The term memory encoding defines the processes that mediate between an experience and the memory of that experience—in other words, the physiological events that lead to memory formation. This section addresses the questions: Are there different kinds of memories, where do they occur in the brain, and what happens physiologically to make them occur?
New scientific facts about memory are being generated at a tremendous pace, and the difficulty comes when one tries to fit this information into an overall, workable scheme. First, memory can be viewed in two broad categories: Declarative memory is involved in answering the question, "What is it, or when and where did it happen?" and is based on one's past experience. One example is the memory of having perceived an object or event and, therefore, recognizing it as familiar and maybe even knowing the specific time and place when the memory was instigated. A second example would be one's general knowledge of the world such as names and facts. The hippocampus, amygdala, and diencephalon—all parts of the limbic system—are required for the formation of declarative memories.
The second broad category of memory, nonde-clarative memory, includes procedural memory, which can be thought of as the memory of how to do things. In other words, it is the memory for skilled behaviors independent of any understanding, as for example, riding a bicycle. Individuals can suffer severe deficits in declarative memory but have intact procedural memory. One case study describes a pianist who learned a new piece to accompany a singer at a concert but had no recollection the following morning of having performed the composition. He could remember how to play the music but could not remember having done so. The category of nondeclarative memory also includes learned emotional responses, such as fear of thunder, and the classic example of Pavlov's dog, which learned to salivate at the sound of a bell after the bell had previously been associated with food. The primary areas of the brain involved in non-declarative memory are regions of sensorimotor cortex, the basal ganglia, and the cerebellum. As we have seen, memory can be considered as to type—declarative or nondeclarative—and the brain areas involved in its formation; it can also be looked at in terms of duration—does it last for a long or only a short time?
Working Memory Working memory, also known as primary or short-term memory, registers and retains incoming information for a short time—a matter of seconds—after its input. In other words, it is the memory that we use when we keep information consciously "in mind." Working memory makes possible a temporary impression of one's present environment in a readily accessible form and is an essential ingredient of many forms of higher mental activity. It is not surprising then that working memory is associated with a second component—the so-called executive processes—that can operate on the contents of working memory. The executive processes include such functions as selective attention, switching attention between parts of a complex task, and planning the sequence of tasks to achieve a specific goal.
Focusing attention is essential for many memory-based skills. The longer the span of attention in working memory, the better the chess player, the greater the ability to reason, and the better a student is at understanding complicated sentences and drawing inferences from texts. In fact, there is a strong correlation between working memory and standard measures of intelligence. Conversely, the specific memory deficit in victims of Alzheimer's disease, a condition marked by serious memory losses, may be in this attention-focusing component of working memory.
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This ebook provides an introductory explanation of the workings of the human body, with an effort to draw connections between the body systems and explain their interdependencies. A framework for the book is homeostasis and how the body maintains balance within each system. This is intended as a first introduction to physiology for a college-level course.