flocculus

Aging is accompanied by macro-structural alterations in the brain that may relate to age-associated cognitive decline. Animal studies could allow us to study this relationship, but so far it remains unclear whether their structural aging patterns correspond to those in humans. Therefore, by applying magnetic resonance imaging (MRI) and deformation-based morphometry (DBM), we longitudinally screened the brains of male RccHan:WIST rats for structural changes across their average lifespan. By combining dedicated region of interest (ROI) and voxel-wise approaches, we observed an increase in their global brain volume that was superimposed by divergent local morphologic alterations, with the largest aging effects in early and middle life...

Procedural memories formed in the cerebellum in response to motor errors depend on changes to Purkinje cell (PC) spiking patterns that correct movement when the erroneous context is repeated. Because molecular layer interneurons (MLIs) inhibit PCs, learning-induced changes to MLI output may participate in reshaping PC spiking patterns. Yet, it remains unclear whether error-driven learning alters MLI activity and whether such changes are necessary for the memory engram. We addressed this knowledge gap by measuring and manipulating MLI activity in the flocculus of both sexes of mice before and after vestibulo-ocular reflex (VOR) adaptation...

BACKGROUND AND OBJECTIVES: Lesions of the cerebellar flocculus cause enduring downbeat nystagmus (DBN) with unrelenting oscillopsia. Unlike most patients with DBN, the flocculus is structurally spared in nonalcoholic Wernicke encephalopathy (nWE) with chronic DBN. The objective was to study the effects of alcohol in nWE. METHODS: We recorded eye movements of a unique patient with nWE under controlled alcohol consumption who said his oscillopsia disappeared with a few drinks of alcohol...

BACKGROUND: A thorough observation of the root exit zone (REZ) and secure transposition of the offending arteries is crucial for a successful microvascular decompression (MVD) for hemifacial spasm (HFS). Decompression procedures are not always feasible in a narrow operative field through a retrosigmoid approach. In such instances, extending the craniectomy laterally is useful in accomplishing the procedure safely. This study aims to introduce the benefits of a skull base approach in MVD for HFS...

The flocculus is a region of the vestibulocerebellum dedicated to the coordination of neck, head, and eye movements for optimal posture, balance, and orienting responses. Despite growing evidence of vestibular and oculomotor impairments in the aftermath of traumatic stress, little is known about the effects of chronic psychological trauma on vestibulocerebellar functioning. Here, we investigated alterations in functional connectivity of the flocculus at rest among individuals with post-traumatic stress disorder (PTSD) and its dissociative subtype (PTSD + DS) as compared to healthy controls...

Objectives  Endoscopic endonasal approaches (EEAs) for petrosectomies are evolving to reduce perioperative brain injuries and complications. Surgical terminology, techniques, landmarks, advantages, and limitations of these approaches remain ill defined. We quantitatively analyzed the anatomical relationships and differences between EEA exposures for medial, inferior, and inferomedial petrosectomies. Design  This study presents anatomical dissection and quantitative analysis. Setting  Cadaveric heads were used for dissection...

Spinocerebellar Ataxia Type 6 (SCA6) is a mid-life onset neurodegenerative disease characterized by progressive ataxia, dysarthria, and eye movement impairment. This autosomal dominant disease is caused by the expansion of a CAG repeat tract in the CACNA1A gene that encodes the α1A subunit of the P/Q type voltage-gated Ca2+ channel. Mouse models of SCA6 demonstrate impaired locomotive function and reduced firing precision of cerebellar Purkinje in the anterior vermis. Here, to further assess deficits in other cerebellar-dependent behaviors, we characterized the oculomotor phenotype of a knock-in mouse model with hyper-expanded polyQ repeats (SCA684Q )...

Proprioceptive sensory information from muscle spindles is essential for the regulation of motor functions. However, little is known about the motor control regions in the cerebellar cortex that receive proprioceptive signals from muscle spindles distributed throughout the body, including the orofacial muscles. Therefore, in this study, we investigated the pattern of projections in the rat cerebellar cortex derived from the supratrigeminal nucleus (Su5), which conveys orofacial proprioceptive information from jaw-closing muscle spindles (JCMSs)...

Tinnitus is the perception of sound without an external source. The flocculus (FL) and paraflocculus (PFL), which are small lobules of the cerebellum, have recently been implicated in its pathophysiology. In a previous study, the volume of the (P)FL-complex correlated with tinnitus severity in patients that had undergone cerebellopontine angle (CPA) tumor removal. In this study, the relation between tinnitus and gray matter volume (GMV) of the (P)FL-complex, GMV of the other cerebellar lobules and GMV of the cerebellar nuclei is investigated in otherwise healthy participants...

This chapter summarizes early electrophysiological and lesion studies to elucidate cortical, subcortical and cerebellar mechanisms for extracting visual target motion and programming a smooth-pursuit response. The importance of a descending pursuit pathway from the middle temporal (MT) cortical visual area, which extracts the speed and direction of a moving target, the projections to dorsolateral pontine nuclei, and onto the cerebellum are outlined. Contributions of the cerebellum to pursuit are discussed and models are presented to account for the ways in which floccular gaze Purkinje cells behave during smooth pursuit, combined eye-head tracking, and during head rotation while viewing a stationary target...

This chapter discusses the neurophysiology and function of subcortical circuits and cortical areas involved in saccade generation. While cells within the different nuclei of the brainstem reticular formation shape the temporal details of ipsiversive horizontal and vertical/cyclotorsional saccade components, the cerebellar flocculus, vermis and fastigial nucleus are thought to modulate these saccadic waveforms. Burst neurons in the deep layers of the superior colliculus encode the saccade vector in the contralateral field by a localized population in a motor-error map...

This chapter discusses the premotor neural mechanisms that control horizontal saccadic eye movements. Oculomotoneurons carry a pulse-step signal that underlies the pulse-step force driving the overdamped plant. The pulse and step are both generated by a common signal, arising from medium-lead burst neurons in the pons. Their burst signal encodes saccadic eye velocity, while the number of spikes in the burst relates to the saccade amplitude. The step component, which encodes the eye position, is obtained by neural integration of the burst...

This chapter provides a review of early studies into the neural substrate for optokinetic-vestibular responses. Properties and connections of retinal and brainstem neurons contributing to optokinetic responses in the afoveate rabbit are summarized. Electrophysiological and lesion studies provide support for confluence of optokinetic and vestibular signals in the vestibular nucleus to provide the brain's estimate of self-rotation. Evidence for optokinetic-vestibular symbiosis in humans comes from the observation that individuals who have lost vestibular function show no optokinetic after-nystagmus in darkness, following full-field stimulus motion...

It is self-evident, once one thinks about it, that the vestibulo-ocular reflex must have caretaker systems that keep it operating correctly over the span of a lifetime. When a movement is not correct (e.g., in position, speed, direction) it is said to be dysmetric. For the vestibulo-ocular reflex (VOR), if eye velocity is not equal and opposite to head velocity within reasonable limits, one has vestibulo-ocular dysmetria. Consequently, the function of the caretaker systems is to eliminate vestibulo-ocular dysmetria...

Purkinje cells (PCs) in the cerebellar flocculus carry rate-coded information that ultimately drives eye movement. Floccular PCs lying nearby each other exhibit partial synchrony of their simple spikes (SS). Elsewhere in the cerebellum, PC SS synchrony has been demonstrated to influence activity of the PCs' synaptic targets, and some suggest it constitutes another vector for information transfer. We investigated in the cerebellar flocculus the extent to which the rate code and PC synchrony interact. One motivation for the study was to explain the cerebellar deficits in ataxic mice like tottering; we speculated that PC synchrony has a positive effect on rate code transmission that is lost in the mutants...

BACKGROUND: To assess efficacy and safety of a newly developed decompression technique in microvascular decompression for hemifacial spasm (HFS) with vertebral artery (VA) involvement. METHODS: A rigid Teflon (Bard®  PTFE Felt Pledget, USA) with the ends placed between the lower pons and the flocculus creates a free space over the root exit zone (REZ) of the facial nerve (bridge technique). The bridge technique and the conventional sling technique for VA-related neurovascular compression were compared retrospectively in 60 patients...

The review article provides a definition and classification of different nystagmus types, a comparative description of the central and peripheral vestibular nystagmus. The pathogenetic patterns of up-beating and down-beating nystagmus are accurately described. The features of nystagmus formation in various diseases are discussed, such as Wernicke encephalopathy, Arnold-Chiari anomaly, spinocerebellar ataxia and vestibular migraine. The authors provide their own data on oculomotor disorders in 100 patients with vestibular migraine and migraine with a brain stem aura...

The climbing fiber input to the cerebellum conveys instructive signals that can induce synaptic plasticity and learning by triggering complex spikes accompanied by large calcium transients in Purkinje cells. In the cerebellar flocculus, which supports oculomotor learning, complex spikes are driven by image motion on the retina, which could indicate an oculomotor error. In the same neurons, complex spikes also can be driven by nonvisual signals. It has been shown that the calcium transients accompanying each complex spike can vary in amplitude, even within a given cell, therefore, we compared the calcium responses associated with the visual and nonvisual inputs to floccular Purkinje cells...

Acute pancreatitis (AP) is one of the common acute abdominal inflammatory diseases in clinic with acute onset and rapid progress. About 20% of the patients will eventually develop into severe acute pancreatitis (SAP) characterized by a large number of inflammatory cells infiltration, gland flocculus flaky necrosis and hemorrhage, finally inducing systemic inflammatory response syndrome (SIRS) and multiple organ dysfunction syndrome (MODS). Pancreatic enzyme activation, intestinal endotoxemia (IETM), cytokine activation, microcirculation disturbance, autonomic nerve dysfunction and autophagy dysregulation all play an essential role in the occurrence and progression of SAP...

A woman, age 44, with a positive anti-YO paraneoplastic cerebellar syndrome and normal imaging developed an ocular motor disorder including periodic alternating nystagmus (PAN), gaze-evoked nystagmus (GEN) and rebound nystagmus (RN). During fixation there was typical PAN but changes in gaze position evoked complex, time-varying oscillations of GEN and RN. To unravel the pathophysiology of this unusual pattern of nystagmus, we developed a mathematical model of normal function of the circuits mediating the vestibular-ocular reflex and gaze-holding including their adaptive mechanisms...