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Some physical phenomena associated with the anxiety states and their relation to hyperventilation
(1937)
The authors believe that there is a physiological background for the perseverance of an anxiety state as part of a psychoneurosis; that this background is produced by the constant presence of purely emotional disturbances; and that the resultant physiological state aggravates the psychic component to such a degree that a vicioris cycle is instituted, the symptoms of which are manifold. These symptoms increase the severity of the emotional tension ; and, if they are prolonged, permanent structural change with the production of organic clisease results. The mechanism is at first a repetition of attacks, from the stimulation by an emotion such as fear upon the sympathetic nervous system, which in turn becomes increasingly labile. The mechanism is perpetuated by the effects of the simulus on the system of self-defense, which is dispatched by the endocrine group. This reaction causes a state of hyperirritability to exist through the presence of tissue alkalosis, tissue liydremia, and tissue anoxemia; and results in a state of tetany which may be regional or generalized. The Symptoms of tetany, and allied rnanifestations such ac tachycardia, distended stomach and dilated urinary bladder, are enough to aggravate the neurosis because of the patient's fear of impending dissolution. Multiplication of impulses increases the bombardment of the sympathetic nervous system, making repetition of tlie reaction more easy at subsequent intervals. The cure is accomplished through elimination of tlie fear-impulse by psychotherapy. The symptoms may be alleviated medically, and by this rneans that part of the neurosis which is on the basis of anxiety concerning health may be eliminated. Because of the subjective and objective improvement in the patient's condition, contact for psychotherapy is more easily obtained. Medical treatment is directed toward preservation of the acid-base balance; toward decreasing the effect of adrenalin on the nerve-tissue by means of a known chemical antagonist; or toward converting the state of tone of the individual from extreme to moderate, whether parasympathic or sympathetic in type.
A consistent muscle activation strategy underlies crawling and swimming in Caenorhabditis elegans
(2014)
Although undulatory swimming is observed in many organisms, the neuromuscular basis for undulatory movement patterns is not well understood. To better understand the basis for the generation of these movement patterns, we studied muscle activity in the nematode Caenorhabditis elegans. Caenorhabditis elegans exhibits a range of locomotion patterns: in low viscosity fluids the undulation has a wavelength longer than the body and propagates rapidly, while in high viscosity fluids or on agar media the undulatory waves are shorter and slower. Theoretical treatment of observed behaviour has suggested a large change in force–posture relationships at different viscosities, but analysis of bend propagation suggests that short-range proprioceptive feedback is used to control and generate body bends. How muscles could be activated in a way consistent with both these results is unclear. We therefore combined automated worm tracking with calcium imaging to determine muscle activation strategy in a variety of external substrates. Remarkably, we observed that across locomotion patterns spanning a threefold change in wavelength, peak muscle activation occurs approximately 45° (1/8th of a cycle) ahead of peak midline curvature. Although the location of peak force is predicted to vary widely, the activation pattern is consistent with required force in a model incorporating putative length- and velocity-dependence of muscle strength. Furthermore, a linear combination of local curvature and velocity can match the pattern of activation. This suggests that proprioception can enable the worm to swim effectively while working within the limitations of muscle biomechanics and neural control.