Abstract:To clarify the role of the pretectal nucleus of the optic tract (NOT) in ocular following, we traced NOT efferents with tritiated leucine in the monkey and identified the cell groups they targeted. Strong local projections from the NOT were demonstrated to the superior colliculus and the dorsal terminal nucleus bilaterally and to the contralateral NOT. The contralateral oculomotor complex, including motoneurons (C-group) and subdivisions of the Edinger-Westphal complex, including motoneurons (C-group) and subd… Show more
“…Buttner-Ennever and Horn [43] describe a 'dual control' system where two distinct pathways are responsible for afferent input into the oculomotor nuclei. One pathway serves to generate eye rotations, while the second pathway provides sensory information regarding eye alignment and stabilization [44]. This is an important part of the visual postural control pathway, as this pathway may compensate for visual deprivation such as in darkness.…”
Objective: This review details the anatomy and interactions of the postural and somatosensory reflexes. We attempt to identify the important role the nervous system plays in maintaining reflex control of the spine and posture. We also review, illustrate, and discuss how the human vertebral column develops, functions, and adapts to Earth's gravity in an upright position. We identify functional characteristics of the postural reflexes by reporting previous observations of subjects during periods of microgravity or weightlessness.Background: Historically, chiropractic has centered around the concept that the nervous system controls and regulates all other bodily systems; and that disruption to normal nervous system function can contribute to a wide variety of common ailments. Surprisingly, the chiropractic literature has paid relatively little attention to the importance of neurological regulation of static upright human posture. With so much information available on how posture may affect health and function, we felt it important to review the neuroanatomical structures and pathways responsible for maintaining the spine and posture. Maintenance of static upright posture is regulated by the nervous system through the various postural reflexes. Hence, from a chiropractic standpoint, it is clinically beneficial to understand how the individual postural reflexes work, as it may explain some of the clinical presentations seen in chiropractic practice.
“…Buttner-Ennever and Horn [43] describe a 'dual control' system where two distinct pathways are responsible for afferent input into the oculomotor nuclei. One pathway serves to generate eye rotations, while the second pathway provides sensory information regarding eye alignment and stabilization [44]. This is an important part of the visual postural control pathway, as this pathway may compensate for visual deprivation such as in darkness.…”
Objective: This review details the anatomy and interactions of the postural and somatosensory reflexes. We attempt to identify the important role the nervous system plays in maintaining reflex control of the spine and posture. We also review, illustrate, and discuss how the human vertebral column develops, functions, and adapts to Earth's gravity in an upright position. We identify functional characteristics of the postural reflexes by reporting previous observations of subjects during periods of microgravity or weightlessness.Background: Historically, chiropractic has centered around the concept that the nervous system controls and regulates all other bodily systems; and that disruption to normal nervous system function can contribute to a wide variety of common ailments. Surprisingly, the chiropractic literature has paid relatively little attention to the importance of neurological regulation of static upright human posture. With so much information available on how posture may affect health and function, we felt it important to review the neuroanatomical structures and pathways responsible for maintaining the spine and posture. Maintenance of static upright posture is regulated by the nervous system through the various postural reflexes. Hence, from a chiropractic standpoint, it is clinically beneficial to understand how the individual postural reflexes work, as it may explain some of the clinical presentations seen in chiropractic practice.
“…Interestingly, the NOT in primates is also innervated by afferents from striate and extrastriate cortical areas such as the middle temporal (MT) and the middle superior temporal (MST) motion-sensitive areas [4]. A projection of the NOT to the vestibular nuclei has been substantiated in monkeys [5, 6], but not in the rabbit [7], The nucleus prepositus hypoglossi, which receives afferents from the NOT, is a link in an alternative NOT vestibular pathway. Fig.…”
Section: Pathways Underlying Vor and Okr: Connections With The Floccumentioning
confidence: 99%
“…A projection from the NOT to the NRTP is still controversial. It was documented in monkeys with the use of anterograde tracing [5, 6], but not confirmed with the use of retrograde tracing [5, 6, 21]. Moreover, this projection has not been found in rabbits or rats, neither with anterograde nor with retrograde tracing [7, 22, 23].…”
Section: Mossy Fiber Input To the Floccular Lobementioning
confidence: 99%
“…In addition, the dorsolateral pontine nuclei receive afferents from the ipsilateral superior colliculus [77] and the NOT [5–7, 23]. The dorsolateral pontine nuclei give rise to a mossy fiber projection that terminates, mainly contralaterally, in the dorsal paraflocculus and uvula [24, 25] (Fig.…”
In this paper, we will review the anatomical components of the visuomotor cerebellum in human and, where possible, in non-human primates and discuss their function in relation to those of extracerebellar visuomotor regions with which they are connected. The floccular lobe, the dorsal paraflocculus, the oculomotor vermis, the uvula–nodulus, and the ansiform lobule are more or less independent components of the visuomotor cerebellum that are involved in different corticocerebellar and/or brain stem olivocerebellar loops. The floccular lobe and the oculomotor vermis share different mossy fiber inputs from the brain stem; the dorsal paraflocculus and the ansiform lobule receive corticopontine mossy fibers from postrolandic visual areas and the frontal eye fields, respectively. Of the visuomotor functions of the cerebellum, the vestibulo-ocular reflex is controlled by the floccular lobe; saccadic eye movements are controlled by the oculomotor vermis and ansiform lobule, while control of smooth pursuit involves all these cerebellar visuomotor regions. Functional imaging studies in humans further emphasize cerebellar involvement in visual reflexive eye movements and are discussed.
“…The intergeniculate leaflet of the hamster is the homologue to the pregeniculate nucleus in monkey (Livingston and Mustari, 2000), which corresponds to the ventral lateral geniculate nucleus (Nakamura and Itoh, 2004). The ventral geniculate nucleus has several subdivisions, some of which have been shown to be involved in visuomotor functions (Büttner and Fuchs 1973; Büttner-Ennever et al, 1996b). In our results the medial division of the pregeniculate nucleus received a strong supply of orexin-A boutons as well (own observations), and confirm the hypothesis that orexin modulates visuomotor systems.…”
Orexin-A, synthesized by neurons of the lateral hypothalamus, helps to maintain wakefulness through excitatory projections to nuclei involved in arousal. Obvious changes in eye movements, eyelid position and pupil reactions seen in the transition to sleep led to the investigation of orexin-A projections to visuomotor cell groups to determine whether direct pathways exist that may modify visuomotor behaviors during the sleep/wake cycle. Histological markers were used to define these specific visuomotor cell groups in monkey brainstem sections and combined with orexin-A immunostaining. The dense supply by orexin-A boutons around adjacent neurons in the dorsal raphe nucleus served as a control standard for a strong orexin-A input. The quantitative analysis assessing various functional cell groups of the oculomotor system revealed that almost no input from orexin-A terminals reached motoneurons supplying the singly-innervated muscle fibers of the extraocular muscles in the oculomotor nucleus, the omnipause neurons in the nucleus raphe interpositus and the premotor neurons in the rostral interstitial nucleus of the medial longitudinal fasciculus. In contrast, the motoneurons supplying the multiply-innervated muscle fibers of the extraocular muscles, the motoneurons of the levator palpebrae muscle in the central caudal nucleus, and especially the preganglionic neurons supplying the ciliary ganglion received a strong orexin input. We interpret these results as evidence that orexin-A does modulate pupil size, lid position, and possibly convergence and eye alignment via the motoneurons of multiply-innervated muscle fibres. However orexin-A does not directly modulate premotor pathways for saccades or the SIF motoneurons.
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