scholarly journals Homeostatic regulation of presynaptic NMDA receptor subunit composition modulates action potential driven Ca2+ influx into boutons setting the bandwidth for information transfer

2021 ◽  
Author(s):  
Carla C. Schmidt ◽  
Rudi Tong ◽  
Nigel J. Emptage
Keyword(s):  
Action Potential ◽  
Information Transfer ◽  
Time Window ◽  
Functional Expression ◽  
Subunit Composition ◽  
Integration Time ◽  
Sk Channels ◽  
Electrophysiological Recordings ◽  
Short And Long Term ◽  
Central Synapses

SummaryN-Methyl-D-aspartate receptors (NMDARs) play a pivotal role in both short and long-term plasticity. While the functional role of postsynaptic NMDARs is well established, a framework of presynaptic NMDAR (preNMDAR) function is missing. Differences in subunit composition of preNMDARs are documented at central synapses, raising the possibility that subtype composition plays a role in transmission performance. Here, we use electrophysiological recordings at Schaffer collateral - CA1 synapses and Ca2+ imaging coupled to focal glutamate uncaging at boutons of CA3 pyramidal neurones to reveal two populations of presynaptic NMDARs that contain either the GluN2A or GluN2B subunit. Activation of the GluN2B population decreases action potential (AP)-evoked Ca2+ influx via modulation of small conductance Ca2+-activated K+ channels (SK-channels) while activation of the GluN2A containing population does the opposite. Moreover, the level of functional expression of each receptor population can be homeostatically modified, bidirectionally affecting short-term facilitation during burst firing, thus providing a capacity for a fine adjustment of the presynaptic integration time window and therefore the bandwidth of information transfer.

scholarly journals The Rate of Information Transfer of Naturalistic Stimulation by Graded Potentials

2003 ◽  
Vol 122 (2) ◽  
pp. 191-206 ◽  
Author(s):  
Mikko Juusola ◽  
Gonzalo G. de Polavieja
Keyword(s):  
Time Scale ◽  
Information Transfer ◽  
Bright Light ◽  
Scale Structure ◽  
Finite Duration ◽  
Adaptation Mechanisms ◽  
Short And Long Term ◽  
Signaling Strategies

We present a method to measure the rate of information transfer for any continuous signals of finite duration without assumptions. After testing the method with simulated responses, we measure the encoding performance of Calliphora photoreceptors. We find that especially for naturalistic stimulation the responses are nonlinear and noise is nonadditive, and show that adaptation mechanisms affect signal and noise differentially depending on the time scale, structure, and speed of the stimulus. Different signaling strategies for short- and long-term and dim and bright light are found for this graded system when stimulated with naturalistic light changes.

scholarly journals Intracellular Ca2+ Release and Synaptic Plasticity: A Tale of Many Stores

2018 ◽  
Vol 25 (3) ◽  
pp. 208-226 ◽  
Author(s):  
Zahid Padamsey ◽  
William J. Foster ◽  
Nigel J. Emptage
Keyword(s):  
Endoplasmic Reticulum ◽  
Synaptic Plasticity ◽  
Synaptic Function ◽  
Intracellular Organelles ◽  
Short And Long Term ◽  
Central Synapses ◽  
Neural Signaling ◽  
Temporal Extent

Ca2+ is an essential trigger for most forms of synaptic plasticity. Ca2+ signaling occurs not only by Ca2+ entry via plasma membrane channels but also via Ca2+ signals generated by intracellular organelles. These organelles, by dynamically regulating the spatial and temporal extent of Ca2+ elevations within neurons, play a pivotal role in determining the downstream consequences of neural signaling on synaptic function. Here, we review the role of three major intracellular stores: the endoplasmic reticulum, mitochondria, and acidic Ca2+ stores, such as lysosomes, in neuronal Ca2+ signaling and plasticity. We provide a comprehensive account of how Ca2+ release from these stores regulates short- and long-term plasticity at the pre- and postsynaptic terminals of central synapses.

Selective activation of heteromeric SK channels contributes to action potential repolarization in mouse atrial myocytes

Heart Rhythm ◽  
2015 ◽  
Vol 12 (5) ◽  
pp. 1003-1015 ◽  
Author(s):  
Jane M. Hancock ◽  
Kate L. Weatherall ◽  
Stéphanie C. Choisy ◽  
Andrew F. James ◽  
Jules C. Hancox ◽  
...  
Keyword(s):  
Action Potential ◽  
Sk Channels ◽  
Atrial Myocytes ◽  
Selective Activation ◽  
Action Potential Repolarization

scholarly journals Multiple-scale neuroendocrine signals connect brain and pituitary hormone rhythms

2017 ◽  
Vol 114 (9) ◽  
pp. 2379-2382 ◽  
Author(s):  
Nicola Romanò ◽  
Anne Guillou ◽  
David J. Hodson ◽  
Agnès O Martin ◽  
Patrice Mollard
Keyword(s):  
Time Window ◽  
Hormone Secretion ◽  
Multiple Scale ◽  
Building Blocks ◽  
Prolactin Secretion ◽  
Temporal Organization ◽  
Integration Time ◽  
Pituitary Hormone ◽  
Global Integration ◽  
Da Release

Small assemblies of hypothalamic “parvocellular” neurons release their neuroendocrine signals at the median eminence (ME) to control long-lasting pituitary hormone rhythms essential for homeostasis. How such rapid hypothalamic neurotransmission leads to slowly evolving hormonal signals remains unknown. Here, we show that the temporal organization of dopamine (DA) release events in freely behaving animals relies on a set of characteristic features that are adapted to the dynamic dopaminergic control of pituitary prolactin secretion, a key reproductive hormone. First, locally generated DA release signals are organized over more than four orders of magnitude (0.001 Hz–10 Hz). Second, these DA events are finely tuned within and between frequency domains as building blocks that recur over days to weeks. Third, an integration time window is detected across the ME and consists of high-frequency DA discharges that are coordinated within the minutes range. Thus, a hierarchical combination of time-scaled neuroendocrine signals displays local–global integration to connect brain–pituitary rhythms and pace hormone secretion.

scholarly journals Small-conductance calcium-activated potassium (SK) channels contribute to action potential repolarization in human atria

2014 ◽  
Vol 103 (1) ◽  
pp. 156-167 ◽  
Author(s):  
Lasse Skibsbye ◽  
Claire Poulet ◽  
Jonas Goldin Diness ◽  
Bo Hjorth Bentzen ◽  
Lei Yuan ◽  
...  
Keyword(s):  
Action Potential ◽  
Sk Channels ◽  
Action Potential Repolarization ◽  
Small Conductance

scholarly journals Large and fast human pyramidal neurons associate with intelligence

2018 ◽  
Author(s):  
Natalia A. Goriounova ◽  
Djai B. Heyer ◽  
René Wilbers ◽  
Matthijs B. Verhoog ◽  
Michele Giugliano ◽  
...  
Keyword(s):  
Action Potential ◽  
Brain Imaging ◽  
Cortical Thickness ◽  
Cortical Neurons ◽  
Information Transfer ◽  
Pyramidal Neurons ◽  
Temporal Cortex ◽  
Neuron Activity ◽  
Human Intelligence ◽  
Iq Scores

AbstractIt is generally assumed that human intelligence relies on efficient processing by neurons in our brain. Behavioral and brain-imaging studies robustly show that higher intelligence associates with faster reaction times and thicker gray matter in temporal and frontal cortical areas. However, no direct evidence exists that links individual neuron activity and structure to human intelligence. Since a large part of cortical grey matter consists of dendrites, these structures likely determine cortical architecture. In addition, dendrites strongly affect functional properties of neurons, including action potential speed. Thereby, dendritic size and action potential firing may constitute variation in cortical thickness, processing speed, and ultimately IQ.To investigate this, we took advantage of brain tissue available from neurosurgery and recorded from pyramidal neurons in the medial temporal cortex, an area showing high association between cortical thickness, cortical activity and intelligence. Next, we reconstructed full dendritic structures of recorded neurons and combined these with brain-imaging data and IQ scores from the same subjects. We find that high IQ scores and large temporal cortical thickness associate with larger, more complex dendrites of human pyramidal neurons. We show in silico that larger dendrites enable pyramidal neurons to track activity of synaptic inputs with higher temporal precision, due to fast action potential initiation. Finally, we find that human pyramidal neurons of individuals with higher IQ scores sustain faster action potentials during repeated firing. These findings provide first evidence that human intelligence is associated with neuronal complexity, action potential speed and efficient information transfer in cortical neurons.

scholarly journals Identification of a developmental switch in information transfer between whisker S1 and S2 cortex in mice

2021 ◽  
Author(s):  
Theofanis Karayannis ◽  
Linbi Cai ◽  
Jenq-Wei Yang ◽  
Shen-Ju Chou ◽  
Chia-Fang Wang ◽  
...  
Keyword(s):  
Information Transfer ◽  
Barrel Cortex ◽  
Wide Field ◽  
Sensory Stimuli ◽  
Knock Out ◽  
Electrophysiological Recordings ◽  
Primary Sensory Cortex ◽  
Animal Navigation ◽  
Knock Out Mice

The whiskers of rodents are a key sensory organ that provides critical tactile information for animal navigation and object exploration throughout life. Previous work has explored the developmental sensory-driven activation of the primary sensory cortex processing whisker information (wS1), also called barrel cortex. This body of work has shown that the barrel cortex is already activated by sensory stimuli during the first post-natal week. However, it is currently unknown when over the course of development these stimuli begin being processed by higher order cortical areas, such as secondary whisker somatosensory area (wS2). Here we investigate for the first time the developmental engagement of wS2 by sensory stimuli and the emergence of cortico-cortical communication from wS1 to wS2. Using in vivo wide-field imaging and electrophysiological recordings in control and conditional knock-out mice we find that wS1 and wS2 are able to process bottom-up information coming from the thalamus already right after birth. We identify that it is only at the end of the first post-natal week that wS1 begins to provide excitation into wS2, a connection which begins to acquire feed-forward inhibition characteristics after the second post-natal week. Therefore, we have uncovered a developmental window during which excitatory versus inhibitory functional connectivity between wS1 and wS2 takes place.

scholarly journals Calcium stores regulate excitability in cultured rat hippocampal neurons

2018 ◽  
Vol 120 (5) ◽  
pp. 2694-2705 ◽  
Author(s):  
Menahem Segal
Keyword(s):  
Action Potential ◽  
Hippocampal Neurons ◽  
Extracellular Calcium ◽  
Calcium Stores ◽  
Sk Channels ◽  
Central Neurons ◽  
Action Potential Threshold ◽  
Potential Threshold ◽  
Small Conductance ◽  
Cultured Hippocampal Neurons

Extracellular calcium ions support synaptic activity but also reduce excitability of central neurons. In the present study, the effect of calcium on excitability was explored in cultured hippocampal neurons. CaCl2 injected by pressure in the vicinity of a neuron that is bathed only in MgCl2 as the main divalent cation caused a depolarizing shift in action potential threshold and a reduction in excitability. This effect was not seen if the intracellular milieu consisted of Cs+ instead of K-gluconate as the main cation or when it contained ruthenium red, which blocks release of calcium from stores. The suppression of excitability by calcium was mimicked by caffeine, and calcium store antagonists cyclopiazonic acid or thapsigargin blocked this action. Neurons taken from synaptopodin-knockout mice show significantly reduced efficacy of calcium modulation of action potential threshold. Likewise, in Orai1 knockdown cells, calcium is less effective in modulating excitability of neurons. Activation of small-conductance K (SK) channels increased action potential threshold akin to that produced by calcium ions, whereas blockade of SK channels but not big K channels reduced the threshold for action potential discharge. These results indicate that calcium released from stores may suppress excitability of central neurons. NEW & NOTEWORTHY Extracellular calcium reduces excitability of cultured hippocampal neurons. This effect is mediated by calcium-gated potassium currents, possibly small-conductance K channels. Release of calcium from internal stores mimics the effect of extracellular calcium. It is proposed that calcium stores modulate excitability of central neurons.

Sign in / Sign up

Export Citation Format

Share Document