A rare type of fibrillation-like EMG activity

Non peer reviewe

Muscle Pain and Muscle Spindles

Muscle pain is a common symptom associated with, for example, myofascial syndrome, fibromyalgia and polymyalgia rheumatica. Many diseases of the muscle tissue are, however, completely or nearly painless such as polymyositis and inclusion body myositis. Thus, a mere inflammation cannot be the cause of muscle pain. In needle electromyography (EMG), the insertion of a needle electrode causes pain but further advancement is usually painless. However, there are small spots of muscle tissue where sudden pain is elicited with the needle. In EMG, these ‘active spots’ are observed to produce spontaneous activity in the form of end plate noise and spikes (EPSs). End plate noise is elicited at the neuromuscular junction of α, β or γ motor neuron. EPSs are action potentials of γ or β motor units. Muscle spindles are the main nociceptors in muscle tissue, both in healthy muscle and in diseases with muscle pain by inflammation of the muscle spindles. Multiple possible mechanisms of muscle pain exist. Polymyalgia rheumatica may have interstitial pain and possibly pain associated with muscle spindle capsules. Delayed onset muscle soreness may reflect both interstitial muscle pain caused by minor injuries and pain generated in mildly inflamed muscle spindles

Myotonia lihaksen ionikanavataudeissa

English summaryPeer reviewe

Can very early music interventions promote at-risk infants’ development?

Music and musical activities are often a natural part of parenting. As accumulating evidence shows, music can promote auditory and language development in infancy and early childhood. It may even help to support auditory and language skills in infants whose development is compromised by heritable conditions, like the reading deficit dyslexia, or by environmental factors, such as premature birth. For example, infants born to dyslexic parents can have atypical brain responses to speech sounds and subsequent challenges in language development. Children born very preterm, in turn, have an increased likelihood of sensory, cognitive, and motor deficits. To ameliorate these deficits, we have developed early interventions focusing on music. Preliminary results of our ongoing longitudinal studies suggest that music making and parental singing promote infants' early language development and auditory neural processing. Together with previous findings in the field, the present studies highlight the role of active, social music making in supporting auditory and language development in at-risk children and infants. Once completed, the studies will illuminate both risk and protective factors in development and offer a comprehensive model of understanding the promises of music activities in promoting positive developmental outcomes during the first years of life.Peer reviewe

Recording of Proprioceptive Muscle Reflexes in the Lower Extremity

Proprioception is the sense of body position and movement, with conscious and unconscious components, that determines and conditions the human body’s relationship with the environment. This quality of mechanosensitivity deteriorates in some pathologies and is responsible for some alterations of the locomotor system that appear in elderly persons. In those situations, the failure of proprioception reduces the quality of life of the subjects. The widespread use in developed countries of substitute joint prostheses makes it necessary to rethink the concepts of movement detection and perception. As such, this book examines the basics of proprioception as well as its function in the lower extremities, the head, in children with disabilities, and its connection with virtual reality.Peer reviewe

Electromyography of the muscle spindle

In needle electromyography, there are two spontaneous waveforms, miniature end plate potentials and "end plate spikes", appearing usually together. Miniature end plate potentials are local, non-propagating postsynaptic waves, caused by spontaneous exocytosis of acetylcholine in the neuromuscular junction. The prevailing hypothesis states that "end plate spikes" are propagated postsynaptic action potentials of muscle fibers, caused by presynaptic irritation of the motor nerve or nerve terminal. Using several small concentric needle electrodes in parallel with the muscle fibers, most "end plate spikes" are strictly local or propagating for 2-4 mm. At the end plate zone, there are miniature end plate potentials without "end plate spikes". Local "end plate spikes" are junctional potentials of intrafusal gamma neuromuscular junctions of the nuclear bag fibers, and propagated "end plate spikes" are potentials of nuclear chain muscle fibers of muscle spindles. Miniature end plate potentials without "end plate spikes" at the end plate zone derive from alpha neuromuscular junctions. These findings contrast with the prevailing hypothesis. The history of observations and different hypotheses of the origin of end plate spikes are described.Peer reviewe

Altered N100-potential associates with working memory impairment in Parkinson's disease

The diagnosis of cognitive impairment and dementia often occurring with Parkinson's disease (PD) is still based on the clinical picture and neuropsychological examination. Ancillary methods to detect cognitive decline in these patients are, therefore, needed. Alterations in the latencies and amplitudes of evoked response potential (ERP) components N100 and P200 have been described in PD. Due to limited number of studies their relation to cognitive deficits in PD remains obscure. The present study was designed to examine if alterations in the N100- and P200-potentials associate with neuropsychological impairment in PD. EEG-ERP was conducted to 18 PD patients and 24 healthy controls. The patients underwent a thorough neuropsychological evaluation. The controls were screened for cognitive impairment with Consortium to Establish Alzheimer's disease (CERAD)-testing and a normal result were required to be included in the study. The N100-latency was prolonged in the patients compared to the controls (p = 0.05). In the patients, the N100 latency correlated significantly with a visual working memory task (p = 0.01). Also N100 latency was prolonged and N100 amplitude habituation diminished in the patients achieving poorly in this task. We conclude that prolonged N100-latency and diminished amplitude habituation associate with visual working memory impairment in PD.Peer reviewe

Optimal digital filters for analyzing the mid-latency auditory P50 event-related potential in patients with Alzheimer's disease

Background: Filtering is an effective pre-processing technique for improving the signal-to-noise ratio of ERP waveforms. Filters can, however, introduce substantial distortions into the time-domain representations of ERP waveforms. Inappropriate filter parameters may lead to the presence of statistically significant but artificial effects, whereas true effects may appear as insignificant. New method: The present study aimed to determine the optimal digital filters for analyzing the auditory P50 component in patients with Alzheimer's disease. To provide evidence of the optimal filter settings, different high-pass and low-pass filters were applied to ERP waveforms obtained from a conditioning testing paradigm. The results facilitate practical recommendations for selection of filters that maximize the signal-to-noise ratio of the P50 components without introducing significant distortions. Results: The present study confirms that filter parameters have a significant effect on the amplitude and gating measures of the P50 component. Setting the high-pass cut-off at 0.1 Hz and the low-pass cut-off at 90Hz (or above) is recommended for P50 component analyses. Comparison with existing methods: The majority of ERP studies on sensory gating report using high-pass filters with 10-Hz cut-offs to measure P50 suppression. Such a high cut-off appeared to induce significant distortions into the ERP waveforms; thus, the authors advise against using these excessive high-pass cut-offs. Conclusions: Filtering broadband signals, such as ERP signals, necessary results in time-domain distortions. However, by adjusting the filter parameters carefully according to the components of interest, it is possible to minimize filter artifacts and obtain more easily interpretable ERP waveforms. (C) 2016 Elsevier B.V. All rights reserved.Peer reviewe