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Jeong-Yoon Choi, Hyo-Jung Kim, Ji-Soo Kim
The head impulse test (HIT) is used to evaluate the vestibulo-ocular reflex (VOR) during a high-velocity head rotation. Corrective catch-up saccades that occur during or after the HITs usually indicate peripheral vestibular hypofunction, whereas in acute vestibular syndrome, normal clinical (bedside) HITs should prompt a search for a central lesion. However, recent quantitative studies that evaluated HITs using magnetic search coils or video-based techniques have demonstrated that specific patterns of HIT abnormalities are associated with central vestibular disorders...
February 28, 2018: Neurology
Lilian M Mennink, J Marc C Van Dijk, Bernard F A M Van Der Laan, Jan D M Metzemaekers, Peter Jan Van Laar, Pim Van Dijk
PURPOSE: Chronic tinnitus is a common symptom after cerebellopontine angle (CPA) tumor removal. Sometimes, the tinnitus is gaze-modulated. In that case, patients can change the loudness or pitch of their tinnitus by ocular movements. During tumor removal by a retrosigmoid craniotomy, the cerebellar flocculus is manipulated by the surgical approach to access the tumor. The flocculus has been associated with tinnitus in rats, and is involved in eye-gaze control. This suggests that the flocculus may have a role in gaze-modulated tinnitus after CPA tumor removal...
January 31, 2018: Hearing Research
Toshiyuki Tanaka, Hideo Akiyoshi, Hitoshi Shimazaki, Ryo Kawakami, Keiichiro Mie, Yuki Yamada, Fumihito Ohashi
Case summary: This report involves a 10-year-old male mixed-breed cat with a B-cell central nervous system (CNS) lymphoma. The cat presented with ataxia progressing to left hemiparesis. While haematological findings were normal, serum biochemistry showed a high creatine phosphokinase concentration. MRI revealed a homogeneously enhancing well-demarcated extra-axial lesion involving the region of the left lateral aperture with oedema in left flocculus and left medulla oblongata. On diffusion-weighted imaging, the lesion margins showed marked hyperintensity relative to the right cerebellar hemisphere...
January 2018: JFMS Open Reports
Helbert de Oliveira Manduca Palmiero, Marcos Devanir Silva da Costa, Ricardo Lourenço Caramanti, Feres Eduardo Aparecido Chaddad-Neto
INTRODUCTION: The cerebellopontine angle (CPA) is a subarachnoid space in the lateral aspect of the posterior fossa. In this study, we propose a complementary analysis of the CPA from the cerebellopontine fissure. METHODS: We studied 50 hemi-cerebelli in the laboratory of neuroanatomy and included a description of the CPA anatomy from the cerebellopontine fissure and its relationship with the flocculus and the 5th, 6th, 7th, and 8th cranial nerves (CN) origins. RESULTS: The average distance from the 5th CN to the mid-line (ML) was 19...
January 15, 2018: British Journal of Neurosurgery
Dario Andres Yacovino, Manuel Perez Akly, Leonel Luis, David S Zee
The cerebellar flocculus is a critical structure involved in the control of eye movements. Both static and dynamic abnormalities of the vestibulo-ocular reflex (VOR) have been described in animals with experimental lesions of the flocculus/paraflocculus complex. In humans, lesions restricted to the flocculus are rare so they can become an exceptional model to contrast with the clinical features in experimental animals or in patients with more generalized cerebellar diseases. Here, we examined a 67-year-old patient with an acute vestibular syndrome due to an isolated infarct of the right flocculus...
August 26, 2017: Cerebellum
Douglas R Wylie, Cristián Gutiérrez-Ibáñez, Jeremy R Corfield, Iulia Craciun, David J Graham, Peter L Hurd
Zebrin II (ZII; a.k.a. aldolase C) is expressed heterogeneously in Purkinje cells (PCs) such that there are sagittal stripes of high expression (ZII+) interdigitated with stripes of little or no expression (ZII-). The pigeon flocculus receives visual-optokinetic information and is important for generating compensatory eye movements. It consists of 4 sagittal zones based on PC complex spike activity (CSA) in response to rotational optokinetic stimuli. There are two zones where CSA responds best to rotation about the vertical axis (VA), interdigitated with two zones where CSA responds best to rotation about an horizontal axis (HA)...
October 1, 2017: Journal of Comparative Neurology
Ria Maxine Ruehl, Carolin Hinkel, Thomas Bauermann, Peter Zu Eulenburg
Optokinetic eye movements are crucial for keeping a stable image on the retina during movements of the head. These eye movements can be differentiated into a cortically generated response (optokinetic look nystagmus) and the highly reflexive optokinetic stare nystagmus, which is controlled by circuits in the brainstem and cerebellum. The contributions of these infratentorial networks and their functional connectivity with the cortical eye fields are still poorly understood in humans. To map ocular motor centres in the cerebellum and brainstem, we studied stare nystagmus using small-field optokinetic stimuli in the horizontal and vertical directions in 22 healthy subjects...
June 23, 2017: Brain Structure & Function
Ryo Wakita, Soshi Tanabe, Kazunari Tabei, Asako Funaki, Takuma Inoshita, Tomoo Hirano
Norepinephrine modulates synaptic plasticity in various brain regions and is implicated in memory formation, consolidation and retrieval. The cerebellum is involved in motor learning, and adaptations of the vestibulo-ocular reflex (VOR) and optokinetic response (OKR) have been studied as models of cerebellum-dependent motor learning. Previous studies showed the involvement of adrenergic systems in the regulation of VOR, OKR and cerebellar synaptic functions. Here, we show differential contributions of β- and α2-adrenergic receptors in the mouse cerebellar flocculus to VOR and OKR control...
June 21, 2017: Scientific Reports
Kenichi Amagasaki, Nobuhiko Kurita, Saiko Watanabe, Naoyuki Shono, Atsushi Hosono, Kazuaki Naemura, Hiroshi Nakaguchi
BACKGROUND: The infrafloccular approach was introduced as a variation in microvascular decompression (MVD) for hemifacial spasm. However, the rate of postoperative lower cranial nerve (CN) palsy can be high. This study investigated the surgical factors in relation to the occurrence of postoperative lower CN palsy. METHODS: The case records of 103 patients who underwent MVD were reviewed. Dissection around the lower CNs to approach the root exit zone of CN VII was divided into two steps - incision of the rhomboid lip at the root of the lower CNs and separation of CN IX and flocculus/choroid plexus...
2017: Surgical Neurology International
Sunil Goyal, Shyam Sundar Krishnan, Mohan Kameswaran, M C Vasudevan, Ranjith, Kiran Natarajan
OBJECTIVES: The objectives of study was to 1) Describe relevant surgical anatomy in defining and accessing the lateral recess for placement of electrode, 2) Propose a working classification for grades of Flocculus; 3) To determine if different grades of cerebellar flocculus effects placement of ABI electrode and subjective outcomes in implantees. METHODS: Our study was a prospective study, and comprised of cohort of 12 patients who underwent ABI surgery via retrosigmoid approach between 1 Jan 2012 to 31 Dec 2014...
June 2017: International Journal of Pediatric Otorhinolaryngology
Keiichiro Inagaki, Yutaka Hirata
The vestibulo-ocular reflex (VOR) can be viewed as an adaptive control system that maintains compensatory eye movements during head motion. As the cerebellar flocculus is intimately involved in this adaptive motor control of the VOR, the VOR has been a popular model system for investigating cerebellar motor learning. Long-term depression (LTD) and long-term potentiation (LTP) at the parallel fiber-Purkinje cell synapses are considered to play major roles in cerebellar motor learning. A recent study using mutant mice demonstrated cerebellar motor learning with hampered LTD; the study concluded that the parallel fiber-Purkinje cell LTD is not essential...
August 2017: Cerebellum
Sung-Hee Kim, Hyo Jung Kim, Ji-Soo Kim
Dizziness/vertigo is the most common symptoms of posterior circulation strokes. Isolated vestibular symptoms and signs without other neurologic deficits have been found in infarctions involving the brainstem and cerebellum. In the brainstem, infarctions responsible for isolated vestibular syndrome are usually restricted to the dorsal portion that contains the vestibular nucleus and the nucleus prepositus hypoglossi. Cerebellar lesions confined to the flocculus, tonsil, and nodulus also produce isolated vertigo and imbalance...
October 2017: Journal of Neurology
Catherine Mankiw, Min Tae M Park, P K Reardon, Ari M Fish, Liv S Clasen, Deanna Greenstein, Jay N Giedd, Jonathan D Blumenthal, Jason P Lerch, M Mallar Chakravarty, Armin Raznahan
The cerebellum is a large hindbrain structure that is increasingly recognized for its contribution to diverse domains of cognitive and affective processing in human health and disease. Although several of these domains are sex biased, our fundamental understanding of cerebellar sex differences-including their spatial distribution, potential biological determinants, and independence from brain volume variation-lags far behind that for the cerebrum. Here, we harness automated neuroimaging methods for cerebellar morphometrics in 417 individuals to (1) localize normative male-female differences in raw cerebellar volume, (2) compare these to sex chromosome effects estimated across five rare sex (X/Y) chromosome aneuploidy (SCA) syndromes, and (3) clarify brain size-independent effects of sex and SCA on cerebellar anatomy using a generalizable allometric approach that considers scaling relationships between regional cerebellar volume and brain volume in health...
May 24, 2017: Journal of Neuroscience: the Official Journal of the Society for Neuroscience
Julie Carcaud, Filipa França de Barros, Erwin Idoux, Daniel Eugène, Lionel Reveret, Lee E Moore, Pierre-Paul Vidal, Mathieu Beraneck
Calibration of the vestibulo-ocular reflex (VOR) depends on the presence of visual feedback. However, the cellular mechanisms associated with VOR modifications at the level of the brainstem remain largely unknown. A new protocol was designed to expose freely behaving mice to a visuo-vestibular mismatch during a 2-week period. This protocol induced a 50% reduction of the VOR. In vivo pharmacological experiments demonstrated that the VOR reduction depends on changes located outside the flocculus/paraflocculus complex...
January 2017: ENeuro
Douglas R Wylie, Daniel Hoops, Joel W Aspden, Andrew N Iwaniuk
Aldolase C, also known as zebrin II (ZII), is a glycolytic enzyme that is expressed in cerebellar Purkinje cells of the vertebrate cerebellum. In both mammals and birds, ZII is expressed heterogeneously, such that there are sagittal stripes of Purkinje cells with high ZII expression (ZII+) alternating with stripes of Purkinje cells with little or no expression (ZII-). In contrast, in snakes and turtles, ZII is not expressed heterogeneously; rather all Purkinje cells are ZII+. Here, we examined the expression of ZII in the cerebellum of lizards to elucidate the evolutionary origins of ZII stripes in Sauropsida...
2016: Brain, Behavior and Evolution
Ming Zhi, Xiao J Lu, Qing Wang, Bing Li
OBJECTIVE: To explore the value of neuroendoscopy in surgery for primary hemifacial spasm (HFS) in patients with complicated local anatomy. METHODS: Endoscopic-assisted microvascular decompression (MVD) was performed in 42 patients with HFS with complicated local anatomy from Janurary 2008 to Janurary 2012 in our department, in the event of a significant blind spot, endoscopic exploration was performed with multi-angle 360-degree observation, including exploration of the brainstem facial nerve root exit zone (REZ) and exploration of the distal end of the nerve, and the relationships between blood vessels and nerves were carefully determined...
January 2017: Neurosciences: the Official Journal of the Pan Arab Union of Neurological Sciences
Wen Zhou, Liu-Qing Zhou, Hong Shi, Yang-Ming Leng, Bo Liu, Su-Lin Zhang, Wei-Jia Kong
The medial vestibular nucleus (MVN) and the cerebellar flocculus have been known to be the key areas involved in vestibular compensation (VC) following unilateral labyrinthectomy (UL). In this study, we examined the role of gephyrin and glycine receptor (GlyR) in VC using Sprague-Dawley rats, in an aim to gain deeper insight into the mechanisms responsible for VC. The expression of the α1 and β subunits of GlyR and gephyrin was immunohistochemically localized in rat MVN and flocculi. The mRNA and protein expression of GlyR (α1 and β subunits) and gephyrin was quantitatively determined by RT-qPCR and western blot analysis at 8 h, and at 1, 3 and 7 days following UL...
November 2016: International Journal of Molecular Medicine
Sung-Hee Kim, David S Zee, Sascha du Lac, Hyo Jung Kim, Ji-Soo Kim
OBJECTIVE: To describe the ocular motor abnormalities in 9 patients with a lesion involving the nucleus prepositus hypoglossi (NPH), a key constituent of a vestibular-cerebellar-brainstem neural network that ensures that the eyes are held steady in all positions of gaze. METHODS: We recorded eye movements, including the vestibulo-ocular reflex during head impulses, in patients with vertigo and a lesion involving the NPH. RESULTS: Our patients showed an ipsilesional-beating spontaneous nystagmus, horizontal gaze-evoked nystagmus more intense on looking toward the ipsilesional side, impaired pursuit more to the ipsilesional side, central patterns of head-shaking nystagmus, contralateral eye deviation, and decreased vestibulo-ocular reflex gain during contralesionally directed head impulses...
November 8, 2016: Neurology
Hitomi Matsuno, Moeko Kudoh, Akiya Watakabe, Tetsuo Yamamori, Ryuichi Shigemoto, Soichi Nagao
Adaptations of vestibulo-ocular and optokinetic response eye movements have been studied as an experimental model of cerebellum-dependent motor learning. Several previous physiological and pharmacological studies have consistently suggested that the cerebellar flocculus (FL) Purkinje cells (P-cells) and the medial vestibular nucleus (MVN) neurons targeted by FL (FL-targeted MVN neurons) may respectively maintain the memory traces of short- and long-term adaptation. To study the basic structures of the FL-MVN synapses by light microscopy (LM) and electron microscopy (EM), we injected green florescence protein (GFP)-expressing lentivirus into FL to anterogradely label the FL P-cell axons in C57BL/6J mice...
2016: PloS One
Shin C Beh, Teresa C Frohman, Elliot M Frohman
BACKGROUND: The cerebellum plays a central role in the online, real-time control, and long-term modulation of eye movements. EVIDENCE ACQUISITION: We reviewed the latest (fifth) edition of Leigh and Zee's textbook, The Neurology of Eye Movements, and literature in PUBMED using the following terms: cerebellum, flocculus, paraflocculus, vermis, oculomotor vermis, dorsal vermis, caudal fastigial nucleus, fastigial oculomotor region, uvula, nodulus, ansiform lobule, eye movements, saccades, ipsipulsion, contrapulsion, smooth pursuit, vergence, convergence, divergence, gaze-holding, down beat nystagmus, vestibulo-ocular reflex (VOR), angular VOR, translational VOR, skew deviation, velocity storage...
March 2017: Journal of Neuro-ophthalmology: the Official Journal of the North American Neuro-Ophthalmology Society
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