scholarly journals Membrane and synaptic properties of pyramidal neurons in the anterior olfactory nucleus

2011 ◽  
Vol 105 (4) ◽  
pp. 1444-1453 ◽  
Author(s):  
Matthew J. McGinley ◽  
Gary L. Westbrook
Keyword(s):  
Pyramidal Neurons ◽  
Piriform Cortex ◽  
Brain Slices ◽  
Membrane Properties ◽  
Inward Rectification ◽  
Excitatory Synapses ◽  
Membrane Excitability ◽  
Anterior Olfactory Nucleus ◽  
Firing Rates ◽  
Synaptic Excitation

The anterior olfactory nucleus (AON) is positioned to coordinate activity between the piriform cortex and olfactory bulbs, yet the physiology of AON principal neurons has been little explored. Here, we examined the membrane properties and excitatory synapses of AON principal neurons in brain slices of PND22–28 mice and compared their properties to principal cells in other olfactory cortical areas. AON principal neurons had firing rates, spike rate adaptation, spike widths, and I-V relationships that were generally similar to pyramidal neurons in piriform cortex, and typical of cerebral cortex, consistent with a role for AON in cortical processing. Principal neurons in AON had more hyperpolarized action potential thresholds, smaller afterhyperpolarizations, and tended to fire doublets of action potentials on depolarization compared with ventral anterior piriform cortex and the adjacent epileptogenic region preendopiriform nucleus (pEN). Thus, AON pyramidal neurons have enhanced membrane excitability compared with surrounding subregions. Interestingly, principal neurons in pEN were the least excitable, as measured by a larger input conductance, lower firing rates, and more inward rectification. Afferent and recurrent excitatory synapses onto AON pyramidal neurons had small amplitudes, paired pulse facilitation at afferent synapses, and GABAB modulation at recurrent synapses, a pattern similar to piriform cortex. The enhanced membrane excitability and recurrent synaptic excitation within the AON, together with its widespread outputs, suggest that the AON can boost and distribute activity in feedforward and feedback circuits throughout the olfactory system.

Physiological Properties of Central Medial and Central Lateral Amygdala Neurons

1999 ◽  
Vol 82 (4) ◽  
pp. 1843-1854 ◽  
Author(s):  
Marzia Martina ◽  
Sébastien Royer ◽  
Denis Paré
Keyword(s):  
Conditioned Fear ◽  
Brain Slices ◽  
Cell Types ◽  
Membrane Depolarization ◽  
Membrane Properties ◽  
Repetitive Firing ◽  
Inward Rectification ◽  
Current Pulses ◽  
Outward Rectification ◽  
Physiological Properties

Mounting evidence implicates the central (CE) nucleus of the amygdala in the mediation of classically conditioned fear responses. However, little data are available regarding the intrinsic membrane properties of CE amygdala neurons. Here, we characterized the physiological properties of CE medial (CEM) and CE lateral (CEL) amygdala neurons using whole cell recordings in brain slices maintained in vitro. Several classes of CE neurons were distinguished on the basis of their physiological properties. Most CEM cells (95%), here termed “late-firing neurons,” displayed a marked voltage- and time-dependent outward rectification in the depolarizing direction. This phenomenon was associated with a conspicuous delay between the onset of depolarizing current pulses and the first action potential. During this delay, the membrane potential ( V m) depolarized slowly, the steepness of this depolarizing ramp increasing as the prepulse V m was hyperpolarized from −60 to −90 mV. Low extracellular concentrations of 4-aminopyridine (30 μM) reversibly abolished the outward rectification and the delay to firing. Late-firing CEM neurons displayed a continuum of repetitive firing properties with cells generating single spikes at one pole and high-frequency (≥90 Hz) spike bursts at the other. In contrast, only 56% of CEL cells displayed the late-firing behavior prevalent among CEM neurons. Moreover, these CEL neurons only generated single spikes in response to membrane depolarization. A second major class of CEL cells (38%) lacked the characteristic delay to firing observed in CEM cells, generated single spikes in response to membrane depolarization, and displayed various degrees of inward rectification in the hyperpolarizing direction. In both regions of the CE nucleus, two additional cell types were encountered infrequently (≤ 6% of our samples). One type of neurons, termed “low-threshold bursting cells” had a behavior reminiscent of thalamocortical neurons. The second type of cells, called “fast-spiking cells,” generated brief action potentials at high rates with little spike frequency adaptation in response to depolarizing current pulses. These findings indicate that the CE nucleus contains several types of neurons endowed with distinct physiological properties. Moreover, these various cell types are not distributed uniformly in the medial and lateral sector of the CE nucleus. This heterogeneity parallels anatomic data indicating that these subnuclei are part of different circuits.

scholarly journals Coincidence Detection in Pyramidal Neurons Is Tuned by Their Dendritic Branching Pattern

2003 ◽  
Vol 89 (6) ◽  
pp. 3143-3154 ◽  
Author(s):  
Andreas T. Schaefer ◽  
Matthew E. Larkum ◽  
Bert Sakmann ◽  
Arnd Roth
Keyword(s):  
Pyramidal Neurons ◽  
Experimental Studies ◽  
Brain Slices ◽  
Apical Dendrite ◽  
Dendritic Arborization ◽  
Coincidence Detection ◽  
Membrane Properties ◽  
Relative Reduction ◽  
Close Proximity ◽  
The Relationship

Neurons display a variety of complex dendritic morphologies even within the same class. We examined the relationship between dendritic arborization and the coupling between somatic and dendritic action potential (AP) initiation sites in layer 5 (L5) neocortical pyramidal neurons. Coupling was defined as the relative reduction in threshold for initiation of a dendritic calcium AP due to a coincident back-propagating AP. Simulations based on reconstructions of biocytin-filled cells showed that addition of oblique branches of the main apical dendrite in close proximity to the soma ( d < 140 μm) increases the coupling between the apical and axosomatic AP initiation zones, whereas incorporation of distal branches decreases coupling. Experimental studies on L5 pyramids in acute brain slices revealed a highly significant ( n = 28, r = 0.63, P < 0.0005) correlation: increasing the fraction of proximal oblique dendrites ( d < 140 μm), e.g., from 30 to 60% resulted on average in an increase of the coupling from approximately 35% to almost 60%. We conclude that variation in dendritic arborization may be a key determinant of variability in coupling (49 ± 17%; range 19–83%; n = 37) and is likely to outweigh the contribution made by variations in active membrane properties. Thus coincidence detection of inputs arriving from different cortical layers is strongly regulated by differences in dendritic arborization.

Astrocytic iNOS-Dependent Enhancement of Synaptic Release in Mouse Neocortex

2010 ◽  
Vol 103 (3) ◽  
pp. 1322-1328 ◽  
Author(s):  
Yossi Buskila ◽  
Yael Amitai
Keyword(s):  
Pyramidal Neurons ◽  
Brain Slices ◽  
Selective Inhibition ◽  
Inhibitory Neurons ◽  
Small Subset ◽  
Excitatory Synapses ◽  
Brain Areas ◽  
Synaptic Release ◽  
Cellular Source ◽  
Inos Inhibition

Nitric oxide (NO) has been recognized as an atypical neuronal messenger affecting synaptic transmission, but its cellular source has remained unresolved as the neuronal NO synthase isoform (nNOS) in brain areas such as the neocortex is expressed only by a small subset of inhibitory neurons. The involvement of the glial NOS isoform (iNOS) in modulating neuronal activity has been largely ignored because it has been accepted that this enzyme is regulated by gene induction following detrimental stimuli. Using acute brain slices from mouse neocortex and electrophysiology, we found that selective inhibition of iNOS reduced both spontaneous and evoked synaptic release. Moreover, iNOS inhibition partially prevented and reversed the potentiation of excitatory synapses in layer 2/3 pyramidal neurons. NOS enzymatic assay confirmed a small but reliable Ca2+-independent activity fraction, consistent with the existence of functioning iNOS in the tissue. Together these data point to astrocytes as a source for the nitrosative regulation of synaptic release in the neocortex.

Modulation of Spontaneous Firing in Rat Subthalamic Neurons by 5-HT Receptor Subtypes

2005 ◽  
Vol 93 (3) ◽  
pp. 1145-1157 ◽  
Author(s):  
Zixiu Xiang ◽  
Lie Wang ◽  
Stephen T. Kitai
Keyword(s):  
Receptor Antagonist ◽  
Receptor Agonist ◽  
Driving Forces ◽  
Brain Slices ◽  
Potassium Conductance ◽  
Firing Frequency ◽  
Membrane Properties ◽  
Receptor Subtype ◽  
Receptor Subtypes ◽  
Membrane Excitability

The subthalamic nucleus (STN) is considered to be one of the driving forces in the basal ganglia circuit. The STN is innervated by serotonergic afferents from the raphe nucleus and expresses a variety of 5-HT receptor subtypes. We investigated the effects of 5-HT and 5-HT receptor subtype agonists and antagonists on the firing properties of STN neurons in rat brain slices. We used cell-attached, perforated-patch, and whole cell recording techniques to detect changes in firing frequency and pattern and electrical membrane properties. Due to the depolarization of membrane potential caused by reduced potassium conductance, 5-HT (10 μM) increased the firing frequency of STN neurons without changing their firing pattern. Cadmium failed to occlude the effect of 5-HT on firing frequency. 5-HT had no effect on afterhyperpolarization current. These results indicated that the 5-HT action was not mediated by high-voltage–activated calcium channel currents and calcium-dependent potassium currents. 5-HT had no effect on hyperpolarization-activated cation current ( IH) amplitude and voltage-dependence of IH activation, suggesting that IH was not involved in 5-HT–induced excitation. The increased firing by 5-HT was mimicked by 5-HT2/4 receptor agonist α-methyl-5-HT and was partially mimicked by 5-HT2 receptor agonist DOI or 5-HT4 receptor agonist cisapride. The 5-HT action was partially reversed by 5-HT4 receptor antagonist SB 23597-190, 5-HT2 receptor antagonist ketanserin, and 5-HT2C receptor antagonist RS 102221. Our data indicate that 5-HT has significant ability to modulate membrane excitability in STN neurons; modulation is accomplished by decreasing potassium conductance by activating 5-HT4 and 5-HT2C receptors.

scholarly journals Single Prolonged Stress Reduces Intrinsic Excitability and Excitatory Synaptic Drive onto Pyramidal Neurons in the Infralimbic Prefrontal Cortex of Adult Rats

2021 ◽  
Author(s):  
Nawshaba Nawreen ◽  
Mark L Baccei ◽  
James P Herman
Keyword(s):  
Prefrontal Cortex ◽  
Traumatic Stress ◽  
Pyramidal Neurons ◽  
Brain Slices ◽  
Intrinsic Excitability ◽  
Repetitive Firing ◽  
Membrane Excitability ◽  
Single Prolonged Stress ◽  
Prolonged Stress ◽  
Synaptic Drive

ABSTRACTPost-traumatic stress disorder (PTSD) is a chronic, debilitating mental illness marked by abnormal fear responses and deficits in extinction of fear memories. The pathophysiology of PTSD is linked to decreased activation of the ventromedial prefrontal cortex (vmPFC). This study aims to investigate underlying functional changes in synaptic drive and intrinsic excitability of pyramidal neurons in the rodent homolog of the vmPFC, the infralimbic cortex (IL), following exposure to single prolonged stress (SPS), a paradigm that mimics core symptoms of PTSD in rats. Rats were exposed to SPS and allowed one week of recovery following which brain slices containing the PFC were prepared for whole-cell patch clamp recordings from layer V pyramidal neurons in the IL. Our results indicate that SPS reduces spontaneous excitatory synaptic drive to pyramidal neurons. In addition, SPS decreases the intrinsic membrane excitability of IL PFC pyramidal cells, as indicated by an increase in rheobase, decrease in input resistance, hyperpolarization of resting membrane potential, and a reduction in repetitive firing rate. Our results suggest that SPS causes a lasting reduction in PFC activity, supporting a body of evidence linking traumatic stress with prefrontal hypoactivity.Graphical AbstractSPS causes a decrease in excitatory synaptic drive and intrinsic excitability of IL pyramidal neurons.

scholarly journals Age-Dependent Vulnerability to Oxidative Stress of Postnatal Rat Pyramidal Motor Cortex Neurons

Antioxidants ◽  
2020 ◽  
Vol 9 (12) ◽  
pp. 1307
Author(s):  
Livia Carrascal ◽  
Ella Gorton ◽  
Ricardo Pardillo-Díaz ◽  
Patricia Perez-García ◽  
Ricardo Gómez-Oliva ◽  
...  
Keyword(s):  
Oxidative Stress ◽  
Young Adult ◽  
Motor Cortex ◽  
Pyramidal Neurons ◽  
Neuronal Degeneration ◽  
Reductase Activity ◽  
Brain Slices ◽  
Newborn Rats ◽  
Membrane Excitability ◽  
Patch Clamp Technique

Oxidative stress is one of the main proposed mechanisms involved in neuronal degeneration. To evaluate the consequences of oxidative stress on motor cortex pyramidal neurons during postnatal development, rats were classified into three groups: Newborn (P2–P7); infantile (P11–P15); and young adult (P20–P40). Oxidative stress was induced by 10 µM of cumene hydroperoxide (CH) application. In newborn rats, using the whole cell patch-clamp technique in brain slices, no significant modifications in membrane excitability were found. In infantile rats, the input resistance increased and rheobase decreased due to the blockage of GABAergic tonic conductance. Lipid peroxidation induced by CH resulted in a noticeable increase in protein-bound 4-hidroxynonenal in homogenates in only infantile and young adult rat slices. Interestingly, homogenates of newborn rat brain slices showed the highest capacity to respond to oxidative stress by dramatically increasing their glutathione and free thiol content. This increase correlated with a time-dependent increase in the glutathione reductase activity, suggesting a greater buffering capacity of newborn rats to resist oxidative stress. Furthermore, pre-treatment of the slices with glutathione monoethyl ester acted as a neuroprotector in pyramidal neurons of infantile rats. We conclude that during maturation, the vulnerability to oxidative stress in rat motor neurons increases with age.

scholarly journals Intrinsic membrane properties of locus coeruleus neurons in Mecp2-null mice

2010 ◽  
Vol 298 (3) ◽  
pp. C635-C646 ◽  
Author(s):  
Xiaoli Zhang ◽  
Ningren Cui ◽  
Zhongying Wu ◽  
Junda Su ◽  
Jyothirmayee S. Tadepalli ◽  
...  
Keyword(s):  
Locus Coeruleus ◽  
Rett Syndrome ◽  
Brain Slices ◽  
Firing Frequency ◽  
Membrane Properties ◽  
Inward Rectification ◽  
Frequency Variation ◽  
Norepinephrine System ◽  
Cell Current ◽  
Intrinsic Membrane Properties

Rett syndrome caused by mutations in methyl-CpG-binding protein 2 ( Mecp2) gene shows abnormalities in autonomic functions in which brain stem norepinephrinergic systems play an important role. Here we present systematic comparisons of intrinsic membrane properties of locus coeruleus (LC) neurons between Mecp2−/Y and wild-type (WT) mice. Whole cell current clamp was performed in brain slices of 3- to 4-wk-old mice. Mecp2−/Y neurons showed stronger inward rectification and had shorter time constant than WT cells. The former was likely due to overexpression of inward rectifier K+ (Kir)4.1 channel, and the latter was attributable to the smaller cell surface area. The action potential duration was prolonged in Mecp2−/Y cells with an extended rise time. This was associated with a significant reduction in the voltage-activated Na+ current density. After action potentials, >60% Mecp2−/Y neurons displayed fast and medium afterhyperpolarizations (fAHP and mAHP), while nearly 90% WT neurons showed only mAHP. The mAHP amplitude was smaller in Mecp2−/Y neurons. The firing frequency was higher in neurons with mAHP, and the frequency variation was greater in cells with both fAHP and mAHP in Mecp2−/Y mice. Small but significant differences in spike frequency adaptation and delayed excitation were found in Mecp2−/Y neurons. These results indicate that there are several electrophysiological abnormalities in LC neurons of Mecp2−/Y mice, which may contribute to the dysfunction of the norepinephrine system in Rett syndrome.

Learning-Induced Enhancement of Postsynaptic Potentials in Pyramidal Neurons

2002 ◽  
Vol 87 (5) ◽  
pp. 2358-2363 ◽  
Author(s):  
Drorit Saar ◽  
Yoram Grossman ◽  
Edi Barkai
Keyword(s):  
Pyramidal Neurons ◽  
Piriform Cortex ◽  
Brain Slices ◽  
Pyramidal Cells ◽  
Proximal Region ◽  
Intrinsic Pathway ◽  
Postsynaptic Potentials ◽  
Basal Dendrites ◽  
Cortical Fibers ◽  
Stimulation Of

We studied the effect of olfactory learning-induced modifications in piriform (olfactory) cortex pyramidal neurons on the propagation of postsynaptic potentials (PSPs). Rats were trained to distinguish between odors in pairs, in an olfactory discrimination task. Three days after training completion, PSPs were evoked in layer II pyramidal cells in piriform cortex brain slices by electrical stimulation of two pathways. Stimulation of layer Ib activated the intra-cortical fibers that terminate on the proximal region of the apical and basal dendrites. Stimulation of layer Ia activated the afferent axons that originate from the olfactory bulb and terminate on the distal apical dendrites. We have previously shown that olfactory training is accompanied by enhanced synaptic transmission in the intrinsic pathway, but not in the afferent pathway at 3 days after training. Here we show that at this stage, in both pathways PSPs evoked in neurons from trained rats had significantly faster rise time measured at the soma compared with PSPs in neurons from pseudo-trained and naive rats. Activation of the slow afterhyperpolarization (AHP), which is generated by potassium channels probably located at the proximal region of both apical and basal dendrites, reduced the amplitude measured at the soma of the proximal intrinsic pathway PSPs more effectively than PSPs that were generated distally by the afferent fibers. Thus the amount of reduction by AHP was used as a measure for the relative distance of PSP-generating sites from the soma. In neurons from trained rats, despite the previously reported reduction in AHP amplitude, AHP conductance shunted the PSPs from both synaptic pathways more efficiently compared with neurons from the control rats. We suggest that in neurons from trained rats PSPs are electrotonicly closer to the soma.

scholarly journals Loss of Calretinin in L5a impairs the formation of the barrel cortex leading to abnormal whisker-mediated behaviors

2021 ◽  
Vol 14 (1) ◽  
Author(s):  
Mingzhao Su ◽  
Junhua Liu ◽  
Baocong Yu ◽  
Kaixing Zhou ◽  
Congli Sun ◽  
...  
Keyword(s):  
Information Integration ◽  
Pyramidal Neurons ◽  
Barrel Cortex ◽  
Sensory Information ◽  
Membrane Excitability ◽  
Novelty Preference ◽  
Layer 4 ◽  
Dendritic Complexity ◽  
Cortex System

AbstractThe rodent whisker-barrel cortex system has been established as an ideal model for studying sensory information integration. The barrel cortex consists of barrel and septa columns that receive information input from the lemniscal and paralemniscal pathways, respectively. Layer 5a is involved in both barrel and septa circuits and play a key role in information integration. However, the role of layer 5a in the development of the barrel cortex remains unclear. Previously, we found that calretinin is dynamically expressed in layer 5a. In this study, we analyzed calretinin KO mice and found that the dendritic complexity and length of layer 5a pyramidal neurons were significantly decreased after calretinin ablation. The membrane excitability and excitatory synaptic transmission of layer 5a neurons were increased. Consequently, the organization of the barrels was impaired. Moreover, layer 4 spiny stellate cells were not able to properly gather, leading to abnormal formation of barrel walls as the ratio of barrel/septum size obviously decreased. Calretinin KO mice exhibited deficits in exploratory and whisker-associated tactile behaviors as well as social novelty preference. Our study expands our knowledge of layer 5a pyramidal neurons in the formation of barrel walls and deepens the understanding of the development of the whisker-barrel cortex system.

Properties of visceral primary afferent neurons in the nodose ganglion of the rabbit

1985 ◽  
Vol 54 (2) ◽  
pp. 245-260 ◽  
Author(s):  
C. E. Stansfeld ◽  
D. I. Wallis
Keyword(s):  
Action Potentials ◽  
Input Resistance ◽  
Nodose Ganglion ◽  
Time Dependent ◽  
Membrane Properties ◽  
Resting Potential ◽  
Inward Rectification ◽  
C Cells ◽  
Axonal Conduction ◽  
A Cells

The active and passive membrane properties of rabbit nodose ganglion cells and their responsiveness to depolarizing agents have been examined in vitro. Neurons with an axonal conduction velocity of less than 3 m/s were classified as C-cells and the remainder as A-cells. Mean axonal conduction velocities of A- and C-cells were 16.4 m/s and 0.99 m/s, respectively. A-cells had action potentials of brief duration (1.16 ms), high rate of rise (385 V/s), an overshoot of 23 mV, and relatively high spike following frequency (SFF). C-cells typically had action potentials with a "humped" configuration (duration 2.51 ms), lower rate of rise (255 V/s), an overshoot of 28.6 mV, an after potential of longer duration than A-cells, and relatively low SFF. Eight of 15 A-cells whose axons conducted at less than 10 m/s had action potentials of longer duration with a humped configuration; these were termed Ah-cells. They formed about 10% of cells whose axons conducted above 2.5 m/s. The soma action potential of A-cells was blocked by tetrodotoxin (TTX), but that of 6/11 C-cells was unaffected by TTX. Typically, A-cells showed strong delayed (outward) rectification on passage of depolarizing current through the soma membrane and time-dependent (inward) rectification on inward current passage. Input resistance was thus highly sensitive to membrane potential close to rest. In C-cells, delayed rectification was not marked, and slight time-dependent rectification occurred in only 3 of 25 cells; I/V curves were normally linear over the range: resting potential to 40 mV more negative. Data on Ah-cells were incomplete, but in our sample of eight cells time-dependent rectification was absent or mild. C-cells had a higher input resistance and a higher neuronal capacitance than A-cells. In a proportion of A-cells, RN was low at resting potential (5 M omega) but increased as the membrane was hyperpolarized by a few millivolts. A-cells were depolarized by GABA but were normally unaffected by 5-HT or DMPP. C-cells were depolarized by GABA in a similar manner to A-cells but also responded strongly to 5-HT; 53/66 gave a depolarizing response, and 3/66, a hyperpolarizing response. Of C-cells, 75% gave a depolarizing response to DMPP.(ABSTRACT TRUNCATED AT 400 WORDS)

Sign in / Sign up

Export Citation Format

Share Document