DOCSLIB.ORG

Current Concepts of Climbing Fiber Function

Total Page：16

File Type：pdf, Size：1020Kb

Download full-text PDF Read full-text
Current Concepts of Climbing Fiber Function 118 THE ANATOMICAL RECORD (NEW ANAT.) REVIEW Current Concepts of Climbing Fiber Function JAMES R. BLOEDEL AND VLASTISLAV BRACHA This review examines several of the current postulates regarding the function of one of the most intriguing afferent systems in the brain, the climbing fiber system. The fact that these afferents are activated under a variety of conditions has contributed substantially to the diversity of postulates that have been proposed. In part because of the unique anatomical relationship between individual climbing fibers and the dendritic tree of Purkinje cells, these afferents have been proposed as a key input in establishing long-term plastic changes in the cerebellar cortex. This concept is contrasted with other postulates proposing that the heterosynaptic action of this system produces a short-lasting enhancement rather than a long-term depression of Purkinje cell responsiveness. Although a generally accepted view regarding climbing fiber function does not exist, this review emphasizes the extensive functional insights that have been reported and supports the notion that progress toward a complete understanding of these afferents will require an integration of their morphological characteristics with the fundamental physiological properties of their responses assessed in a variety of contexts and conditions. Anat. Rec. (New Anat.) 253:118–126, 1998. ௠ 1998 Wiley-Liss, Inc. KEY WORDS: cerebellum; climbing fiber; cerebellar circuits; Purkinje cells; olivocerebellar Cajal’s elegant description of one of is not graded and which occurs at a tions, Eccles and colleagues (for over- the most unique anatomical relation- relatively low frequency. view, see 1) formulated one of the first ships in the brain, the extensive inter- From the onset of the electrophysi- postulates regarding the functional ac- face between the dendritic tree of a ological studies characterizing the re- tion of this system, the read-out hy- Purkinje cell and a single climbing sponses of Purkinje cells to these in- pothesis. This view proposed that the fiber, triggered a century-long debate puts, the responses evoked by these depolarization evoked by the climbing regarding the function of this unique fibers were found to be as unique as fiber ‘‘read out’’ the level of excitability afferent system. This relationship is their morphology. Primarily as a con- produced via the combined action of illustrated in Figure 1, which also sequence of the classical experiments the mossy fiber–parallel fiber input shows the organization of the other by Eccles, Llinas, and Sasaki (re- directly to Purkinje cells and to the major input to these neurons, the viewed in 1), these afferents were dendrites of the inhibitory interneu- mossy fiber–granule cell–parallel fiber shown to evoke a characteristic, large rons. Although this postulate is no projection. In general, the mossy fiber depolarization of Purkinje cells and an longer considered tenable, it focused input is responsible for modulating associated complex spike response that the attention of physiologists on the unique role these fibers may play in the discharge of Purkinje cells in re- is distinctively different from the ac- regulating the output of the cerebellar sponse to activity in descending path- tion potentials modulated by the other cortex and more generally in regulat- ways as well as to a wide variety of major afferent system to the Purkinje ing the functional properties of the sensory inputs. In contrast, the climb- cell dendrites, the parallel fibers. An cerebellum itself. ing fiber input evokes a response which example of both the intracellularly While not intended to be compre- and extracellularly recorded response hensive, this review will provide an of Purkinje cells to a climbing fiber encapsulation of several theories of input is shown in Figure 2. These climbing fiber function that are rel- responses were produced by stimulat- evant to current discussions regarding Dr. Bloedel is currently the Chair of the ing the cerebellar white matter and this system. Interestingly, none of these Division of Neurobiology at the Barrow consequently contain both an anti- Neurological Institute in Phoenix, AZ. theories have been disproved, and all He and Dr. Bracha, a faculty member in dromically evoked action potential (the have at least some experimental sup- the same Division, codirect a laboratory initial spike in both records evoked by port. Perhaps because critical ques- focused on the learning and control of a variety of movements, with an empha- stimulating the axon of the neuron tions remain unanswered, controversy sis on understanding the role of the in the cerebellar white matter) and still abounds on this topic, contribut- cerebellum in these processes. His fax the complex spike response evoked by ing to the fact that there are almost as number is 602–406–4172; his e-mail ad- dress is [email protected] the climbing fiber input. Based on many viewpoints on this topic as there their electrophysiological observa- are investigators in the field! ௠ 1998 Wiley-Liss, Inc. REVIEW THE ANATOMICAL RECORD (NEW ANAT.) 119 Figure 1. Illustration of the mammalian cerebellar cortex. A single folium is sectioned to reveal the planar organization of the Purkinje cell dendrites, the relationship of the climbing fiber to these structures, the interneurons (basket, Golgi, and stellate cells), and the mossy fiber system. (Reproduced from Bloedel28 with permission of the publisher). SPECIFIC VIEWS OF CLIMBING the body. These experiments as well as flecting a discrepancy or mismatch FIBER FUNCTION earlier electrophysiological studies between the intended and the actual characterizing the inputs to a variety movement. Other proponents of this Climbing Fibers as an Event or of olivocerebellar projections2 led to concept argued that this sensory infor- Error Signal the proposal that the climbing fiber mation is critical to the operation of Several studies in unanesthetized de- may be signaling the occurrence of an the modules consisting of cerebellar cerebrate animals revealed that climb- unexpected sensory stimulus during cortical sagittal zones and the topo- ing fibers were capable of responding the course of a movement. This view graphically organized output from re- to very low intensity stimuli applied to was extended by postulating that these lated regions of the cerebellar nuclei.3 their receptive field on the surface of signals may represent error signals re- At least three lines of experimenta- 120 THE ANATOMICAL RECORD (NEW ANAT.) REVIEW tion in awake behaving animals pro- employed experimental conditions in vide strong evidence supporting the which the animal encountered an un- view that the climbing fiber input can expected sensory input whose charac- signal an unexpected interruption of teristics were difficult to quantify or intended and/or ongoing movement. simply were not measured accurately First, Gellman et al.4 demonstrated as a systematic component of the pro- that olivary neurons (neurons originat- tocol. Simpson and colleagues9 have ing in the inferior olive) that were obviated this problem by employing a highly responsive to low intensity cuta- paradigm in which a very specific, neous stimuli applied passively were quantifiable sensory stimulus was em- not activated when their receptive ployed, this being the movement of fields came in contact with the floor multiple spots of light across the retina during ongoing locomotion. Second, in a specific direction. This visual in- in other experiments,5 climbing fibers put provides a directionally specific were activated by a unique, unex- retinal slip signal which these investi- pected perturbation. Cats were trained gators found to be very effective in to walk on the rungs of a ladder. A activating climbing fiber inputs to spe- rung was permitted to give way unex- cific locations within the cerebellar pectedly when contacted by the cat, flocculus of the rabbit, a region having Figure 2. An extracellularly recorded (A) and numerous interconnections with re- producing a substantial deviation from intracellularly recorded (B) response evoked the expected movement. Under this in two different Purkinje cells by a stimulus gions of the brainstem important in condition, climbing fiber inputs to Pur- applied to the cerebellar white matter (WM). kinje cells were activated. Third, ex- periments in our laboratory employed Together these data multiple single unit recordings from ample, Ojakangas and Ebner8 ob- up to five sagittally oriented Purkinje served that climbing fiber inputs to suggest that this general cells in the intermediate cerebellar Purkinje cells were activated in trials class of events, namely a cortex to examine their responses in which a monkey made errors in when the forelimb of cats and ferrets moving a joystick to a target position mismatch between ambulating encountered a bar inter- after the relationship between the expected and mittently placed in the trajectory of movement of the joystick and the swing phase (reviewed in 6). These movement of the cursor was changed. unexpected behaviors unexpected perturbations were very Together these data suggest that this or external stimuli, is one effective in evoking the synchronous general class of events, namely a mis- activation of climbing fiber inputs to match between expected and unex- condition in which neighboring Purkinje cells within a pected behaviors or external stimuli, climbing fibers frequently sagittal zone. is one condition in which climbing The results of these studies indicate fibers frequently are activated.
Load more

Recommended publications
  • FIRST PROOF Cerebellum
    Article Number : EONS : 0736 GROSS ANATOMY Cerebellum Cortex The cerebellar cortex is an extensive three-layered sheet with a surface approximately 15 cm laterally THE HUMAN CEREBELLUM (‘‘little brain’’) is a and 180 cm rostrocaudally but densely folded around significant part of the central nervous system both three pairs of nuclei. The cortex is divided into three in size and in neural structure. It occupies approxi- transverse lobes: Anterior and posterior lobes are mately one-tenth of the cranial cavity, sitting astride separated by the primary fissure, and the smaller the brainstem, beneath the occipital cortex, and flocculonodular lobe is separated by the poster- contains more neurons than the whole of the cerebral olateral fissure (Fig. 1). The anterior and posterior cortex. It consists of an extensive cortical sheet, lobes are folded into a number of lobules and further densely folded around three pairs of nuclei. The folded into a series of folia. This transverse organiza- cortex contains only five main neural cell types and is tion is then divided at right angles into broad one of the most regular and uniform structures in the longitudinal regions. The central vermis, named for central nervous system (CNS), with an orthogonal its worm-like appearance, is most obvious in the ‘‘crystalline’’ organization. Major connections are posterior lobe. On either side is the paravermal or made to and from the spinal cord, brainstem, and intermediate cortex, which merges into the lateral sensorimotor areas of the cerebral cortex. hemispheres. The most common causes of damage to the cerebellum are stroke, tumors, or multiple sclerosis.
    [Show full text]
  • Three-Dimensional Comparison of Ultrastructural Characteristics at Depressing and Facilitating Synapses Onto Cerebellar Purkinje Cells
    The Journal of Neuroscience, September 1, 2001, 21(17):6666–6672 Three-Dimensional Comparison of Ultrastructural Characteristics at Depressing and Facilitating Synapses onto Cerebellar Purkinje Cells Matthew A. Xu-Friedman,1 Kristen M. Harris,2 and Wade G. Regehr1 1Department of Neurobiology, Harvard Medical School, Boston, Massachusetts 02115, and 2Department of Biology, Boston University, Boston, Massachusetts 02215 Cerebellar Purkinje cells receive two distinctive types of exci- vesicles per release site to test whether this number determines tatory inputs. Climbing fiber (CF) synapses have a high proba- the probability of release and synaptic plasticity. PF and CF bility of release and show paired-pulse depression (PPD), synapses had the same number of anatomically docked vesi- whereas parallel fiber (PF) synapses facilitate and have a low cles (7–8). The number of docked vesicles at the CF does not probability of release. We examined both types of synapses support a simple model of PPD in which release of a single using serial electron microscopic reconstructions in 15-d-old vesicle during the first pulse depletes the anatomically docked rats to look for anatomical correlates of these differences. PF vesicle pool at a synapse. Alternatively, only a fraction of ana- and CF synapses were distinguishable by their overall ultra- tomically docked vesicles may be release ready, or PPD could structural organization. There were differences between PF and result from multivesicular release at each site. Similarities in the CF synapses in how many release sites were within 1 ␮mofa number of docked vesicles for PF and CF synapses indicate mitochondrion (67 vs 84%) and in the degree of astrocytic that differences in probability of release are unrelated to the ensheathment (67 vs 94%).
    [Show full text]
  • Cerebellar Histology & Circuitry
    Cerebellar Histology & Circuitry Histology > Neurological System > Neurological System CEREBELLAR HISTOLOGY & CIRCUITRY SUMMARY OVERVIEW Gross Anatomy • The folding of the cerebellum into lobes, lobules, and folia allows it to assume a tightly packed, inconspicuous appearance in the posterior fossa. • The cerebellum has a vast surface area, however, and when stretched, it has a rostrocaudal expanse of roughly 120 centimeters, which allows it to hold an estimated one hundred billion granule cells — more cells than exist within the entire cerebral cortex. - It is presumed that the cerebellum's extraordinary cell count plays an important role in the remarkable rehabilitation commonly observed in cerebellar stroke. Histology Two main classes of cerebellar nuclei • Cerebellar cortical neurons • Deep cerebellar nuclei CEREBELLAR CORTICAL CELL LAYERS Internal to external: Subcortical white matter Granule layer (highly cellular) • Contains granule cells, Golgi cells, and unipolar brush cells. Purkinje layer 1 / 9 • Single layer of large Purkinje cell bodies. • Purkinje cells project a fine axon through the granule cell layer. - Purkinje cells possess a large dendritic system that arborizes (branches) extensively and a single fine axon. Molecular layer • Primarily comprises cell processes but also contains stellate and basket cells. DEEP CEREBELLAR NUCLEI From medial to lateral: Fastigial Globose Emboliform Dentate The globose and emboliform nuclei are also known as the interposed nuclei • A classic acronym for the lateral to medial organization of the deep nuclei is "Don't Eat Greasy Food," for dentate, emboliform, globose, and fastigial. NEURONS/FUNCTIONAL MODULES • Fastigial nucleus plays a role in the vestibulo- and spinocerebellum. • Interposed nuclei are part of the spinocerebellum. • Dentate nucleus is part of the pontocerebellum.
    [Show full text]
  • 2141.Full.Pdf
    The Journal of Neuroscience, June 1989, g(8): 2141-2150 Physiological and Anatomical Studies of the Interactions Between Purkinje Cells and Basket Cells in the Cat’s Cerebellar Cortex: Evidence for a Unitary Relationship Daniel L. O’Donoghue,a James S. King, and Georgia A. Bishop Department of Anatomy and Neuroscience Program, The Ohio State University, Columbus, Ohio 43210 Intracellular recordings have been obtained from neurons in tions of these units with HRP revealed that the responseswere lobule V of the cat’s vermis, which were identified as basket obtained from basket cells. cells following intracellular injections of HRP. Stimulation of Basket cells are interneurons that are located in the lower the inferior cerebellar peduncle or peripheral nerves elicited molecular layer of the cerebellar cortex (Fox et al., 1967; Mug- an initial depolarizing and subsequent hyperpolarizing re- naini, 1972; Palay and Chan-Palay, 1974). Their somata are sponse. Neither potential could be graded with changes in interspersedbetween and within the dendritic trees of Purkinje stimulus intensity; both displayed all-or-none properties at cells (Fox et al., 1967; Palay and Chan-Palay, 1974); their den- threshold levels of stimulation. The depolarization and hy- drites extend toward the pial surface, and their axons are pri- perpolarization were confirmed as an excitatory postsyn- marily oriented in the sagittal plane. Descendingcollaterals of aptic potential and an inhibitory postsynaptic potential (IPSP), theseaxons form a unique pericellular basket around the somata respectively, on the basis of their response to intracellular and axon hillocks of Purkinje cells, defined as the pinceau by injections of hyperpolarizing and depolarizing currents into Ram6n y Cajal (19 11).
    [Show full text]
  • Synaptic Remodeling Between Climbing Fibers and Purkinje Cells in the Developing Cerebellum Begins with Positive Feedback Addition of Synapses
    bioRxiv preprint doi: https://doi.org/10.1101/627299; this version posted May 3, 2019. The copyright holder for this preprint (which was not certified by peer review) is the author/funder, who has granted bioRxiv a license to display the preprint in perpetuity. It is made available under aCC-BY 4.0 International license. The rich get richer: synaptic remodeling between climbing fibers and Purkinje cells in the developing cerebellum begins with positive feedback addition of synapses. AUTHORS Alyssa Michelle Wilson1*✝, Richard Schalek2, Adi Suissa-Peleg2,3, Thouis Ray Jones4, Seymour Knowles-Barley5, Hanspeter Pfister3, Jeff William Lichtman6*. 1Department of Physics, Harvard University, Cambridge, MA 02138, USA 2Center for Brain Science, Harvard University, Cambridge, MA 02138, USA 3School of Engineering and Applied Sciences, Harvard University, Cambridge, MA 02138, USA 4Broad Institute, Cambridge, MA 02142, USA 5Volpara Health Technologies, Wellington, 6011, New Zealand 6Department of Molecular and Cellular Biology, Harvard University, Cambridge, MA 02138, USA *Correspondence: [email protected] (A.M.W.), [email protected] (J.W.L.) ✝Lead Contact SUMMARY During postnatal development, cerebellar climbing fibers strongly innervate a subset of their original Purkinje cell targets and eliminate their connections from the rest. In the adult, each climbing fiber innervates a small number of Purkinje cells and each Purkinje cell is innervated by a single climbing fiber. To get insight about the processes responsible for this remapping, we reconstructed serial electron microscopy datasets from mice during the first postnatal week. In contrast to adult connectivity, individual neonatal climbing fibers innervate many nearby Purkinje cells, and multiple climbing fibers innervate each Purkinje cell.
    [Show full text]
  • Multiple Climbing Fibers Signal to Molecular Layer Interneurons
    ARTICLES Multiple climbing fibers signal to molecular layer interneurons exclusively via glutamate spillover Germa´n Szapiro & Boris Barbour Spillover of glutamate under physiological conditions has only been established as an adjunct to conventional synaptic transmission. Here we describe a pure spillover connection between the climbing fiber and molecular layer interneurons in the rat cerebellar cortex. We show that, instead of acting via conventional synapses, multiple climbing fibers activate AMPA- and NMDA- type glutamate receptors on interneurons exclusively via spillover. Spillover from the climbing fiber represents a form of glutamatergic volume transmission that could be triggered in a regionalized manner by experimentally observed synchronous climbing fiber activity. Climbing fibers are known to direct parallel fiber synaptic plasticity in interneurons, so one function of this spillover is likely to involve controlling synaptic plasticity. http://www.nature.com/natureneuroscience Spillover of neurotransmitter—action at synaptic contacts other than unknown type of axodendritic (or axosomatic) contact17. Despite those where it was released—has proved to be a controversial subject. extensive and tight apposition between axonal (climbing fiber) and For simple, small glutamatergic synapses, spillover has only rarely been somatodendritic (interneuron) membranes, the apparent absence of reported1,2 at activity levels that are physiologically plausible, and vesicles and glutamate receptors argues against classical synaptic modeling suggests that the spillover of glutamate at simple synapses transmission occurring at these junctions. is probably not significant3 (but see ref. 4). It has been argued that Here we confirm the existence of the climbing fiber–interneuron spillover would reduce synaptic independence and thus reduce the connection and characterize its mechanism of transmission.
    [Show full text]
  • Cerebellum and Activation of the Cerebellum IO ST During Nonmotor Tasks
    Cerebellum (Kandel & Schwartz & Jessell, 4th ed.) Granule186 cells are irreducibly smallChapter (6-8 7 μm) stellate cell basket cell outer synaptic layer PC rs cap PC layer grc Go inner 6 μm synaptic layer Figure 7.15 Largest cerebellar neuron occupies more than a 1,000-fold greater volume than smallest neuron. Thin section (~1 μ m) through monkey cerebellar cortex. Purkinje cell body (PC) and nucleus are far larger than those of granule cell (grc). The latter cluster to leave space for mossy fiber terminals to form glomeruli with grc dendritic claws and space for Golgi cells (Go). Note rich network of capillaries (cap). Fine, scat- tered dots are mitochondria. Courtesy of E. Mugnaini. brain ’ s most numerous neuron, this small cost grows large (see also chapter 13). Much of the inner synaptic layer is occupied by the large axon terminals of mossy fibers (figures 7.1 and 7.16). A terminal interlaces with multiple (~15) dendritic claws, each from a different but neighboring granule cell, and forms a complex knot (glomerulus ), nearly as large as a granule cell body (figures 7.1 and 7.16). The mossy fiber axon fires at an unusually high mean rate (up to 200 Hz) and is therefore among the brain’ s thickest (figure 4.6). To match the axon’ s high rate, a terminal expresses 150 active zones, 10 per postsynaptic granule cell (figure 7.16). These sites are capable of driving … and most expensive. 190 Chapter 7 10 4 8 3 9 19 10 10 × 6 × 2 2 4 ATP/s/cell ATP/s/cell ATP/s/m 1 2 0 0 astrocyte astrocyte Golgi cell Golgi cell basket cell basket cell stellate cell stellate cell granule cell granule cell mossy fiber mossy fiber Purkinje cell Purkinje Purkinje cell Purkinje Bergman glia Bergman glia climbing fiber climbing fiber Figure 7.18 Energy costs by cell type.
    [Show full text]
  • The Organization of the Corticonuclear and Olivocerebellar Climbing Fiber
    Journal of Neurocytology 33, 5–21 (2004) The organization of the corticonuclear and olivocerebellar climbing fiber projections to the rat cerebellar vermis: The congruence of projection zones and the zebrin pattern JAN VOOGD∗ and TOMJ.H.RUIGROK Department of Neuroscience, Erasmus MC, Rotterdam, P.O. Box 1738, 3000 DR Rotterdam, The Netherlands [email protected] Received 23 May 2003; revised 2 September 2003; accepted 2 September 2003 Abstract The zonal organization of the corticonuclear and the olivocerebellar climbing fiber projections to the vermis of the cerebellum of the rat was compared to the pattern of zebrin-positive and zebrin-negative bands in material double-stained for zebrin II and for different anterograde tracers injected in subnuclei of the inferior olive, or retrograde tracers injected in the cerebellar and vestibular target nuclei of the Purkinje cells of the vermis. Projection zones A1,AX,X,B,CX in the vermis and A2 (accessory A zone) and C2 in the hemisphere were defined by their efferent corticonuclear and their afferent climbing fiber connections, and were found to share the same topographical framework with the zebrin pattern. Introduction There are words that stick in your mind. Among our 1994), the low affinity nerve growth factor receptor favorites are Sanford L. Palay’s statement on synaptic protein (Dusart et al., 1994), protein kinase C delta vesicles, which “like chocolates, come in a variety of (Chen & Hillman, 1993) the glutamate transporter shapes and sizes, and are stuffed with different kind EAAT4 (Dehnes et al., 1998) and the metabotropic of fillings’’ (1967) and his remark on the “chemical id- glutamate receptor mGluR1b (Mateos et al., 2001), to iosyncrasy’’ of non-synaptic monoaminergic cerebellar name only a few.
    [Show full text]
  • 3. Climbing Fiber Input Preferentially Signals Correctly Timed Movements
    Evidence for Reinforcement Learning Signals in the Climbing Fiber Pathway Expands the Possible Repertoire of Cerebellar Learning Rules by William Heffley II Department of Neurobiology Duke University Date:_______________________ Approved: ___________________________ Court Hull, Supervisor ___________________________ Stephen Lisberger ___________________________ Richard Mooney ___________________________ Gregory Field Dissertation submitted in partial fulfillment of the requirements for the degree of Doctor of Philosophy in the Department of Neurobiology in the Graduate School of Duke University 2019 i v ABSTRACT Evidence for Reinforcement Learning Signals in the Climbing Fiber Pathway Expands the Possible Repertoire of Cerebellar Learning Rules by William Heffley II Department of Neurobiology Duke University Date:_______________________ Approved: ___________________________ Court Hull, Supervisor ___________________________ Stephen Lisberger ___________________________ Richard Mooney ___________________________ Gregory Field An abstract of a dissertation submitted in partial fulfillment of the requirements for the degree of Doctor of Philosophy in the Department of Neurobiology in the Graduate School of Duke University 2019 i v Copyright by William Edward Heffley II 2019 Abstract Classical models of cerebellar learning posit that climbing fibers operate according to a supervised learning rule to instruct changes in motor output by signaling the occurrence of movement errors. This model is grounded largely in studies of behaviors that utilize hardwired neural pathways to link sensory input to motor output. Yet, cerebellar output is also associated with non-motor behaviors, and recently with modulating reward association pathways in the VTA. Here, I test whether the supervised learning model applies to more flexible learning regimes and how the cerebellum processes reward related signals. I have used both classical and operant condition paradigms in combination with calcium imaging.
    [Show full text]
  • Zonal Organization of the Climbing Fiber Projection to the Flocculus And
    THE JOURNAL OF COMPARATIVE NEUROLOGY ,7562340 (1995) Zonal Organization of the Climbing Fiber Projection to the Flocculus and Nodulus of the Rabbit: A Combined Axonal Tracing and Acetylcholinesterase Histochemical Study J. TAN, N.M. GERRITS, R. NANHOE, J.I. SIMPSON, AND J. VOOGD Department of Anatomy, Erasmus University Rotterdam, 3000 DR Rotterdam, The Netherlands; (J.T., N.M.G., J.V.), General Hospital Middelheim, Department of Neurology, Middelheim, Belgium (R.N.),and Department of Physiology and Biophysics, New York University Medical Center, New York, New York 10016 (J.I.S.) ABSTRACT The localization and termination of olivocerebellar fibers in the flocculus and nodulus of the rabbit were studied with anterograde axonal transport methods [wheatgerm agglutinin- horseradish peroxidase (WGA-HRP) and tritiated leucinel and correlated with the compart- ments in the white matter of these lobules delineated with acetylcholinesterase histochemistry (Tan et al. J. Comp. Neurol., 1995, this issue). Olivocerebellar fibers originating from the caudal dorsal cap travel through floccular compartments FC2 and FC4 to terminate as climbing fibers in floccular zones FZII and FZIv. Fibers from the rostral dorsal cap and the ventrolateral outgrowth traverse compartments FC1 and FC3,which are interleaved with compartments FC2 and FC4! and terminate in zones FZ1 and FZiIi. Fibers from the rostral pole of the medial accessory olive traverse the Cz compartment and terminate in the Cz zone. FZ1-111 extend into the adjoining folium (folium p) of the ventral paraflocculus. The C2 zone continues across folium p into other folia of the ventral paraflocculus and into the dorsal paraflocculus. Four compartments and five zones were distinguished in the nodulus.
    [Show full text]
  • The Distribution of Climbing and Mossy
    The Journal of Neuroscience, June 1, 2003 • 23(11):4645–4656 • 4645 The Distribution of Climbing and Mossy Fiber Collateral Branches from the Copula Pyramidis and the Paramedian Lobule: Congruence of Climbing Fiber Cortical Zones and the Pattern of Zebrin Banding within the Rat Cerebellum Jan Voogd,2 Joanne Pardoe,1 Tom J. H. Ruigrok,2 and Richard Apps1 1Department of Physiology, University of Bristol, BS8 1TD Bristol, United Kingdom, and 2Department of Neuroscience, Erasmus MC, 3000 DR Rotterdam, The Netherlands Individual cerebellar cortical zones defined by the somatotopy of climbing fiber responses and by their olivo-cortico-nuclear connections located in the paramedian lobule and the copula pyramidis of the rat cerebellum were microinjected with cholera toxin B subunit. Collateral branches of climbing and mossy fibers were mapped and related to the pattern of zebrin-positive and -negative bands of Purkinje cells. Climbing fiber collaterals from the copula distribute to the anterior lobe: from the paramedian lobule mainly to lobulus simplex and rostral crus I. Climbing fibers terminating in particular zones (X, A2 ,C1 ,CX ,C2 ,C3 ,D1 , and D2 ) in the paramedian lobule or the copula collateralize to one or two corresponding zones in lobulus simplex, crus I and II, the paraflocculus, and/or the anterior lobe. These zones can be defined by their relationship to the pattern of zebrin banding. Collaterals from mossy fibers, labeled from the same injection sites in the copula and paramedian lobule, often distribute bilaterally in a symmetrical pattern of multiple but ill-defined longitudinalstripsintheanteriorlobeand/orlobulussimplex.Oneormoreoftheselongitudinalaggregatesofmossyfibercollateralswas always found subjacent to the strip(s) of labeled climbing fiber collaterals arising from the same locus in the paramedian lobule or the copula.
    [Show full text]
  • Neocortex-Cerebellum Circuits for Cognitive Processing
    Trends in Neurosciences Review Neocortex–Cerebellum Circuits for Cognitive Processing Mark J. Wagner1,* and Liqun Luo1,* Although classically thought of as a motor circuit, the cerebellum is now understood to Highlights contribute to a wide variety of cognitive functions through its dense interconnections with the Classic studies have mainly focused neocortex, the center of brain cognition. Recent investigations have shed light on the nature on sensorimotor information trans- of cerebellar cognitive processing and information exchange with the neocortex. We review mitted through the two cerebellar findings that demonstrate widespread reward-related cognitive input to the cerebellum, as input pathways, granule cells and well as new studies that have characterized the codependence of processing in the neocortex climbing fibers. Recent in- and cerebellum. Together, these data support a view of the neocortex–cerebellum circuit as a vestigations indicate that the cere- joint dynamic system both in classical sensorimotor contexts and reward-related, cognitive pro- bellum receives diverse reward expectation-related information via cessing. These studies have also expanded classical theory on the computations performed by granule cells, and reward predic- the cerebellar circuit. tion error signals via climbing fi- bers. The cerebellum may in turn Cerebellum and Cognitive Function reciprocally influence brain-wide The cerebellum was traditionally thought to contribute mainly to motor coordination [1–4]. However, reward circuitry via output path- more
    [Show full text]