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Henrik Jörntell - One of the best experts on this subject based on the ideXlab platform.
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No Medium-Term Spinocerebellar Input Plasticity in Deep Cerebellar Nuclear Neurons In Vivo?
The Cerebellum, 2017Co-Authors: Hannes Mogensen, Fredrik Bengtsson, Henrik JörntellAbstract:The existence of input plasticity in the deep cerebellar nuclear (DCN) cells of the adult cerebellum could have profound implications for our understanding of cerebellar function. Whereas the existence of plastic changes in mossy fiber (mf) synaptic responses in DCN neurons has been demonstrated in juvenile slices, there has so far been no direct demonstration of this form of plasticity in the adult cerebellum in vivo. In the present paper, we recorded from neurons in the anterior Interposed Nucleus (AIN) and stimulated the spinocerebellar tracts (SCT) directly or via the skin to obtain mf activation and the inferior olive to activate climbing fibers (cfs) in the nonanesthetized, adult, decerebrated cat. We used three different types of protocols that theoretically could be expected to induce plasticity, each of which involved episodically intense afferent activation lasting for 10 min. These were conjunctive mf-cf activation, which effectively induces plasticity in cortical neurons; mf and cf activation in a pattern resembling the protocol for inducing classical conditioning; and conjunctive activation of two excitatory mf inputs. None of these protocols had any statistically significant effect on the evoked responses in the AIN neurons. We conclude that the input plasticity for excitatory mfs in the AIN cells of the adult cerebellum in vivo is likely to be less effective than that of parallel fiber synaptic inputs in cerebellar cortical cells, at least in the timespan of 1 h.
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The information conveyed to DCN neurons.
2014Co-Authors: Fredrik Bengtsson, Henrik JörntellAbstract:The AIP is composed of multiple functional cell groups, each of which forms the output of a cerebellar corticonuclear microcomplex (ucplx). The main mossy fiber input to the DCN cells is derived from spinal motor circuits, which are conveyed to the cerebellum either directly in a spinocerebellar tract (SCT), or via a synaptic relay in the LRN, in a spino-reticulo cerebellar tract (SRCT). These tracts are in turn driven by spinal interneurons, which target specific combinations of muscles or synergies. Pentagons in the ventral horn are alpha-motorneurons encircled by dashed lines to indicate separate spinal motor nuclei, and each spinal interneuron targets a limited number of motor nuclei [58], [59] as indicated by example. Hence, the information carried in SCTs/SRCTs informs the DCN cells of the final composition of the motor command, i.e. which muscle synergies that are currently driven. Also the input that drives the CFs is derived from the spinal motor circuitry (indicated by dashed line from the spinal interneurons), via relays at least in the cuneate Nucleus and the inferior olive (IO). The spinal motor circuitry is driven by motor commands from the neocortex and the brainstem. The output of the DCN cell represents the cerebellar correction of ongoing motor commands and targets the neocortex and the brainstem. Since the CF receptive field identifies the microcomplex the DCN cell is located in and consequently the muscle synergy it is connected with, comparing the SCT/SRCT input with the location of the CF receptive field is equal to comparing the motor information it receives with the motor information it issues. Accordingly, our findings suggest that the input and the output of the DCN cell are functionally matched. AIP, Anterior Interposed Nucleus; PC, Purkinje cell; CF, climbing fiber; ucplx, microcomplex; MF, mossy fiber; IO, inferior olive; LRN, lateral reticular Nucleus; SRCT, spinoreticulocerebellar tract; SCT, spinocerebellar tract.
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Responses of DCN cells to manual skin stimulation.
2014Co-Authors: Fredrik Bengtsson, Henrik JörntellAbstract:(A) Location of a recorded, stained DCN neuron in the anterior Interposed Nucleus. The outlines of the Nucleus and the electrode track are indicated with white dotted lines. (B) Sample IC recording illustrating an excitatory response. The neuron was slightly hyperpolarized from resting membrane potential. (C) Strain gauge signal indicating the time course of the force applied during the skin stimulation. (D) Averaged intracellular recording after removing spikes in software from raw data (N = 50 stimulations). (E) Spike responses for the same cell as in (B)–(D) but recorded without hyperpolarization. The bin width of the peristimulus histogram (obtained using N = 50 stimulations) is 10 ms.
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Identification of DCN neurons in whole cell recordings.
2013Co-Authors: Fredrik Bengtsson, Carl-fredrik Ekerot, Henrik JörntellAbstract:(A) Location in the forelimb region (dashed line) of the anterior Interposed Nucleus (reconstructed in 3D) and morphological reconstruction of a DCN neuron, recorded with neurobiotin in the recording solution. (B) Responses of a DCN neuron to rectangular current step commands. (C) Average of 100 spikes recorded in one DCN neuron. Dashed lines indicate the start and the end of the spike, with the starting point defined as the point at which the second derivative of the voltage trace reached its peak value. (D) Frequency histogram of interspike intervals recorded in this cell. (E) Examples of spontaneous activity recorded at rest (0 pA bias current).
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functional organization of climbing fibre projection to the cerebellar anterior lobe of the rat
The Journal of Physiology, 2000Co-Authors: Henrik Jörntell, Carl-fredrik Ekerot, Martin Garwicz, X L LuoAbstract:1. The input characteristics and distribution of climbing fibre field potentials evoked by electrical stimulation of various parts of the skin were investigated in the cerebellum of barbiturate anaesthetized rats. 2. Climbing fibre responses were recorded in sagittally oriented microelectrode tracks across the mediolateral width of the anterior lobe. Climbing fibres with similar response latencies and convergence patterns terminated in sagittal bands with widths of 0.5-1.5 mm. The principal organization of the anterior lobe with respect to input characteristics and locations of sagittal zones was similar to that in the cat and ferret. Hence, the sagittal bands in the rat were tentatively named the a, b, c1, c2 and d1 zones. 3. In contrast to the cat and ferret, the a zone of the rat was characterized by short latency ipsilateral climbing fibre input. Furthermore, it was divisible into a medial 'a1' zone with convergent, proximal input and a lateral 'ax' zone with somatotopically organized input. A forelimb area with similar location and input characteristics as the X zone of the cat was found, but it formed an integral part of the ax zone. A somatotopic organization of ipsilateral, short latency climbing fibre input was also found in the c1 zone. 4. Rostrally in the anterior lobe, climbing fibres activated at short latencies from the ipsilateral side of the body terminated in a somatotopically organized transverse band which extended from the midline to the lateral end of the anterior lobe. 5. The absence of the C3 and Y zones may be interpreted as a reflection of differences in the organization of the motor systems in the rat as compared with the cat. Skilled movements, which in the cat are controlled by the C1, C3 and Y zones via the anterior Interposed Nucleus, may in the rat be partly controlled by the ax zone via the rostrolateral part of the fastigial Nucleus.
Chris I De Zeeuw - One of the best experts on this subject based on the ideXlab platform.
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excitatory cerebellar nucleocortical circuit provides internal amplification during associative conditioning
Neuron, 2016Co-Authors: Martina Proiettionori, Tom J H Ruigrok, Michiel Ten M Brinke, Henkjan Boele, Janwillem Potters, Freek E Hoebeek, Chris I De ZeeuwAbstract:Closed-loop circuitries between cortical and subcortical regions can facilitate precision of output patterns, but the role of such networks in the cerebellum remains to be elucidated. Here, we characterize the role of internal feedback from the cerebellar nuclei to the cerebellar cortex in classical eyeblink conditioning. We find that excitatory output neurons in the Interposed Nucleus provide efference-copy signals via mossy fibers to the cerebellar cortical zones that belong to the same module, triggering monosynaptic responses in granule and Golgi cells and indirectly inhibiting Purkinje cells. Upon conditioning, the local density of nucleocortical mossy fiber terminals significantly increases. Optogenetic activation and inhibition of nucleocortical fibers in conditioned animals increases and decreases the amplitude of learned eyeblink responses, respectively. Our data show that the excitatory nucleocortical closed-loop circuitry of the cerebellum relays a corollary discharge of premotor signals and suggests an amplifying role of this circuitry in controlling associative motor learning.
Katrin Amunts - One of the best experts on this subject based on the ideXlab platform.
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cytoarchitectonic mapping of the human brain cerebellar nuclei in stereotaxic space and delineation of their co activation patterns
Frontiers in Neuroanatomy, 2015Co-Authors: Stefanie Tellmann, Sebastian Bludau, Simon B Eickhoff, Hartmut Mohlberg, Martina Minnerop, Katrin AmuntsAbstract:The cerebellar nuclei are involved in several brain functions, including the modulation of motor and cognitive performance. To differentiate their participation in these functions, and to analyze their changes in neurodegenerative and other diseases as revealed by neuroimaging, stereotaxic maps are necessary. These maps reflect the complex spatial structure of cerebellar nuclei with adequate spatial resolution and detail. Here we report on the cytoarchitecture of the dentate, Interposed (emboliform and globose) and fastigial nuclei, and introduce 3D probability maps in stereotaxic MNI-Colin27 space as a prerequisite for subsequent meta-analysis of their functional involvement. Histological sections of ten human post mortem brains were therefore examined. Differences in cell density were measured and used to distinguish a dorsal from a ventral part of the dentate Nucleus. Probabilistic maps were calculated, which indicate the position and extent of the nuclei in 3D-space, while considering their intersubject variability. The maps of the Interposed and the dentate nuclei differed with respect to their interaction patterns and functions based on meta-analytic connectivity modelling and quantitative functional decoding, respectively. For the dentate Nucleus, significant (p < 0.05) co-activations were observed with thalamus, supplementary motor area (SMA), putamen, BA 44 of Broca’s region, areas of superior and inferior parietal cortex and the superior frontal gyrus (SFG). In contrast, the Interposed Nucleus showed more limited co-activations with SMA, area 44, putamen and SFG. Thus, the new stereotaxic maps contribute to analyze structure and function of the cerebellum. These maps can be used for anatomically reliable and precise identification of degenerative alteration in MRI-data of patients who suffer from various cerebellar diseases.
Michiel Ten M Brinke - One of the best experts on this subject based on the ideXlab platform.
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Conditioned climbing fiber responses in cerebellar cortex and nuclei.
Neuroscience letters, 2018Co-Authors: Michiel Ten M Brinke, Henkjan Boele, C I De ZeeuwAbstract:The eyeblink conditioning paradigm captures an elementary form of associative learning in a neural circuitry that is understood to an extraordinary degree. Cerebellar cortical Purkinje cell simple spike suppression is widely regarded as the main process underlying conditioned responses (CRs), leading to disinhibition of neurons in the cerebellar nuclei that innervate eyelid muscles downstream. However, recent work highlights the addition of a conditioned Purkinje cell complex spike response, which at the level of the Interposed Nucleus seems to translate to a transient spike suppression that can be followed by a rapid spike facilitation. Here, we review the characteristics of these responses at the cerebellar cortical and nuclear level, and discuss possible origins and functions.
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excitatory cerebellar nucleocortical circuit provides internal amplification during associative conditioning
Neuron, 2016Co-Authors: Martina Proiettionori, Tom J H Ruigrok, Michiel Ten M Brinke, Henkjan Boele, Janwillem Potters, Freek E Hoebeek, Chris I De ZeeuwAbstract:Closed-loop circuitries between cortical and subcortical regions can facilitate precision of output patterns, but the role of such networks in the cerebellum remains to be elucidated. Here, we characterize the role of internal feedback from the cerebellar nuclei to the cerebellar cortex in classical eyeblink conditioning. We find that excitatory output neurons in the Interposed Nucleus provide efference-copy signals via mossy fibers to the cerebellar cortical zones that belong to the same module, triggering monosynaptic responses in granule and Golgi cells and indirectly inhibiting Purkinje cells. Upon conditioning, the local density of nucleocortical mossy fiber terminals significantly increases. Optogenetic activation and inhibition of nucleocortical fibers in conditioned animals increases and decreases the amplitude of learned eyeblink responses, respectively. Our data show that the excitatory nucleocortical closed-loop circuitry of the cerebellum relays a corollary discharge of premotor signals and suggests an amplifying role of this circuitry in controlling associative motor learning.
Vallabh E Das - One of the best experts on this subject based on the ideXlab platform.
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muscimol inactivation of caudal fastigial Nucleus and posterior Interposed Nucleus in monkeys with strabismus
Journal of Neurophysiology, 2013Co-Authors: Anand C Joshi, Vallabh E DasAbstract:Previously, we showed that neurons in the supraoculomotor area (SOA), known to encode vergence angle in normal monkeys, encode the horizontal eye misalignment in strabismic monkeys. The SOA receive...
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Eye Movements, Strabismus, Amblyopia, and Neuro-Ophthalmology Responses of Cells in the Midbrain Near-Response Area in Monkeys with Strabismus
2012Co-Authors: Vallabh E DasAbstract:PURPOSE. To investigate whether neuronal activity within the supraoculomotor area (SOA-monosynaptically connected to medial rectus motoneurons and encode vergence angle) of strabismic monkeys was correlated with the angle of horizontal misalignment and therefore helps to define the state of strabismus. METHODS. Single-cell neural activity was recorded from SOA neurons in two monkeys with exotropia as they performed eye movement tasks during monocular viewing. RESULTS. Horizontal strabismus angle varied depending on eye of fixation (dissociated horizontal deviation) and the activity of SOA cells (n ¼ 35) varied in correlation with the angle of strabismus. Both near-response (cells that showed larger firing rates for smaller angles of exotropia) and far-response (cells that showed lower firing rates for smaller angles of exotropia) cells were identified. SOA cells showed no modulation of activity with changes in conjugate eye position as tested during smooth-pursuit, thereby verifying that the responses were related to binocular misalignment. SOA cell activity was also not correlated with change in horizontal misalignment due to A-patterns of strabismus. Comparison of SOA population activity in strabismic animals and normal monkeys (described in the literature) show that both neural thresholds and neural sensitivities are altered in the strabismic animals compared with the normal animals. CONCLUSIONS. SOA cell activity is important in determining the state of horizontal strabismus, possibly by altering vergence tone in extraocular muscle. The lack of correlated SOA activity with changes in misalignment due to A/V patterns suggest that circuits mediating horizontal strabismus angle and those that mediate A/V patterns are different. (Invest Ophthalmol Vis Sci. 2012;53:3858-3864) DOI:10.1167/iovs.11-9145 I nfantile forms of strabismus occur in as much as 5% of all children. 1-3 The exact cause of strabismus is often unknown. 3-5 Many diverse factors, including refractive errors (anisometropia); visual acuity factors (congenital cataracts); genetic factors (congenital fibrosis of extraocular muscle, Marfan's syndrome); brainstem pathology (Duane's syndrome); and muscle pathology (dysthyroid opthalmopathy), likely trigger a cascade of events that result in misaligned eyes. 2,16,17 In cases of strabismus that is not due to an obvious paralytic or restrictive factor, a common feature among the different trigger factors and correspondingly the different approaches to producing animal models for strabismus is that binocular vision is disrupted in early life due to breakdown in either motor fusion (e.g., surgical strabismus models) or sensory fusion (e.g., optically induced strabismus). Although motoneurons showed correlated activity with abnormal alignment and abnormal eye movements associated with strabismus, it is unlikely that they are the source of the problem. Central structures are likely providing aberrant inputs to motoneurons. When considering sources of such aberrant input to the motoneurons, the supraoculomotor area (SOA) is implicated because of its purported role in binocular eye movements. The SOA is the area immediately adjacent to the oculomotor Nucleus. Neurons in this area receive major projections from the fastigial Nucleus and the posterior Interposed Nucleus in the cerebellum, and also project monosynaptically to the medial rectus motoneurons in the oculomotor Nucleus
