Chaotic mossy fiber stimulation efficiently increases the frequency of epileptiform bursts in rat CA3 hippocampal slices

2006 ◽  
Vol 1291 ◽  
pp. 93-96
Author(s):  
Satoru Ishizuka ◽  
Hatsuo Hayashi
Keyword(s):  
Mossy Fiber ◽  
Hippocampal Slices ◽  
Fiber Stimulation

Hyperexcitability in Combined Entorhinal/Hippocampal Slices of Adult Rat After Exposure to Brain-Derived Neurotrophic Factor

1997 ◽  
Vol 78 (2) ◽  
pp. 1082-1095 ◽  
Author(s):  
Helen E. Scharfman
Keyword(s):  
Entorhinal Cortex ◽  
Neurotrophic Factor ◽  
Mossy Fiber ◽  
Hippocampal Slices ◽  
Brain Derived Neurotrophic Factor ◽  
Field Potentials ◽  
Adult Rat ◽  
Bath Application ◽  
Fiber Stimulation ◽  
Area Ca3

Scharfman, Helen E. Hyperexcitability in combined entorhinal/hippocampal slices of adult rat after exposure to brain-derived neurotrophic factor. J. Neurophysiol. 78: 1082–1095, 1997. Effects of brain-derived neurotrophic factor (BDNF) in area CA3, the dentate gyrus, and medial entorhinal cortex were examined electrophysiologically by bath application of BDNF in slices containing the hippocampus and entorhinal cortex. Bath application of 25–100 ng/ml BDNF for 30–90 min increased responses to single afferent stimuli in selective pathways in the majority of slices. In area CA3, responses to mossy fiber stimulation increased in 73% of slices and entorhinal cortex responses to white matter stimulation increased in 64% of slices. After exposure to BDNF, these areas also demonstrated evidence of hyperexcitability, because responses to repetitive stimulation (1-Hz paired pulses for several s) produced multiple population spikes in response to mossy fiber stimulation in CA3 or multiple field potentials in response to white matter stimulation in the entorhinal cortex. Repetitive field potentials persisted after repetitive stimulation ended and usually were followed by spreading depression. Enhancement of responses to single stimuli and hyperexcitability were never evoked in untreated slices or after bath application of boiled BDNF or cytochrome C. The tyrosine kinase antagonist K252a (2 μM) blocked the effects of BDNF. In area CA3, both the potentiation of responses to single stimuli and hyperexcitability showed afferent specificity, because responses to mossy fiber stimulation were affected but responses to fimbria or Schaffer collateral stimulation were not. In addition, regional specificity was demonstrated in that the dentate gyrus was much less affected. The effects of BDNF in area CA3 were similar to those produced by bath application of low doses of kainic acid, which is thought to modulate glutamate release from mossy fiber terminals by a presynaptic action. These results suggest that BDNF has acute effects on excitability in different areas of the hippocampal-entorhinal circuit. These effects appear to be greatest in areas that are highly immunoreactive for BDNF, such as the mossy fibers and the entorhinal cortex. Although the present experiments do not elucidate mechanism(s) definitively, the afferent specificity, similarity to the effects of kainic acid, and block by K252a are consistent with previous hypotheses that BDNF affects acute excitability by a presynaptic action on trkB receptors that modulate excitatory amino acid transmission. However, we cannot rule out actions on inhibitory synapses or postsynaptic processes.

Delayed Signal Propagation via CA2 in Rat Hippocampal Slices Revealed by Optical Recording

1997 ◽  
Vol 78 (3) ◽  
pp. 1662-1668 ◽  
Author(s):  
Yuko Sekino ◽  
Kunihiko Obata ◽  
Manabu Tanifuji ◽  
Makoto Mizuno ◽  
Jin Murayama
Keyword(s):  
Mossy Fiber ◽  
Hippocampal Slices ◽  
Mossy Fibers ◽  
Signal Propagation ◽  
Middle Part ◽  
Optical Recording ◽  
Stratum Radiatum ◽  
Ca1 Neurons ◽  
Optical Signals ◽  
Fiber Stimulation

Sekino, Yuko, Kunihiko Obata, Manabu Tanifuji, Makoto Mizuno, and Jin Murayama. Delayed signal propagation via CA2 in rat hippocampal slices revealed by optical recording. J. Neurophysiol. 78: 1662–1668, 1997. Signal propagation from mossy fibers to CA1 neurons was investigated in rat hippocampal slices by a combination of electrical and optical recordings. The slices were prepared by oblique sectioning of the middle part of the hippocampus to preserve fiber connections. The mossy fibers were stimulated to induce population spikes (PSs) and excitatory postsynaptic potentials in the middle part of the CA1 region. Latencies of maximal PSs in CA1 varied widely among slices; they ranged from 7 to 13.5 ms, with two maxima at 9 and 11.5 ms. The fastest PSs probably are evoked by the Schaffer collaterals that connect the CA3 and CA1 regions in the well-known trisynaptic circuit. However, the slower PSs suggest the existence of additional delayed inputs. To determine the source of the delayed input, slices were stained with a voltage-sensitive dye, RH482, and the optical signals relevant to membrane potential changes were detected by a high-resolution optical imaging system. Optical recording of responses to mossy fiber stimulation indicated two distinct types of signal propagation from CA3 to CA1. In preparations evincing the fast type of propagation, signals spread to CA1 within 7.2 ms after the mossy fiber stimulation. During such propagation, activity flowed directly from CA3 to the stratum radiatum of CA1. Other preparations illustrated slow signal propagation, in which optical signals were generated in CA2 before spreading to CA1. During such slow signal transmission, activity persisted in CA2 and its surrounding area for 3 ms before propagating to the strata radiatum and oriens in CA1. In such cases, CA1 activity was detected within 10.8 ms of mossy fiber stimulation. In some slices, a mixture of the fast and slow propagation patterns was observed, indicating that these two transmission modes can coexist. Our data reveal that CA2 neurons can transmit delayed excitatory signals to CA1 neurons. We therefore conclude that consideration of electrical signal propagation through the hippocampus should include flow through the CA2 region in addition to the traditional dentate gyrus–CA3–CA1 trisynaptic circuit.

Ultrastructure of mossy fiber endings in in vitro hippocampal slices

1981 ◽  
Vol 41-41 (3-4) ◽  
Author(s):  
M. Frotscher ◽  
U. Misgeld ◽  
C. Nitsch
Keyword(s):  
Mossy Fiber ◽  
Hippocampal Slices

scholarly journals Non-synaptic signaling from cerebellar climbing fibers modulates Golgi cell activity

eLife ◽  
2017 ◽  
Vol 6 ◽  
Author(s):  
Angela K Nietz ◽  
Jada H Vaden ◽  
Luke T Coddington ◽  
Linda Overstreet-Wadiche ◽  
Jacques I Wadiche
Keyword(s):  
Feedback Inhibition ◽  
Mossy Fiber ◽  
Molecular Layer ◽  
Cell Activity ◽  
Climbing Fiber ◽  
Climbing Fibers ◽  
In Vivo Studies ◽  
Golgi Cell ◽  
Golgi Cells ◽  
Fiber Stimulation

Golgi cells are the principal inhibitory neurons at the input stage of the cerebellum, providing feedforward and feedback inhibition through mossy fiber and parallel fiber synapses. In vivo studies have shown that Golgi cell activity is regulated by climbing fiber stimulation, yet there is little functional or anatomical evidence for synapses between climbing fibers and Golgi cells. Here, we show that glutamate released from climbing fibers activates ionotropic and metabotropic receptors on Golgi cells through spillover-mediated transmission. The interplay of excitatory and inhibitory conductances provides flexible control over Golgi cell spiking, allowing either excitation or a biphasic sequence of excitation and inhibition following single climbing fiber stimulation. Together with prior studies of spillover transmission to molecular layer interneurons, these results reveal that climbing fibers exert control over inhibition at both the input and output layers of the cerebellar cortex.

scholarly journals Mossy fiber growth and synaptogenesis in rat hippocampal slices in vitro

1994 ◽  
Vol 14 (3) ◽  
pp. 1060-1078 ◽  
Author(s):  
ME Dailey ◽  
J Buchanan ◽  
DE Bergles ◽  
SJ Smith
Keyword(s):  
Mossy Fiber ◽  
Hippocampal Slices ◽  
Fiber Growth
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