Cerebellar Afferent Systems

Bloedel, James R.; Courville, J.

doi:10.1002/cphy.cp010216

Cited by 117 publications

(65 citation statements)

References 638 publications

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“…It is conceivable that the rhythmic discharge reflects oscillations in the afferent input projecting to the inferior olive. However, this type of behaviour has not yet been described in an olivary afferent projection (Bloedel & Courville, 1981). Therefore, in the remainder of the Discussion we will make the assumption that the rhythmicity underlying the periodicity in the p.s.t.h.s originates in the inferior olivary nucleus.…”

Section: Discussionmentioning

confidence: 99%

“…The 5-10 Hz periodicity observed in the climbing fibre p.s.t.h.s could be considered somewhat paradoxical in the light of the much slower spontaneous discharge rate of climbing fibre afferents or inferior olivary neurones (Armstrong, 1974;Bloedel & Courville, 1981). During spontaneous activity as well as during the application of natural inputs these neurones discharge at mean frequencies ranging from 0 5 to 2 Hz in a wide varity of preparations (Armstrong, 1974).…”

Section: Discussionmentioning

confidence: 99%

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Rhythmic discharge of climbing fibre afferents in response to natural peripheral stimuli in the cat.

Bloedel¹,

Ebner²

1984

The Journal of Physiology

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SUMMARY1. The rhythmicity of inferior olivary neurones evoked by natural ipsilateral forepaw inputs was evaluated in the climbing fibre afferent discharge of Purkinje cells recorded in the cerebellar cortex ofthe decerebrate, unanaesthetized cat. Almost 50 % of all Purkinje cells responding to the forepaw stimulus with an increase in complex spike activity exhibited periodic discharge, with the dominant periodicity being between 100 and 160 ms. In ten of twenty-five neighbouring, simultaneously recorded Purkinje cells the forepaw stimulus evoked similar periodicity in their complex spike discharge.2. For some cells two peaks of complex spike activity were evoked by a forepaw stimulus without an obvious third peak. By altering the stimulus duration the second peak of the response was shown to be temporally uncoupled to the 'off' phase of the displacement for many cells.3. The interdependence of the trials contributing to the periodic peaks in the peristimulus time histogram (p.s.t.h.) was examined by a 'separation technique'. This analysis indicated that the complex spikes contributing to a specific peak in the p.s.t.h. were generated with a high degree of independence (i.e. in different trials) from the complex spikes contributing to any other peak.4. It was hypothesized that the independence of the rhythmic complex spike peaks is due to the long relative refractoriness following a complex spike in a single cell. Therefore, the probability of a complex spike occurring at the next one or two cycles is decreased significantly. As a consequence, an inferior olivary neurone fires usually at only one of the various peaks in response to a single presentation of the forepaw stimulus.5. This hypothesis predicts that stimuli evoking a complex spike at the initial peak in a high percentage of trials should give rise to less periodicity. This prediction was tested by comparing the presence or absence ofevoked oscillation with the probability of evoking a complex spike in the first peak of the p.s.t.h. Cells exhibiting a probability for complex spike discharge of over 50 % in the first peak showed much less periodicity than cells with a complex spike occurring in less than 50 % of the trials in the first peak.6. These results are discussed in the context of the inferior olive being viewed as a population of coupled elements with a tendency to oscillate. The natural forepaw 5 P HY 352 J. R. BLOEDEL AND T. J. EBNER stimulus is hypothesized as synchronizing the phases of spontaneously oscillating climbing fibre afferents, resulting in the observed periodicity in the complex spike p.s.t.h.

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Section: Discussionmentioning

confidence: 99%

Section: Discussionmentioning

confidence: 99%

Rhythmic discharge of climbing fibre afferents in response to natural peripheral stimuli in the cat.

Bloedel¹,

Ebner²

1984

The Journal of Physiology

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“…Activation of the mouse Raldh2 intron 1G enhancer and of Raldh2 expression in the RP, coupled with transient Raldh2 expression in dIs, suggests that RA signaling is involved in dI1 development. Math1-expressing dI1 interneurons migrate to ventral locations in the gray matter, coming to rest between laminae VI and VIII to form integrative centers that receive proprioceptive input from fore and hindlimbs, as well as from trunk, neck and thorax, relaying it to the cerebellum via dorsal and ventral spinocerebellar tracts, which are depleted in Math1-null mice (Bermingham et al, 2001;Bloedel and Courville, 1981;Brodal, 1981;Helms and Johnson, 1998;Lewis, 2006). The integrative SC center that serves the dorsal spinocerebellar system is Clarke's nucleus.…”

Section: Research Articlementioning

confidence: 99%

“…The integrative SC center that serves the dorsal spinocerebellar system is Clarke's nucleus. These interneuron cells receive afferents from lower trunk and hindlimbs and are concentrated in lamina VII, which also receives information from posterior trunk, hindlimbs and forelimbs and projects to the cerebellum via ventral spinocerebellar and rostral spinocerebellar tracts (Bloedel and Courville, 1981;Brodal, 1981). Therefore, RPderived RA is poised to influence dI1 interneurons, which give rise to proprioceptive spinocerebellar circuits.…”

Section: Research Articlementioning

confidence: 99%

Insights into the organization of dorsal spinal cord pathways from an evolutionarily conserved raldh2 intronic enhancer

Castillo¹,

Cravo²,

Azambujá³

et al. 2010

Development

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SUMMARYComparative studies of the tetrapod raldh2 (aldh1a2) gene, which encodes a retinoic acid (RA) synthesis enzyme, have led to the identification of a dorsal spinal cord enhancer. Enhancer activity is directed dorsally to the roof plate and dorsal-most (dI1) interneurons through predicted Tcf-and Cdx-homeodomain binding sites and is repressed ventrally via predicted Tgif homeobox and ventral Lim-homeodomain binding sites. Raldh2 and Math1/Cath1 expression in mouse and chicken highlights a novel, transient, endogenous Raldh2 expression domain in dI1 interneurons, which give rise to ascending circuits and intraspinal commissural interneurons, suggesting roles for RA in the ontogeny of spinocerebellar and intraspinal proprioceptive circuits. Consistent with expression of raldh2 in the dorsal interneurons of tetrapods, we also found that raldh2 is expressed in dorsal interneurons throughout the agnathan spinal cord, suggesting ancestral roles for RA signaling in the ontogenesis of intraspinal proprioception.

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“…Assuming that the Golgi cells influence the Purkinje cells nearest to them most powerfully (see above), the present results suggest that in some cases Golgi cell disfacilitation is greatest at the time of peak discharge of the Purkinje cells, whereas in other cases it is greatest at the time of minimum activity. It Oscarsson, 1973;Bloedel & Courville, 1981) and many are thought to provide the cerebellum 330 GOLGI CELLS AND LOCOMOTION with information regarding the progress of movements. Considerable alterations in the activity of these afferents might therefore be expected as the speed or angle of the belt was varied.…”

Section: Discharges Of Golgi Cells During Locomotionmentioning

confidence: 99%

The discharges of cerebellar Golgi cells during locomotion in the cat.

Edgley¹,

Lidierth²

1987

The Journal of Physiology

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SUMMARY1. Extracellular recordings have been obtained from 134 units in the paravermal cortex of lobule V in the anterior lobe of the cerebellum in free-to-move cats. Each unit discharged action potentials in a characteristic pattern with no complex spikes. Previous investigators have described such discharges and have assigned them to Golgi cells. We provide further evidence to support this identification.2. In cats which were sitting quietly, each putative Golgi cell discharged tonically at a low rate (overall mean (±S.D.) was 14-5+7-3 spikes/s). Eighty-one of the neurones were also recorded during steady walking on a moving belt and the discharge rate then averaged 17-7 (S.D. + 19-4) spikes/s.3. All eighty-one putative Golgi cells discharged rythmically during locomotion. Many different patterns of discharge were seen but as a population the neurones were most active in early stance and at the onset of the swing phase of the step cycle in the ipsilateral forelimb.4. Over a range of different walking speeds (0 5-09 m/s) and of different uphill inclines (0-25 deg), putative Golgi cells discharged with similar patterns and rates, despite large changes in the vigour of the locomotor movements and in the amplitude of limb muscle electromyograms.

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Cerebellar Afferent Systems

Cited by 117 publications

References 638 publications

Rhythmic discharge of climbing fibre afferents in response to natural peripheral stimuli in the cat.

Rhythmic discharge of climbing fibre afferents in response to natural peripheral stimuli in the cat.

Insights into the organization of dorsal spinal cord pathways from an evolutionarily conserved raldh2 intronic enhancer

The discharges of cerebellar Golgi cells during locomotion in the cat.

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