Broad directional tuning in spinal projections to the cerebellum

1993 ◽  
Vol 70 (2) ◽  
pp. 863-866 ◽  
Author(s):  
G. Bosco ◽  
R. E. Poppele
Keyword(s):  
Functional Organization ◽  
Sagittal Plane ◽  
Mossy Fiber ◽  
Cerebellar Nuclei ◽  
Limb Movement ◽  
Response Patterns ◽  
Hind Foot ◽  
Limb Posture ◽  
Spinocerebellar Neurons ◽  
Tuning Function

1. Spinocerebellar neurons that project in the dorsal spinocerebellar tract (DSCT) receive mono- and polysynaptic inputs from specific sensory receptors in the hindlimb, and they project mossy fiber terminals to the cerebellar vermis. We examined the functional organization of these neurons and found that it relates to whole-limb parameters like limb posture and direction of limb movement. 2. We recorded the activity of 444 DSCT units during passive perturbations of the hind foot in anesthetized cats. The movements were either confined a single joint (the ankle; 234 cells) or involved the entire hindlimb (210 cells). The cells exhibited opposite responses for opposite directions of whole-limb movement, but a variety of response patterns for opposite directions of movement at one joint. We interpret the result to imply that the population encodes information about the whole limb rather than single joints. 3. Most of the 78 neurons recorded during passive limb placements (63%) responded to changes in limb length and also changes in limb orientation. In fact, the activity of most of the cells was broadly tuned with respect to the direction of passive limb movements generated by moving the hind foot in the sagittal plane. Changes in unit activity could be described by a cosine tuning function with respect to foot positions (72% of responses) and directions of foot movement (50%). 4. The similarity of this behavior to that of neurons in the motor cortex and cerebellar nuclei recorded during voluntary movements is consistent with a common neural code to represent the sensorimotor parameters of limb movement.

Components of responses of a population of DSCT neurons to muscle stretch and contraction

1989 ◽  
Vol 61 (2) ◽  
pp. 456-465 ◽  
Author(s):  
C. E. Osborn ◽  
R. E. Poppele
Keyword(s):  
Time Course ◽  
Functional Organization ◽  
Afferent Fiber ◽  
Response Probability ◽  
Principal Component ◽  
Response Patterns ◽  
Afferent Pathways ◽  
Hindlimb Muscles ◽  
Spinocerebellar Tract ◽  
And Cluster Analysis

1. Impulse activity of 264 units of the dorsal spinocerebellar tract (DSCT) was recorded during random contraction or stretch in hindlimb muscles. Contractions were evoked in either the isolated gastrocnemius-soleus (GS) muscles or the intact limb during crossed-extensor reflexes; stretches were applied to the isolated GS. 2. The time course of poststimulus changes in spike activity of DSCT neurons was determined from the response probability function (RPF; Ref. 15). These data were analyzed using principal component and cluster analysis to group the responses according to the RPF waveforms. 3. The responses to each type of stimulus displayed a remarkable similarity in time course, regardless of the type of stimulus used. The responses were also similar to those observed previously during single shock nerve stimulation (14). 4. The most reasonable explanation for these results is that the time course of excitability changes in DSCT neurons is determined less by particular types of receptors or patterns of afferent fiber activity than by the circuitry and afferent pathways impinging on the neurons of the DSCT. 5. The functional organization of DSCT suggested by these results includes a wide divergence from sensory receptors along polysynaptic pathways to DSCT neurons and considerable convergence onto each neuron from a diversity of receptors. Individual DSCT cells may respond to stimuli with one of a few stereo-typical response patterns yet the distribution of those patterns among the units of the DSCT population may be unique for each stimulus.

scholarly journals Physiological and Morphological Principles Underpinning Recruitment of the Cerebellar Reserve

2018 ◽  
Vol 17 (3) ◽  
pp. 184-192 ◽  
Author(s):  
Shinji Kakei ◽  
Takahiro Ishikawa ◽  
Jongho Lee ◽  
Takeru Honda ◽  
Donna S. Hoffman
Keyword(s):  
Mossy Fiber ◽  
Cell Loss ◽  
Cerebellar Nuclei ◽  
Cerebellar Neuron ◽  
Cerebellar Diseases ◽  
Cerebellar Ataxias ◽  
Cerebellar Cell ◽  
Points Of View ◽  
Future Therapy ◽  
Real Challenge

Background: In order to optimize outcomes of novel therapies for cerebellar ataxias (CAs), it is desirable to start these therapies while declined functions are restorable: i.e. while the so-called cerebellar reserve remains. Objective: In this mini-review, we tried to define and discuss the cerebellar reserve from physiological and morphological points of view. Method: The cerebellar neuron circuitry is designed to generate spatiotemporally organized outputs, regardless of the region. Therefore, the cerebellar reserve may be defined as a mechanism to restore its proper input-output organization of the cerebellar neuron circuitry, when it is damaged. Then, the following four components are essential for recruitment of the cerebellar reserve: operational local neuron circuitry; proper combination of mossy fiber inputs to be integrated; climbing fiber inputs to instruct favorable reorganization of the integration; deep cerebellar nuclei to generate reorganized outputs. Results: We discussed three topics related to these resources, 1) principles of generating organized cerebellar outputs, 2) redundant mossy fiber inputs to the cerebellum, 3) plasticity of the cerebellar neuron circuitry. Conclusion: To make most of the cerebellar reserve, it is desirable to start any intervention as early as possible when the cerebellar cell loss is minimal or even negligible. Therefore, an ideal future therapy for degenerative cerebellar diseases should start before consuming the cerebellar reserve at all. In the meantime, our real challenge is to establish a reliable method to identify the decrease in the cerebellar reserve as early as possible.

scholarly journals Evidence for genetically distinct direct and indirect spinocerebellar pathways mediating proprioception

2020 ◽  
Author(s):  
Iliodora V. Pop ◽  
Felipe Espinosa ◽  
Megan Goyal ◽  
Bishakha Mona ◽  
Mark A. Landy ◽  
...  
Keyword(s):  
Spinal Cord ◽  
Granule Cells ◽  
Mossy Fiber ◽  
Cerebellar Nuclei ◽  
Reticular Nucleus ◽  
Proprioceptive Information ◽  
Lateral Reticular Nucleus ◽  
Axon Collaterals ◽  
Progenitor Domain ◽  
Clarke's Column

AbstractProprioception, the sense of limb and body position, generates a map of the body that is essential for proper motor control, yet we know little about precisely how neurons in proprioceptive pathways develop and are wired. Proprioceptive and cutaneous information from the periphery is sent to secondary neurons in the spinal cord that integrate and relay this information to the cerebellum either directly or indirectly through the medulla. Defining the anatomy of these direct and indirect pathways is fundamental to understanding how proprioceptive circuits function. Here, we use genetic tools in mice to define the developmental origins and unique anatomical trajectories of these pathways. Developmentally, we find that Clarke’s column (CC) neurons, a major contributor to the direct spinocerebellar pathway, derive from the Neurog1 progenitor domain. By contrast, we find that two of the indirect pathways, the spino-lateral reticular nucleus (spino-LRt) and spino-olivary pathways, are derived from the Atoh1 progenitor domain, despite previous evidence that Atoh1-lineage neurons form the direct pathway. Anatomically, we also find that the mossy fiber terminals of CC neurons diversify extensively with some axons terminating bilaterally in the cerebellar cortex. Intriguingly, we find that CC axons do not send axon collaterals to the medulla or cerebellar nuclei like other mossy fiber sources. Altogether, we conclude that the direct and indirect spinocerebellar pathways derive from distinct progenitor domains in the developing spinal cord and that the proprioceptive information from CC neurons is processed only at the level of granule cells in the cerebellum.Significance StatementWe find that a majority of direct spinocerebellar neurons in mice originate from Clarke’s column (CC), which derives from the Neurog1-lineage, while few originate from Atoh1-lineage neurons as previously thought. Instead, we find that spinal cord Atoh1-lineage neurons form mainly the indirect spino-lateral reticular nucleus and spino-olivary tracts. Moreover, we observe that mossy fiber axon terminals of CC neurons diversify proprioceptive information across granule cells in multiple lobules on both ipsilateral and contralateral sides without sending axon collaterals to the medulla or cerebellar nuclei. Altogether, we define the development and the anatomical projections of direct and indirect pathways to the cerebellum from the spinal cord.

scholarly journals Responses of pigeon vestibulocerebellar neurons to optokinetic stimulation. I. Functional organization of neurons discriminating between translational and rotational visual flow

1993 ◽  
Vol 70 (6) ◽  
pp. 2632-2646 ◽  
Author(s):  
D. R. Wylie ◽  
T. Kripalani ◽  
B. J. Frost
Keyword(s):  
Functional Organization ◽  
Mossy Fiber ◽  
Receptive Fields ◽  
Direction Selectivity ◽  
Maximum Depth ◽  
Large Field ◽  
Directional Tuning ◽  
Tuning Curves ◽  
Downward Motion ◽  
Stimulation Of

1. Extracellular recordings were made from 235 neurons in the vestibulocerebellum (VbC), including the flocculus (lateral VbC), nodulus (folium X), and ventral uvula (ventral folium IXc,d), of the anesthetized pigeon, in response to an optokinetic stimulus. 2. The optokinetic stimuli consisted of two black and white random-dot patterns that were back-projected onto two large tangent screens. The screens were oriented parallel to each other and placed on either side of the bird's head. The resultant stimulus covered the central 100 degrees x 100 degrees of each hemifield. The directional tuning characteristics of each unit were assessed by moving the largefield stimulus in 12 different directions, 30 degrees apart. The directional tuning curves were performed monocularly or binocularly. The binocular directional tuning curves were performed with the direction of motion the same in both eyes (in-phase; e.g., ipsi = upward, contra = upward) or with the direction of motion opposite in either eye (antiphase; e.g., ipsi = upward, contra = downward). 3. Mossy fiber units (n = 17) found throughout folia IXa,b and IXc,d had monocular receptive fields and exhibited direction selectivity in response to stimulation of either the ipsilateral (n = 12) or contralateral (n = 5) eye. None had binocular receptive fields. 4. The complex spike (CS) activity of 218 Purkinje cells in folia IXc,d and X exhibited direction selectivity in response to the large-field visual stimulus moving in one or both visual fields. Ninety-one percent of the cells had binocular receptive fields that could be classified into four groups: descent neurons (n = 112) preferred upward motion in both eyes; ascent neurons (n = 14) preferred downward motion in both eyes; roll neurons (n = 33) preferred upward and downward motion in the ipsilateral and contralateral eyes, respectively; and yaw neurons (n = 40) preferred forward and backward motion in the ipsilateral and contralateral eyes, respectively. Within all groups, most neurons (70%) showed an ipsilateral dominance. 5. For most binocular neurons (91%), the maximum depth of modulation occurred with simultaneous stimulation of both eyes, compared with monocular stimulation of the dominant eye alone. For the translation neurons (descent and ascent), binocular inphase stimulation produced the maximum depth of modulation, whereas for the rotation neurons (roll and yaw), binocular antiphase stimulation produced the maximum depth of modulation. 6. There was a clear functional segregation of the translation and rotation neurons.(ABSTRACT TRUNCATED AT 400 WORDS)

Closely overlapping responses to tools and hands in left lateral occipitotemporal cortex

2012 ◽  
Vol 107 (5) ◽  
pp. 1443-1456 ◽  
Author(s):  
Stefania Bracci ◽  
Cristiana Cavina-Pratesi ◽  
Magdalena Ietswaart ◽  
Alfonso Caramazza ◽  
Marius V. Peelen
Keyword(s):  
Visual Cortex ◽  
Visual Motion ◽  
Functional Organization ◽  
Premotor Cortex ◽  
High Order ◽  
Body Motion ◽  
Response Patterns ◽  
Body Parts ◽  
Hand Tool ◽  
Occipitotemporal Cortex

The perception of object-directed actions performed by either hands or tools recruits regions in left fronto-parietal cortex. Here, using functional MRI (fMRI), we tested whether the common role of hands and tools in object manipulation is also reflected in the distribution of response patterns to these categories in visual cortex. In two experiments we found that static pictures of hands and tools activated closely overlapping regions in left lateral occipitotemporal cortex (LOTC). Left LOTC responses to tools selectively overlapped with responses to hands but not with responses to whole bodies, nonhand body parts, other objects, or visual motion. Multivoxel pattern analysis in left LOTC indicated a high degree of similarity between response patterns to hands and tools but not between hands or tools and other body parts. Finally, functional connectivity analysis showed that the left LOTC hand/tool region was selectively connected, relative to neighboring body-, motion-, and object-responsive regions, with regions in left intraparietal sulcus and left premotor cortex that have previously been implicated in hand/tool action-related processing. Taken together, these results suggest that action-related object properties shared by hands and tools are reflected in the organization of high-order visual cortex. We propose that the functional organization of high-order visual cortex partly reflects the organization of downstream functional networks, such as the fronto-parietal action network, due to differences within visual cortex in the connectivity to these networks.

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