of which only becomes active when the rat is located in a very specific part of its environment.
All together they can form a very precise cognitive map that tells the animal where it is at any given time.
When the rat explores a new environment, it forms a new cognitive map of place cells that can be very stable, lasting weeks or months.