Changes of synaptic input frequency in the dentate gyrus induce feedback regulation of synaptic strength in vivo

2010 ◽  
Vol 68 ◽  
pp. e340
Author(s):  
Daisuke Miyamoto ◽  
Hiroshi Nomura ◽  
Norio Matsuki
Keyword(s):  
Dentate Gyrus ◽  
Synaptic Input ◽  
Feedback Regulation ◽  
Synaptic Strength ◽  
Input Frequency

Sodium salicylate enhances neural excitation via reducing GABAergic transmission in the dentate gyrus area of rat hippocampus in vivo

Hippocampus ◽  
2021 ◽  
Author(s):  
Hui‐Ping Tang ◽  
Hua‐Rui Gong ◽  
Xu‐Lai Zhang ◽  
Yi‐Na Huang ◽  
Chuan‐Yun Wu ◽  
...  
Keyword(s):  
Dentate Gyrus ◽  
Sodium Salicylate ◽  
Rat Hippocampus ◽  
Gabaergic Transmission ◽  
Neural Excitation

scholarly journals Prolactin and Male Fertility: The Long and Short Feedback Regulation

2009 ◽  
Vol 2009 ◽  
pp. 1-13 ◽  
Author(s):  
M. K. Gill-Sharma
Keyword(s):  
Chromatin Condensation ◽  
Feedback Regulation ◽  
Pituitary Hormones ◽  
Feedback Mechanism ◽  
Reproductive Hormones ◽  
Male Rats ◽  
Normal Men

In the last 20 years, a pituitary-hypothalamus tissue culture system with intact neural and portal connections has been developed in our lab and used to understand the feedback mechanisms that regulate the secretions of adenohypophyseal hormones and fertility of male rats. In the last decade, several in vivo rat models have also been developed in our lab with a view to substantiate the in vitro findings, in order to delineate the role of pituitary hormones in the regulation of fertility of male rats. These studies have relied on both surgical and pharmacological interventions to modulate the secretions of gonadotropins and testosterone. The interrelationship between the circadian release of reproductive hormones has also been ascertained in normal men. Our studies suggest that testosterone regulates the secretion of prolactin through a long feedback mechanism, which appears to have been conserved from rats to humans. These studies have filled in a major lacuna pertaining to the role of prolactin in male reproductive physiology by demonstrating the interdependence between testosterone and prolactin. Systemic levels of prolactin play a deterministic role in the mechanism of chromatin condensation during spermiogenesis.

scholarly journals Active membrane conductances and morphology of a collision detection neuron broaden its impedance profile and improve membrane synchrony

2018 ◽  
Author(s):  
Richard Dewell ◽  
Fabrizio Gabbiani
Keyword(s):  
Synaptic Input ◽  
Collision Detection ◽  
Dendritic Morphology ◽  
Synaptic Integration ◽  
Neuronal Membrane ◽  
Hcn Channels ◽  
Movement Detector ◽  
Membrane Impedance ◽  
Wide Range

Brains processes information through the coordinated efforts of billions of individual neurons, each encoding a small part of the overall information stream. Central to this is how neurons integrate and transform complex patterns of synaptic inputs. The neuronal membrane impedance sets the gain and timing for synaptic integration, determining a neuron's ability to discriminate between synaptic input patterns. Using single and dual dendritic recordings in vivo, pharmacology, and computational modeling, we characterized the membrane impedance of a collision detection neuron in the grasshopper, Schistocerca americana. We examined how the cellular properties of the lobula giant movement detector (LGMD) neuron are tuned to enable the discrimination of synaptic input patterns key to its role in collision detection. We found that two common active conductances gH and gM, mediated respectively by hyperpolarization-activated cyclic nucleotide gated (HCN) channels and by muscarine sensitive M-type K+ channels, promote broadband integration with high temporal precision over the LGMD's natural range of membrane potentials and synaptic input frequencies. Additionally, we found that the LGMD's branching morphology increased the gain and decreased delays associated with the mapping of synaptic input currents to membrane potential. We investigated whether other branching dendritic morphologies fulfill a similar function and found this to be true for a wide range of morphologies, including those of neocortical pyramidal neurons and cerebellar Purkinje cells. These findings further our understanding of the integration properties of individual neurons by showing the unexpected role played by two widespread active conductances and by dendritic morphology in shaping synaptic integration.

scholarly journals Differential Modulation of Synaptic Strength and Timing Regulate Synaptic Efficacy in a Motor Network

2011 ◽  
Vol 105 (1) ◽  
pp. 293-304 ◽  
Author(s):  
Bruce R. Johnson ◽  
Jessica M. Brown ◽  
Mark D. Kvarta ◽  
Jay Y. J. Lu ◽  
Lauren R. Schneider ◽  
...  
Keyword(s):  
Synaptic Input ◽  
Synaptic Strength ◽  
Neuronal Firing ◽  
Cycle Period ◽  
Cycle Frequency ◽  
Pyloric Network ◽  
Motor Network ◽  
Pyloric Dilator ◽  
Network Output ◽  
Firing Properties

Neuromodulators modify network output by altering neuronal firing properties and synaptic strength at multiple sites; however, the functional importance of each site is often unclear. We determined the importance of monoamine modulation of a single synapse for regulation of network cycle frequency in the oscillatory pyloric network of the lobster. The pacemaker kernel of the pyloric network receives only one chemical synaptic feedback, an inhibitory synapse from the lateral pyloric (LP) neuron to the pyloric dilator (PD) neurons, which can limit cycle frequency. We measured the effects of dopamine (DA), octopamine (Oct), and serotonin (5HT) on the strength of the LP→PD synapse and the ability of the modified synapse to regulate pyloric cycle frequency. DA and Oct strengthened, whereas 5HT weakened, LP→PD inhibition. Surprisingly, the DA-strengthened LP→PD synapse lost its ability to slow the pyloric oscillations, whereas the 5HT-weakened LP→PD synapse gained a greater influence on the oscillations. These results are explained by monoamine modulation of factors that determine the firing phase of the LP neuron in each cycle. DA acts via multiple mechanisms to phase-advance the LP neuron into the pacemaker's refractory period, where the strengthened synapse has little effect. In contrast, 5HT phase-delays LP activity into a region of greater pacemaker sensitivity to LP synaptic input. Only Oct enhanced LP regulation of cycle period simply by enhancing LP→PD synaptic strength. These results show that modulation of the strength and timing of a synaptic input can differentially affect the synapse's efficacy in the network.

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