Background: The objective of this study was to determine whether differentiation between demyelinating and axonal neuropathies could be enhanced by comparing conduction time changes in defined ...segments of the total peripheral nerve pathway. Methods: Compound muscle action potentials (CMAPs) were elicited by cathodal stimulation of the tibial nerve at the ankle and popliteal fossa, and by paravertebral neuromagnetic stimulation at proximal and distal cauda equina while recording from muscles of the foot, shin, and thigh. Segmental conduction times were calculated in normal subjects; in patients with lumbosacral radiculopathy, distal symmetric diabetic neuropathy, amyotrophic lateral sclerosis, acute and chronic inflammatory demyelinating polyneuropathy; and in patients with anti–myelin‐associated glycoprotein, myelomatous, and Charcot–Marie–Tooth type 1a polyneuropathies. Results: Distal cauda equina latency and CMAP duration and segmental conduction times in upper leg and cauda equina facilitated differentiation of demyelinating from axonal neuropathies, even in the presence of a range of reduced amplitude CMAPs. Conclusions: Within the demyelinating neuropathy spectrum, it was further possible to distinguish subtypes. Muscle Nerve, 2011
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BFBNIB, FZAB, GIS, IJS, KILJ, NLZOH, NUK, OILJ, SAZU, SBCE, SBMB, UL, UM, UPUK
2.
The Genomic Landscape of Male Breast Cancers Piscuoglio, Salvatore; Ng, Charlotte K Y; Murray, Melissa P ...
Clinical cancer research,
08/2016, Volume:
22, Issue:
16
Journal Article
Previous studies suggest that the autonomic nervous system plays an important role in the generation of complex heart rate dynamics. Therefore, we hypothesized that the complexity (irregularity) of ...cardiac interbeat intervals would evolve with the maturation of autonomic innervation to the heart. Twelve healthy newborn piglets were implanted with ECG transmitters and studied at one or more different ages up to 33 days of age, the period during which pigs develop functional sympathetic innervation of the heart from the stellate ganglia. Three animals underwent right stellate ganglionectomy, two a left stellate ganglionectomy, two a right cardiac vagotomy and five a sham procedure. The statistic, approximate entropy (ApEn), was used to quantify the regularity of interbeat interval fluctuations. Sham-operated animals showed an increase in the standard deviation (SD) and irregularity (ApEn) of cardiac interval fluctuations with increasing age. Right stellate ganglionectomized piglets had lower interbeat interval ApEn values, but similar SD's by 26–27 days of age compared to sham-operated animals. Left stellate ganglionectomy, which affects cardiac inotropy rather than chronotropy, had no effect on cardiac interval irregularity, while vagotomy had an indeterminant effect. The increasing irregularity of interbeat interval dynamics during autonomic maturation and the apparent attenuation of heartbeat irregularity when right stellate ganglion innervation is interrupted, provides empirical support for the notion that complex heartbeat dynamics in the mature animal are the result of a network of autonomic neural pathways that enables an organism to adapt to stress.
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IJS, IMTLJ, KILJ, KISLJ, NUK, SBCE, SBJE, UL, UM, UPCLJ, UPUK
The effects of two levels of Saffan anesthesia (standard recording level: 2-4 mg/kg/min, and 10X recording level) and a single level of pentobarbital (5 mg/kg) on the power spectral density of ...efferent phrenic discharge were investigated in piglets aged from less than 1 day to 50 days. The phrenic high frequency oscillation (HFO) was present in decerebrate, unanesthetized piglets and in piglets anesthetized with Saffan, albeit reduced at 10 times recording level, but was absent under pentobarbital. The results indicate that Saffan does not have a significantly depressant effect on the phrenic HFO in developing swine.
The authors critically reviewed experiments in which transcranial magnetic stimulation (TMS) and repetitive TMS (rTMS) of the higher visual pathway were used. Topics include basic mechanisms of ...neural excitation by TMS and their relevance to the visual pathway (excitatory and inhibitory effects), TMS and rTMS of calcarine cortex (suppression, unmasking, and phosphenes), TMS of V5 (suppression), TMS and rTMS of higher level temporoparietooccipital areas (perceptual errors, unmasking, and inattention), the role of frontal lobe output in visual perception, and vocalization of perceived visual stimuli (role of consciousness of linguistic symbols).
The Role of Visual Perception in Spoken Responses Amassian, Vahe E; Cracco, Roger Q; Maccabee, Paul J ...
Biocybernetics and biomedical engineering,
2011, 2011-1-00, Volume:
31, Issue:
3
Journal Article
Peer reviewed
How subjects voice responses to flashed visual symbols was investigated at successive stages of the information processing. The representation exits from V1 mainly by 120–140, mean 130ms; cortical ...motor output to voice onset has a mean delay of 85ms. The latencies of voicing only a noise, blurting versus perceiving before responding correctly yield mean delays for perception (85ms) and for spatio-temporal motor coding of digits (45ms), with a mean total delay of 345ms. Prefrontal cortex and Intralaminar N. also contribute to perception.
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GEOZS, IJS, IMTLJ, KILJ, KISLJ, NUK, OILJ, PNG, SAZU, SBCE, SBJE, UL, UM, UPCLJ, UPUK
Previous work disclosed that single magnetic coil (MC) pulses applied over human calcarine cortex could suppress perception of letters briefly presented, e.g. 80-100 ms earlier. Although individual ...MC stimuli presented 0-60 ms, or more than 140 ms after the visual stimulus were apparently ineffective, combinations of 2 or 3 MC pulses at such intervals temporarily depressed visual perception. Thus, progressing of such language information could be slowed, without being abolished. By contrast, when the first MC pulse was delivered 120 ms or later, a second MC pulse 40 ms later had no detectable effect, implying that calcarine cortex had already transmitted the information. Perceptual recovery of 5-character words initially occurred no earlier than that of random letters, nor or random letters vs. arbitrary linear patterns, implying that the processing delays in calcarine cortex were similar.
The kinetics of receptor up-regulation was examined in isolated neutrophils and in whole blood by flow cytometry during cell activation. Stimulation of neutrophils prepared without exposure to LPS ...with chemoattractants induced fast up-regulation of N-formyl peptide receptors and C receptor type 3 (CR3). Biphasic N-formyl peptide binding curves were detected for saturating concentrations of N-formyl peptide at 37 degrees C. The bulk of the rapid binding during the first 30 to 60 s is attributed to already expressed binding sites whereas the slow binding over the next 3 to 4 min represents a time course of receptor up-regulation. Support for this interpretation comes from conditions under which the number of binding sites and the progress of the binding curves were affected. Cells treated with LPS, which caused expression of internal N-formyl peptide receptors, exhibited rapid, monophasic binding curves with increased total binding. In LPS-untreated, calcium-depleted cells, N-formyl peptide receptor up-regulation was inhibited and rapid, monophasic binding to a smaller total number of expressed sites was observed. Cytochalasin B enhanced the total number of available N-formyl peptide receptors in LPS-untreated but not LPS-treated cells. In both cases binding was rapid and monophasic suggesting that receptors were either fully or rapidly up-regulated. Although not studied in real-time, C receptor type 3 up-regulation was similar to N-formyl peptide receptor up-regulation in response to LPS, or stimulation by N-formyl peptide, C product C5a, leukotriene B4, and platelet-activating factor in isolated cells and in whole blood. After stimulation with formyl peptide, LPS, or C product 5a, the release of vitamin B12-binding protein paralleled up-regulation of receptors. These data indicate that untreated cells up-regulate N-formyl peptide receptors during cell response at a rate of approximately 10,000/min in a calcium-dependent manner whereas LPS-treated cells already express the bulk of their receptors. In cytochalasin B-treated, degranulating cells 30,000 to 50,000 receptors were up-regulated within a minute.
Visual suppression by a magnetic coil (MC) pulse delivered over human calcarine cortex after a transient visual stimulus 80-100 ms earlier has been used to suppress the representation of a 'masking' ...visual stimulus and thus to unmask a 'target' visual stimulus given, e.g., 100 ms before the mask. The resulting target unmasking as a function of the interval between mask and MC pulse is approximately the inverse of the visual suppression curve. Arbitrary visual linear patterns can similarly be unmasked. At the long target-mask interval used, the site of masking is deduced to lie beyond calcarine cortex. In several right-handed subjects tested, powerful MC stimulation of the left (but not right) temporo-parieto-occipital cortex also led to (weaker) unmasking.
To help elucidate some basic principles of magnetic coil (MC) excitation of cerebral cortex, a model system was devised in which mammalian phrenic nerve, or amphibian sciatic nerve with its branches ...was suspended in appropriate Ringer's solution in a human brain-shaped volume conductor, an inverted plastic skull. The nerve was recorded monophasically out of the volume conductor. The site of nerve excitation by the MC was identified by finding where along the nerve a bipolar electrical stimulus yielded a similar action potential latency. MC excitation of hand-related corticospinal (CT) neurons was modelled by giving the distal end of nerve attached to the lateral skull an initial radial (perpendicular) trajectory, with subsequent bends towards the base and posterior part of the skull; this nerve was optimally excited by a laterally placed figure 8 or round MC when the induced electric field led to outward membrane current at the initial bend. By contrast, nerve given a trajectory modelling CT neurons related to the foot was optimally excited when the coil windings were across the midline, but again when membrane current flowed outward at the first bend. Corticocortical fibers were modelled by placing the nerve in the anteroposterior axis lateral to the midline; with the round MC vertex-tangentially orientated, optimal excitation occurred at the bend nearest the interaural line, i.e., near the peak electric field. The findings emphasize the importance of orientation and direction of current in the MC and fiber bends in determining nerve excitation. The findings in the peripheral nerve-skull model help explain (1) why lateral and vertex-tangentially orientated MCs preferentially excite arm-related CT neurons directly and indirectly (through corticocortical fibers), respectively, and (2) why the MC orientations for optimally exciting directly arm and leg-related CT neurons differ.
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