1
|
Daly DT, Ariel M. A novel cerebellar commissure and other myelinated axons in the Purkinje cell layer of a pond turtle (Trachemys scripta elegans). J Comp Neurol 2018; 526:2802-2823. [PMID: 30173417 DOI: 10.1002/cne.24528] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 02/14/2018] [Revised: 07/23/2018] [Accepted: 07/30/2018] [Indexed: 11/10/2022]
Abstract
Parallel fibers in the molecular layer of the vertebrate cerebellum mediate slow spike conduction in the transverse plane. In contrast, electrophysiological recordings have indicated that rapid spike conduction exists between the lateral regions of the cerebellar cortex of the red-ear pond turtle (Trachemys scripta). The anatomical basis for this commissure is now examined in that species using neuronal tracing techniques. Fluorescently tagged dextrans and lipophilic carbocyanine dyes placed in one lateral edge of this nonfoliated cortex are transported across the midline of living brains in vitro and along the axonal membranes of fixed tissues, respectively. Surprisingly, the labeled commissural axons traversed the cortex within the Purkinje cell layer, and not in the white matter of the molecular layer or the white matter below the granule cell layer. Unlike thin parallel fibers that exhibit characteristic varicosities, this commissure is composed of smooth axons of large diameter that also extend beyond the cerebellar cortex via the cerebellar peduncles. Double labeling with myelin basic protein antibody demonstrated that these commissural axons are ensheathed with myelin. In contrast to this transverse pathway, an orthogonal myelinated tract was observed along the cerebellar midline. The connections of this transverse commissure with the lateral cerebellum, the vestibular nuclear complex, and the cochlear vestibular ganglia indicate that this commissure plays a role in bilateral vestibular connectivity.
Collapse
Affiliation(s)
- Daniel T Daly
- Center for Anatomical Sciences and Education, Department of Surgery, Saint Louis University School of Medicine, St. Louis, Missouri
| | - Michael Ariel
- Center for Anatomical Sciences and Education, Department of Surgery, Saint Louis University School of Medicine, St. Louis, Missouri.,Department of Pharmacology & Physiology, Saint Louis University School of Medicine, St. Louis, Missouri
| |
Collapse
|
2
|
Limitations of PET and lesion studies in defining the role of the human cerebellum in motor learning. Behav Brain Sci 2011. [DOI: 10.1017/s0140525x00081899] [Citation(s) in RCA: 3] [Impact Index Per Article: 0.2] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/07/2022]
|
3
|
|
4
|
|
5
|
Eyeblink conditioning, motor control, and the analysis of limbic-cerebellar interactions. Behav Brain Sci 2011. [DOI: 10.1017/s0140525x00081929] [Citation(s) in RCA: 41] [Impact Index Per Article: 3.2] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/05/2022]
|
6
|
|
7
|
Grasping cerebellar function depends on our understanding the principles of sensorimotor integration: The frame of reference hypothesis. Behav Brain Sci 2011. [DOI: 10.1017/s0140525x00081607] [Citation(s) in RCA: 3] [Impact Index Per Article: 0.2] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/26/2022]
|
8
|
Dysmetria of thought: Correlations and conundrums in the relationship between the cerebellum, learning, and cognitive processing. Behav Brain Sci 2011. [DOI: 10.1017/s0140525x00081851] [Citation(s) in RCA: 32] [Impact Index Per Article: 2.5] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/07/2022]
|
9
|
|
10
|
|
11
|
Q: Is the cerebellum an adaptive combiner of motor and mental/motor activities? A: Yes, maybe, certainly not, who can say? Behav Brain Sci 2011. [DOI: 10.1017/s0140525x00082017] [Citation(s) in RCA: 22] [Impact Index Per Article: 1.7] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/07/2022]
|
12
|
|
13
|
What behavioral benefit does stiffness control have? An elaboration of Smith's proposal. Behav Brain Sci 2011. [DOI: 10.1017/s0140525x00081917] [Citation(s) in RCA: 3] [Impact Index Per Article: 0.2] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/07/2022]
|
14
|
|
15
|
Okubo Y, Kanemaru K, Iino M. Imaging of Ca2+ and related signaling molecules and investigation of their functions in the brain. Antioxid Redox Signal 2011; 14:1303-14. [PMID: 20615120 DOI: 10.1089/ars.2010.3367] [Citation(s) in RCA: 7] [Impact Index Per Article: 0.5] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Indexed: 11/12/2022]
Abstract
Intracellular Ca(2+) signaling, and related mechanisms involving inositol 1,4,5-trisphosphate (IP(3)), nitric oxide, and the excitatory neurotransmitter glutamate, play a major role in the regulation of cellular function in the brain. Due to the complex morphology of central neurons, the correct spatiotemporal distribution of signaling molecules is essential. Thus, imaging studies have been particularly useful in elucidating the functions of these signaling molecules. The advancement of imaging methods, together with the development of a new method for the specific inhibition of intracellular IP(3) signaling, have made it possible to identify pathways that are regulated by Ca(2+) signals in the brain, including Ca(2+)-dependent synaptic maintenance and glial cell-dependent neurite growth. Further investigation of Ca(2+)-related signaling is expected to increase our understanding of brain function in the future.
Collapse
Affiliation(s)
- Yohei Okubo
- Department of Pharmacology, Graduate School of Medicine, The University of Tokyo, Tokyo, Japan
| | | | | |
Collapse
|
16
|
Okubo Y, Kakizawa S, Hirose K, Iino M. Cross talk between metabotropic and ionotropic glutamate receptor-mediated signaling in parallel fiber-induced inositol 1,4,5-trisphosphate production in cerebellar Purkinje cells. J Neurosci 2005; 24:9513-20. [PMID: 15509738 PMCID: PMC6730146 DOI: 10.1523/jneurosci.1829-04.2004] [Citation(s) in RCA: 50] [Impact Index Per Article: 2.6] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/21/2022] Open
Abstract
In many excitatory glutamatergic synapses, both ionotropic glutamate receptors (iGluRs) and metabotropic glutamate receptors (mGluRs) are closely distributed on the postsynaptic membrane. However, the functional significance of the close distribution of the two types of glutamate receptors has not been fully clarified. In this study, we examined the functional interaction between iGluR and mGluR at parallel fiber (PF)--> Purkinje cell synapses in the generation of inositol 1,4,5-trisphosphate (IP3), a key second messenger that regulates many important cellular functions. We visualized local IP3 dynamics in Purkinje cells using the green fluorescent protein-tagged pleckstrin homology domain (GFP-PHD) as a fluorescent IP3 probe. Purkinje cells were transduced with Sindbis virus encoding GFP-PHD and imaged with a two-photon laser scanning microscope. Translocation of GFP-PHD from the plasma membrane to the cytoplasm attributable to an increase in IP3 concentration was observed on PF stimulation in fine dendrites of Purkinje cells. Surprisingly, this PF-induced IP3 production was blocked not only by the group I mGluR antagonist but also by the AMPA receptor (AMPAR) antagonist. The PF-induced IP3 production was blocked by either the inhibition of G-protein activation by GDP-betaS or intracellular Ca2+ buffering by BAPTA. These results show that IP3 production is mediated cooperatively by group I mGluR and AMPAR through G-protein activation and Ca2+ influx at PF--> Purkinje cell synapses, identifying the robust cross talk between iGluR and mGluR for the generation of IP3 signals.
Collapse
Affiliation(s)
- Yohei Okubo
- Department of Pharmacology, Graduate School of Medicine, The University of Tokyo, Tokyo 113-0033, Japan
| | | | | | | |
Collapse
|
17
|
Dunbar RL, Chen G, Gao W, Reinert KC, Feddersen R, Ebner TJ. Imaging parallel fiber and climbing fiber responses and their short-term interactions in the mouse cerebellar cortex in vivo. Neuroscience 2004; 126:213-27. [PMID: 15145087 DOI: 10.1016/j.neuroscience.2004.02.020] [Citation(s) in RCA: 23] [Impact Index Per Article: 1.2] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Accepted: 02/11/2004] [Indexed: 11/25/2022]
Abstract
A major question in the study of cerebellar cortical function is how parallel fiber and climbing fiber inputs interact to shape information processing. Emphasis has been placed on the long-term effects due to conjunctive stimulation of climbing fibers and parallel fibers. Much less emphasis has been placed on short-term interactions and their spatial nature. To address this question the responses to parallel fiber and climbing fiber inputs and their short-term interaction were characterized using optical imaging with Neutral Red in the anesthetized mouse in vivo. Electrical stimulation of the cerebellar surface evoked an increase in fluorescence consisting of a transverse optical beam. The linear relationship between the optical responses and stimulus parameters, high spatial resolution and close coupling to the electrophysiological recordings show the utility of this imaging methodology. The majority of the optical response was due to activation of postsynaptic alpha-amino-3-hydroxyl-5-methyl-4-isoxazole propionate (AMPA) and metabotropic glutamate receptors with a minor contribution from the presynaptic parallel fibers. Stimulation of the inferior olive evoked parasagittal bands that were abolished by blocking AMPA glutamate receptors. Conjunctive stimulation of the cerebellar surface and inferior olive resulted in inhibition of the climbing fiber evoked optical responses. This lateral inhibition of the parasagittal bands extended out from both sides of an activated parallel fiber beam and was mediated by GABA(A) but not GABA(B) receptors. One hypothesized role for lateral inhibition of this type is to spatially focus the interactions between parallel fiber and climbing fiber input on Purkinje cells. In summary optical imaging with Neutral Red permitted visualization of cerebellar cortical responses to parallel fiber and climbing fiber activation. The GABA(A) dependent lateral inhibition of the climbing fiber evoked parasagittal bands by parallel fiber stimulation shows that cerebellar interneurons play a short-term role in shaping the responses of Purkinje cells to climbing fiber input.
Collapse
Affiliation(s)
- R L Dunbar
- Department of Neuroscience, University of Minnesota, Lions Research Building, Room 421, 2001 Sixth Street Southeast, Minneapolis, MN 55455, USA
| | | | | | | | | | | |
Collapse
|
18
|
Abstract
Conjunctive stimulation of climbing fiber and parallel fiber inputs results in long-term depression (LTD) at parallel fiber-Purkinje cell synapses. Although hypothesized to play a major role in cerebellar motor learning, there has been no characterization of the cellular and molecular mechanisms of LTD in the whole animal, let alone its spatial properties, both of which are critical to understanding the role of LTD in cerebellar function. Neutral red optical imaging of the cerebellar cortex in the anesthetized mouse was used to visualize the spatial patterns of activation. Stimulation of the parallel fibers evoked a transverse beam of optical activity, and stimulation of the contralateral inferior olive evoked parasagittal bands. Conjunctive stimulation of parallel fibers and climbing fibers induced a long-term decrease (at least 1 hr) in the optical response to subsequent parallel fiber activation confined to the region of interaction between these two inputs. Activation of climbing fibers alone failed to induce the long-term decrease. Field potential recordings confirmed that the depression is postsynaptic and restricted to the interaction site. The long-term depression in the beam was prevented by a group 1 metabotropic glutamate receptor (mGluR(1)) antagonist and was absent in transgenic mice selectively expressing an inhibitor of protein kinase C (PKC) in Purkinje cells. Conversely, the long-term depression occurred in the mGluR(4) knock-out mouse, consistent with its postsynaptic origin. In addition to providing the first visualization of parallel fiber-Purkinje cell LTD in the cerebellar cortex, this study demonstrates the spatial specificity of LTD and its dependence on mGluR(1) and PKC in vivo.
Collapse
|
19
|
Abstract
For more than 35 years there has been experimental evidence that parallel fiber activity does not generate the beams of activated Purkinje cells hypothesized on the basis of cortical anatomy and assumed by most theories of cerebellar cortical function. This paper first reviews the evidence for and against the parallel fiber beam hypothesis, and then discusses the findings of our recent experimental and model-based investigations intended to better understand parallel fiber effects on Purkinje cells. A principal conclusion of these studies is that the excitatory effects of parallel fibers on Purkinje cell dendrites are modulating and must be considered in the context of a balancing inhibitory influence provided by molecular layer interneurons to these same dendrites. It is proposed that this association of excitation and inhibition can account for the lack of beam-like effects on Purkinje cells. The paper concludes by considering the consequences of this new interpretation of cerebellar cortical circuitry for current theories of cerebellar function.
Collapse
Affiliation(s)
- James M Bower
- The Research Imaging Center at The University of Texas Health Science Center-San Antonio, Texas 78284-6240, USA.
| |
Collapse
|
20
|
Hanson CL, Chen G, Ebner TJ. Role of climbing fibers in determining the spatial patterns of activation in the cerebellar cortex to peripheral stimulation: an optical imaging study. Neuroscience 2000; 96:317-31. [PMID: 10683572 DOI: 10.1016/s0306-4522(99)00470-4] [Citation(s) in RCA: 47] [Impact Index Per Article: 2.0] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/27/2022]
Abstract
The spatial patterns of activation in the rat cerebellar cortex evoked by ipsilateral face stimulation were mapped using optical imaging based on the pH sensitive dye, Neutral Red. The aims of the study were to characterize the optical responses evoked by peripheral stimulation and test the hypothesis that the resultant parasagittal banding is due to climbing fiber activation. In the anesthetized rat Crus I and II of the cerebellar cortex were stained with Neutral Red. Epi-fluorescent changes produced by a train of stimuli (5-10s and 4-20 Hz) to the ipsilateral face were monitored in time using a fast, high resolution charge-coupled device camera. The patterns of activation were quantified using a two-dimensional fast Fourier transform analysis that removed signals with high spatial frequencies and minimized the contribution of horizontal structural elements (i.e. blood vessels). The dominant spatial pattern of activation evoked by face stimulation was that of parasagittal bands. The bands were highly frequency-dependent and were elicited most strongly by stimulus frequencies in the range of 6-8 Hz. There was a large fall-off in the response for frequencies above and below. The optical signal evoked by face stimulation built up over a period of 10s and then gradually decayed. Within a folium the individual parasagittal bands exhibited some frequency and temporal specificity. Stimulation of the contralateral inferior olive also resulted in the activation of parasagittal bands with characteristics similar to the bands evoked by face stimulation, including a preferred stimulus frequency which peaked at 10 Hz. Injection of lidocaine into the contralateral inferior olive blocked the parasagittal bands evoked by ipsilateral face stimulation, while control injections of saline had no effect. The results confirm that a parasagittal banding pattern is a dominant feature of the functional architecture of the cerebellar cortex. The parasagittal banding pattern observed with Neutral Red is due primarily to the activation of climbing fiber afferents. The frequency tuning of the responses, with the preference for peripheral stimuli of 6-8 Hz, is in agreement with previous findings that the inferior olive is inherently rhythmic. These observations support the hypothesis that inferior olivary neurons are dynamically coupled into groups that activate parasagittal bands of Purkinje cells in the cerebellar cortex. The frequency tuning also supports the hypothesis that the climbing fiber system is involved with timing. Activation of this afferent system may require stimuli with appropriate frequency content and stimuli synchronized to the rhythmicity of the inferior olive.
Collapse
Affiliation(s)
- C L Hanson
- Departments of Neuroscience and Neurosurgery, University of Minnesota, Minneapolis 55455, USA
| | | | | |
Collapse
|
21
|
Miyata M, Okada D, Hashimoto K, Kano M, Ito M. Corticotropin-releasing factor plays a permissive role in cerebellar long-term depression. Neuron 1999; 22:763-75. [PMID: 10230796 DOI: 10.1016/s0896-6273(00)80735-7] [Citation(s) in RCA: 105] [Impact Index Per Article: 4.2] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/27/2022]
Abstract
This study of rat cerebellar slices yielded two lines of evidence indicating that the corticotropin-releasing factor (CRF) found in climbing fibers (CFs) is critical for the induction of long-term depression (LTD) at the parallel fiber (PF) synapses of Purkinje cells (PCs) by their conjunctive activation with either stimulation of CFs or depolarization of PCs. First, LTD induction was effectively blocked by specific CRF receptor antagonists, alpha-helical CRF-(9-41) (alpha-h CRF) and astressin; and second, LTD was no longer observed in CF-deprived cerebella but was restored by CRF replenishment. The data obtained in this study suggest that these effects are mediated by protein kinase C (PKC) and not by Ca2+ signaling or cyclic GMP (cGMP) production.
Collapse
Affiliation(s)
- M Miyata
- Laboratory for Memory and Learning, Brain Science Institute, RIKEN (Institute of Physical and Chemical Research), Saitama, Japan.
| | | | | | | | | |
Collapse
|
22
|
Hauge SA, Tracy JA, Baudry M, Thompson RF. Selective changes in AMPA receptors in rabbit cerebellum following classical conditioning of the eyelid-nictitating membrane response. Brain Res 1998; 803:9-18. [PMID: 9729243 DOI: 10.1016/s0006-8993(98)00525-3] [Citation(s) in RCA: 15] [Impact Index Per Article: 0.6] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/21/2022]
Abstract
alpha-Amino-3-hydroxy-5-methylisoxazole-4-propionic acid (AMPA) receptors are critically involved in several forms of synaptic plasticity proposed to be neural substrates for learning and memory, e.g., long-term potentiation and long-term depression (LTD). The present study was designed to determine changes in cerebellar AMPA receptors following classical conditioning of the eyeblink-nictitating membrane response (NMR) in the rabbit. Quantitative autoradiography was used to assess changes in ligand binding properties of cerebellar AMPA receptors following NMR conditioning elicited by pairing electrical stimulation of the pontine nuclei with an airpuff to the eye. [3H]AMPA and [3H]-6-cyano-7-nitroquinoxaline-2,3-dion (CNQX) binding were determined following preincubation of frozen-thawed brain tissue sections at 0 or 35 degreesC. With 0 degreesC preincubation, no significant differences in [3H]AMPA binding to cerebellar AMPA receptors were seen between any of the experimental groups tested. In contrast, preincubation at 35 degreesC revealed significant decreases in [3H]AMPA binding to the trained side of the cerebellar cortex resulting from paired presentations of the conditioned and the unconditioned stimuli, while unpaired presentations of the stimuli resulted in no significant effect. With 35 degreesC preincubation, there were no significant differences in [3H]CNQX binding between any of the experimental groups and no significant differences in [3H]AMPA binding in the untrained side of the cerebellum. These results indicate that NMR conditioning is associated with a selective modification of AMPA-receptor properties in brain structures involved in the storage of the associative memory. Furthermore, they support the hypothesis that cerebellar LTD, resulting from decreased synaptic efficacy at parallel fiber-Purkinje cell synapses mediated by a change in AMPA-receptor properties, is a form of synaptic plasticity that supports this type of learning.
Collapse
Affiliation(s)
- S A Hauge
- Neuroscience Program, University of Southern California, Los Angeles, CA 90089, USA
| | | | | | | |
Collapse
|
23
|
Kenyon GT, Medina JF, Mauk MD. A mathematical model of the cerebellar-olivary system II: motor adaptation through systematic disruption of climbing fiber equilibrium. J Comput Neurosci 1998; 5:71-90. [PMID: 9540050 DOI: 10.1023/a:1008830427738] [Citation(s) in RCA: 38] [Impact Index Per Article: 1.5] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 02/07/2023]
Abstract
The implications for motor learning of the model developed in the previous article are analyzed using idealized Pavlovian eyelid conditioning trials, a simple example of cerebellar motor learning. Results suggest that changes in gr-->Pkj synapses produced by a training trial disrupt equilibrium and lead to subsequent changes in the opposite direction that restore equilibrium. We show that these opposing phases would make the net plasticity at each gr-->Pkj synapse proportional to the change in its activity during the training trial, as influenced by a factor that precludes plasticity when changes in activity are inconsistent. This yields an expression for the component of granule cell activity that supports learning, the across-trials consistency vector, the square of which determines the expected rate of learning. These results suggest that the equilibrium maintained by the cerebellar-olivary system must be disrupted in a specific and systematic manner to promote cerebellar-mediated motor learning.
Collapse
Affiliation(s)
- G T Kenyon
- Department of Neurobiology and Anatomy, University of Texas Medical School at Houston 77030, USA
| | | | | |
Collapse
|
24
|
Kenyon GT. A model of long-term memory storage in the cerebellar cortex: a possible role for plasticity at parallel fiber synapses onto stellate/basket interneurons. Proc Natl Acad Sci U S A 1997; 94:14200-5. [PMID: 9391177 PMCID: PMC28457 DOI: 10.1073/pnas.94.25.14200] [Citation(s) in RCA: 39] [Impact Index Per Article: 1.4] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 04/14/1997] [Indexed: 02/05/2023] Open
Abstract
By evoking changes in climbing fiber activity, movement errors are thought to modify synapses from parallel fibers onto Purkinje cells (pf*Pkj) so as to improve subsequent motor performance. Theoretical arguments suggest there is an intrinsic tradeoff, however, between motor adaptation and long-term storage. Assuming a baseline rate of motor errors is always present, then repeated performance of any learned movement will generate a series of climbing fiber-mediated corrections. By reshuffling the synaptic weights responsible for any given movement, such corrections will degrade the memories for other learned movements stored in overlapping sets of synapses. The present paper shows that long-term storage can be accomplished by a second site of plasticity at synapses from parallel fibers onto stellate/basket interneurons (pf*St/Bk). Plasticity at pf*St/Bk synapses can be insulated from ongoing fluctuations in climbing fiber activity by assuming that changes in pf*St/Bk synapses occur only after changes in pf*Pkj synapses have built up to a threshold level. Although climbing fiber-dependent plasticity at pf*Pkj synapses allows for the exploration of novel motor strategies in response to changing environmental conditions, plasticity at pf*St/Bk synapses transfers successful strategies to stable long-term storage. To quantify this hypothesis, both sites of plasticity are incorporated into a dynamical model of the cerebellar cortex and its interactions with the inferior olive. When used to simulate idealized motor conditioning trials, the model predicts that plasticity develops first at pf*Pkj synapses, but with additional training is transferred to pf*St/Bk synapses for long-term storage.
Collapse
Affiliation(s)
- G T Kenyon
- Department of Neurobiology and Anatomy, University of Texas Medical School at Houston, 6431 Fannin, Houston, TX 77030, USA.
| |
Collapse
|
25
|
Mauk MD, Donegan NH. A model of Pavlovian eyelid conditioning based on the synaptic organization of the cerebellum. Learn Mem 1997; 4:130-58. [PMID: 10456059 DOI: 10.1101/lm.4.1.130] [Citation(s) in RCA: 183] [Impact Index Per Article: 6.8] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/25/2022]
Abstract
We present a model based on the synaptic and cellular organization of the cerebellum to derive a diverse range of phenomena observed in Pavlovian eyelid conditioning. These phenomena are addressed in terms of critical pathways and network properties, as well as the sites and rules for synaptic plasticity. The theory is based on four primary hypotheses: (1) Two cerebellar sites of plasticity are involved in conditioning: (a) bidirectional long-term depression/potentiation at granule cell synapses onto Purkinje cells (gr-->Pkj) in the cerebellar cortex and (b) bidirectional plasticity in the interpositus nucleus that is controlled by inhibitory inputs from Purkinje cells; (2) climbing fiber activity is regulated to an equilibrium level at which the net strength of gr-->Pkj synapses remains constant unless an unexpected unconditioned stimulus (US) is presented or an expected US is omitted; (3) a time-varying representation of the conditioned stimulus (CS) in the cerebellar cortex permits the temporal discrimination required for conditioned response timing; and (4) the ability of a particular segment of the CS to be represented consistently across trials varies as a function of time since CS onset. This variation in across-trials consistency is thought to contribute to the ISI function. The model suggests several empirically testable predictions, some of which have been tested recently.
Collapse
Affiliation(s)
- M D Mauk
- Department of Neurobiology and Anatomy, University of Texas Medical School at Houston 77030, USA
| | | |
Collapse
|
26
|
Kettner RE, Mahamud S, Leung HC, Sitkoff N, Houk JC, Peterson BW, Barto AG. Prediction of complex two-dimensional trajectories by a cerebellar model of smooth pursuit eye movement. J Neurophysiol 1997; 77:2115-30. [PMID: 9114259 DOI: 10.1152/jn.1997.77.4.2115] [Citation(s) in RCA: 110] [Impact Index Per Article: 4.1] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 02/04/2023] Open
Abstract
A neural network model based on the anatomy and physiology of the cerebellum is presented that can generate both simple and complex predictive pursuit, while also responding in a feedback mode to visual perturbations from an ongoing trajectory. The model allows the prediction of complex movements by adding two features that are not present in other pursuit models: an array of inputs distributed over a range of physiologically justified delays, and a novel, biologically plausible learning rule that generated changes in synaptic strengths in response to retinal slip errors that arrive after long delays. To directly test the model, its output was compared with the behavior of monkeys tracking the same trajectories. There was a close correspondence between model and monkey performance. Complex target trajectories were created by summing two or three sinusoidal components of different frequencies along horizontal and/or vertical axes. Both the model and the monkeys were able to track these complex sum-of-sines trajectories with small phase delays that averaged 8 and 20 ms in magnitude, respectively. Both the model and the monkeys showed a consistent relationship between the high- and low-frequency components of pursuit: high-frequency components were tracked with small phase lags, whereas low-frequency components were tracked with phase leads. The model was also trained to track targets moving along a circular trajectory with infrequent right-angle perturbations that moved the target along a circle meridian. Before the perturbation, the model tracked the target with very small phase differences that averaged 5 ms. After the perturbation, the model overshot the target while continuing along the expected nonperturbed circular trajectory for 80 ms, before it moved toward the new perturbed trajectory. Monkeys showed similar behaviors with an average phase difference of 3 ms during circular pursuit, followed by a perturbation response after 90 ms. In both cases, the delays required to process visual information were much longer than delays associated with nonperturbed circular and sum-of-sines pursuit. This suggests that both the model and the eye make short-term predictions about future events to compensate for visual feedback delays in receiving information about the direction of a target moving along a changing trajectory. In addition, both the eye and the model can adjust to abrupt changes in target direction on the basis of visual feedback, but do so after significant processing delays.
Collapse
Affiliation(s)
- R E Kettner
- Department of Physiology M211, Northwestern University Medical School, Chicago, Illinois 60611, USA
| | | | | | | | | | | | | |
Collapse
|
27
|
We know a lot about the cerebellum, but do we know what motor learning is? Behav Brain Sci 1996. [DOI: 10.1017/s0140525x00081875] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/07/2022]
|
28
|
Sensorimotor learning in structures “upstream” from the cerebellum. Behav Brain Sci 1996. [DOI: 10.1017/s0140525x00081905] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/06/2022]
|
29
|
Cerebellar arm ataxia: Theories still have a lot to explain. Behav Brain Sci 1996. [DOI: 10.1017/s0140525x00081723] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/07/2022]
|
30
|
|
31
|
Resilient cerebellar theory complies with stiff opposition. Behav Brain Sci 1996. [DOI: 10.1017/s0140525x00082005] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/06/2022]
|
32
|
The cerebellum and cerebral cortex: Contrasting and converging contributions to spatial navigation and memory. Behav Brain Sci 1996. [DOI: 10.1017/s0140525x00081826] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/06/2022]
|
33
|
Cerebellum does more than recalibration of movements after perturbations. Behav Brain Sci 1996. [DOI: 10.1017/s0140525x00081632] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/07/2022]
|
34
|
A cerebellar long-term depression update. Behav Brain Sci 1996. [DOI: 10.1017/s0140525x00081942] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/06/2022]
|
35
|
What has to be learned in motor learning? Behav Brain Sci 1996. [DOI: 10.1017/s0140525x0008153x] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/07/2022]
|
36
|
Further evidence for the involvement of nitric oxide in trans-ACPD-induced suppression of AMPA responses in cultured chick Purkinje neurons. Behav Brain Sci 1996. [DOI: 10.1017/s0140525x00081802] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/07/2022]
|
37
|
|
38
|
More models of the cerebellum. Behav Brain Sci 1996. [DOI: 10.1017/s0140525x0008198x] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/06/2022]
|
39
|
Cerebellar rhythms: Exploring another metaphor. Behav Brain Sci 1996. [DOI: 10.1017/s0140525x0008184x] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/07/2022]
|
40
|
The notions of joint stiffness and synaptic plasticity in motor memory. Behav Brain Sci 1996. [DOI: 10.1017/s0140525x00081784] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/06/2022]
|
41
|
How and what does the cerebellum learn? Behav Brain Sci 1996. [DOI: 10.1017/s0140525x00081644] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/07/2022]
|
42
|
Plasticity of cerebro-cerebellar interactions in patients with cerebellar dysfunction. Behav Brain Sci 1996. [DOI: 10.1017/s0140525x00081930] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/06/2022]
|
43
|
How to link the specificity of cerebellar anatomy to motor learning? Behav Brain Sci 1996. [DOI: 10.1017/s0140525x00081863] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/06/2022]
|
44
|
Long-term changes of synaptic transmission: A topic of long-term interest. Behav Brain Sci 1996. [DOI: 10.1017/s0140525x00081565] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/06/2022]
|
45
|
Nitric oxide is involved in cerebellar long-term depression. Behav Brain Sci 1996. [DOI: 10.1017/s0140525x00081814] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/07/2022]
|
46
|
No more news from the cerebellum. Behav Brain Sci 1996. [DOI: 10.1017/s0140525x00081978] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/07/2022]
|
47
|
A bridge between cerebellar long-term depression and discrete motor learning: Studies on gene knockout mice. Behav Brain Sci 1996. [DOI: 10.1017/s0140525x00081966] [Citation(s) in RCA: 1] [Impact Index Per Article: 0.0] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/07/2022]
|
48
|
Cellular mechanisms of long-term depression: From consensus to open questions. Behav Brain Sci 1996. [DOI: 10.1017/s0140525x00081954] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/05/2022]
|
49
|
How can the cerebellum match “error signal” and “error correction”? Behav Brain Sci 1996. [DOI: 10.1017/s0140525x00081590] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/07/2022]
|
50
|
Boxall AR, Lancaster B, Garthwaite J. Tyrosine kinase is required for long-term depression in the cerebellum. Neuron 1996; 16:805-13. [PMID: 8607998 DOI: 10.1016/s0896-6273(00)80100-2] [Citation(s) in RCA: 59] [Impact Index Per Article: 2.1] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 01/31/2023]
Abstract
Long-term depression (LTD) at the parallel fiber-Purkinje cell synapse in the cerebellum is a well-known example of synaptic plasticity. Although LTD is thought to reflect an enduring loss of postsynaptic AMPA receptor sensitivity, the underlying mechanisms are unclear. Protein-tyrosine kinases (PTKs) are able to modulate ionotropic receptor function and are enriched in Purkinje cells. Using intracellular recording from Purkinje cells, it is shown that two structurally and mechanistically distinct PTK inhibitors, lavendustin A and herbimycin A, block LTD induced by pairing parallel fiber stimulation with postsynaptic Ca2+ spiking. Intracellular application of the protein kinase C (PKC) activator, (-)-indolactam V, consistently depressed parallel fiber-Purkinje cells EPSPs and occluded pairing-induced LTD. Herbimycin A nullified the run-down produced by (-)-indolactam V. These data suggest that PTKs are necessary for LTD at the parallel fiber-Purkinje cell synapse and that PKC-induced synaptic depression requires PTK activity.
Collapse
Affiliation(s)
- A R Boxall
- University College London, Rayne Institute, United Kingdom
| | | | | |
Collapse
|