Learning and the development of memory are processes that cannot be strictly separated from psychology and sociology. Thus, this article deals with the physiology of learning and memory. Topics include understanding the relationship between experience and storage of acquired knowledge, how the brain deals with “useless” knowledge, and how a baby starts to understand its surroundings.
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Limbic Lobe

Picture: “Illustration from Anatomy & Physiology” by Anatomy & Physiology, Connexions Web site. Licence: CC-BY 3.0

What Is Learning?

The word learning is originally related to “teaching somebody” and “trick.” Furthermore, learning also etymologically related to “tracing something.” The conclusion is that learning is a process to acquire new knowledge. Learning is the precondition for the brain to store experiences and to use those experiences in our actions to gain benefits and prevent damage.

Formation of synapses

Learning processes during the first six months of a baby’s life hold great significance for the development of the nervous system. Environmental stimuli and experiences also play a role in this process since they lead to the formation of new synapses and the improvement of already existing synaptic connections. The ability for the brain to from and improve these connections is referred to as neuroplasticity, whether they are based on physiological or neuroanatomical conditions.

How do infants learn?

Most brain cells are already formed during pregnancy. However, an infant’s nerve cells still cannot communicate at the time of birth, since they are not yet connected with each other. These connections are developed during the first three years of life. This process takes place by developing dendrites, which enable cells to absorb information. Moreover, synaptic connections, which are responsible for relaying information, are formed. The extent of these connections is far greater than what is required. This makes it easy to make adjustments later on anywhere they are needed.

Learning capacity of babies

Babies react strongly to stimuli. This is also an important indication that a learning process is carried out. Besides, these stimuli are necessary for the brain to even be able to develop at all. This means that an environment with few stimuli hinders the development of babies.

During this development stage, the ability to differentiate faces and vocal sounds are better developed than it is in adults, which enables the baby to differentiate between close reference persons, intimates, and strangers. After the first imprinting to the personal surroundings, the baby loses a certain amount of flexibility considering its mental abilities. However, learning processes become more specific. This development takes place during the first six months of life.

How Does the Brain Work?

The brain uses neurons to communicate and, to a large extent, manage itself. However, the development of neurons and the resulting brain capacities depend on environmental and sensory stimuli. The brain works in connection with the spinal cord to send and receive information via the neurons. The brain processes all perceptions, which are also connected with each other. For this process, the brain uses already stored experiences. However, most perceptions are suppressed. Perceptions that have to be processed during the learning process are differentiated by the brain according to:

  • Relevance
  • Value of new knowledge
  • Significance
  • Meaningfulness
The Neuron

Picture: “Parts of a Neuron” by philschatz.de. License: CC-BY 4.0

Importance of Emotions During the Learning Process

Cognition and emotions play a major role in the process of learning. Sensations are used as somatic markers, which influence processing, storage, and memory. Learning also includes the strengthening of the most used neuronal pathways so they can be used longer and above all faster.

Learning as Formation and Deformation Inside the Brain

The process of learning starts with processing external influences. Learning leads to changes in the brain that can be classified into four categories: expanding, tuning, re-constructing, and pruning.

Expanding means to improve the number and strength of neuronal connections by developing a network of already existing information. Tuning describes the process of creating new connections.  During the process of re-constructing, relearning takes place. In this time-consuming and exhausting process, preexisting learning achievements (motor patterns and routine processes) are replaced by new ones that are better suited for the respective task. Pruning describes the regression of neuronal potential, which is used little or not at all. During this process, connections can be changed in such a way that they cannot be activated anymore.

Learning is differentiated into:

  • Intentional learning
  • Individual learning
  • Collective learning
  • Physical learning
  • Social learning

Significance of social interaction and physical activity

Humans need social interactions. This also applies to the brain. Mirror neurons inside the brain are responsible for the development of the required cognitive orientation pattern. Physical activity is important for brain performance as well. This particularly applies in the first years of life.

Localization of Learning Processes and Memory

Cerebrellum Animation

Picture: “Cerebellum” by Database Center for Life Science(DBCLS). License: CC-BY-SA-2.1

Temporal Lobe Animation

Picture: “temporal lobe” by Database Center for Life Science(DBCLS). License: CC-BY-SA-2.1

Motor learning is located in the neurons of the cerebellum and basal ganglia. The declarative memory is located in the medial temporal lobe. A lesion of the hippocampus leads to an anterograde amnesia. This means that new information cannot be stored anymore.

Memory Systems

The procedural memory is located in the striatum and uses the pathway of the neocortex. Associative learning takes place inside the amygdala for emotional processes and in the cerebellum for motor processes. Non-associative learning occurs in the form of habituation and sensitization (both via reflex circuits).

Hebbian theory

The Hebbian theory explains how the connection between certain neurons can be strengthened.

If an axon of neuron A is located close enough to neuron B so that neuron B can be stimulated by neuron A repeatedly or continuously, the efficiency of neuron A for the stimulation by neuron B is increased by growth processes or changes in metabolism in both or one of the two neurons. This means that experience-related changes of the nervous systems depend on certain conditions.

Development of Memory and the Papez Circuit

Limbic SystemThe Papez circuit is of great importance for the development of memory. The circuit is located in the center of the limbic system. The limbic system is located above the brain stem and exists in all mammals. It has an important role in social behavior, solicitude, love, fear, and learning by imitation.

Papez circuit

The Papez circuit is a chain of neurons, named after its discoverer, James Papez. Research on the tasks of the Papez circuit for memory performance is still ongoing. However, the assumption that the circuit controls anger and rage are already outdated, since it has been discovered that the circuit is even more complex than Papez himself thought.

These days, it is assumed that the Papez circuit serves the storage of memories by transferring information from the primary memory (short-term memory) to the secondary memory (long-term memory) or to the tertiary memory (an independent part of the long-term memory).

The Papez circuit proceeds as follows: hippocampus → fornix → mammillary body inside the hypothalamus (corpora mammillaria) → cingulate cortex → hippocampus

Papez Circuit

The Different Types of Memory

The specialist term for mind and memory is called the mnestic function. Some things are easier to remember than other things. For example, important things are easier to remember than events that hold no meaning and positive experiences are easier to remember than neutral experiences. Moreover, the process of remembering is easier in a positive prevailing mood. This also means that remembering things is more difficult in a state of fatigue or grief.

Process of encoding information

Note: Encoding is the process of transferring sensory information into a construct which is then stored in our memory system.

Working memory stores information for immediate use as part of a mental activity (i.e. learning or problem solving).

  • encodingIs thought to include phonological loop, visuospatial sketchpad, central executive, and episodic buffer
  • Allows for manipulation and organization of info vs. short-term memory

The primary effect is a cognitive bias that results in a subject recalling the first items on a list.

  • (Theory) these items have had the most time to be encoded and transferred into long-term memory

Recency effect is a cognitive bias that results in a subject recalling the last items on a list.

  • (Theory) these items are in the phonological loop and are highly accessible.


Humans have a declarative memory (explicit memory) and a procedural memory (implicit memory). The declarative memory stores information that can be reproduced because we are conscious of the experience/information. The procedural memory, on the other hand, contains experiences for which one has no direct memory of the learning process. Still, this type of memory has an influence on our behavior. A classic example is the process of learning a new language.

Sensory memory (ultra-short-term memory)

The ultra-short-term memory receives stimuli from sensory organs in the form of a neuronal excitation. This process has a duration of less than one second, and the perception can take place via the eyes or ears. The ultra-short-term memory via the eye is also referred to as iconic memory, and via the ears, echoic memory (and it perishes just as fast). Only stimuli that reach the short-term memory remain because the ultra-short-term memory has no storage capabilities.

Short-term memory (primary memory)

Memories in the primary memory (short-term memory) are available as long as we occupy ourselves with them. If that process is interrupted, the memory is lost too. Memories that begin in the primary memory can be available permanently but only if they are transferred to the long-term memory. It is assumed that the short-term memory is a transit for experiences into the long-term memory.

The hippocampus, located in the cerebral cortex, is apparently involved in the process of transmitting information from the primary memory to the long-term memory.  The Hippocampus is thought to be involved in this process because when lesions appear in the hippocampus, only the short-term memory remains intact. Another term for primary memory is “labile memory” since it is very unstable. One distraction is enough to forget the perceived or heard information. Calcium has a major importance for these processes.

Long-term memory

For storing memories in the long-term memory, repetition is particularly important. This is easily understandable when one considers the high amount of repetition required to learn new movement patterns, e.g. when learning a new sport.

Semantic networks and spreading networks

  • semantic-connectionsInformation stored in our long-term memory is done as an organized network
  • Individual ideas or hubs are called nodes (i.e. cities on a map)
  • Nodes are connected by links or associations (i.e. roads between cities)
  • Strength of association is related to how frequently and deeply the connection is made
  • Processing material in different ways leads to the establishment of multiple connections
  • Nodes are only activated once they reach a response threshold
  • Response threshold is reached by the summation of input signals from multiple nodes
  • Activation of a node leads to stimulation of neighboring connecting nodes
  • The activation of a few nodes can lead to a pattern of activation within the network that spreads inward (known as spreading activation)
  • Explains contextual cues, priming, and associations

Process that aid in encoding memories

  • Mnemonic is any technique for improving retention and retrieval from memory
  • Rehearsal: use of the phonological loop
  • Chunking is a strategy which organizes information into discrete groups of data
  • Hierarchies organizes words or information into categories
  • Depth of processing: deeper level, semantic content leads to better recall
  • Acronym (i.e. AIDS, CD-ROM, FAQ)

Dual coding hypothesis indicates that it is easier to remember words with associated images than either along.

  • More connections made to the memory
  • Deeper content

method-of-lociThe method of loci involves imagining moving through a familiar place and having stops or loci.

  • Items to be recalled are mentally associated with these physical locations or loci
  • Provides a deeper representation
  • Also known as the “Journey Method”

Self-reference effect involves making new info personally relevant

  • E.g. “I live on Beatrice Ave…”

The process of Learning Inside the Brain

The hippocampus also plays an important role in the process of learning. There exists a connection between nerve cells and the neuronal mechanism which is assumed to be the physiologic substrate of learning. This physiologic substrate consists of continuous electrophysiologic, morphologic and molecular changes of nerve cells. For information to be available long-term, long-term potentiation (LTP) is necessary. LTP facilitates the stimulation of afferent axons over a period of weeks as well as a stronger Ca-influx.

Everything stored in the long-term memory is available during one’s entire life. The processes of the long-term memory take place under the influence of the neurotransmitter glutamate (glutamic acid).

Pathology of Memory Performance

The highly complex system of learning and memory is susceptible to malfunctions. If anomalies occur, the differential diagnosis has to be made with the greatest care. This is also because even changes in the mineral balance of the body can lead to disorders that give the impression of a disease (e.g. calcium deficiency). Furthermore, cases of dementia are increasing, which is partly due to increase life expectancy. Currently, approximately 1.5 million people with dementia are estimated to live in Germany.


Amnesia is one type of memory disorder in which a patient loses access to stored information. The term “amnesia” originates from the Greek a (without ) and mnémē (memory). Amnesia is not an independent disease but is the symptom of a disease or the consequence of an influence on the brain. This influence can be internal or external.

In the case of amnesia, it is not possible for patients to store experiences or learned knowledge. This can affect all types of information or only certain parts, for example patients can lose access to memories from certain stages of their lives. In most cases, the patient is able to remember events that happened long ago rather than events that occurred just lately. There are different forms of amnesia. However, they cannot be strictly separated from each other. The following forms are of importance:

  • Retrograde amnesia
  • Global amnesia
  • Transient global amnesia
  • Congrade amnesia
  • Psychogenic amnesia

Alzheimer’s Disease

Alzheimer‘s Disease is characterized by a regression of nerve cells, which can result in the brain shrinking up to 20%. The consequence is an impaired relay of information. Furthermore, Alzheimer’s may make processing information nearly impossible. At the same time, plaques of protein fragments form. Particularly affected by Alzheimer’s are those brain regions responsible for processing information and memory performance.

Left: healthy brain; right: brain with alzheimer

Review Questions

Solutions can be found below the references.

1. Which statement concerning short-term memory is true?

  1. It is available for about one hour.
  2. It relays all information to the long-term memory.
  3. It depends on the functionality of the hippocampus.
  4. It stores the most important information.
  5. It does not absorb information from the ear.

2. Which statement is true?

  1. Newborns have yet to develop nerve cells.
  2. Newborns still have no connections between nerve cells.
  3. Connections between nerve cells develop during the third year of life.
  4. The development of connections is fixed and unchangeable.
  5. Dendrites are responsible for relaying information inside the brain.

3. The brain processes information according to:

  1. Amount
  2. Experience
  3. Significance
  4. Individual impression
  5. Duration of the time it remains inside the short-time memory
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