scholarly journals Generation of directional selectivity by individual thin dendrites in neocortical pyramidal neurons

2010 ◽  
Author(s):  
Guy Major
Keyword(s):  
Pyramidal Neurons ◽  
Directional Selectivity ◽  
Neocortical Pyramidal Neurons

scholarly journals Ciliary neuropeptidergic signaling dynamically regulates excitatory synapses in postnatal neocortical pyramidal neurons

2020 ◽  
Author(s):  
Lauren Tereshko ◽  
Ya Gao ◽  
Brian A. Cary ◽  
Gina G. Turrigiano ◽  
Piali Sengupta
Keyword(s):  
Primary Cilia ◽  
Neuronal Development ◽  
Pyramidal Neurons ◽  
Somatostatin Receptor ◽  
Cognitive Disorders ◽  
Mammalian Brain ◽  
Excitatory Synapses ◽  
Ciliary Signaling ◽  
Neocortical Pyramidal Neurons

ABSTRACTPrimary cilia are compartmentalized sensory organelles present on the majority of neurons in the mammalian brain throughout adulthood. Recent evidence suggests that cilia regulate multiple aspects of neuronal development, including the maintenance of neuronal connectivity. However, whether ciliary signals can dynamically modulate postnatal circuit excitability is unknown. Here we show that acute cell-autonomous knockdown of ciliary signaling rapidly strengthens glutamatergic inputs onto cultured neocortical pyramidal neurons, and increases spontaneous firing. This increased excitability occurs without changes to passive neuronal properties or intrinsic excitability. Further, the neuropeptide receptor somatostatin receptor 3 (SSTR3) is localized nearly exclusively to pyramidal neuron cilia both in vivo and in culture, and pharmacological manipulation of SSTR3 signaling bidirectionally modulates excitatory synaptic inputs onto these neurons. Our results indicate that ciliary neuropeptidergic signaling dynamically modulates excitatory synapses, and suggest that defects in this regulation may underlie a subset of behavioral and cognitive disorders associated with ciliopathies.

Specificity in the Interaction of HVA Ca2+ Channel Types With Ca2+-Dependent AHPs and Firing Behavior in Neocortical Pyramidal Neurons

1998 ◽  
Vol 79 (5) ◽  
pp. 2522-2534 ◽  
Author(s):  
Juan Carlos Pineda ◽  
Robert S. Waters ◽  
Robert C. Foehring
Keyword(s):  
Brain Slice ◽  
Pyramidal Neurons ◽  
Repetitive Firing ◽  
Channel Blockers ◽  
Firing Behavior ◽  
Inward Currents ◽  
Functional Consequences ◽  
P Type ◽  
Brain Slice Preparation ◽  
Neocortical Pyramidal Neurons

Pineda, Juan Carlos, Roberts S. Waters, and Robert C. Foehring. Specificity in the interaction of HVA Ca2+ channel types with Ca2+-dependent AHPs and firing behavior in neocortical pyramidal neurons. J. Neurophysiol. 79: 2522–2534, 1998. Intracellular recordings and organic and inorganic Ca2+ channel blockers were used in a neocortical brain slice preparation to test whether high-voltage–activated (HVA) Ca2+ channels are differentially coupled to Ca2+-dependent afterhyperpolarizations (AHPs) in sensorimotor neocortical pyramidal neurons. For the most part, spike repolarization was not Ca2+ dependent in these cells, although the final phase of repolarization (after the fast AHP) was sensitive to block of N-type current. Between 30 and 60% of the medium afterhyperpolarization (mAHP) and between ∼80 and 90% of the slow AHP (sAHP) were Ca2+ dependent. Based on the effects of specific organic Ca2+ channel blockers (dihydropyridines, ω-conotoxin GVIA, ω-agatoxin IVA, and ω-conotoxin MVIIC), the sAHP is coupled to N-, P-, and Q-type currents. P-type currents were coupled to the mAHP. L-type current was not involved in the generation of either AHP but (with other HVA currents) contributes to the inward currents that regulate interspike intervals during repetitive firing. These data suggest different functional consequences for modulation of Ca2+ current subtypes.

Relationships Between Intracellular Calcium and Afterhyperpolarizations in Neocortical Pyramidal Neurons

2004 ◽  
Vol 91 (1) ◽  
pp. 324-335 ◽  
Author(s):  
H. J. Abel ◽  
J.C.F. Lee ◽  
J. C. Callaway ◽  
R. C. Foehring
Keyword(s):  
Intracellular Calcium ◽  
Linear Relationship ◽  
Pyramidal Neurons ◽  
Pyramidal Cells ◽  
Firing Frequency ◽  
Discharge Activity ◽  
Apical Dendrites ◽  
Neocortical Pyramidal Neurons

We examined the effects of recent discharge activity on [Ca2+]i in neocortical pyramidal cells. Our data confirm and extend the observation that there is a linear relationship between plateau [Ca2+]i and firing frequency in soma and proximal apical dendrites. The rise in [Ca2+] activates K+ channels underlying the afterhyperpolarization (AHP), which consists of 2 Ca2+-dependent components: the medium AHP (mAHP) and the slow AHP (sAHP). The mAHP is blocked by apamin, indicating involvement of SK-type Ca2+-dependent K+ channels. The identity of the apamin-insensitive sAHP channel is unknown. We compared the sAHP and the mAHP with regard to: 1) number and frequency of spikes versus AHP amplitude; 2) number and frequency of spikes versus [Ca2+]i; 3) IAHP versus [Ca2+]i. Our data suggest that sAHP channels require an elevation of [Ca2+]i in the cytoplasm, rather than at the membrane, consistent with a role for a cytoplasmic intermediate between Ca2+ and the K+ channels. The mAHP channels appear to respond to a restricted Ca2+ domain.

Modification of Current Transmitted From Apical Dendrite to Soma by Blockade of Voltage- and Ca2+-Dependent Conductances in Rat Neocortical Pyramidal Neurons

1997 ◽  
Vol 78 (1) ◽  
pp. 187-198 ◽  
Author(s):  
Peter C. Schwindt ◽  
Wayne E. Crill
Keyword(s):  
Membrane Potential ◽  
Pyramidal Neurons ◽  
Reversal Potential ◽  
Apical Dendrite ◽  
Axial Current ◽  
Resting Potential ◽  
High Threshold ◽  
Voltage Gated ◽  
Distal Site ◽  
Neocortical Pyramidal Neurons

Schwindt, Peter C. and Wayne E. Crill. Modification of current transmitted from apical dendrite to soma by blockade of voltage- and Ca2+-dependent conductances in rat neocortical pyramidal neurons. J. Neurophysiol. 78: 187–198, 1997. The axial current transmitted to the soma during the long-lasting iontophoresis of glutamate at a distal site on the apical dendrite was measured by somatic voltage clamp of rat neocortical pyramidal neurons. Evidence for voltage- and Ca2+-gated channels in the apical dendrite was sought by examining the modification of this transmitted current resulting from the alteration of membrane potential and the application of channel-blocking agents. After N-methyl-d-aspartate receptor blockade, iontophoresis of glutamate on the soma evoked a current whose amplitude decreased linearly with depolarization to an extrapolated reversal potential near 0 mV. Under the same conditions, glutamate iontophoresis on the apical dendrite 241–537 μm from the soma resulted in a transmitted axial current that increased with depolarization over the same range of membrane potential (about −90 to −40 mV). Current transmitted from dendrite to soma was thus amplified during depolarization from resting potential (about −70 mV) and attenuated during hyperpolarization. After Ca2+ influx was blocked to eliminate Ca2+-dependent K+ currents, application of 10 mM tetraethylammonium chloride (TEA) altered the amplitude and voltage dependence of the transmitted current in a manner consistent with the reduction of dendritic voltage-gated K+ current. We conclude that dendritic, TEA-sensitive, voltage-gated K+ channels can be activated by tonic dendritic depolarization. The most prominent effects of blocking Ca2+ influx resembled those elicited by TEA application, suggesting that these effects were caused predominantly by blockade of a dendritic Ca2+-dependent K+ current. When cells were impaled with microelectrodes containing ethylene glycol-bis(β-amino-ethyl ether)- N,N′,N′-tetraacetic acid to prevent a rise in intracellular Ca2+ concentration, blockade of Ca2+ influx altered the tonic transmitted current in different manner consistent with the blockade of a inward dendritic current carried by high-threshold-activated Ca2+ channels. We conclude that the primary effect of Ca2+ influx during tonic dendritic depolarization is the activation of a dendritic Ca2+-dependent K+ current. The hyperpolarizing attenuation of transmitted current was unaffected by blocking all known voltage-gated inward currents except the hyperpolarization-activated cation current ( I h). Extracellular Cs+ (3 mM) reversibly abolished both the hyperpolarizing attenuation of transmitted current and I h measured at the soma. We conclude that activation of I h by hyperpolarization of the proximal apical dendrite would cause less axial current to arrive at the soma from a distal site than in a passive dendrite. Several functional implications of dendritic K+ and I h channels are discussed.

Simulations of Intrinsically Bursting Neocortical Pyramidal Neurons

1994 ◽  
Vol 6 (6) ◽  
pp. 1086-1110 ◽  
Author(s):  
Paul A. Rhodes ◽  
Charles M. Gray
Keyword(s):  
Visual Cortex ◽  
Ion Channels ◽  
Pyramidal Neurons ◽  
Compartment Model ◽  
Morphological Data ◽  
High Threshold ◽  
Simulation Results ◽  
Dendritic Branches ◽  
Neocortical Pyramidal Neurons

Neocortical layer 5 intrinsically bursting (IB) pyramidal neurons were simulated using compartment model methods. Morphological data as well as target neurophysiological responses were taken from a series of published studies on the same set of rat visual cortex pyramidal neurons (Mason, A. and Larkman, A. J., 1990. J. Neurosci. 9,1440-1447; Larkman, A. J. 1991. J. Comp. Neurol. 306, 307-319). A dendritic distribution of ion channels was found that reproduced the range of in vitro responses of layer 5 IB pyramidal neurons, including the transition from repetitive bursting to the burst/tonic spiking mode seen in these neurons as input magnitude increases. In light of available data, the simulation results suggest that in these neurons bursts are driven by an inward flow of current during a high threshold Ca2+ spike extending throughout both the basal and apical dendritic branches.

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