Short and Long Term Procedural Learning and Memory

*Neural systems and synaptic changes that allow learning and memory to 
take place.
Tara Thelen
Teena George 

Introduction:

The learning and memory process varies according to the nature of 
what information we are taking into our neural system.  Internally our 
brains process all kinds of information at the same time. The 
information or stimulus is encoded, then stored and retrieve at a later 
time.  The brain-wave activity distinguishes and deciphers which 
memories belong in various memory systems.  In addition each individual 
memory winds up being connected with, and influenced by, all other 
memories.  
The types of memory classifications involved in procedural memory 
are short and long term memory.  Short term memory usually last for 
seconds or minutes.  Long term memory can last for a lifetime or only a 
few hours.  Long term memory holds declarative and non-declarative 
(procedural) memories.  Declarative memories (a.k.a. explicit memory) 
are verbally expressed (consciously) and non-declarative memories 
(a.k.a. implicit memory) are not verbally expressible (unconsciously).  
Declarative memories break into subgroups of episodic (recall 
experience) and semantic memories (general world knowledge).  Non-
declarative memories also break into subgroups that include skills, 
priming, and conditioning.   
Procedural memory is the most primitive form of memory.  This is 
because it is the most basic form of memory to develop first in 
infancy.  This memory involves skill learning, which is used for doing 
task, skills, actions, conditioned responses and procedures.  These 
procedural memories are usually acquired from repeating the specific 
learned skill.  Learned skills are usually done unconsciously and can 
be stored in our memory for several years.  It is sometimes compared to 
riding a bicycle, it was difficult practicing to ride the bike but 
after several attempts the skill became almost natural and hard to put 
into words just how the entire process was learned and remembered.  Now 
when the person gets on a bike they remember how to ride it without 
having to think about how they learned (for example: how to balance 
their body with the bike and move our feet at the same time to maintain 
perpendicular on the bike to control a riding motion), they just know.  
A study of infant monkeys suggests that procedural memory is 
developed right away before other memories.  The study also showed that 
given lesions to the prefrontal cortex and the hippocampal formation 
would not cause any loss in procedural memories but a severe loss in 
the declarative memories.  This also gives supporting evidence that 
procedural memory involves the neostriatum and the cerebellum. A 
completely different structure than that of declarative memories that 
involve the medial temporal lobe, medial diencephalon, and the ventral 
portion of the prefrontal cortex in primates as well as humans 
(Bachevalier,2000). 

Neural Mechanisms underlying Procedural Learning and Memory
Tara Thelen

	There are at least two categories of memories, which can be 
distinguished by the type of information learned and the neural 
structures required.  These include declarative, or explicit memory, 
and procedural, or implicit memory.  Declarative memories can be 
brought into conscious awareness and include autobiographical memories.  
This type of memory depends much on the limbic structures and multiple 
areas of the neocortex.  The other type of memory, which we are 
discussing, is procedural memory.  Procedural memories are not 
available to conscious awareness.  The knowledge acquired through 
procedural learning includes skills, habits, and experience dependent 
modifications of reflexes.  Procedural memory can either be long-term 
or short-term.  Long-term procedural memories are stored in the basal 
ganglia, cerebellum and motor cortices. Short-term procedural memory is 
widespread, but the actual location is unknown.  Emotional 
associations, which are dependent on the amygdala, are also considered 
a type of procedural memory.  
	 Information needed for procedural learning first takes place in 
the neocortex. The neocortex is located at the base the frontal lobes. 
The inputs given to the neocortex provide information about what is 
happening in the environment and what plans are being made by the rest 
of the frontal lobes.  Its outputs are sent to many areas, including 
the basal ganglia and cerebellum, which affect a variety of behaviors 
and physiological responses.
The contributions of the basil ganglia to motor control and other 
aspects of brain function are still somewhat unclear.  However, it is 
said that this area provides postural background for movements, insures 
the pertinence of movements, or acts as automated function generators 
for slowly building contractions (Anjevine 1981).  The basal ganglion 
consists of a group of subcortical structures left and right of the 
thalamus, including three major structures: the caudate nucleus, the 
putamen and the globus pallidus.  It is made up of many subdivisions, 
which exchange information with a different part of the cerebral 
cortex.  These connections are most abundant in the frontal areas of 
the cortex, which are responsible for procedural memory, as well as 
planning sequence of behavior and emotional expression. Damage to the 
loop between the caudate and the prefrontal cortex has been shown to 
disrupt procedural learning and memory.  Furthermore, it is said that 
procedural learning involves the automatic connections between a 
stimulus and a response.  Some have suggested that the basal ganglia 
may not be involved with learning per se, but may be crucial for the 
proper execution of motor programs that are required for procedural 
knowledge (Curran 1995).  
	The cerebellum is another area responsible for procedural 
learning and memory.  One of the primary functions of the cerebellum is 
planning a movement.  During this time, information from the posterior 
parietal cortex is conveyed to the pontine grey neurons. The grey 
neurons then relay the planning information to the lateral zone of the 
cerebellum through mossy fibers.   Before this movement begins, cells 
in the dentate nucleus are firing their simple spikes.  As a wave of 
mossy fiber planning information hits the cerebellum, there will be an 
increase in the firing of the dentate and an increase of spikes fired 
from the Purkunje cells.  The message sent from the Purjunke cell will 
change and a new message will then be relayed.  This is the basic 
process of planning is necessary before procedural learning and memory 
can takes place.
	Although both the basal ganglia and cerebellum are involved with 
procedural learning, there roles are very different.  The influence of 
the basal ganglia on the prefrontal cortex may be required for timely 
action to and from the working memory buffer, whereas, the cerebellum 
may index and order events in the time domain.  Therefore, the 
cerebellum is essential for any cognitive functions involving sequence 
(Peterson 1998).
	An important aspect of procedural memory is it seems to be 
independent of other types of learning.  An individual that has had 
damage to other areas associated with learning and memory, such as the 
hippocampus, are often able to maintain their procedural memory, as 
well.  An experiment conducted by Sidman, Stoddard, and Morr  (1968) 
examined how a person's hippocampal formation receives information 
about the context in which learning takes place.  Different information 
was presented about the room and other individuals in the room. The 
person collected the information and the patterns of activity in the 
association cortex in different regions of the brain were attached.  
The person was later asked to recall about the task, causing the 
retrieval of the memory of the episode stored throughout the brain.  It 
was found that the person that was lacking this hippocampal formation, 
such as H.M., was unable to complete this task.  However, they were 
able to maintain their procedural memory (Carlson 2001).   
	Procedural memory is unique in its ability to be maintained once 
it has been learned, as well as continue normal functioning after 
damage to systems of the brain normally associated with learning and 
memory.  Although it is processed in the brain much like other 
memories, it is different in the areas of which it is stored. 
 
Synaptic Changes in Procedural Learning and Memory
Teena George

There are two limbic nuclei, the amygdala and the hippocampus 
that play key roles in cellular changes that are involved with memory 
and learning.  The amygdala acts as a type of memory filter, labeling 
information to be saved by tying it into an event or emotion.  In the 
hippocampus, a functional change at certain synapses is directly 
related to memory storage and learning, called long-term potentiation.  
This change is an enhanced response by a postsynaptic cell to an action 
potential.  This can result when a presynaptic cell bombards a synapse 
with a series of brief, repeated action potentials that strongly 
depolarize the postsynaptic membrane.  With long term potentiation 
(LTP) established, a single action from the presynaptic cell has a much 
greater effect at the synapse than previously.  Depending on the 
frequency and number of repeated action potentials, LTP can last for 
hours, days, or weeks.  LTP is associated with the release of the 
neurotransmitter glutamate by the presynaptic cell. Glutamate is the 
main excitatory neurotransmitter in the hippocampus, LTP depends on the 
activation of glutamate receptors.  Glutamate binds with a specific 
receptor in the postsynaptic membrane, opening gated channels that are 
highly permeable to calcium ions.  The calcium ions trigger a cascade 
of intracellular changes.  
Intracellular calcium is stored in two structures, the 
endoplasmic reticulum and the mitochondria.  The endoplasmic reticulum 
structure acts as the storehouse for calcium and is a primary site of 
protein synthesis.  The mitochondria are the site of cellular 
respiration, which generates energy fuel for the cell ATP (Martinez 
Jr., 218).
Extracellular measurement of the postsynaptic excitatory 
potentials are produced by the synapses of the perforate path.  LTP 
takes place at the area where the axons of the perforate path are 
stimulated.  LTP is very complex and happens at more than one are, for 
example LTP can take place in the motor cortex which allows the body to 
begin the procedural task physically.    
Dopamine and neural plasticity play a role in learning by 
strengthening the neural connections.  This is supported by an 
experiment done with rats.  When the rats are hungry for food learn to 
press a lever to obtain food.  When the reinforcing stimulus (food) 
turns on the reinforcement mechanism that strengthens the synapses 
between the terminal buttons that were just active and the motor 
neurons that have just been fired (Carlson, 446).  
The phenomena behind long-term potentiation are basically the 
same for all memory except where it is stored.  This is supported by 
several studies on amnesic persons with severe to moderate memory loss.  
Most memories that were not intact were declarative memories, 
procedural task were still intact which confirms the storage for these 
types of memories are not in the same locations.  Moreover, like H.M. 
and other amnesic people showed improvement on skill test but could not 
recall anything about it or even remember seeing it before.  Displayed 
learning is taking place without any conscious awareness. (Kimble, 
413).  
	In conclusion, the procedural learning and memory systems have 
had extensive research in these fields to have some understanding of 
our brains and what they are able to do at high functioning level.  
Many experiments have been done on rats, monkeys, and humans with 
amnesia.  The most important finding is that procedural memory does 
don't seem to be effected when other memory systems fail.  Even when 
presented with lesions to the brain the skills learned are still 
intact.



References:

Carlson, Neil R.  	Physiology of Behavior. 	Allyn and Bacon, 
1998.

Martinez Jr., Joe, Raymond P, Kesner
			Learning and Memory		Academic Press, 1991

Kalat W, James	Biological Psychology	Brooks/Cole Publishing, 1998

Kimble P, Daniel	Biological Psychology	Holt, Rinehart, and Winston, 
1992

Bachevalier Ph.D., Jocelyne	"How Developing Memory Systems Affect 
Emotion and Behavior" 
http://lcweb.loc.gov/loc/brain/emotion/Bacheval.html.
	
Anjevine, Jay B.,  Cotman, Carl W.  Principles of Neuroanatomy.  New 
York: Oxford University Press,  1981.

Carlson, Neil R.  Physiology of Behavior.  Boston: Allen and Bacon, 
2001.

Curran, Tim.  "On the Neural Mechanisms of Sequence Learning".  
http://psyche.cs.monash.edu.au/v2/psyche-2-12-curran.html

Grover, Larry.  Learning and Memory.  Marshall University School of 
Medicine, 1994.	  

Copyright © 2001, Dr. John M. Morgan, All rights reserved - This page last edited March 12, 2001
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