Fourth Translation: Memory
Pielmaire, L., Walder, B., Rebetez, M.M. L., & Maercker, A. (2011). Post-traumatic stress symptoms in relatives in the first weeks after-severe traumatic brain injury. Brain Injury, 25, 3, 259-265.
Background:
Severe traumatic brain injury (STBI) occurs in developing countries 12 out of every 100,000 per population every year. According to this study 53% of STBI patients died within 6 months, 17% had poor outcomes and 29 % had reasonable outcomes. Those who survive STBI may be profoundly impaired throughout their life time and require full time supervision by family members or their spouses. Those who are related to STBI patients have been found to suffer symptoms of depression and anxiety soon after their loved one’s accident. This study is the first to research the effects of short-term post-traumatic stress (PTS) on the relatives (proxies) of STBI patients.
Theory:
The severity of TBI was assessed with the Abbreviated Injury Scale score of the head region (AIS head) this classified all categories of injuries by their degree of threat to life on a scale from 0= no injury to 6= lethal. In this study all patients had an AIS head score of 4= severe to 5 = critical. The Glasgow Coma Scale (GCS) was also used which is a measure of brain injury scale. The Impact of Event Scale-Revised (IES-R) was used to measure the severity of PTS in proxies.
Findings:
This study showed significant levels of PTS in proxies of patients which sustained STBI within the time of one month after their loved one’s injury. This study found that women proxies suffered from significantly higher levels of stress than men. In addition a significant level of PTS was identified 3-5 days after their family member was admitted to the ICU. The relationship between the state of consciousness of the TBI patient and their relative was associated with the proxies level of stress as well.
Clinical Applications:
This is important information to know when working with STBI patients and their families. Knowing how to provide information on their family member’s condition and outcome to some one who may be experiencing PTS will modify your delivery of this information. We as occupational therapist practitioners educate and inform patients and families as part of our job. Often we have to break down complex information on anatomy or the workings of the nervous system for our clients and their families to understand. In the event of a TBI, you need to explain why the patient is agitated or why they are making inappropriate sexual advances to everyone in the room. It is important to understand what the family member is going through as well, if you want to treat the patient as a whole. By better understanding of their experience, you will be able to inform them of what to expect and prepare them in a way that will help them deal with stress.
Take Home Point:
Working with brain injury patients means you are working closely with their families and spouses in addition. From the first time you meet your patient, most have had their families in the hospital room or in a hallway ever since their accident. They have held a watch over their family member to see if they will survive.
You see the stress in their faces and you know they have been through an emotional ringer. From the first phone call notifying them that of their loved one have been in an accident; waiting in an ER hallway to the intensive care unit, waiting to hear if their wife or child will live through the night. It must be one of the worst things to live through. I often see my patient’s family in inpatient rehab and there is a relief that they will be OK now but the real work is just beginning. With years of adjustment and adaptation to a different person than the one they once knew.
Mary Groves, M.S. Anatomy, OTR/L
Glossary:
Third Translation: Memory
Wilhem, I. , Diekelman, S., Molzow, I. , Ayoub, A., Molle, M., & Born, J. (2011). Sleep Selectively Enhances Memory Expected to Be of Future Relevance. The Journal of Neuroscience, 31, 5, 1563-1569.
Background:
Have you ever wondered what your brain is doing while you sleep and why we need sleep? It has been suggested the functions of sleep are multifold; physical reparative functions of the body take place during sleep, conservation of energy, adaptive strategies for future planning and memory reprocessing. Our brain encodes thousands of bits of information during our waking day but most of us do not remember every bit of information. We could say that our brain is selective with memory. It has been suggested for some time that our memory may be enhanced during our sleep. It has also been reported that the hippocampus of the brain is a mediator of dependant declarative memories during slow-wave sleep (SWS) which are activated after learning. This is so fascinating to signal out a very specific area of the brain for this function!
Theory:
There are several cycles or stages in human sleep; rapid-eye-movement sleep (REM) and 4 stages of non- REM (NREM) sleep; stages 1, 2, 3, and 4. The deeper stages of NREM sleep, stages 3 and 4 are also know as slow-wave sleep (SWS) these stages are considered to be the most restorative. This is when the body repairs its self and grows. Research has suggested that encoding of long-term memory occurs during sleep but the process is poorly understood. The consolidation of memory may be facilitated during SWS particularly within the hippocampal region for declarative memory. SWS may be reactivated during this state of sleep in the hippocampus. This is exciting to think that during our deepest stages of sleep and the lowest wave production of our brain we may be laying down memory!
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| Slow Wave Sleep |
Findings:
This study found that sleep facilitated memories which were expected to be recalled later on and had relevance for future use than memories which were not expected to be recalled. When participants in this study were informed that the information which they were learning was to be used later their memory systems were improved for declarative and procedural memories after sleeping on it. Their learning was based on expectant learning behaviors and the hippocampus region adapted to consolidate these neural networks! Great stuff indeed, this means if we are expected to learn something which has importance and for later use sleeping may help to incorporate new learning in to long-term memories.
Clinical Applications:
As clinicians we know when our patients have not had enough sleep, their participation in therapy my not be as effective. They may be struggling to pay attention or to stay awake. Those of us who work with the pediatric population may know this so well! Trying to work with a child who has not had enough sleep may be dealing with a crabby child and refusing to work with you. Not a pretty sight! Our patients and our selves need too sleep especially if we are to learn and thrive. I like the idea of learning something and sleeping on it and ingesting it during the SWS stage.
Talk Home Point:
I love to sleep but I do not always get a chance to sleep enough, at least not since 1993. Sometimes I crave sleep. I will be walking on campus at CSUDH on a nice warm day and spot a beautiful patch of green grass surrounded by trees and flowers, and think to my self that would be lovely place to take a nap if there were not about a hundred people walking past me including my own students, may be I could hide in the bushes. I move on and fall asleep some time around or the next day. I rely on power naps, I sleep for an hour and then do work, just enough to get some rest till I can sleep longer for a more few hours. My father took power naps, he would come home nap for an hour and then go to his garage and work on his projects till late at night and then get up early the next day for full days work, “Daughter like father”. Some of us do not need a full nights sleep, we can work for long hours and not suffer from sleep depravation. But, let us not forget that sleep is a gift, it restores our bodies. The phrase “beauty sleep” is so true! This may explain why I look so tired all the time. To those of you who have the chance to get a full night sleep- enjoy and dream on! I envy you.
Mary Groves, M.S., OTR/L
Glossary:
Declarative memory- Declarative memory is the part of long term memory which is concerned with the storage of factual information.
Hippocampus: a ridge on the surface of the cerebral cortex and is associated with memory functions.
Procedural memory- is involved with the storage of the physical memory of how to do something. When you tie your shoes, procedural memory is the part of the memory which allows you to remember how to tie your shoes.
Maex, R., and Steuber, V. (2009). The first second: Models of short-term memory traces in the brain. Neural Networks, 22, 1105-1112.
Background:
This article is a review of several models for understanding short-term memory formation. I liked this article because it discusses other process to form memory which is valuable to consider understanding this complex function of our brain. The lasting effects of the stimulation of the neural circuitry involves many factors some of which includes; the duration of the memory stimulus, relationship to other stimuli, association with reward, attention, emotion, and cell membrane potentials. A memory stimulus leaves a short-term trace which is called ‘memory’ traces. We do not know how these exactly work but they can do several functions; form a decay response, form a persistent change in activity, change the synaptic response, or be absorbed into the temporal process to be integrated.
Theory:
Memory functions do not only include cognitive memory tasks but also sensory and motor tasks which require two signals in real time to be correlated. An example would be receiving sound vibrations from the right and left ear to localize the sound source or a stimulus stored in working memory and the stimulus triggered its recall later. For memory tasks, a stimulus has to be temporarily stored or have a response delayed to compare with other stimulus later. The time delay can range from tens of microseconds to several seconds later. Two other events to consider with memory are temporal (pathway) integration and network oscillations. Temporal integration means the neural pathway of a memory trace will follow a discreet path to be incorporated into the memory formation. An oscillation refers to the signaling of the neuronal impulses in the network or connections of a memory pathway. These tasks are thought too require a delayed response in order to lay down the formation of short-term memory traces.
Findings:
There are several basic mechanisms for generating response delays which are; discrete delays, linear versus nonlinear mechanisms, chemical reactions, diffusion and transport mechanisms, transitory cell assemblies, oscillations and phase coding, and synaptic weight adaptation. In addition, different regions of the brain may implement delay mechanisms for memory traces these include; the vestibular brainstem and oculomotor systems, auditory brainstem and sound localization, visual cortex and direction selectivity, cerebellum, basal ganglia structures, and working memory in the sensory, limbic and prefrontal cortices.
Clinical Applications:
How do we apply memory with our patients? Do we give them extra time to lay down a memory for motor function or repeat the motor task over and over again? This all depends on the person we are working with and many other factors as well. If we incorporate something which is meaningful to our patients the memory for the task or treatment effect may be integrated. Or if they had fun and made them laugh this may work. The point is to recruit many different levels of our nervous system to lay down memory. Short-term memory will become long-term memory when we use all of our functions, auditory, olfactory, gustatory, visual, proprioceptive, touch, and vestibular. These are all at our disposal to simulate our neurons to oscillate and fire off memory traces. This is the power of our profession; we know how to recruit memory with meaningful activities. We know how to incorporate function with successful tasks for our patients which leads to memory function.
Take Home Point:
As a professor I try to incorporate auditory, visual and kinesthetic learning for my students. This semester I am teaching Human Anatomy, and as you all know this requires lots of memorization of anatomical structures and concepts. This week we are learning the muscles; origins, insertion, innervation, and main action. Lots and lots of detail! Part of my plan to help my students lay down the memory for this detail is to use auditory tasks, each student is given a muscle to present to the class and describe the muscle’s insertion, origin, nerve supply and action. Then we palpate the muscle on each other. They draw the muscle on a paper skeleton or I will show a picture of the muscle or a picture of an injured muscle. I like to use pictures which may be some what gruesome because this may trigger a memory. I also like to make them laugh, this triggers memories as well. I tell my students that the muscles are my old friends, after working for 17 years with patients with these muscles I am very familiar finding them. I also tell my students what are my favorite bone, nerve, and muscle of the body. For some reason they find this funny? A couple of days ago, I received an email from one of the other cohort of students I had for Neurology. She told me she missed me because I made her laugh in class. This was a very nice way of letting me know we laid down some happy memories and we learned as well.
Mary Groves, M.S., OTR/L
Glossary:
Declarative memory- Declarative memory is the part of long term memory which is concerned with the storage of factual information.
Procedural memory- is involved with the storage of the physical memory of how to do something. When you tie your shoes, procedural memory is the part of the memory which allows you to remember how to tie your shoes.
Working memory- Working memory is a system for temporarily storing and managing the information required to carry out complex cognitive tasks such as learning, reasoning, and comprehension. Working memory is involved in the selection, initiation, and termination of information-processing functions such as encoding, storing, and retrieving data.
Memory
Mizuno, K. and Giese, K., P. (2010). Towards a molecular understanding of sex differences in memory formation. Trends in Neurosciences, Vol. 33,285-291.
Background;
Has anyone accused you of thinking like a female or male? This may have been a way of putting the sexes in their so called “place” but maybe we should not take this as an insult. There are indeed differences in the brain between the sexes, so let’s find out what they are! Male and female brains do work differently. This article discusses the molecular processes which take place in the hippocampus which are different in males and females. The hippocampus is a structure which has roles in memory formation in humans and rodents. These functions include declarative and spatial memory. It has been found that males perform better than females in some spatial memory tasks, as where other spatial tasks such as object location are better performed by females. Males and females have been found to use different strategies to solve spatial memory tasks by using geometric or landmark cues.
Theory:
Time: 1949, Psychologist: Donald O. Hebb, theorized that memory formation would be a result of cellular processes that would amplify the firing rate of a first order neuron down to a second order neuron in the chain of fire and this would allow the neuron become more efficient. As a result, synaptic plasticity which improves the synaptic strength between neurons is believed to be a part of memory formation. Ok, what does this mean? What Dr. Hebb meant was this: memory function requires much more synaptic activity than other neurological functions in our brain. Neurons are specialized cells and in order to lay down memory, these cells require molecules to inform the neuron and their surrounding support cells (astrocytes, Oligodendrites) on various synapse functions. These functions may range from stimulating dendritic spine formation to changing the neuroanatomy of the neuron or the brain.
The formation of memory is the result of synaptic plasticity. The increased surface areas on dendrites allow a higher volume of information to reach the neuron. Changes in the efficiency of transmission of existing synapses are also a mechanism for plasticity as well.
Findings:
N-methyl-D-aspartate (NMDA) is a molecule important for gene transcription and protein synthesis which is needed for memory formation. Evidence suggests the expression of this molecule may be different in males and females, thus affecting hippocampal memory formation between the sexes. Sex differences in the hippocampus may be a result of synaptic plasticity before birth. Wow, even before we are born our sex distinctions are set in the brain! Estrogen long thought to influence memory formation in females does not directly influence this process but modulates memory formation. Estrogen influences synaptic strengthens and regulates the number of synapse on dendrites in females. Estradiol enhances memory formation but not all types of memory and depending on the level of Estradiol may impair memory formation. Recent studies suggest that synaptic kinases molecules Ca2+/calmodulin (CaM ) kinases kinase ﻪ are required for memory formation in males but not in female mice. This molecule is important for long term memory formation.
Clinical Applications:
What is the first thing you notice about a person who walks in a room? Their sex, age, or clothing. I usually notice their sex, and then their age, the clothing I could take or leave, ok may be their shoes. When working with a client we will have to now take into account the person’s learning and memory formation by their sex. The main point is to remember dendrite formation is the most important process. And we as therapist can influence this by providing stimulating activities and treatment which promotes dendrite formation.
Take Home Point:
The important question to ask is why brain functions are different in the male and female brain? Why do dendrites synapse and form differently between the sexes? We do not know the answer to these questions. We do know that dendrites are the key to memory, the more the better. But why are men and women so different? This is a fascinating question, which some would say it is so obvious, both sexes serve a reproductive purpose, make the world an interesting place, or serve to complement each other. I think about the anatomical differences, hormonal changes in both sexes, and now I find out the formations of our dendrites are different as well! It is as if the sexes are hybrids, we are humans but different between each sex- strange, very strange.
Mary Groves, M.S. OTR/L
Glossary:
Estrogen- a class of sex steroid hormones, predominantly synthesized by the ovary. Is concentration fluctuates during the estrous cycle. It is present in males but at a lower level.
Estradiol- part of the estrogen steroid hormones, most abundant in females
Hebb, Donald O. - creator of the Hebbian Theory. This describes a basic mechanism for
Synaptic plasticity the increase in synaptic efficacy arises from the
Presynaptic cell’s repeated and persistent stimulation of the postsynaptic cell.
