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Rapid monocular adaptation of saccade amplitude in constant strabismus
Published in Jan-Tjeerd de Faber, 28th European Strabismological Association Meeting, 2020
H.J. Griffiths, D. Buckley, J.P. Whittle
This present study found anomalous disconjugacy in two subjects with small angled strabismus. Bucci et al. (1997) found anomalous disconjugacy only in subjects with large angle strabismus and no fusion. They proposed that this might be driven by monocular visual inputs occurring to improve fixation of each eye and not to reduce binocular disparity. They suggest that the movements of the two eyes are controlled independently, so-called utrocular vision (or vision with each eye separately), as described by Schor (1991). This is a primitive form of binocular vision found in vertebrates with complete decussation of the visual pathways. Bucci et al. (1997) suggested that this form of independent eye control could allow avoidance of diplopia, but not establishment of a true binocular linkage.
The Spinal Cord and the Spinal Canal
Published in Bernard J. Dalens, Jean-Pierre Monnet, Yves Harmand, Pediatric Regional Anesthesia, 2019
Bernard J. Dalens, Jean-Pierre Monnet, Yves Harmand
The anterior spinothalamic tract is formed by fibers from (mostly) contralateral laminae III and IV (classical view) and/or laminae VI, VII, and VIII, crossing in the anterior white commissure (Figure 1.28). The decussation occurs through several spinal segments. This tract conveys impulses of light touch to the ventral posterolateral nucleus of the thalamus and, after relaying in the thalamus, to sensory areas of the cerebral cortex.
Clinical Neuroanatomy
Published in John C Watkinson, Raymond W Clarke, Christopher P Aldren, Doris-Eva Bamiou, Raymond W Clarke, Richard M Irving, Haytham Kubba, Shakeel R Saeed, Paediatrics, The Ear, Skull Base, 2018
The sensory nucleus is very extensive. The cell bodies of the sensory fibres lie in the gasserian ganglion overlying the petrous apex. At least 50% of the fibres do not enter the main sensory nucleus but are concerned solely with stretch reflex activity. The other fibres form ascending and descending branches. The ascending fibres enter the mesencephalic nucleus of the Vth nerve. Their subsequent course and exact function is not understood. The descending fibres convey pain and temperature sensation and synapse in the nucleus of the descending tract of the Vth nerve, which lies adjacent to the descending tract itself and extends as low as C2 cord level. The sensory fibres derived from the facial, glossopharyngeal and vagus nerves all join the same tract and relay in the same nucleus. The secondary ascending pathway fibres swing across the brainstem, ventral to the central canal to become the secondary ascending tract of the Vth nerve, which is adjacent to the medial lemniscus, adding sensation derived from the face to that of the arm and leg in the latter pathway. In the decussation, these fibres are very vulnerable to damage by midline lesions, such as syringomyelia and syringobulbia, producing a classical sensory deficit, typically extending forwards from the back of the head. This is the so-called ‘onion peel’ or ‘balaclava’ sensory deficit, which may leave sensation intact only over the nose and central face in the final stages of its development.
Horizontal Gaze Palsy and Progressive Scoliosis in Dizygotic Twins
Published in Journal of Binocular Vision and Ocular Motility, 2022
Catarina Xavier, Miguel Vieira, Ana Filipa Duarte, Ana Xavier, Eduardo D. Silva
Brain MRI of our patients demonstrates the typical features of the disease showing a normal appearing brain, corpus callosum and cerebellum, in contrast with a brainstem malformation consisting of abnormal flattening of dorsal pons and medulla with deep anterior and posterior midline clefts with a butterfly-like bifid appearance.3,10 These MRI features likely result from the absence of normal decussation of the descending cortical spinal tracts and the ascending somatosensory tracts.3,6 As shown in previous studies,7,15 on our patients the brain MRI showed no changes of the extraocular muscles and their motor nerves, supporting the causal inter and supranuclear mechanism of the horizontal gaze palsy that is probably caused by aberrant supranuclear input onto the abducens motoneurons and hypoplasia and disruption of decussating projections in the medial longitudinal fasciculus.4,6,11
Spatial hearing processing: electrophysiological documentation at subcortical and cortical levels
Published in International Journal of Neuroscience, 2019
Nematollah Rouhbakhsh, John Mahdi, Jacob Hwo, Baran Nobel, Fati Mousave
In spatial conditions being tested in this study, two possible processing mechanisms were in progress. In co-located condition, due to periodic entity of the target and aperiodic entity of the distractors, the target stimuli relatively became augmented and therefore relatively unaffected by inhibition neural networks and unlike to the target stimuli, the distractors, in contrast, became squelched [57,58]. In the separated condition, removing the distractors from the target spatially results in augmenting of the target energy, thus making the neural cue detectors more accessible to spatial cues. At the IC level, the encoded signals receive an extra level of refinement through the lateral lemniscus neural networks whereas decussating to the opposite side of the auditory pathways [59]. This decussation could be used to establish another contrast and then converge information coming up at the level of the IC from inferior auditory pathways [60].
Structural muscular adaptations in upper limb after stroke: a systematic review
Published in Topics in Stroke Rehabilitation, 2019
Fernanda Maria Faturi, Gabriela Lopes Santos, Gabriela Nagai Ocamoto, Thiago Luiz Russo
One important aspect not considered among studies is that sensorimotor changes may occur bilaterally in poststroke subjects.27,32 Changes in the nonparetic muscle can be related to the fact that 10% of the corticospinal connections to the motoneurons in the spinal cord do not undergo decussation.47,48 However, other factors can also contribute to muscle alterations in nonparetic UL, such as sedentary lifestyle,39,49 metabolic disorder, or nutrition.50 Some studies have shown that an important muscle change is the shift of fiber type.14,51 Conrad and Kamper52 showed a decrease in isokinetic performance and an increase in power deficits greater in finger extensors. They discuss that this can happen due to the fiber type shift from type I to type II rather than atrophy alterations. Thus, besides the comparison between paretic and nonparetic UL, it is important to compare both limbs with limbs of healthy subjects matched by age and gender.