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Higher Brain Areas Involved in Respiratory Control
Published in Alan D. Miller, Armand L. Bianchi, Beverly P. Bishop, Neural Control of the Respiratory Muscles, 2019
Some of the most common respiratory disorders, such as asthma and obstructive sleep apnea, are characterized by increased resistance to airflow. The motor and afferent activity in brain regions responding to such resistance challenges can be visualized with fMRI techniques. Integration of activity associated with inspiratory loading activates rostral, midbrain, ventral medullary, and cerebellar structures (Figure 3).17 These areas include the putamen, anterior hypothalamus, interpeduncular nucleus, parabrachial and basal pons, locus coeruleus, and distinct portions of the cerebellum (culmen and central portion of vermis, and tuber and uvula of vermis). Brain areas activated by expiratory loading additionally include the ventral medulla, in addition to cerebellar, pontine, and rostral sites.18 Rapid off-transients accompany removal of loads, and reapplication of a load results in accommodation of the signal, i.e., the signal is smaller on reapplication. If the loads are sustained, the fMRI signal progressively decreases. The accommodation of the signal to the load suggests a neural adaptation process.
Clinical Management of Spasticity and Contractures in Spinal Cord Injury
Published in Anand D. Pandyan, Hermie J. Hermens, Bernard A. Conway, Neurological Rehabilitation, 2018
There is more human experimental data supporting the idea that spasticity involves synaptic mechanisms such as recurrent inhibition [25], reduction in Ia-reciprocal inhibition [26,27], and reciprocal inhibition of flexor reflex afferents [28]. In summary, changes of motoneuron and interneuron plasticity are assumed to play a significant role in spinal spasticity, which early after an SCI are thought related to postsynaptic mechanisms such as receptor up-regulation, and later during the recovery phase would be associated primarily with pre-synaptic mechanisms [1,9,29]. However, these changes are not observed immediately after spinal trauma. They evolve with time, suggesting gradual changes of neural adaptation following SCI.
Specificity of Training Effects on Control Functions and the Connective Tissue
Published in Atko Viru, Adaptation in Sports Training, 2017
Neural adaptation takes place at the level of spinal motoneurons as well as at higher levels of the central nervous system. The existence of neural adaptation explains why (1) the changes in cross-sectional area of muscle fibers are much smaller than the changes in maximal force production,15,18 (2) training-induced increases in voluntary strength may occur without increases in twitch and tetanic tension evoked by electrical stimulation,19 (3) training of one limb causes increases in strength of the contralateral limb (see p. 189–190), and (4) a specificity of training effects exists; increases in voluntary strength are specific to the movement pattern,20,21 joint position,22 contraction type,23,24 and movement velocity20,25,26 used in training.
Auditory brainstem responses obtained with randomised stimulation level
Published in International Journal of Audiology, 2023
Marta Martinez, Joaquin T. Valderrama, Isaac M. Alvarez, Angel de la Torre, Jose L. Vargas
The present study also evaluated the hearing comfort of the proposed stimulation strategy. Hearing comfort is a critical variable for the success of the test session, particularly in newborns and infants, since hearing discomfort may prevent them from remaining quiet and still during the test (Diefendorf, 2014). In most instances, the auditory stimulus is found unpleasant when abrupt changes of sound are presented (e.g. the sudden presentation of a high sound level; Pitchforth, 2010); however, the continuous presentation of a particular auditory stimulus pattern is easier to inhibit due to two mechanisms: (i) neural adaptation – a decrease in the activity pattern when a continuous stimulus is presented (Thornton and Coleman, 1975; Gillespie and Muller, 2009); and (ii) habituation – a cognitive process associated with selective attention which enables filtering out non-essential stimuli by decreasing the response to a stimulus after prolonged presentations of that stimulus (Rankin et al., 2009; Thompson, 2009). Since the proposed stimulus paradigm consists of a stimulus pattern repeated all along the test session, we predicted that this auditory stimulus would be easier to inhibit, and that the general population would report higher levels of hearing comfort. Furthermore, we also anticipated that due to the adaptation and habituation mechanisms described in the literature, RSL and the conventional paradigm would elicit auditory evoked potentials of different morphology.
Physical therapy to address fall risk in an individual with neurofibromatosis
Published in Physiotherapy Theory and Practice, 2022
Robert B. Adams, Justin T. Dudley, Tamara S. Struessel
The plan of care primarily aimed to remediate strength and balance impairments, as well as identify compensation strategies to prevent future falls. To specifically address the patient’s observed challenge with balance, exercises that emphasized maintenance of center of mass over base of support were incorporated into the plan for strengthening and balance. Previous literature reports that changes in neural adaptation required for balance improvement can take 2–6 weeks (Bloomer and Ives, 2000), and changes in strength can take up to 8 weeks (Schoenfeld et al., 2019). Therefore, a 6- to 8-week treatment plan was devised to address the patient goals of improving balance and enhancing independence (Table 1). Since strength and neural adaptations require training two to three times per week (Bloomer and Ives, 2000; Schoenfeld et al., 2019), but the patient’s commute from his rural home was over 1 hour long, visits were scheduled twice a week for the first month. Visits were scheduled less frequently once or twice a week for the second month while shifting emphasis to a more independent home-exercise program. By the end of 3 weeks, the patient was expected to demonstrate improvements of balance in tandem stance (Table 1). By the end of the 8 weeks, he was expected to demonstrate decreased fall risk and increased independence at home and within his community by scoring above the cutoffs for fall risk on the BBS and DGI (Table 1).
Comparison of two cortical measures of binaural hearing acuity
Published in International Journal of Audiology, 2021
An important factor to consider before including a specific test in a clinical battery is how long the test takes to perform. We compared time-to-detect measurements for ACC and IPM-FR to assess which test would be more feasible with the former consideration in mind. For larger IPDs (±67.5° and ±90°), time-to-detect did not differ; however, the IPM-FR demonstrated a clear advantage for smaller IPDs (±22.5° and 45°). The reason for this difference may be because time-voltage-means used to estimate ACC waveforms are more inherently inclusive of noise than the frequency domain measurements used in the IPM-FR. As noted in the methods section, ACC and IPM-FR stimuli differed in several ways, including the rate of presentation and duration. While we selected ACC parameters to yield measurable responses at the fastest rate possible, this approach may have disadvantaged the ACC response in our analyses by causing greater neural adaptation. Smaller amplitude ACC responses would be closer to the noise floor of the measurement and thus more difficult to objectively detect. A longer duration ACC stimulus may have yielded a more robust response while still allowing us to achieve short test times. In summary, if the goal of an objective binaural hearing test is to determine the smallest IPD change that a patient or research subject can detect, the IPM-FR may provide threefold time savings versus the ACC. If the purpose of the test is to determine gross binaural hearing acuity using (physiologically impossible) IPDs, either metric may be appropriate.