Short-Term, Long-Term, and Working Memory - Oh My!
There is a fleeting moment when we cannot remember something that we fear for our memory. Memory is something that we take for granted and expect it to function when we need it. When memory slips and gaps in memory start to occur, we flip out. Memory is a very complicated process and one that we don’t take the time to learn about because we just expect it to work. Let’s review the processes of memory and perhaps we will understand what is happening.
First let’s look at working definitions of each category of memory:
Working Memory:
Temporary holding and manipulating information in short-term memory
Vulnerable to distraction and disruption
Very limited in capacity
Must constantly be dumped
Involves multiple areas of the prefrontal cortex (executive function/ control behavior)
Employs the use of attention to manage short-term memory
Short-Term Memory:
Temporarily holds a limited amount of information in a very accessible state
Capacity is 7 plus/minus 2 random objects simultaneously – human memory span
Believed that short-term memory is a function of the prefrontal cortex
Processing though the hippocampus is necessary for learning and for memory consolidation to occur
Only lasts seconds -> minutes
Vulnerable to distraction and disruption
Long-Term Memory:
An unlimited store of knowledge
Record of past events
Involves widespread areas of the cortex
Not vulnerable to distraction or disruption
The prefrontal cortex area of the brain plays a fundamental role in both short-term and working memory function. This area of the brain serves as the temporary storage facility for short-term memory while consecutively making memory available for recall and manipulation. Short-term memory is used to describe the ability to retrieve and discard information while working memory describes the use of information for manipulation.
How is memory formed within the brain? The brain is composed of two types of cells: neurons and glia. Neurons form the biological basis of memories and glia support this process by delivering nutrients, recycling molecules, providing electrical stimulation, etc. Each neuron connects to other neurons through a system of dendrites and axons and form large networks. Neurons do not attach to each other but the point where the neurons meet is called the synapse. Neurons are continually forming new synapses and pruning old ones. Synapses are responsible for communication and can become stronger or weaker over time. This results in greater or weaker efficiencies in the brain. When we learn something, the brain stores this information by changing the strength of the synapses. Memories are encoded in the area between the neurons, and different kinds of memories are stored in different areas of the brain. Neuroscientists believe that the hippocampus participates in memory formation by helping with the changes in the synapses between neurons throughout the brain.
Sensory input starts this whole cascade of memory formation. The process then becomes Encoding. Encoding of working memory involves the spiking of the neurons. Encoding of episodic memory involves persistent changes in molecular structures that alter synaptic transmission between neurons. (Jansen and Lisman 2005).
Short-term memory is a temporary state and vulnerable to disruption. Long-term memory, once consolidated, is not vulnerable to disruption and is permanent. However, recent studies have shown that retrieved memory is not a carbon copy of the initial experiences because memories are updated during retrieval. This concept punches a hole in eye-witness testimony.
Memories are complex. In the next blog I will demonstrate the affect of lifestyle and aging on the memory process. Then I will share some strategies and tools to aid in memory formation. Congratulations on following this!!
Cowan,N. (2008). Differences between long-term memory, short-term and working memory. Prog.Brain Res,pp.169,323-338.Retrieved April, 7,2015 from http://ncbi.nim.nih.gov.
Difference between short-term, long-term and working memory (2015). Retrieved April 7, 2015 from http://examinedexistance.com
Hendel,R. (2011). The neuroscience of learning: a new paradigm for corporate education. The Maritz Institute, May 2010. Retrieved March 2015 from http://themaritzinstitute.com.
Jensen,O. and Lisman,J.E. (2005) Hippocampal sequence-encoding driven by cortical multi-item working memory buffer. Trends in Neuroscience, 26, 696-705. Retrieved April 9, 2015 from http://en.wikipedia.org/wiki/Memory
Memory. Retrieved April 9, 2015 from http://en.wikipedia.org/wiki/Memory