Role of climbing fiber afferent input in determining responsiveness of Purkinje cells to mossy fiber inputs.

1981 ◽  
Vol 45 (5) ◽  
pp. 962-971 ◽  
Author(s):  
T J Ebner ◽  
J R Bloedel
Keyword(s):  
Purkinje Cells ◽  
Mossy Fiber ◽  
Afferent Input ◽  
Climbing Fiber

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.

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: synchronous activation of climbing fiber inputs

1992 ◽  
Vol 68 (2) ◽  
pp. 570-580 ◽  
Author(s):  
J. S. Lou ◽  
J. R. Bloedel
Keyword(s):  
Purkinje Cells ◽  
Single Unit ◽  
Climbing Fiber ◽  
Single Unit Recording ◽  
Step Cycle ◽  
Unit Recording ◽  
Recording Technique ◽  
Afferent System ◽  
Fixed Array

1. These experiments were performed to test the hypothesis that climbing fiber inputs to sagittally aligned Purkinje cells located in a single folium are activated synchronously in response to a perturbation of the step cycle that interrupts the trajectory of the ipsilateral forelimb. 2. The experiments were performed in acutely decerebrate ferrets capable of walking spontaneously on a moving treadmill. A multiple single-unit recording technique was employed utilizing a fixed array of five sagittally oriented electrodes with electrode tips approximately 200 microns apart. 3. The extent to which the climbing fiber inputs to the recorded Purkinje cells were activated synchronously by the perturbation was calculated for individual trials by determining the synchrony index, a measure of the fraction of the cells responding to each perturbation. 4. The data indicate that there was a statistically significant increase in the synchronous activation of climbing fiber inputs at times immediately after the perturbation. No comparable complex spike modulation was found at the same phase of the unperturbed step cycle. 5. The specific combinations of climbing fiber inputs to neighboring Purkinje cells activated by successive perturbations varied from trial to trial. 6. The implications of these observations are discussed in the context of the nature of the inputs encoded by climbing fiber activation and the role of this afferent system in cerebellar cortical information processing.

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.

scholarly journals Sensory processing and corollary discharge effects in posterior caudal lobe Purkinje cells in a weakly electric mormyrid fish

2014 ◽  
Vol 112 (2) ◽  
pp. 328-339 ◽  
Author(s):  
Karina Alviña ◽  
Nathaniel B. Sawtell
Keyword(s):  
Purkinje Cells ◽  
Mossy Fiber ◽  
Corollary Discharge ◽  
Electrophysiological Response ◽  
Caudal Lobe ◽  
Mormyrid Fish ◽  
Sensory Structures ◽  
Proprioceptive Inputs ◽  
Weakly Electric ◽  
Complete Account

Although it has been suggested that the cerebellum functions to predict the sensory consequences of motor commands, how such predictions are implemented in cerebellar circuitry remains largely unknown. A detailed and relatively complete account of predictive mechanisms has emerged from studies of cerebellum-like sensory structures in fish, suggesting that comparisons of the cerebellum and cerebellum-like structures may be useful. Here we characterize electrophysiological response properties of Purkinje cells in a region of the cerebellum proper of weakly electric mormyrid fish, the posterior caudal lobe (LCp), which receives the same mossy fiber inputs and projects to the same target structures as the electrosensory lobe (ELL), a well-studied cerebellum-like structure. We describe patterns of simple spike and climbing fiber activation in LCp Purkinje cells in response to motor corollary discharge, electrosensory, and proprioceptive inputs and provide evidence for two functionally distinct Purkinje cell subtypes within LCp. Protocols that induce rapid associative plasticity in ELL fail to induce plasticity in LCp, suggesting differences in the adaptive functions of the two structures. Similarities and differences between LCp and ELL are discussed in light of these results.

scholarly journals Efficient generation of reciprocal signals by inhibition

2012 ◽  
Vol 107 (9) ◽  
pp. 2453-2462 ◽  
Author(s):  
Sung-min Park ◽  
Esra Tara ◽  
Kamran Khodakhah
Keyword(s):  
Purkinje Cells ◽  
Granule Cell ◽  
Granule Cells ◽  
Mossy Fiber ◽  
Cell Activity ◽  
Common Mechanism ◽  
Input Output ◽  
Firing Rates ◽  
Neuronal Computation ◽  
The Brain

Reciprocal activity between populations of neurons has been widely observed in the brain and is essential for neuronal computation. The different mechanisms by which reciprocal neuronal activity is generated remain to be established. A common motif in neuronal circuits is the presence of afferents that provide excitation to one set of principal neurons and, via interneurons, inhibition to a second set of principal neurons. This circuitry can be the substrate for generation of reciprocal signals. Here we demonstrate that this equivalent circuit in the cerebellar cortex enables the reciprocal firing rates of Purkinje cells to be efficiently generated from a common set of mossy fiber inputs. The activity of a mossy fiber is relayed to Purkinje cells positioned immediately above it by excitatory granule cells. The firing rates of these Purkinje cells increase as a linear function of mossy fiber, and thus granule cell, activity. In addition to exciting Purkinje cells positioned immediately above it, the activity of a mossy fiber is relayed to laterally positioned Purkinje cells by a disynaptic granule cell → molecular layer interneuron pathway. Here we show in acutely prepared cerebellar slices that the input-output relationship of these laterally positioned Purkinje cells is linear and reciprocal to the first set. A similar linear input-output relationship between decreases in Purkinje cell firing and strength of stimulation of laterally positioned granule cells was also observed in vivo. Use of interneurons to generate reciprocal firing rates may be a common mechanism by which the brain generates reciprocal signals.

scholarly journals The intellectual disability gene Kirrel3 regulates target-specific mossy fiber synapse development in the hippocampus

eLife ◽  
2015 ◽  
Vol 4 ◽  
Author(s):  
E Anne Martin ◽  
Shruti Muralidhar ◽  
Zhirong Wang ◽  
Diégo Cordero Cervantes ◽  
Raunak Basu ◽  
...  
Keyword(s):  
Synapse Formation ◽  
Mossy Fiber ◽  
Neuron Activity ◽  
Target Cells ◽  
Synaptic Changes ◽  
Mossy Fiber Synapse ◽  
Ca3 Neurons ◽  
Circuit Function ◽  
Feed Forward Inhibition

Synaptic target specificity, whereby neurons make distinct types of synapses with different target cells, is critical for brain function, yet the mechanisms driving it are poorly understood. In this study, we demonstrate Kirrel3 regulates target-specific synapse formation at hippocampal mossy fiber (MF) synapses, which connect dentate granule (DG) neurons to both CA3 and GABAergic neurons. Here, we show Kirrel3 is required for formation of MF filopodia; the structures that give rise to DG-GABA synapses and that regulate feed-forward inhibition of CA3 neurons. Consequently, loss of Kirrel3 robustly increases CA3 neuron activity in developing mice. Alterations in the Kirrel3 gene are repeatedly associated with intellectual disabilities, but the role of Kirrel3 at synapses remained largely unknown. Our findings demonstrate that subtle synaptic changes during development impact circuit function and provide the first insight toward understanding the cellular basis of Kirrel3-dependent neurodevelopmental disorders.

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