Consolidation of Memory


The process by which a short-term memory is crystallized into a long-term memory is called memory

consolidation. Consolidation causes permanent facilitation of synapses. It is possible by rehearsal mechanism, i.e. rehearsal of same information again and again accelerates and potentiates the degree of transfer of short-term memory into long-term memory. This is what happens in memorizing a poem or a phrase.


Memory is classified by different methods, on the basis of various factors.

Short-term Memories and Long-term Memories

Generally, memory is classified as short-term memory and long-term memory.

1. Short-term memory

Short-term memory is the recalling events that happened very recently, i.e. within hours or days. It is

also known as recent memory. For example, telephone number that is known today may be remembered till tomorrow. But if it is not recalled repeatedly, it may be forgotten on the third day. Short-term memory may be interrupted by many factors such as stress, trauma, drug abuse, etc. There is another form of short-term memory called working memory. Short-term memory may be interrupted by many factors such as stress, trauma, drug abuse, etc. There is another form of short-term memory called working memory. It is concerned with recollection of past experience for a very short period, on the basis of

which an action is executed.

2. Long-term memory

Long-term memory is the recalling of events of weeks, months, years or sometimes lifetime. It is otherwise called the remote memory. Examples are, recalling firstday of schooling, birthday celebration of previous year, picnic enjoyed last week, etc. Long-term memory is more resistant and is not disrupted easily.

Explicit and Implicit Memories

Physiologically, memory is classified into two types, namely explicit memory and implicit memory.

1. Explicit memory

Explicit memory is defined as the memory that involves conscious recollection of past experience. It consists of memories regarding events, which occurred in the external world around us. The information stored may be about a particular event that happened at a particular time and place. Explicit memory is otherwise known as declarative memory or recognition memory. Examples of explicit memory are recollection of a birthday party celebrated three days ago, events taken place while taking breakfast, etc.

Explicit memory involves hippocampus and medial part of temporal lobe.

2. Implicit memory

Implicit memory is defined as the memory in which past experience is utilized without conscious awareness. It helps to perform various skilled activities properly. Implicit memory is otherwise known as non-declarative memory or skilled memory. Examples of implicit memory are cycling, driving,

playing tennis, dancing, typing, etc. Implicit memory involves the sensory and motor pathways.

Memories Depending upon Duration

Depending upon duration, memory is classified into

three types:

1. Sensory memory

2. Primary memory

3. Secondary memory.

1. Sensory memory

Sensory memory is the ability to retain sensory signals in sensory areas of brain, for a very short period of few seconds after the actual sensory experience, i.e. few hundred milliseconds. But, the signals are replaced by new sensory signals in less than 1 second. It is the initial stage of memory. It resembles working memory.

2. Primary memory

Primary memory is the memory of facts, words, numbers, letters or other information retained for few minutes at a time. telephone number in the directory, we remember the number for a short while. After appreciating beautiful scenery, the details of it could be recalled for some time. Afterwards, it disappears from the memory. Characteristic feature of this type of memory is that the information is available for recall easily from memory store itself. One need not search or squeeze through the mind, but this memory is easily replaced by new bits of memory, i.e. by looking into another telephone number, the first one may disappear.

3. Secondary memory

Secondary memory is the storage of information in brain for a longer period. The information could

be recalled after hours, days, months or years. It is also called fixed memory or permanent memory. It

resembles long-term memory.

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