Vestibular and visual climbing fiber signals evoked in the uvula-nodulus of the rabbit cerebellum by natural stimulation

1995 ◽  
Vol 74 (6) ◽  
pp. 2573-2589 ◽  
Author(s):  
N. H. Barmack ◽  
H. Shojaku
Keyword(s):  
Purkinje Cells ◽  
Semicircular Canal ◽  
Mossy Fiber ◽  
Semicircular Canals ◽  
Longitudinal Axis ◽  
Climbing Fiber ◽  
Optokinetic Stimulation ◽  
Simple Spike ◽  
Postural Responses ◽  
Stimulation Of

1. The cerebellar uvula-nodulus receives vestibular projections from primary and secondary vestibular afferents as well as vestibularly related climbing fibers. It also receives visually related information from climbing fiber pathways. In this experiment we investigated how this information is mapped onto the uvula-nodulus. We studied the specificity, dynamics, and topographic distribution of climbing fiber responses (CFRs), simple spike responses, and mossy fiber terminal responses evoked by vestibular and optokinetic stimulation in rabbits anesthetized with alpha-chloralose. 2. Vestibularly evoked CFRs were found in the ventral uvula and nodulus. These responses were evoked during static roll tilt of the rabbit about a longitudinal axis and by sinusoidal oscillation about the longitudinal axis. Purely static responses were attributed to stimulation of the utricular otolith by the linear acceleration of gravity. CFRs that lacked a static component were attributed to activation of the semicircular canals. 3. Using a "null technique" we showed that the canal-sensitive CFRs were caused by stimulation of the anterior or posterior semicircular canals. Of the CFRs classified as canal related, 96% could be attributed to stimulation of the vertical semicircular canals. 4. Increases in CFRs were correlated with decreases in simple spike responses in half the Purkinje cells from which we recorded. These climbing-fiber-induced pauses in simple spikes occurred during spontaneous climbing fiber discharge as well as during climbing fiber discharge evoked by vestibular stimulation. The duration of this pause was inversely proportional to the spontaneous level of simple spikes before the occurrence of a CFR. In the other half of the recorded population of Purkinje cells, vestibularly driven CFRs did not alter the simple spike responses. 5. Vestibularly and visually mediated CFRs were topographically represented on the surface of the uvula-nodulus. CFRs driven by ipsilateral otolithic inputs were distributed over the entire mediolateral surface of the uvula-nodulus. CFRs driven by the ipsilateral posterior semicircular canal were distributed in a sagittal strip approximately 1.5 mm wide, extending laterally from the midline of the nodulus. CFRs driven exclusively by horizontal, posterior-->anterior optokinetic stimulation of the ipsilateral eye were distributed in a sagittal strip approximately 0.5 mm wide located 0.5-1.0 mm from the midline and restricted to the ventral nodulus. CFRs driven by the ipsilateral anterior semicircular canal were found in a sagittal strip approximately 1.0 mm wide extending 1.0-2.0 mm from the midline. 6. The sagittal, topographically arrayed climbing fiber strips effectively map a mediolateral gradient of possible postural responses based on vestibular and optokinetic information.

Topography and Reciprocal Activity of Cerebellar Purkinje Cells in the Uvula-Nodulus Modulated by Vestibular Stimulation

1997 ◽  
Vol 78 (6) ◽  
pp. 3083-3094 ◽  
Author(s):  
H. Fushiki ◽  
N. H. Barmack
Keyword(s):  
Purkinje Cell ◽  
Purkinje Cells ◽  
Semicircular Canals ◽  
Vertical Axis ◽  
Longitudinal Axis ◽  
Vestibular Stimulation ◽  
Climbing Fiber ◽  
Null Plane ◽  
Cerebellar Purkinje Cells ◽  
Vertical Semicircular Canals

Fushiki, H. and N. H. Barmack. Topography and reciprocal activity of cerebellar Purkinje cells in the uvula-nodulus modulated by vestibular stimulation. J. Neurophysiol. 78: 3083–3094, 1997. In the rabbit uvula-nodulus, vestibular and optokinetic information is mapped onto parasagittal zones by climbing fibers. These zones are related functionally to different pairs of vertical semicircular canals, otolithic inputs and horizontal optokinetic inputs. Vestibular stimulation restricted to one of these zones modulates climbing fiber responses (CFRs). Within each of these zones, simple spikes (SSs) are modulated reciprocally with CFRs. In rabbits anesthetized with chloralose-urethan, we have used vestibular and optokinetic stimulation to evoke CFRs within a parasagittal zone while recording from Purkinje cells in adjacent zones. We have examined whether the CFRs evoked by vestibular stimulation in one zone influence the SSs of an adjacent zone. CFRs and SSs were recorded during roll vestibular stimulation. The orientation of the head of the rabbit with respect to the axis of rotation was varied systematically so that a climbing fiber null plane could be determined. This null plane was the orientation of the head about the vertical axis at which no modulation of the CFR was observed during rotation about the longitudinal axis of the vestibular rate table. In the left uvula-nodulus, a medial sagittal strip extending through all the folia contained Purkinje cells with CFRs that had optimal planes of stimulation coplanar with the left posterior-right anterior semicircular canals (LPC-RAC). Lateral to this strip was a strip of Purkinje cells with CFRs that were characterized by optimal planes corresponding to stimulation of the left anterior-right posterior semicircular canals (LAC-RPC). SSs in Purkinje cells were modulated out of phase with CFRs from the same Purkinje cell. The depth of modulation of both CFRs and SSs was reduced during rotation in the climbing fiber “null plane”. The depth of modulation of SSs was greatest when recorded from Purkinje cells located at the center of semicircular canal-related strip. We observed that 1) all folia of the uvula-nodulus receive vestibular climbing fiber inputs; 2) these climbing fiber inputs convey information from the vertical semicircular canals and otoliths but not the horizontal semicircular canals; 3) CFRs evoked in a particular sagittal zone do not influence SSs in adjacent zones; 4) modulation of a CFRs in a particular Purkinje cell can occur without modulation of SSs in the same Purkinje cell, although modulation of SSs was not observed in the absence of CFR modulation; and 5) modulation of SSs sometimes preceded that of CFRs in the same cell, implying that interneuronal pathways may contribute to SS modulation. Climbing fiber-driven Golgi cells, the inhibitory axon terminals of which end on granule cell dendrites in the classic glomerular synapse, may provide this interneuronal mechanism.

Increase in Purkinje cell gain associated with naturally activated climbing fiber input

1983 ◽  
Vol 50 (1) ◽  
pp. 205-219 ◽  
Author(s):  
T. J. Ebner ◽  
Q. X. Yu ◽  
J. R. Bloedel
Keyword(s):  
Purkinje Cell ◽  
Purkinje Cells ◽  
Mossy Fiber ◽  
Climbing Fiber ◽  
Peripheral Stimulus ◽  
Short Term ◽  
Spike Response ◽  
Complex Spike ◽  
Simple Spike ◽  
Complex Spikes

These experiments were designed to test the hypothesis that climbing fiber inputs evoked by a peripheral stimulus increase the responsiveness of Purkinje cells to mossy fiber inputs. This hypothesis was based on a previous series of observations demonstrating that spontaneous climbing fiber inputs are associated with an accentuation of the Purkinje cell responses to subsequent mossy fiber inputs (10, 12). Furthermore, short-term nonpersistent interactions between climbing and mossy fiber inputs have been an important aspect of many theories of cerebellar function (5, 7, 8, 12, 36). Extracellular unitary recordings were made from Purkinje cells in lobule V of decerebrate, unanesthetized cats. To activate mossy and climbing fiber inputs, the forepaw was passively flexed by a Ling vibrator system. A data analysis was developed to sort the simple spike trials into two groups, based on the presence or absence of complex spikes activated by the stimulus. In addition, during those trials in which complex spikes were activated, the simple spike train was aligned on the occurrence of the complex spike. For each simple spike response to the forepaw input, the average firing rate during the response was compared to background both in those trials in which complex spikes were activated and in those in which they were not. The ratio of the response amplitudes in the histograms constructed from these two groups of trials permitted a quantification of the change in responsiveness when climbing fiber inputs were activated. The results show that both excitatory and inhibitory simple spike responses are accentuated when associated with the activation of a complex spike. Using an arbitrary level of a gain change ratio of 120% as indicating a significant modification, 64% of the response components analyzed increased their amplitude when climbing fiber input was present. Simple spike response components occurring prior to complex spike activation were usually not accentuated, although in a few cells the amplitude of this component of the response increased. In addition, in a small number of cells the occurrence of complex spikes was associated with a new simple spike component. For excitatory responses, the magnitude of the gain change ratio was shown to be inversely related to the amplitude of the simple spike response evoked by the mossy fiber inputs. The data obtained is consistent with the hypothesis that the climbing fiber input is associated with an increase in the responsiveness of Purkinje cells to mossy fiber inputs. The increased responsiveness occurs whether the simple spike modulation evoked by the peripheral stimulus is excitatory or inhibitory. The change in responsiveness is short term and nonpersistent. It is argued that the activation of climbing fiber inputs to the cerebellar cortex is associated with an increase in the gain of Purkinje cells to mossy fiber inputs activated by natural peripheral stimuli.

Responses of sagittally aligned Purkinje cells during perturbed locomotion: relation of climbing fiber activation to simple spike modulation

1992 ◽  
Vol 68 (5) ◽  
pp. 1820-1833 ◽  
Author(s):  
J. S. Lou ◽  
J. R. Bloedel
Keyword(s):  
Data Analysis ◽  
Real Time ◽  
Purkinje Cells ◽  
Mossy Fiber ◽  
Swing Phase ◽  
Climbing Fiber ◽  
Relevant Stimulus ◽  
Simple Spike ◽  
Trial Basis ◽  
Discrete Populations

1. The purpose of these experiments is to test the hypothesis that the synchronous activation of sagittally aligned Purkinje cells by a physiologically relevant stimulus is associated with an increase in the simple spike responses of the same neurons. 2. This hypothesis was tested using a perturbed locomotion paradigm in decerebrate locomoting ferrets. The responses of 3-5 sagittally aligned Purkinje cells were recorded simultaneously in response to the intermittent perturbation of the forelimb during swing phase. A data analysis is introduced, the real time postsynaptic response (RTPR), that permits the quantification of the simple spike responses of Purkinje cells in a manner that can be related to their complex spike responses on a trial-by-trial basis. 3. The data support the above hypothesis by illustrating that the amplitude of the combined simple spike responses across the population of Purkinje cells is correlated with the extent to which their climbing fiber inputs are synchronously activated. These findings together with an analysis of the gain-change ratio support the view that the synchronous climbing fiber input may be responsible for mediating this increased responsiveness. 4. More generally, the data suggest that the task- and/or behaviorally dependent activation of sagittal strips of climbing fiber inputs may provide a mechanism whereby the responsiveness of discrete populations of Purkinje cells can be selectively regulated, specifying the groups of neurons that will be most dramatically modulated by mossy fiber inputs activated by the same conditions.

Vestibular Signals in the Parasolitary Nucleus

2000 ◽  
Vol 83 (6) ◽  
pp. 3559-3569 ◽  
Author(s):  
N. H. Barmack ◽  
V. Yakhnitsa
Keyword(s):  
Inferior Olive ◽  
Granule Cells ◽  
Vestibular Nucleus ◽  
Semicircular Canals ◽  
Longitudinal Axis ◽  
Vestibular Stimulation ◽  
Primary Afferents ◽  
Climbing Fiber ◽  
Large Sphere ◽  
Optimal Response

Vestibular primary afferents project to secondary vestibular neurons located in the vestibular complex. Vestibular primary afferents also project to the uvula-nodulus of the cerebellum where they terminate on granule cells. In this report we describe the physiological properties of neurons in a “new” vestibular nucleus, the parasolitary nucleus (Psol). This nucleus consists of 2,300 GABAergic neurons that project onto the ipsilateral inferior olive (β-nucleus and dorsomedial cell column) as well as the nucleus reticularis gigantocellularis. These olivary neurons are the exclusive source of vestibularly modulated climbing fiber inputs to the cerebellum. We recorded the activity of Psol neurons during natural vestibular stimulation in anesthetized rabbits. The rabbits were placed in a three-axis rate table at the center of a large sphere, permitting vestibular and optokinetic stimulation. We recorded from 74 neurons in the Psol and from 23 neurons in the regions bordering Psol. The activity of 72/74 Psol neurons and 4/23 non-Psol neurons was modulated by vestibular stimulation in either the pitch or roll planes but not the horizontal plane. Psol neurons responded in phase with ipsilateral side-down head position or velocity during sinusoidal stimulation. Approximately 80% of the recorded Psol neurons responded to static roll-tilt. The optimal response planes of evoked vestibular responses were inferred from measurement of null planes. Optimal response planes usually were aligned with the anatomical orientation of one of the two ipsilateral vertical semicircular canals. The frequency dependence of null plane measurements indicated a convergence of vestibular information from otoliths and semicircular canals. None of the recorded neurons evinced optokinetic sensitivity. These results are consistent with the view that Psol neurons provide the vestibular signals to the inferior olive that eventually reached the cerebellum in the form of modulated climbing fiber discharges. These signals provide information about spatial orientation about the longitudinal axis.

scholarly journals Pulsed Infrared Stimulation of Vertical Semicircular Canals Evokes Cardiovascular Changes in the Rat

2021 ◽  
Vol 12 ◽  
Author(s):  
Darrian Rice ◽  
Giorgio P. Martinelli ◽  
Weitao Jiang ◽  
Gay R. Holstein ◽  
Suhrud M. Rajguru
Keyword(s):  
Heart Rate ◽  
Nervous System ◽  
Semicircular Canal ◽  
Parasympathetic Nervous System ◽  
Semicircular Canals ◽  
Whole Body ◽  
Experimental Session ◽  
Otolith Organs ◽  
Vertical Semicircular Canals ◽  
Stimulation Of

A variety of stimuli activating vestibular end organs, including sinusoidal galvanic vestibular stimulation, whole body rotation and tilt, and head flexion have been shown to evoke significant changes in blood pressure (BP) and heart rate (HR). While a role for the vertical semicircular canals in altering autonomic activity has been hypothesized, studies to-date attribute the evoked BP and HR responses to the otolith organs. The present study determined whether unilateral activation of the posterior (PC) or anterior (AC) semicircular canal is sufficient to elicit changes in BP and/or HR. The study employed frequency-modulated pulsed infrared radiation (IR: 1,863 nm) directed via optical fibers to PC or AC of adult male Long-Evans rats. BP and HR changes were detected using a small-animal single pressure telemetry device implanted in the femoral artery. Eye movements evoked during IR of the vestibular endorgans were used to confirm the stimulation site. We found that sinusoidal IR delivered to either PC or AC elicited a rapid decrease in BP and HR followed by a stimulation frequency-matched modulation. The magnitude of the initial decrements in HR and BP did not correlate with the energy of the suprathreshold stimulus. This response pattern was consistent across multiple trials within an experimental session, replicable, and in most animals showed no evidence of habituation or an additive effect. Frequency modulated electrical current delivered to the PC and IR stimulation of the AC, caused decrements in HR and BP that resembled those evoked by IR of the PC. Frequency domain heart rate variability assessment revealed that, in most subjects, IR stimulation increased the low frequency (LF) component and decreased the high frequency (HF) component, resulting in an increase in the LF/HF ratio. This ratio estimates the relative contributions of sympathetic nervous system (SNS) and parasympathetic nervous system (PNS) activities. An injection of atropine, a muscarinic cholinergic receptor antagonist, diminished the IR evoked changes in HR, while the non-selective beta blocker propranolol eliminated changes in both HR and BP. This study provides direct evidence that activation of a single vertical semicircular canal is sufficient to activate and modulate central pathways that control HR and BP.

scholarly journals Adaptive Balance in Posterior Cerebellum

2021 ◽  
Vol 12 ◽  
Author(s):  
Neal H. Barmack ◽  
Vito Enrico Pettorossi
Keyword(s):  
Purkinje Cells ◽  
Stellate Cell ◽  
Semicircular Canals ◽  
Mossy Fibers ◽  
Vestibular Nuclei ◽  
Three Dimensions ◽  
Optokinetic Stimulation ◽  
Afferent Pathways ◽  
Vestibular Nuclear Neurons ◽  
Self Motion

Vestibular and optokinetic space is represented in three-dimensions in vermal lobules IX-X (uvula, nodulus) and hemisphere lobule X (flocculus) of the cerebellum. Vermal lobules IX-X encodes gravity and head movement using the utricular otolith and the two vertical semicircular canals. Hemispheric lobule X encodes self-motion using optokinetic feedback about the three axes of the semicircular canals. Vestibular and visual adaptation of this circuitry is needed to maintain balance during perturbations of self-induced motion. Vestibular and optokinetic (self-motion detection) stimulation is encoded by cerebellar climbing and mossy fibers. These two afferent pathways excite the discharge of Purkinje cells directly. Climbing fibers preferentially decrease the discharge of Purkinje cells by exciting stellate cell inhibitory interneurons. We describe instances adaptive balance at a behavioral level in which prolonged vestibular or optokinetic stimulation evokes reflexive eye movements that persist when the stimulation that initially evoked them stops. Adaptation to prolonged optokinetic stimulation also can be detected at cellular and subcellular levels. The transcription and expression of a neuropeptide, corticotropin releasing factor (CRF), is influenced by optokinetically-evoked olivary discharge and may contribute to optokinetic adaptation. The transcription and expression of microRNAs in floccular Purkinje cells evoked by long-term optokinetic stimulation may provide one of the subcellular mechanisms by which the membrane insertion of the GABAA receptors is regulated. The neurosteroids, estradiol (E2) and dihydrotestosterone (DHT), influence adaptation of vestibular nuclear neurons to electrically-induced potentiation and depression. In each section of this review, we discuss how adaptive changes in the vestibular and optokinetic subsystems of lobule X, inferior olivary nuclei and vestibular nuclei may contribute to the control of balance.

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