Study of Learning, Memory & Attention

Learning refers to the process by which relatively permanent changes occur in behavioral potential as a result of experience.

Memory is the process by which the learned information is encoded, stored, and later retrieved.

The most common theoretical classification of memory distinguishes forms of memory on the basis of the lasting of information storage:

• Short-term memory (properly defined as the ability to store information temporarily (for seconds) before it is consolidated into long-term memory).

• Long-term memory (properly defined as the ability to learn new information and recall this information after some time has passed)

• Working memory (used to refer to the temporary maintenance of information that was just experienced or just retrieved from long-term memory but no longer exists in the external environment).

Another manner to classify forms of memory is based on the nature of the information and the way of acquisition.

• Declarative memory involves explicit information about facts and associations with other events, and must be recalled to consciousness to be used.

• Procedural memory is related to the knowledge of rules of actions and procedures, which can become automatic and unconscious with repetition. Procedural memory itself is often parcelled as associative and non-associative learning.

- Non-associative learning classically refers to habituation (decreased response to a repetitive presentation of a stimulus) and sensitization (enhanced response to many different stimuli after experiencing an intense or noxious one).

- Associative (or Pavlovian) learning, animal learns that two stimuli are associated with each other (classical conditioning) or that a response is associated with a given event/consequence (operant conditioning).

Memory and learning deficits, which severely alter quality of life, appear with normal aging and are associated with numerous diseases, such as Alzheimer’s disease, brain damages, Huntington's disease, multiple sclerosis, Parkinson's disease and HIV, among others. Studying learning and memory neurobiological mechanisms is therefore essential to find efficient therapeutic strategies.

To do so, various behavioral tasks have been developed in laboratory rodents and are largely validated. There are nowadays commonly used to assess learning and memory abilities in response to drugs administration and to study their neurobiological mechanisms.

Attention is fundamental to the processing of information that occurs during learning and memory. Attentional processes enable subjects to efficiently perceive or focus on certain environmental stimuli, and to ignore others.

Impairments of attentional processes result in severe cognitive and behavioral dysfunctions, and are found in various pathologies, in particular in attention-deficit/hyperactivity disorder (ADHD), the most commonly psychiatric disorder of childhood. Moreover, deficits in attention are commonly associated with schizophrenia and with age-related decline of memory performances.