scholarly journals A Model of In vitro Plasticity at the Parallel Fiber—Molecular Layer Interneuron Synapses

2015 ◽  
Vol 9 ◽  
Author(s):  
William Lennon ◽  
Tadashi Yamazaki ◽  
Robert Hecht-Nielsen
Keyword(s):  
Molecular Layer ◽  
Parallel Fiber ◽  
Molecular Layer Interneuron

scholarly journals Topography and Response Timing of Intact Cerebellum Stained With Absorbance Voltage-Sensitive Dye

2009 ◽  
Vol 101 (1) ◽  
pp. 474-490 ◽  
Author(s):  
Michael E. Brown ◽  
Michael Ariel
Keyword(s):  
Time Course ◽  
Granule Cells ◽  
Physiological Activity ◽  
Timing Analysis ◽  
Molecular Layer ◽  
Stimulus Position ◽  
Voltage Sensitive Dye ◽  
Limited Region ◽  
Response Timing

Physiological activity of the turtle cerebellar cortex (Cb), maintained in vitro, was recorded during microstimulation of inferior olive (IO). Previous single-electrode responses to such stimulation showed similar latencies across a limited region of Cb, yet those recordings lacked spatial and temporal resolution and the recording depth was variable. The topography and timing of those responses were reexamined using photodiode optical recordings. Because turtle Cb is thin and unfoliated, its entire surface can be stained by a voltage-sensitive dye and transilluminated to measure changes in its local absorbance. Microstimulation of the IO evoked widespread depolarization from the rostral to the caudal edge of the contralateral Cb. The time course of responses measured at a single photodiode matched that of single-microelectrode responses in the corresponding Cb locus. The largest and most readily evoked response was a sagittal band centered about 0.7 mm from the midline. Focal white-matter (WM) microstimulation on the ventricular surface also activated sagittal bands, whereas stimulation of adjacent granule cells evoked a radial patch of activation. In contrast, molecular-layer (ML) microstimulation evoked transverse beams of activation, centered on the rostrocaudal stimulus position, which traveled bidirectionally across the midline to the lateral edges of the Cb. A timing analysis demonstrated that both IO and WM microstimulation evoked responses with a nearly simultaneous onset along a sagittal band, whereas ML microstimulation evoked a slowly propagating wave traveling about 25 cm/s. The response similarity to IO and WM microstimulation suggests that the responses to WM microstimulation are dominated by activation of its climbing fibers. The Cb's role in the generation of precise motor control may result from these temporal and topographic differences in orthogonally oriented pathways. Optical recordings of the turtle's thin flat Cb can provide insights into that role.

scholarly journals Stereotyped spatial patterns of functional synaptic connectivity in the cerebellar cortex

eLife ◽  
2016 ◽  
Vol 5 ◽  
Author(s):  
Antoine M Valera ◽  
Francesca Binda ◽  
Sophie A Pawlowski ◽  
Jean-Luc Dupont ◽  
Jean-François Casella ◽  
...  
Keyword(s):  
Purkinje Cells ◽  
Cerebellar Cortex ◽  
Granule Cell ◽  
Motor Coordination ◽  
Molecular Layer ◽  
Granule Cell Layer ◽  
Synaptic Organization ◽  
Cerebellar Modules ◽  
Activity Dependent

Motor coordination is supported by an array of highly organized heterogeneous modules in the cerebellum. How incoming sensorimotor information is channeled and communicated between these anatomical modules is still poorly understood. In this study, we used transgenic mice expressing GFP in specific subsets of Purkinje cells that allowed us to target a given set of cerebellar modules. Combining in vitro recordings and photostimulation, we identified stereotyped patterns of functional synaptic organization between the granule cell layer and its main targets, the Purkinje cells, Golgi cells and molecular layer interneurons. Each type of connection displayed position-specific patterns of granule cell synaptic inputs that do not strictly match with anatomical boundaries but connect distant cortical modules. Although these patterns can be adjusted by activity-dependent processes, they were found to be consistent and predictable between animals. Our results highlight the operational rules underlying communication between modules in the cerebellar cortex.

In Vivo Intracellular Analysis of Granule Cell Axon Reorganization in Epileptic Rats

1999 ◽  
Vol 81 (2) ◽  
pp. 712-721 ◽  
Author(s):  
Paul S. Buckmaster ◽  
F. Edward Dudek
Keyword(s):  
Granule Cell ◽  
Granule Cells ◽  
Molecular Layer ◽  
Axon Collateral ◽  
Cell Axon ◽  
Recurrent Excitation ◽  
The Difference ◽  
Intracellular Analysis

In vivo intracellular analysis of granule cell axon reorganization in epileptic rats. In vivo intracellular recording and labeling in kainate-induced epileptic rats was used to address questions about granule cell axon reorganization in temporal lobe epilepsy. Individually labeled granule cells were reconstructed three dimensionally and in their entirety. Compared with controls, granule cells in epileptic rats had longer average axon length per cell; the difference was significant in all strata of the dentate gyrus including the hilus. In epileptic rats, at least one-third of the granule cells extended an aberrant axon collateral into the molecular layer. Axon projections into the molecular layer had an average summed length of 1 mm per cell and spanned 600 μm of the septotemporal axis of the hippocampus—a distance within the normal span of granule cell axon collaterals. These findings in vivo confirm results from previous in vitro studies. Surprisingly, 12% of the granule cells in epileptic rats, and none in controls, extended a basal dendrite into the hilus, providing another route for recurrent excitation. Consistent with recurrent excitation, many granule cells (56%) in epileptic rats displayed a long-latency depolarization superimposed on a normal inhibitory postsynaptic potential. These findings demonstrate changes, occurring at the single-cell level after an epileptogenic hippocampal injury, that could result in novel, local, recurrent circuits.

Glutamate microinjections in cerebellar cortex reproduce cerebrovascular effects of parallel fiber stimulation

1996 ◽  
Vol 271 (6) ◽  
pp. R1568-R1575 ◽  
Author(s):  
G. Yang ◽  
C. Iadecola
Keyword(s):  
Glutamate Receptors ◽  
Cerebellar Cortex ◽  
Glutamate Release ◽  
Molecular Layer ◽  
Parallel Fiber ◽  
Synaptic Activity ◽  
No Production ◽  
Doppler Flowmetry ◽  
Cranial Window ◽  
Fiber Stimulation

Electrical stimulation of cerebellar parallel fibers releases glutamate and increases local blood flow (BFcrb), an effect in part mediated by glutamate-induced nitric oxide (NO) production. We studied whether local microinjection of glutamate into the cerebellar cortex would produce increases in BFcrb comparable to those elicited by parallel fiber stimulation. In halothane-anesthetized rats equipped with a cranial window, glutamate was microinjected into the cerebellar molecular layer, and BFcrb was monitored by laser-Doppler flowmetry. Glutamate microinjections increased BFcrb dose dependently (2-200 pmol in 200 nl) (n = 9) and by 55 +/- 6% at 200 pmol (mean +/- SE). The magnitude and temporal profile of the increases in BFcrb compared favorably with the increase in flow produced by parallel fiber stimulation. The glutamate-induced BFcrb increase was attenuated by superfusion with the Na2+ channel blocker tetrodotoxin (10 microM; -50 +/- 10%; n = 5; P < 0.05; t-test) or by blocking synaptic activity by treatment of the cerebellar cortex with Ringer containing 20 mM Mg2+ and 0 mM Ca2+ (-80 +/- 4%; n = 6; P < 0.05). The glutamate-receptor antagonist kynurenate (10 mM) attenuated the increase in BFcrb by 59 +/- 6% (P < 0.05; n = 5). The relatively selective inhibitor of neuronal NO synthase 7-nitroindazole (100 mg/kg ip) reduced the flow response evoked by microinjection of glutamate (-46 +/- 7%; n = 5; P < 0.05) but not acetylcholine (10 microM; P > 0.05; n = 6). We conclude that glutamate microinjections increase local BFcrb via activation of glutamate receptors. The glutamate-induced vasodilation is mediated, in part, by neurally derived NO. The striking similarities between the vascular responses evoked by parallel fiber stimulation and that produced by microinjection of glutamate support the hypothesis that the increase in BFcrb produced by parallel fiber stimulation is mediated by glutamate release and activation of glutamate receptors. The data also strengthen the hypothesis that glutamate and NO are important mediators in the mechanisms linking synaptic activity to BFcrb in cerebellar cortex.

scholarly journals Crossed Entorhino-Dentate Projections Form and Terminate With Correct Layer-Specificity in Organotypic Slice Cultures of the Mouse Hippocampus

2021 ◽  
Vol 15 ◽  
Author(s):  
Lars Hildebrandt-Einfeldt ◽  
Kenrick Yap ◽  
Mandy H. Paul ◽  
Carolin Stoffer ◽  
Nadine Zahn ◽  
...  
Keyword(s):  
Entorhinal Cortex ◽  
Granule Cells ◽  
Molecular Layer ◽  
Medial Entorhinal Cortex ◽  
Functional Connections ◽  
Mouse Hippocampus ◽  
Organotypic Slice Cultures ◽  
High Degree ◽  
Layer Specificity

The entorhino-dentate projection, i.e., the perforant pathway, terminates in a highly ordered and laminated fashion in the rodent dentate gyrus (DG): fibers arising from the medial entorhinal cortex (MEC) terminate in the middle molecular layer, whereas fibers arising from the lateral entorhinal cortex (LEC) terminate in the outer molecular layer of the DG. In rats and rabbits, a crossed entorhino-dentate projection exists, which originates from the entorhinal cortex (EC) and terminates in the contralateral DG. In contrast, in mice, such a crossed projection is reportedly absent. Using single and double mouse organotypic entorhino-hippocampal slice cultures, we studied the ipsi- and crossed entorhino-dentate projections. Viral tracing revealed that entorhino-dentate projections terminate with a high degree of lamina-specificity in single as well as in double cultures. Furthermore, in double cultures, entorhinal axons arising from one slice freely intermingled with entorhinal axons originating from the other slice. In single as well as in double cultures, entorhinal axons exhibited a correct topographical projection to the DG: medial entorhinal axons terminated in the middle and lateral entorhinal axons terminated in the outer molecular layer. Finally, entorhinal neurons were virally transduced with Channelrhodopsin2-YFP and stimulated with light, revealing functional connections between the EC and dentate granule cells. We conclude from our findings that entorhino-dentate projections form bilaterally in the mouse hippocampus in vitro and that the mouse DG provides a permissive environment for crossed entorhinal fibers.

Synaptic plasticity in the mormyrid electrosensory lobe

1999 ◽  
Vol 202 (10) ◽  
pp. 1339-1347 ◽  
Author(s):  
C.C. Bell ◽  
V.Z. Han ◽  
Y. Sugawara ◽  
K. Grant
Keyword(s):  
Synaptic Plasticity ◽  
Sensory Input ◽  
Cellular Level ◽  
Parallel Fiber ◽  
Sensory Inputs ◽  
Associative Process ◽  
Sensory Features ◽  
Negative Images ◽  
Sensory Structures

The mormyrid electrosensory lateral line lobe (ELL) is one of several different sensory structures in fish that behave as adaptive sensory processors. These structures generate negative images of predictable features in the sensory inflow which are added to the actual inflow to minimize the effects of predictable sensory features. The negative images are generated through a process of association between centrally originating predictive signals and sensory inputs from the periphery. In vitro studies in the mormyrid ELL show that pairing of parallel fiber input with Na+ spikes in postsynaptic cells results in synaptic depression at the parallel fiber synapses. The synaptic plasticity observed at the cellular level and the associative process of generating negative images of predicted sensory input at the systems level share a number of properties. Both are rapidly established, anti-Hebbian, reversible, input-specific and tightly restricted in time. These common properties argue strongly that associative depression at the parallel fiber synapse contributes to the adaptive generation of negative images in the mormyrid ELL.

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