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Neurological issues
Published in Andrea Utley, Motor Control, Learning and Development, 2018
More complex reflexes can coordinate the activity of several muscle groups, sometimes on different sides of the body (Feldman and Levin 2016). The crossed extensor reflex often functions in conjunction with the flexion reflex to help maintain postural stability or help a person push away from a painful stimulus. For example, interneuronal connections involved in the crossed extensor reflex cause extensor muscles in the opposite limb to contract at the same time as the flexor muscles remove the limb from a painful stimulation. This provides an excellent example of how nerve impulses pass across the spinal cord from one side of the body to another and not just to and from the spinal cord at a given segment level or up and down the spinal cord.
Discussions (D)
Published in Terence R. Anthoney, Neuroanatomy and the Neurologic Exam, 2017
As noted in D: Flexor reflex, authors of recent textbooks in neuroscience agree that stimulation of cutaneous receptors can elicit “the flexor reflex”—usually described as a reflexive withdrawal of a stimulated limb. Indeed, one synonym for “flexor reflex” is “cutaneous reflex” (see SS: the Cutaneomuscular reflex). In addition, however, many authors describe elicitation of flexor reflexes via stimulation of receptors in deep structures, such as muscles and joints (see D: flexor reflex for citations)—hence, perhaps, the synonym “cutaneomuscular reflex.” Consequently, if authors of recent texts consider “superficial” reflexes to be those elicited by stimulating receptors in skin or in mucous membranes, one would expect them to divide the flexor reflexes into “superficial” and “deep” subgroups, depending upon the sites of stimulated receptors.
Spinal Cord and Reflexes
Published in Nassir H. Sabah, Neuromuscular Fundamentals, 2020
The flexion reflex, also known as the withdrawal reflex, moves a limb away from a harmful, or noxious, stimulus. Suppose, for example, that one accidentally touches a hot plate (Figure 11.8). This activates cutaneous thermoreceptors, resulting in APs traveling to the spinal cord over afferent nerve fibers and innervating interneurons in the spinal cord. Although, for simplicity, a single interneuron is shown in the reflex arc in Figure 11.8, several populations of both excitatory and inhibitory interneurons are in fact involved, making the reflex polysynaptic. The afferent input, acting through interneurons, eventually reaches α-motoneurons that mediate the following responses: Excitation of the α-motoneurons that innervate the homonymous flexor muscles of the arm, where the homonymous muscles are those that are directly associated with the receptors that initiate the reflex. This leads to the withdrawal of the arm away from the hot plate. A more intense stimulus may excite the α-motoneurons that cause internal rotation of the shoulder (Section 9.3.4). In withdrawing the arm from the painful stimulus, the muscles of the arm and shoulder act as synergist muscles. It may be noted that the intensity of the stimulus is coded both in the mean frequency of APs as well as the number of afferent fibers activated. Thus, a more intense stimulus will stimulate receptors over a larger area of the skin, which activates a larger number of afferent fibers in parallel. This parallelism in the organization of the nervous system is not portrayed by single-line diagrams such as Figure 11.8.Concomitant with the excitation of the flexor α-motoneurons, the interneurons inhibit the α-motoneurons innervating the extensor muscles (Figure 11.8), as explained in connection with Ia interneurons (Section 11.2.2.2). This leads to relaxation of the extensor muscles that are antagonists to the contracting flexor muscles – an example of reciprocal inhibition referred to earlier.Withdrawal of a limb from a noxious stimulus generally involves some postural adjustments. This is most easily seen when the foot is withdrawn from a noxious stimulus. Elevation of the foot shifts the weight of the body to the contralateral leg on the other side of the body. The extensor muscles of this leg, which are the antigravity muscles, should contract, and the flexor muscles inhibited in order to support the additional load. Therefore, the afferent input should also activate interneurons that excite extensor α-motoneurons, and inhibit α-motoneurons of the contralateral leg. This is an additional reflex, resulting from the flexion reflex, and is referred to as the crossed extension reflex, or the crossed extensor reflex.
MATE1 expression in the cochlea and its potential involvement in cisplatin cellular uptake and ototoxicity
Published in Acta Oto-Laryngologica, 2023
Sofia Waissbluth, Agustín D. Martínez, Cindel Figueroa-Cares, Helmuth A. Sánchez, Juan C. Maass
CF1 P0 Mice were anesthetized on ice for 5 min. The neonates were put, one by one, over a latex glove on top of ice for 5 min or until they stopped moving. Complete anesthesia is checked with the lack of the leg flexor reflex. The cochleae were dissected in cold sterile HBSS as well as the kidneys. Immediately after dissection, the explants were placed on top of filter membranes with 1 μm pores (SPI-pore or Whatman) floating in DMEM/F12 (Hepes) supplemented with B27 supplements (Life Technologies), 1 mM N-acetylcysteine (Sigma), 5 ng/ml EGF and 2.5 ng/ml FGF2 and 67 μg/ml penicillin (Laboratorio Chile). The cochleae were cultured in 500ul culture medium with or without 15 uM of cisplatin for 24h in 4-well plates on Whatman 13 mm filters in a 25 °C incubator with 5% CO2. Total RNA from whole cochlear explants and kidneys, per replicate, was extracted using the PureLinkTM RNA Micro kit (Thermo Fisher Scientific), and cDNA was synthesized with the SuperScriptTM III First-Strand Synthesis System (Thermo Fisher Scientific); four replicates. PowerUp™ SYBR™ Green Master Mix (Thermo Fisher Scientific) was used, and the instrument was the StepOne™ Real-Time PCR System. The following primers were used for OCT2: forward 5′-ATTACCGTGGCGTGCTTGGGT-3′ and reverse 5′-TGTGGGGTACAGCTCAGCGTT -3′, and MATE1, forward 5′-ATTCCGCTGTCTCTCACGA -3′ and reverse 5′-CAGTTTATTGCTGTCCTTTGGA-3′. Levels of expression of OCT2 and MATE1 were then obtained for the cochlea and kidneys. The housekeeping gene glyceraldehyde-3-phosphate dehydrogenase (GAPDH) was used for normalizing data.
Spinal and supraspinal modulation of pain responses by hypnosis, suggestions, and distraction
Published in American Journal of Clinical Hypnosis, 2021
Bérengère Houzé, Anouk Streff, Mathieu Piché, Pierre Rainville
Painful electrical stimulation delivered at the ankle produces the nociceptive flexion reflex (NFR) which can be measured by an electromyographic set-up. Electromyographic activity (EMG) of the right biceps femoris (ipsilateral to the stimulation) was measured with disposable Ag-AgCl surface electrodes, amplified 2000 times, band-pass filtered between 1– 500 Hz, sampled at 1000 Hz and recorded continuously on a computer for offline analyses. Raw EMG recordings were filtered offline using a notch filter fixed at 60 Hz and a digital IIR high-pass filter with a 10 Hz cutoff. EMG was then transformed using the root mean square function and the NFR amplitude to each shock was measured by the integral value of the resulting signal between 90 and 180 ms after the stimulus onset. NFR amplitude was standardized within participants across the 36 control and experimental stimuli of each condition, using T-scores (i.e. mean = 50 and SD = 10 – see supplementary materials).
Vitamin D supplementation ameliorates arthritis but does not alleviates renal injury in pristane-induced lupus model
Published in Autoimmunity, 2019
Eduarda Correa Freitas, Thaís Evelyn Karnopp, Jordana Miranda de Souza Silva, Rafaela Cavalheiro do Espírito Santo, Thales Hein da Rosa, Mayara Souza de Oliveira, Fabiany da Costa Gonçalves, Francine Hehn de Oliveira, Pedro Guilherme Schaefer, Odirlei André Monticielo
Nociception was evaluated before induction of the experimental model and on days 60, 120 and 180 after induction of the model. Nociception was assessed as Oliveira et al [10]. The nociceptive mechanical threshold from the hinds paws were measured by the electronic Von Frey method (electronic Von Frey, Insight Equipamentos Ltda, Ribeirão Preto, SP, Brazil). Mice were placed in acrylic cages (12 × 20 × 17 cm) with wire grid floors in a quiet room 15–30 min before testing for environmental adaptation. The test consisted of evoking a hind paw flexion reflex with a handheld force transducer adapted with a tip. The investigator was trained to apply the tip in the plantar region with a gradual increase in pressure. The stimulus was automatically discontinued, and its intensity was recorded, in grams (g), when the paw was withdrawn.