Posts Tagged Aging
Neural mechanisms for grip relaxation are relatively unknown and understudied, as compared to mechanisms for grip initiation. Yet, termination of motor activity is as important as initiation in daily function. This knowledge gap presents incomplete understanding of neural control of hand function and its impairment with aging and neurologic disorders.
The purpose of this dissertation was to identify and examine neural mechanisms of grip relaxation in healthy young adults, with aging, and in chronic stroke survivors. A series of experiments in healthy young adults showed that the relaxation from a maximum power grip was mediated by increase in the short-interval intracortical inhibition (SICI). The role of spinal motor excitability modulation for grip relaxation was refuted, in contrast to previous literature for the leg muscle. These data from healthy young adults suggest that the grip relaxation time is a cortically mediated active process. Additionally, these studies also showed that the neural mechanism of grip relaxation is comparable for the dominant and the nondominant hand in healthy young adults. The next step was to identify any delays in relaxing from a grip in healthy older adults.
Assessment of the effects of aging on the role of SICI showed that the delayed grip relaxation time in older adults was accompanied by reduced modulation of SICI for grip relaxation. The cortical silent period and H reflex did not explain delays in grip relaxation observed in older adults.
Another series of experiments showed that the chronic stroke survivors and age-matched control adults demonstrated comparable modulations of SICI, cortical silent period, corticomotor excitability, and H reflex. Yet, the paretic hand of the stroke survivors was significantly delayed in relaxing from a grip.
Correlation and regression analysis showed that the stroke-related delayed grip relaxation time may be explained by increased spasticity, reduced somatosensation, paretic grip weakness relative to the nonparetic, strength of the corticospinal connections and interhemispheric inhibition. An intervention aimed to modulate cortical excitability and interhemispheric inhibition, Active Passive Bilateral Therapy, was employed but was found to be not effective in modulating grip relaxation time and interhemispheric inhibition after a one-time 20-minute session, warranting a longer treatment time.
In summary, this dissertation investigated neural mechanisms of grip relaxation and contributes to the general body of knowledge regarding neural control of hand movements.
Epilepsy remains one of the most common neurological conditions, affecting one in 26 Americans in their lifetime, with one-third having a form of the condition that resists treatment or effective management. With those statistics in mind, more than 5,200 neurologists, scientists, nurses and health professionals came to Philadelphia December 4-8 for the 2015 American Epilepsy Society (AES) Annual Meeting to discuss new discoveries and emerging technologies that can lead to more effective treatment.
“AES hosts its Annual Meeting with one goal in mind — to provide our broad community of epilepsy professionals with world-class education in order to take our understanding of epilepsy to the next level,” said AES Executive Director Eileen Murray. “Thanks to our board, planning committee, members, speakers, exhibitors, attendees, and staff, we accomplished our goal.”
This meeting marked the largest ever in its 69-year history, drawing attendees from all 50 states and more than 60 countries. During the four-day event, AES organized more than 100 symposia, lectures, and platform sessions and more than 1,200 research abstracts were presented. The meeting also featured a sold-out exhibit hall with nearly 200 exhibitors from major therapeutic and research companies and not-for-profit organizations. Popular topics at the Annual Meeting included:
Pharmaceutical CBD (cannabidiol) for severe epilepsy — Global interest is growing in using CBD for children with severe epilepsy, and three studies presented at the meeting looked at safety and efficacy in the largest trial of CBD to date.
Personal monitoring devices – Three personal monitoring devices unveiled at the meeting offer biometric recording technology that could allow patients to monitor clinical and subclinical seizure activity in the everyday home environment and get advance warning before a seizure strikes.
Personalized medicine reveal new targets for epilepsy – Technological advances ranging from gene editing to next-generation sequencing offer unprecedented access to the human genome and promise to reshape the diagnosis and treatment of epilepsy.
Better management options for status epilepticus in children — A medical emergency with a high mortality rate, status epilepticus requires prompt treatment, but what constitutes the appropriate care is an area of intense debate.
Interplay between epilepsy and aging – The largest and fastest-growing segment of people with epilepsy are those age 60 and older. People with epilepsy face a number of related health challenges, including cognitive, physical and psychological disorders. But new research suggests other, less expected consequences on the aging process, providing insights that shed light on the long-term implications of life with epilepsy.
A highlight of the Annual Meeting was the Judith Hoyer Lecture, sponsored by the National Institute of Neurological Disorders and Stroke. Jacqueline French, M.D., spoke on “Obstacles in Epilepsy Diagnosis: If You Don’t Ask, They Won’t Tell.” The lecture is meant for both professionals and members of the public, to raise awareness of epilepsy and stimulate thinking about future advances.
[REVIEW] Sleep and Motor Learning: Implications for Physical Rehabilitation After Stroke – Full Text HTML
Sleep is essential for healthy brain function and plasticity underlying learning and memory. In the context of physical impairment such as following a stroke, sleep may be particularly important for supporting critical recovery of motor function through similar processes of reorganization in the brain. Despite a link between stroke and poor sleep, current approaches to rehabilitative care often neglect the importance of sleep in clinical assessment and treatment. This review assimilates current evidence on the role of sleep in motor learning, with a focus on the implications for physical rehabilitation after stroke. We further outline practical considerations for integrating sleep assessment as a vital part of clinical care.
The adult brain is highly adaptable, even after injury it often exhibits an impressive capacity for reorganization. Activity in the brain during sleep is thought to be critically involved in supporting these processes of plasticity. Briefly, sleep can be thought of as a state of consciousness, or alternations in consciousness, which oscillates between states of reduced awareness of external real-world stimuli to a complete loss of consciousness (1). While the precise mechanisms have yet to be clearly defined, sleep has been associated with many important functions, including those of the immune and memory systems (2–5). In memory, sleep is consistently attributed a particularly prominent role in supporting time-sensitive processes associated with the consolidation of memories. Consolidation here refers to dynamic processes in the brain that occur after initial (“on-line”) memory encoding takes place, such as when we practice a new skill. Subsequent (“off-line”) mechanisms of consolidation serve to further process these new memory traces, for instance, to enable the integration of knowledge and long-term memory storage.
One reason memory consolidation may be particularly important in a clinical context is because of how it applies to neurological rehabilitation, such as motor recovery after lesion to the brain. Here, the primary aim of physical rehabilitation is to facilitate recovery of functional motor capacity after initial impairment. Another way to look at physical rehabilitation, therefore, is as a form of motor learning, or relearning, which in turn may tap into some of the same processes of memory formation and consolidation as other forms of procedural memory (6, 7). Consequently, experimental insights into processes in the brain that support motor memory are likely to have more wide-ranging application that may benefit understanding and development of useful strategies for improving long-term rehabilitative outcomes in the clinic. The primary objective of this review is to provide an assimilation of current evidence on the role of sleep in motor learning and to identify specific factors of learning and consolidation that may have important implications for rehabilitation. For the purposes of this review, we will focus primarily on sleep-dependent motor memory with relevance to physical rehabilitation after stroke, although many of the discussion points included here will likely apply more broadly to other types of memory and rehabilitation. Meanwhile, what is some of the evidence linking sleep, in particular, to motor memory?
[ARTICLE] Efficacy and Feasibility of Functional Upper Extremity Task-Specific Training for Older Adults With and Without Cognitive Impairment
Background. Although functional task-specific training is a viable approach for upper extremity neurorehabilitation, its appropriateness for older populations is unclear. If task-specific training is to be prescribed to older adults, it must be efficacious and feasible, even in patients with cognitive decline due to advancing age.
Objective. This cross-sectional study tested the efficacy and feasibility of upper extremity task-specific training in older adults, including those with lower cognitive scores.
Methods. Fifty older adults (age 65-89 years) without any confounding neuromuscular impairment were randomly assigned to a training group or no-training group. The training group completed 3 days (dosage = 2250 repetitions) of a functional upper extremity motor task (simulated feeding) with their nondominant hand; the no-training group completed no form of training at all. Both groups’ task performance (measured as trial time) was tested at pre- and posttest, and the training group was retested 1 month later. Efficacy was determined by rate, amount, and retention of training-related improvement, and compared across levels of cognitive status. Feasibility was determined by participants’ tolerance of the prescribed training dose.
Results. The training group was able to complete the training dose without adverse responses and showed a significant rate, amount, and retention of improvement compared with the no-training group. Cognitive status did not alter results, although participants with lower scores on the Montreal Cognitive Assessment were slower overall.
Conclusions. Task-specific training may be appropriate for improving upper extremity function in older adults, yet future work in older patients with specific neurological conditions is needed.
By NORMAN DOIDGE
Feb. 6, 2015 5:34 p.m. ET
Can the brain heal and preserve itself—or even improve its functioning—as we get older? For some time, many scientists have tended to think of our brains as machines, most commonly as computers, destined to break down over time under the strain of age and use. In recent years, however, research in neuroscience has begun to show the inadequacy of this metaphor for describing the physiology of the brain. It turns out that our brains, like our bodies in general, are far more likely to waste away from underuse than to wear down from overuse.
As people reach middle age, exercising the brain and the body to which it is attached—keeping both active—becomes more important. It is one of the few reliable ways to offset the natural wasting process and the damaging influence of our unnaturally sedentary modern lives. It also points to new possibilities for the brain to heal itself in the face of disease and trauma.
For decades, physicians and scientists generally believed that the prognosis for most brain problems was grim. The standard view was that the brain had evolved to be so complex and specialized that we had to pay a price for its sophistication: It couldn’t repair or restore itself with replacement parts, as was possible with other organs, such as the skin, liver and blood.
That view fit with, and partly stemmed from, an image that had prevailed since the days of the great French philosopher and scientist René Descartes, who described the brain as a glorious machine with discrete parts. Descartes’s heirs argued that each of these parts performed a single mental function in a single location. If a part was damaged—by a genetic fault, or stroke, or injury or disease—it was assumed that the body had no resources of its own to deal with the problem: After all, machines cannot repair themselves or spontaneously grow new parts.
Once the electrical nature of the brain was delineated in the 19th century, scientists began speaking of it as a grander sort of machine, an electrical one, with “circuits”—a metaphor still very much with us. They came to see its circuits as analogous to those of electronic gadgets—unchangeable or “hard-wired.”
As the machine metaphor evolved, neuroscientists took to describing the brain as a computer. This “master analogy,” as computer scientist David Gelernter calls it (in criticizing this view), encourages us to see thought as “software” and the brain’s structure as “hardware.”
The unhappy practical implication of this view, for anyone wishing to maintain his or her brain, is clear: Hardware inevitably degenerates with time and use. The rule for a machine is, “Use it and lose it.” Many clinicians under the sway of this analogy saw patients’ attempts to resist their brains’ decline through activity and mental exercise as a harmless waste of time.
Fortunately, a growing body of research suggests that this older view is wrong. It seems that a more accurate rule for our brains is “Use it or lose it.”
Continue –> Our Amazingly Plastic Brains – WSJ.
ARTICLE: Timing of motor cortical stimulation during planar robotic training differentially impacts neuroplasticity in older adults – Full Text
– Altering the timing of stimulation during a reaching intervention changes the direction and extent of plasticity
– Non-invasive brain stimulation may be a catalyst to promote plasticity in older adults.
– Robotic reaching plus stimulation facilitated a rapid plastic response that was maintained during the intervention and for a short time period following the intervention.