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Memory Disability Jacques A. Desjardins Université Paris Sorbonne-Paris IV |
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Diagnostic Features As
a skill, memory is inseparable from the intellectual functioning involved in
learning: memory is linked to performance in academic subjects in particular,
and to cognition in general and, therefore, is a critical area of focus in
the field of learning disabilities. There
are several models which view memory as an integrated “multiple memory
system” which gives a comprehensive understanding of what is perceived. Memory-related
disabilities are identified based on the memory systems (e.g., visual, verbal
and conceptual) which are subserved by distinct
areas of the brain: the following five memory systems are involved in memory
dysfunction: Short-Term Memory stores
information that is needed for just a few seconds or minutes. After that, it
vanishes. Information contained within the short-term memory system is, by
definition, transient, and once information passes into long-term memory, it
assumes a more stable form, at least temporarily. Working Memory is a form of
short-term memory; it stores information for a brief time to be used for some
specific purpose. Working memory comprises the central executive controlling
systems which interact with two subsidiary storage systems, the speech-based
phonological system and the visual-spatial system. Long-Term Memory refers to
pieces of information that are stored in brain areas for more than a few
minutes and then retrieved when needed. Long-term memory is the sum total of
what is known: a compendium of data ranging from one’s name, address, and the
names of friends and relatives to more complex information, such as the
sounds and images of events that occurred decades ago. Declarative Memory refers
to information that requires a conscious mental effort to recall. There are
two types of declarative memory: episodic and semantic. Episodic Memory contains
memories that are linked to events which occurred at specific times and in
specific places: e.g., the school attended in Grade 2 is remembered when
revisiting an event memory; sequential-temporal information is recalled along
with the spatial information of where the event took place. Semantic Memory stores
factual knowledge. It contains much of the basic information learned, such as
in school or in social interactions, along with an assortment of other facts,
such as a person’s name and address or parents, as well as the meaning of
words. Unlike episodic memory, semantic memory is not bound to time or place. Procedural Memory refers to
the storing of procedures; the skills and routines that are carried out
automatically to perform actions such as writing numbers in columns and
adding an addition sign to add them up, or even getting dressed in the
morning. Procedural memory relies heavily on spatial-ordering. Diagnostic Criteria A
memory disability entails performance below the 25th percentile on
standardized measures of one or more of the memory systems. The memory
disability has some impact on learning and/or social cognition. Clinical
and neurological standardized memory tests focus on different aspects of
short- and long-term recall of verbal and visual information; recall of story
content, designs and pictures or visual-spatial motor sequences. Other tests
specialize in executive functions. Specific memory disabilities could be
related to different learning disabilities: e.g., phonological memory
weaknesses are often observed in phonological reading disability. Still
other standardized tests measure memory dysfunctions in relation to damage in
specific brain areas (e.g., verbal, visual and motor areas). In all cases,
the person’s memory difficulties will determine the choice of tests and their
appropriateness. Differential Diagnosis If
a memory disability co-exists with a learning disability, the memory
impairment is secondary to the learning disability and/or to a physical or
psychological disorder. If
a working memory disability coexists with some executive function problems
(organization of materials, behavioral/emotional control or inhibition of
impulses), then a diagnosis of executive learning disability could be
considered. It
is important to point out that “forgetting” is a symptom of many learning disabilities
as well as of physical and psychological disorders. In addition, we are all
subject to absentmindedness or misattributions, occasional difficulty
remembering bits of information or an event because it didn’t register
sufficiently in the first place. Forgetfulness can also be the result of a
“block”; e.g., the “tip of the tongue” phenomenon, or suggestibility.
Miss-recall of information is often the result of suggestibility; the
vulnerability of memory being influenced by information learned after the
fact; e.g., implanted false memory. Also,
biases or distortions of memory occur as a result of the unique perspective
of a person’s personality, heuristics, fallacies, mood, beliefs and own
personal experience. The Rashomon is a classic film
that tells the story of a violent crime from the viewpoint of four
characters, including the alleged perpetrator and victim. Each account is
different reflecting each character’s perspective during the event. How
information is presented or integrated can color perceptions of events and
characters along with their motivations and future undertakings. If one read
Julio Cortazar’s novel, Hopscotch, in a
conventional way or by skipping or re-arranging chapters, s/he would have
different perceptions of the story content. Intervention Strategies One
of the most common beliefs is that memory difficulties are irreversible and,
in aging, lead to uncontrollable mental declines. However, the brain
continues to grow new neurons and keep changing throughout the life span, a
process known as neurogenesis. The capacity to
produce new cells is a hallmark of the brain’s plasticity, which allows it to
continuously alter neural circuits and form new synaptic networks. Memory
difficulties and/or stereotyping in children often lead to fear and learning
helplessness; however, memory is a multidimensional “organism” capable of
adaptation and growth. In fact, research in this area stresses the importance
of education, emphasizing that memory involves a body of skills capable of
being developed and maintained with applied effort. Sound bodies promote
sound minds. Persons who engage in regular exercise, do not use alcohol or
smoke, maintain healthful nutrition and get enough sleep not only have a
better memory but are generally healthier and happier. A
number of therapies based on different theoretical approaches were devised to
help people with memory disabilities or impairment. Cognitive-behavioral
therapy whose goals is Developing Rational and Emotional Adaptive Mindsets
(DREAM) has been demonstrated to be helpful in altering maladaptive beliefs,
and replacing them with thoughts and expectations conducive to memory change
and growth. For
memory to be multifaceted and integrative, memory improvement relies on a
multi-approach. RARE emphasizes Relaxation, Attention, Rehearsal and
Envision. For instance, a relaxed and healthy disposition will facilitate
attention; attention deficits have been identified as a primary cause of
memory difficulties. Visualization
techniques to enhance memory functioning focus on the use of sensory
elaboration; e.g., the focus of visual mnemonics is the application of
imagery techniques. Although visual imagery is the most common sensory
techniques utilized, all of the senses (tactile, smell, auditory) can be used
to elaborate potential memory. In interactive imagery, for example, the items
to be remembered are interconnected and interact in some way. Prevalence and Etiology As
mentioned above, there are multiple systems and areas of the brain associated
with memory. And memory disability or dysfunctions are symptoms of many
learning disabilities, and/or psychological disorders (e.g., depression and
anxiety, and dissociative disorder), and physical
diseases (e.g., HIV, diabetes, viral and bacterial infections, Parkinson
disease, alcoholism, cerebrovascular disease), and
rare degenerative brain disorders (e.g., Pick’s disease, progressive supranuclear palsy, Creutzfeldt-Jakob disease, and
Huntington’s disease). Changes within neurons: loss of neural branches (dendritic spines), decrease in density of synapses, and
deterioration of the myelin sheath, either due to neural disease or age, can
cause memory disabilities. The
brain area called the hippocampus (located in the temporal lobe) is generally
considered the central processing unit for memory. Other areas involved in
memory functioning include the medial temporal lobes and the diencephalons.
However, many more brain areas are responsible for memory, including language
and visual areas, all working in harmony. This makes the function of memory
more resilient when damage/dysfunction occurs in one specific area of the
brain. Given the complex patterns of memory functioning, and the fact that
memory is not a single entity, different methods can be created and tailor-made
to encode and retrieve memories, depending on the type of memory
dysfunction. References Aaron,
Nelson (2005). Achieving Optimal Memory. Mason,
D. J., & Kohn, M. L. (2001). The memory workbook. Swanson,
H. L., & Saez, L. (2003). Memory difficulties
in children and adults with learning disabilities. In Swanson, H. L., Harris,
K. R., & Graham, S. (Eds). Handbook of learning
disabilities (pp. 182-198). |
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