Memory is critical to humans and all other living organisms. Practically all of our daily activities—talking, understanding, reading, socializing—depend on our having learned and stored information about our environments. Memory allows us to retrieve events from the distant past or from moments ago. It enables us to learn new skills and to form habits. Without the ability to access past experiences or information, we would be unable to comprehend language, recognize our friends and family members, find our way home, or even tie a shoe. Life would be a series of disconnected experiences, each one new and unfamiliar. Without any sort of memory, humans would quickly perish.
Philosophers, psychologists, writers, and other thinkers have long been fascinated by memory. Among their questions: How does the brain store memories? Why do people remember some bits of information but not others? Can people improve their memories? What is the capacity of memory? Memory also is frequently a subject of controversy because of questions about its accuracy. An eyewitness’s memory of a crime can play a crucial role in determining a suspect’s guilt or innocence. However, psychologists agree that people do not always recall events as they actually happened, and sometimes people mistakenly recall events that never happened.

Definition

Memory refers to the processes that are used to acquire, store, retain, and later retrieve information. There are three major processes involved in memory: encoding, storage, and retrieval.

Encoding refers to the initial perception and registration of information. Storage is the retention of encoded information over time. Retrieval refers to the processes involved in using stored information. Whenever people successfully recall a prior experience, they must have encoded, stored, and retrieved information about the experience. Conversely, memory failure—for example, forgetting an important fact—reflects a breakdown in one of these stages of memory.

Types of Memory

Memory is broken down into two types:

• short term and
• long term.

Short-term memory, also known as working memory, stores information that you need to remember in the following seconds, minutes or hours. An example would be a telephone message that you are given and must remember until you pass it on.

Long-term memory stores information that your brain retains because it is important to you. Basic information remembered includes names of family and friends, your address, as well as information on how to do certain activities and tasks. Long-term memory can be further divided into explicit, implicit and semantic memory.

• Explicit memories are facts that you made a conscious effort to learn and that you can remember at will, for example, the names of state capitals.
• Implicit memory is information you draw on automatically in order to perform actions such as driving a car or riding a bicycle.
• Semantic memories are facts that are so deeply ingrained they require no effort to recall. An example would be the months of the year.

There are large age-related differences with explicit memory, but age has little or no effect on implicit or semantic memory.

Brain Structures involved in Memory

Most types of memory appear to be stored in the cortex. Different areas of cortex specialize in different kinds of information, so that visual information about the Statue of Liberty may be stored in one location (e.g., the inferior temporal cortex), while information about its associations to liberty and immigration might be stored in another (e.g., the frontal cortex). High linkage between these two areas means that seeing a picture of the Statue of Liberty can retrieve memory about its associations. At the same time, damage to specific areas of cortex can produce specific memory deficits. For example, damage to a specific region within the temporal lobe can produce a memory deficit in which the patient loses knowledge about “living things” (e.g. dogs, lions, birds) but maintains knowledge about other categories (e.g. inanimate objects such as furniture and utensils). Formation of new declarative memories depends on the hippocampus and related structures in the medial temporal lobe. When these structures are damaged, a condition of anterograde amnesia can result, in which older declarative memories are largely spared, but few if any new declarative memories are acquired. At this point, the process whereby the hippocampus and other medial temporal lobe structures contribute to long-term memory formation is still incompletely understood. Some researchers believe that the hippocampus acts as a temporary store for new information, which is then gradually transferred to permanent storage in the cortex. Other researchers believe that the hippocampus never actually stores information itself, but is needed by the cortex in the process of developing new memories.

Another important structure is the amygdala, which lies near the hippocampus in the medial temporal lobes. The amygdala is critically involved in emotional memory; an individual with damage to the amygdala may remember the details of a traumatic (or joyful) event but not the emotional content of that event.

Memory and learning

are closely related, and the terms often describe roughly the same processes. The term learning is often used to refer to processes involved in the initial acquisition or encoding of information, whereas the term memory more often refers to later storage and retrieval of information. However, this distinction is not hard and fast. After all, information is learned only when it can be retrieved later, and retrieval cannot occur unless information was learned. Thus, psychologists often refer to the learning/memory process as a means of incorporating all facets of encoding, storage, and retrieval.

By Dr Anmol Arora ( Sr Homoeopathic Physician )