Characteristics of Declarative Memory

Declarative memory, also known as explicit memory, are the memories that we can consciously recall. These are the memories we have of facts and events. It differs from non-declarative (implicit memory) which does not require conscious effort to retrieve the memory of, such as learning to ride a bike without being aware we are remembering how to do it. What we can broadly say characterizes declarative memory are the following:

• conscious awareness
• semantic and episodic memory
• flexibility
• anatomical structures

These are the things that allow for us to learn from and remember our daily experiences, language, and history.

Conscious memory

To say that someone is “consciously recalling” a memory or being “consciously aware” of it is to say that they can retrieve the memory and describe it with their words. This is said to be an intentional act such as trying to recall the capital of a country when asked or what day someone’s birthday is. This makes it so that knowingly thinking of a memory and being able verbally expressing it are central characteristics of declarative memory.

Subdivisions of Declarative Memory

There are two categories that declarative memory falls into which are semantic and episodic memory.

Semantic memory can be referred to as our general knowledge. What makes up our general knowledge are things we learn such as facts, language, interpretations of things, and ideas. An example of this would be knowing what the definition of semantic memory is.

Episodic memory are the memories we have of our experiences or events that have happened. When we go back and “replay” a memory which includes the emotions we felt, who was there, and the setting (time and place) we were in, this is episodic memory.

Flexibility 

Our declarative memory can be called “flexible” because we can apply it to new things or combine it with different memories. For example, if you remember that 4+4 is 8, and the next year you learn that 4X2 is also 8, you can apply the knowledge you gain in understanding 4+4 to the knowledge you gain in of understanding 4X2, to form the new understanding that multiplying a number by another number is to add it that many times. There are many other examples of this, but what is shown is that declarative memory can be recalled and compared to different memories to form new understandings.

Anatomical structures

The structures that are most important to our declarative memory is the hippocampus and diencephalon which are located in the medial temporal lobe. 

How this happens

When you are learning a new fact such as “the hippocampus and diencephalon are important for declarative memory” you read the statement and interpret it to mean something which is semantic memory. The hippocampus then receives this information and combines all of the information you’ve processed into a memory. This is because of synaptic plasticity and specifically LTP.

What happens in the hippocampus when it processes the information is that neurons communicate with each other and LTP allows for glutamate to be released and NMDA receptors allow calcium into the postsynaptic neuron. This causes the firing of pathways that become strengthened and more likely to be used with time.

The diencephalon is composed of three structures: the thalamus, hypothalamus, and epithalamus. Apart of this is the anterior thalamic nuclei (ANT) The hippocampus sends signals to the part of the diencephalon and thus to the cingulate cortex which loops back to the hippocampus. This creates a circuit which allows for the consolidation of the memory.