scholarly journals A computational model of homeostatic cerebellar compensation of ageing in vestibulo-ocular reflex adaptation

2020 ◽  
Author(s):  
Niceto R. Luque ◽  
Francisco Naveros ◽  
Eduardo Ros ◽  
Angelo Arleo
Keyword(s):  
Purkinje Cell ◽  
Mossy Fibre ◽  
Homeostatic Mechanism ◽  
Functional Changes ◽  
Temporal Profile ◽  
Ocular Reflex ◽  
Non Linear ◽  
Vestibulo Ocular Reflex ◽  
Intrinsic Plasticity

AbstractThe vestibulo-ocular reflex (VOR) stabilises vision during head motion. Age-related structural changes predict a linear VOR decay, whereas epidemiological data show a non-linear temporal profile. Here, we model cerebellar-dependent VOR adaptation to link structural and functional changes throughout ageing. We posit that three neurosynaptic factors codetermine VOR ageing patterns: electrical coupling between inferior olive neurons, intrinsic plasticity at Purkinje cell synapses, and long-term spike timing dependent plasticity at parallel fibre - Purkinje cell synapses as well as mossy fibre - medial vestibular nuclei synapses. Our cross-sectional simulations show that long-term plasticity acts as a global homeostatic mechanism mediating the non-linear temporal profile of VOR. Our results also suggest that intrinsic plasticity at Purkinje cells acts as a local homeostatic mechanism sustaining VOR at old ages. Importantly, longitudinal simulations show that residual fibres coding for the peak and trough of the VOR cycle constitute a predictive hallmark of VOR ageing trajectories.

Plasticity in the adult vestibulo-ocular reflex arc

1977 ◽  
Vol 278 (961) ◽  
pp. 319-334 ◽  
Keyword(s):  
Human Subjects ◽  
Neural Model ◽  
Reflex Response ◽  
Normal Vision ◽  
Ocular Reflex ◽  
Field Of Vision ◽  
Reflex Arc ◽  
Vestibulo Ocular Reflex ◽  
Plastic Changes

Human subjects with maintained reversal of their horizontal field of vision exhibit very substantial adaptive changes in their ‘horizontal’ vestibulo-ocular reflex (v.o.r.). Short durations (8 min) of vision reversal during natural head movement led to 20 % v.o.r. attenuation while long periods (4 weeks) eventually led to approximate reversal of the reflex. The reversed condition is approached by a complex, but highly systematic, series of changes in gain and phase of the reflex response relative to normal. Recovery after return to normal vision exhibits a similar duration, but different pattern, to that of the original adaptation. A chronic cat preparation with long-term optical reversal of vision has now been developed and shows similar adaptive and recovery changes at low test stimulus amplitudes, but different patterns of adaptive response at high amplitudes. An adaptive neural model employing mown vestibulo-ocular pathways is proposed to account for these experimentally observed plastic changes. The model is used to predict the adapted response to patterns of stimulation extending beyond the range of experimental investigation.

Noradrenergic influences on the cerebellar cortex: Effects on vestibular reflexes under basic and adaptive conditions

1998 ◽  
Vol 119 (1) ◽  
pp. 93-105 ◽  
Author(s):  
Ottavio Pompeiano
Keyword(s):  
Purkinje Cells ◽  
Immediate Early Genes ◽  
Visual Signals ◽  
Immediate Early ◽  
Vestibular Reflexes ◽  
Opposite Result ◽  
Early Genes ◽  
Ocular Reflex ◽  
Vestibulo Ocular Reflex

Experiments performed either in decerebrate cats or in intact rabbits have shown that functional inactivation of the cerebellar anterior vermis or the flocculus decreased the basic gain of the vestibulospinal or the vestibulo-ocular reflex, respectively. These findings were attributed to the fact that a proportion of the vermal or floccular Purkinje cells, which are inhibitory in function, discharge out of phase with respect to the vestibulospinal or the vestibulo-ocular neurons during sinusoidal animal rotation, thus exerting a facilitatory influence on the gain of the vestibular reflexes. Intravermal injection of a β-noradrenergic agonist slightly increased the gain of the vestibulospinal reflex, whereas the opposite result was obtained after injection of β-antagonists. Similarly, intrafloccular injection of a β-noradrenergic agonist slightly facilitated the gain of the vestibulo-ocular reflex in darkness (but not in light), whereas a small decrease of the reflex occurred after injection of a β-antagonist. It was postulated that the noradrenergic system acts on Purkinje cells by enhancing their amplitude of modulation to a given labyrinth signal, thus increasing the basic gain of the vestibular reflexes. The Purkinje cells of the cerebellar anterior vermis and the flocculus also exert a prominent role on the adaptation of vestibulospinal and vestibulo-ocular reflexes, respectively. In particular, intravermal or intrafloccular injection of β-noradrenergic antagonists decreased or suppressed the adaptive capacity of the vestibulospinal and vestibulo-ocular reflexes that always occurred during sustained out-of-phase neck-vestibular or visual-vestibular stimulation, whereas the opposite result was obtained after local injection of a β-noradrenergic agonist. The noradrenergic innervation of the cere-bellar cortex originates from the locus coeruleus complex, whose neurons respond to vestibular, neck, and visual signals. It was postulated that this structure acts through β-adrenoceptors to increase the expression of immediate-early genes, such as c- fos and Jun-B, in the Purkinje cells during vestibular adaptation. Induction of immediate-early genes could then represent a mechanism by which impulses elicited by sustained neck-vestibular or visuovestibular stimulation are transduced into long-term biochemical changes that are required for cerebellar long-term plasticity. (Otolaryngol Head Neck Surg 1998;119:93-105.)

Long-term effects of vestibular rehabilitation and head-mounted gaming task procedure in unilateral vestibular hypofunction: a 12-month follow-up of a randomized controlled trial

2018 ◽  
Vol 33 (1) ◽  
pp. 24-33 ◽  
Author(s):  
Andrea Viziano ◽  
Alessandro Micarelli ◽  
Ivan Augimeri ◽  
Domenico Micarelli ◽  
Marco Alessandrini
Keyword(s):  
Power Spectra ◽  
Vestibular Rehabilitation ◽  
Performance Measure ◽  
Self Report ◽  
Long Term Effects ◽  
Ocular Reflex ◽  
Vestibular Hypofunction ◽  
Vestibulo Ocular Reflex ◽  
Reflex Gain

Objective: To investigate the long-term effects of adding virtual reality–based home exercises to vestibular rehabilitation in people with unilateral vestibular hypofunction. Design: Follow-up otoneurological examination in two randomized groups following a previous one-month trial. Setting: Tertiary rehabilitation center. Subjects: A total of 47 patients with unilateral vestibular hypofunction, one group ( n = 24) undergoing conventional vestibular rehabilitation and the other one ( n = 23) implementing, in addition, head-mounted gaming home exercises, 20 minutes per day for one month. Interventions: One year after completing rehabilitation, patients underwent testing with static posturography, video head impulse test, self-report questionnaires, and a performance measure. Main measures: Vestibulo-ocular reflex gain, posturographic parameters such as length, surface, and fast Fourier transform power spectra, self-report, and gait performance measure scores. Results: Vestibulo-ocular reflex gain was significantly better with respect to pretreatment in both groups. The mixed-method group showed significantly higher gain scores: mean (standard deviation (SD)) at 12 months was 0.71 (0.04), versus 0.64 (0.03) for the vestibular rehabilitation–only group ( P < 0.001). Accordingly, some classical posturography scores such as surface with eyes open and length with eyes closed and low-frequency power spectra were significantly different between groups, with the virtual reality group showing improvement ( P < 0.001). Self-report measures were significantly better in both groups compared to pretreatment, with significant improvement in the mixed-method group as compared to conventional rehabilitation alone: Dizziness Handicap Inventory mean total score was 24.34 (2.8) versus 35.73 (5.88) with a P-value <0.001. Conclusion: Results suggest that head-mounted gaming home exercises are a viable, effective, additional measure to improve long-term vestibular rehabilitation outcomes.

Sign in / Sign up

Export Citation Format

Share Document