Fourth Translation: Learning
Larson, E. B., Ramaiya, M., Zollman, F.S., Pacini, S., Hsu, N., Patton, J. L., & Dvorkin, A. Y. (2011). Tolerance of a virtual reality intervention for attention remediation in persons with severe TBI. Brain Injury, 25, 3, 274-281.
Background:
After a traumatic brain injury (TBI) multiple problems may result in for the individual after this type of injury. The disruption of axons and release of neurotransmitters into the neural environment causes secondary damage and further trauma. Often, these mechanisms result in hemiparesis, sensory and motor impairment and severe cognitive deficits. These cognitive deficits prove to be challenging for the individual to return back to work, school or to pre-morbid roles. Impaired attention is one of the major deficits for these individuals. As part of an individual’s rehabilitation, treatment of attention deficits is a priority. Pharmaceutical treatment is at times prescribed for attention deficits. Methylphenidate has been proven to provide assistance for this disorder. But long term mediation requires therapy and rehabilitation practitioners have used different approaches to assist in this treatment.
Theory:
There are numerous approaches for attention impairments. One, Attention Process Training (APT) consists of exercises in maintaining selective, alternating and divided attention. Clinical trials have shown improvements in individuals with TBI, with outcomes after treatment, but one year after treatment these individuals were no different in function compared to the control group with out intervention. New technologies are being utilized in cognitive rehabilitation such as virtual reality (VR). VR consists of a computer generated environment which displays objects in a three-dimensional (3-D) space. These objects can be changed to adapt to the individuals needs and attention level. This makes this approach applicable to the individuals’ to provide a meaningful environment and familiar to the individual.
Findings:
In this study participants used a three-dimensional cancellation exercise for sustained attention tasks. The subjects were in an inpatient rehabilitation program and were post TBI. Participants were rated at Rancho level IV to V and all were able to use their right hand and had no visual deficits. They were seated in a dark room in a large space and held in their right hand a robotic arm. The subjects wore glasses and moved the robotic arm with a curser to eliminate shapes superimposed onto the space in front of them. During these exercises most of the subjects were able to maintain attention to these tasks. Behaviors such as restlessness did occur but the subjects were able to tolerate the exercise with out any other disruptive behaviors.
Clinical Applications:
Any one who has worked with TBI individuals knows all too well the challenges in maintaining their attention during treatment. It is very difficult and a very fluid environment. Their behavior may change from calm and quite to agitated and screaming. I use to work on a BI team and I have seen all types of behaviors. An occupational therapist has to “read” their patients mind and anticipate what behavior they may display and be ready to provide the intervention which would best suit their patient at that time. VR may be an adjunctive to other interventions which may provide TBI individuals with the opportunity to develop attention strategies. Of course the cost may be prohibitive to many rehabilitation units and providing a room may be difficult to find.
Take Home Point:
I like the concept of VR, as an adult watching Star Trek the Next Generation the VR deck was a great leisure tool on the starship Enterprise
Mary Groves, M. S. Anatomy, OTR/L
Glossary:
Rancho Levels of Cognitive Functioning: the scale is used mostly for patients who demonstrate cognitive and memory deficits after a TBI. There are 10 levels.
Level I- no response: total assistance
Level II- generalized response: total assistance
Level III- localized response: total assistance
Level IV- confused /agitated: maximal assistance
Level V- confused, inappropriate: moderate assistance
Level VI- confused, appropriate: moderate assistance
Level VII- automatic, appropriate: minimal assistance for ADLs
Level VIII- Purposeful, appropriate: SBA
Level IX- purposeful, appropriate: SBA on request
Level X- purposeful, appropriate: modified independent
Third Translation: Learning
Vasudevan, E. V. L., Torres-Oviedo, G., Morton, S. M., Yang, J. F., & Bastian, A. J. (2011). Younger Is Not Always Better: Development of Locomotor Adaptation from Childhood to Adulthood. The Journal of Neuroscience, 31, 8, 3055- 3065.
Background:
When we think of how children are able to adapt to new experiences and learn quickly we may automatically assume children are better than adults in all learning categories. This study asks whether children or adults are better in acquiring new locomotor patterns and adapting. Adaptation is a type of motor learning which is involved for walking, reaching, eye movement, and balancing functions. When we use our bodies for movement the mechanisms of adaptation help to recalibrate movements in response to these new alterations of motor responses. It may take minutes or hours which will eventually be stored as a new motor pattern. This adaptation requires the ability to use a feedback system for motor responses to predict and re- adjusts motor plans for any new alterations in movement.
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Theory:
Adaptation is essential for coordinating movements with new movements. This study asks, do these mechanisms develop at an early age or does adaptive learning develop over time? The process of adaptation involves several central nervous system structures which includes the cerebellum, the main adapter to new movement of the limbs. The cerebellum is an amazing structure; it is responsible for gross movement of the limbs, associated with emotional behavior and cognitive functions to some extent and is associated closely to the thalamus, basal ganglia structures, vestibular system and the neocortex. The cerebellum is the main player in adaptation of new motor learning experiences.
Findings:
This study used a split-belt walking task to study and measure the walking patterns of participants from age 3 years to adulthood. They also studied the walking patterns of individuals with cerebellar damage. They chose this task because it involved the cerebellum and used alter walking patterns of locomotor response to measure adaptations to this activity. Their data showed that adults were able to adapt to new locomotor movements at a faster rate than children between the ages of 3 years to 5 years. Interestingly, they found that individuals with cerebellar lesions were not able to adjust to new walking patterns and were at the level of the age of 3 years in learning new locomotor adaptations.
Clinical Applications:
There are many questions to ask regarding this study. Children at the age of 3 years to 5 years are still developing motor skills how did this affect the results of their findings? I ask my self is this experience-dependant plasticity or is it a developmental dependant activity? Adaptive learning may require both for the functions of new locomotor learning. Some research suggests that cerebellar connections are a developmental process and requires time to reach maturity. We know that adaptation of timing of movement requires connections from the cerebellum to the vestibulospinal and reticulospinal pathways to the spinal cord. Research has shown that these connections are developed before birth. There are other connections which take time and may influence these findings. It is intriguing to think about these adaptations which we and our patients incorporate for movement.
Take Home Point:
When children play they play with enthusiasm and joy. They may fall but they get up and try again, totally involved in the moment. I like to think of the process involved with that activity. I think of the elaborate connections to participate in any motor activity; it is a symphony of synaptic connections from the motor planning area of the frontal lobes to the primary motor strip to the descending corticalspinal pathways and on to the muscles. Other structures add to this complex process, input from the basal ganglia structures help to coordinate smooth movement of the limbs which sends this information to the cerebellum for further modification and then back to the thalamus and neocortex. This is just a simplified version of what takes place for movement.
Recently I bought an anatomically correct plastic model of a gastropod (snail), complete with a see through shell and the internal parts. As I was happily putting my new model together, I was thinking how they use locomotor movements. Their foot undulates by a series of contractions of muscles as they glide on a clear film of slime. Gastropods have a very primitive nervous system, only rudimentary ganglia no brain but they get by sliming along my pansies and eating holes in my flowers.
Human movement is a gift of which I am grateful for every day!
Mary Groves, M.S. Anatomy, OTR/L
Glossary:
Basal ganglia- collection of nuclei deep in the cortex. These include the caudate nucleus, putamen, and the globus pallidus. These structures are associated with stereotypic and automated movements.
Neocortex- the out most surface of the cortex which contains six layers of neurons,
including the pyramidal neurons
Primary motor area- area of the frontal lobe which contains motor neurons dedicated to specific areas of the body. Often referred as M1 in the Precentral gyrus.
Thalamus- a two lobe structure on the medial side of both hemispheres of the brain composed of a collection of 26 nuclei in each lobe, which are the main relay for sensory information to the Neocortex. The thalamus is also involved in relaying motor information from the cortex and basal ganglia structures to the cerebellum. The thalamus receives and sends visual information of the visual tracts.
Learning :Second Translation
Pinto, J. G. A., Hornby, K.R., Jones, D. G., and Murphy, K.M. (2010). Developmental changes in GABAergic mechanisms in human visual cortex across the lifespan. Frontiers in Cellular Neuroscience, 4, 16, 1-12.
Background:
The visual system has always intrigued me with its complexity and the structural beauty of the eye! Visual detection starts in the lens of the eye where light enters and photo receptors are stimulated in the retina, and then electrical impulses are carried by the optic nerves. From the optic nerve visual information travels ipsilateral and contralateral to the optic chiasm and the optic tracts. Part of this visual information takes a side trip to the Thalamus and then it is rerouted back to the optic tracks and finally all this information reaches the primary visual (VI) cortices located in the occipital lobes. Currently, we know there are about 33 visual functional regions located in the occipital lobes. These visual areas send information to interpret color, shape, shades of gray, or facial recognition, these are just some of the functions of these regions. Developmentally these visual regions require experience-dependant plasticity, which means a person must experience visual stimulation from the beginning of their birth, childhood, and into early- adulthood to learn to interpret visual information. It literally takes all this time to develop these visual functions. Amazing!
Functional development of the visual cortex has been attributed to changes in the synaptic expression of GABAergic neurotransmitters. GABA or Gama-Aminoburtyric Acid is the major inhibitory neurotransmitter of the central nervous system. These signaling mechanisms have been known to alter experience-dependant plasticity through fluctuations of excitatory or inhibitory signaling between visual synaptic connections. During visual development eight different types of GABAergic markers have been identified in ocular plasticity, and orientation selectivity. Intraocular inhibition which is modulated by GABAergic inhibitory pathways has been found to develop binocular visual functions in the visual cortex. I find this information fascinating because up to this point I have only considered the tracks as having influence on visual information, but here is where the workings of the visual system truly happen on a molecular level!! In neurological terms this means there has to be mechanisms to stop excitatory impulses of neurons in order to lay down the circuitry of the human visual system.
Theory:
GABAergic neurotransmitters are involved with pre-synaptic and post-synaptic processes which have been suggested are important to experience-dependant plasticity in the visual cortex. This means the visual experiences which we develop are modulated by these neurotransmitters by inhibiting or exciting neurons associated with our visual cortex to learn visual information as we develop. Other molecules involved with the visual cortex are GAD65 (CBI) this receptor modulates GABA release and VGAT packages GABA in to vesicles which will be released into the synaptic cleft of axonal terminal boutons. There is a balancing of these excitatory and inhibitor molecules which through the lifespan of the human visual system help to develop visual process and are part of the decline in these visual functions. Gephyrin influences receptor sites and helps to anchor these protein dependent sites.
Findings:
Human Tissue samples from postmortem visual cortices in the posterior occipital lobe of the primary visual cortex (VI) were examined from 28 individuals from the age of 20 days to 80 years. The findings of this research demonstrated that transitional changes in the expressions of GABA receptors spans the life time of the human visual development and disruption of these mechanisms can cause long lasting changes in visual acuity.
The first stage of this development begins at the time of birth to preteen years and is considered important for the development of ocular dominance plasticity in VI cortices. Stage two the teenage years to adult years, there is a transition from a greater capacity for using great amounts of this neurotransmitter to creating a reservoir of GABA ready to use at anytime. It was suggested that at this time of the human life span there is a need to maintain a high level of inhibition for optimal coding of neural impulses for perceptual functions and orientation discrimination. Stage three, represents the transition to older adults (55 years and older) the capacity of GABA and VGAT synapse declines. The aging change affects perception of moving objects which represents a loss of perceptual functions. The inhibitory functions of GABA neurotransmitters play an important role to develop the circuitry of these visual regions and it the decline of visual functions through the human lifespan.
Clinical Applications:
It is not enough to know the visual tracks but we need to know what happens and influences the visual system on a molecular level in the development of the visual cortices. Now, when I work with a client I will have to consider their visual function depending at the stage of their life span. This may influence the person’s visual learning and affect treatment strategies. Does this contribute to the decline of vision? Does this require inhibitory process to develop the circuitry of our visual system? Findings of this research may have clinical applications for physicians for treating amblyopia by providing pharmaceuticals in regulating levels of GABA neurotransmitters. But as occupational therapist this is another layer of understanding of the visual development to take in consideration.
Take Home Point:
Growing up I had very bad vision starting at the age of 10 years, and I started to get terrible grades in school. Finally, my teacher figured out that I could not see the board and the pages of a book well. Further proof of my blindness, I walked or literally bounced off a glass door and fell to the ground while trying to enter a shopping mall with my mother. I had not notice that the store opening was an actual glass door. I really need eyeglasses!
I got eyeglasses, which at that age was devastating, I looked like an owl. But I could see again which was great. At 14 my dad bought me my first surfboard and I had to surf with my glasses tied to my head and ears so I could see where I was surfing. The “coolness” effect of taking up surfing was negated by my eyeglasses. Again I looked like a dork. So, like many of us who have to wear eyeglasses or contacts why do we start to lose our vision at an early age, is GABA not working for us? May be the inhibitory neurotransmitters are not working and causes an early decline in visual function. But the regions of our visual cortices do function; we can identify faces, shapes, and color. There is a distinction between function and development. Near sight- ness or diplopia caused by the curvature of the lens versus the levels of GABA or is it the effect of GABA as well? These questions remain but we must consider the smallest and probably the most important elements of the nervous system.
As entertainment, I often like to imagine my self the size of a molecule or a complex compound and I am walking on the axon of a neuron as if it were a fallen Douglas fir tree. I can walk close to the terminal boutons. I can see the synaptic impulses fire off and I am witnessing the neurotransmitters crossing the synaptic cleft. It’s a beautiful sight; too see the inner workings of our brain on this level and the beauty of our inner universe! May be being a nerd and looking like a dork is not so bad.
Mary Groves, M.S., OTR/L
Glossary:
Amblyopia- reduced ability to see, while the eye itself appears structurally normal.
Lateral geniculate nucleus- part of the thalamic nuclei which receives visual information and reroutes this information back to the visual tracks.
Thalamus- a two lobe structure on the medial side of both hemispheres of the brain composed of a collection of 26 nuclei in each lobe, which are the main relay for sensory information to the Neocortex. The thalamus is also involved in relaying motor information from the cortex and basal ganglia structures to the cerebellum. The thalamus receives and sends visual information of the visual tracts.
Occipital lobe- the posterior cortex associated with vision interpretation
Learning
Leuner, B., Glasper, E. R., and Gould, E. (2010). Parenting and Plasticity. Trends in Neuroscience, Vol. 33, No. 10, 465-473.
Background:
Becoming a new parent involves a new learning experience for both first time mothers and fathers. And unlike other species say frogs, we do not just lay eggs in a pond and swim off to leave our offspring to raise themselves. As any new parent soon learns, it takes time and energy to succeed in raising a human being. Through this learning experience our brain change which involves our neural pathways and neuroendocrine functions. There has been an increase in literature which has shown changes in the parental brain’s structure are molecular and electrophysiological changes.This article discusses changes in two regions of the brain, the hippocampus and prefrontal cortex and the role of hormones and environment on learning parenting behaviors.
Mothers and fathers may recruit neural pathways, hormones, and neuromodulators in learning parenting behaviors. Understanding these changes in the brain may be important to better understand the mood changes in first time mothers who often experience postpartum depression which has been associated with poor child care. Infants who have been at the receiving end of this care have been know to suffer impaired cognitive and emotional functioning including developmental anxiety and depression in later life.
Theory:
The experience of parenting and hormonal expression produces neural plasticity in the hypothalamus, amygdala, and the olfactory bulb. These experiences not only produce changes in the maternal parent but can also change the paternal brain as well when they have contact with infants. The hippocampus plays an important role in learning, memory, and anxiety regulation and feedback for stress response. This is an important region of our brain associated with the learning and behavior for parenting. The region of the hippocampus is also an important area for adult neurogenesis. This is the area for renewal of neurons in the adult brain. A high degree of dendritic remodeling, formation, and elimination occurs in this region which in necessary for emotional and behavioral responses. This speaks to me because of the importance of this structure in learning and the high degree of learning associated with a new skill such as parenting; which requires a high volume of synaptic connections. The hippocampus was built for taking in new experiences and transferring them into behaviors.
Studies in postpartum behavioral changes in mammals (rodents) have shown virgin female mice to be unresponsive or aggressive to rodent pups. But postpartum, these mice demonstrated parenting activities which included nursing, nest building, eating the after birth, and licking and grooming the pups. Maternal behaviors emerge after contact with the infant and with the process of endocrine changes after birth. Maternal experience affects the hippocampus and prefrontal cortex which is associated with cognition and mood regulation. The Dentate gyrus region of the hippocampus is the site of formation of new neurons or neurogenesis in the adult brain. This area has demonstrated changes in female mice after birth as well.
Findings:
Hormonal changes after birth causes a decrease in hippocampal neurogenesis. Dendritic remodeling and synaptic functions are affected by a decrease in estrogen and the increase in oxytocin in the dentate gyrus. In contrast, glucocorticoid levels increase which are important for lactation. Hormone changes in fathers include; increased estrogen, oxytocin, prolactin, and glucocorticoids, these changes are not identical to hormone levels in mothers but they are affected by contact with infants and the amount of affection they display to the infant. Environmental enrichment, stress, and learning experiences associated to parenting have been found to change the structure of the hippocampus. Stress has been found to decrease new neuron production where in contrast new learning experiences and environmental enrichment increases new neuron production in this region of the brain. This is a demonstration of neural plasticity through new learning experiences. The balance of hormone expression and dendritic growth in the hippocampus after birth plays a role in remodeling of the brain of new parents. The influence of these hormones has not been entirely understood, but may lead to understanding postpartum depression in females. The prefrontal cortex is activated by parenting experiences, structural changes have been observed in both rodents and humans. The prefrontal cortex has been associated with working memory, cognition, and mood regulation. These functions are important for parental behavior. Hormonal influences affect the dendrite structures in the prefrontal cortex. To me this is exciting, because this illustrates the plasticity of the brain with new experiences. Dendrites are important to receiving neural information and an increase or decrease of dendrite surfaces affects the transmission of information within the brain.
Clinical applications:
As occupational therapist it is important to understand the structures and functions of the nervous system, but also important to ask ourselves questions on how this system integrates to other systems of the human body. This article on the changes of the maternal brain is a beautiful example of the plasticity of our brain working with the endocrine system and the changes which take place. Pediatric occupational therapists understand the importance of creating an environment which is contusive to learning for a child but also for the parent as well. A NICU occupational therapist working with a new parent whose child may have been born with complications needs to experience parenthood as normally as possible to be allowed to experience change in their brain for parental behaviors. This leads to a question, what are the experiences for some one who abuses their child? Did their brain experience different changes in the hippocampus, or the prefrontal cortex fail to change? And why does neurogenesis decline in the maternal brain? Are the neural pathways which have been established strengthening by the use of these pathways to establish parental behaviors? Also, what happens to the brain with multiple births or a second pregnancy do they continue to change as well?
Take Home Point:
Our brain is a beautiful thing indeed! With new experiences it changes and as we go through life it has the ability to adapt to these life events. When my daughter was born, my husband and I were busy changing diapers and making our home comfortable for our new baby. It was May and the beginning of spring, one day we noticed outside our bedroom window a nest of newly hatched birds in the bougainvillea bush and their parents were busy bring food and reinforcing their nest. The birds as well as my husband and I were in the mist of learning how to be parents. Many of us would say birds have an instinct for parenting, but after reading this article I would say humans have an instinct as well for parenting behaviors which has been implemented by our hormone levels after giving birth and the structural changes in the hippocampus and prefrontal cortex. I think back how little I knew about raising a child and stressed over the virtues of breast feeding or bottle feeding. I worried if I did the wrong thing my daughter may not become a good human being or not go to college. In time, I learned how to be a parent, adjust to stress and learned the differences between my daughter’s fussing and cry for a diaper change. My daughter grew up to be a good person and graduate from college. As all new parents, our brains changed and the world begins a new for new life and a new spring begins again in the brain.
Mary Groves, M.S., OTR/L
Glossary:
Amygdala- an almond- shaped nucleus at the frontal portion of the temporal lobe.
The amygdala is involved with memory.
Dendrites-branches of a nerve cell which caries impulses toward the cell body of the
neuron
Glucocorticoid- CORTISOL and other similar hormones produced by the outer cortex of
the adrenal gland.
Hippocampus- a ridge on the surface of the cerebral cortex and is associated with
memory functions.
Hypothalamus- part of the diencephalon and directly below the thalamus in the medal
aspect of the brain. The hypothalamus receives information relating to
hormone level, physical and mental stress, emotions and responds to
pituitary regulation.
Neuromodulators- a substance that, while not affecting the rate of firing or conduction
of nerve impulses, can change the effect on a nerve of other
neurotransmitters.
Oxytocin- a hormone produced by the pituitary gland. This hormone promotes
contraction of the uterus.
Olfactory bulb- cranial nerve one of the brain which detects smell.
Prefrontal cortex- frontal part of the frontal lobe of the brain.
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| Dentate gyrus and pyramidal neurons |
