Questions related to Synaptic Plasticity
I am performing some fEPSP recordings to study LTP on hippocampal slices. I am using a submerged chamber to maintain my hippocampal slices.
However, my baseline is very unstable, with constant fluctuations of fEPSP size (see figure attached). These changes are rather slow.. gradually oscillating from minimal to maximal values in 15-30 minutes.
Does anyone have ever experienced something similar? Do you know what can I do to solve this issue?
I don't think this is a problem with the stimulator electrode/box because it happens in both my two chambers and I also changed the stim box and the problem is still there..
Thank you for your feedback!
The brain remains dynamic even in old age and can benefit from mental exercise. Thus, it is important to understand the concepts of positive neuroplasticity and negative neuroplasticity and how these mechanisms support or decrease cognitive reserve.
Neural plasticity, also known as neuroplasticity or brain plasticity, can be defined as the ability of the nervous system to change its activity in response to intrinsic or extrinsic stimuli by reorganizing its structure, functions or connections. A fundamental property of neurons is their ability to alter the strength and efficiency of synaptic transmission through a large number of activity-dependent mechanisms, generally referred to as synaptic plasticity. Research over the past century has shown that neural plasticity is a fundamental property of the nervous system in species, from insects to humans. Indeed, studies on synaptic plasticity have not only been an important driver in neuroscience research, but they also contribute to the well-being of our societies because this phenomenon is involved in learning and memory, brain development and homeostasis, sensory training and recovery. brain damage. However, despite intense research into the mechanisms governing synaptic plasticity, it is still unclear exactly how plasticity shapes the morphology and physiology of the brain. Thus, the study of synaptic plasticity is clearly still important if one wishes to fully understand how the brain works.
I am currently doing a project on long term plasticity in the amygdala, particularly the BLA. As part of preparing for my own experiment, I have been looking at some of the recording techniques and stimulation paradigms that others have used to induce LTP there.
From my understanding, changes in EPSPs recorded in current clamp are one way that LTP can be quantified. What I'm confused about is that some papers say they use "current clamp", but are still fixing the voltage. For example, this paper
states in the methods
"Cells accepted for analysis had resting membrane potentials more negative than −60 mV.(The majority of neurons in lateral amygdala resemble pyramidal neurons [31, 35].) In most cases, cells were held at about −80 mV by DC current clamp to prevent action potentials, except during tetanization or pairing procedures."
I've always been told (and have read from multiple sources) that you only fix voltage in voltage clamp, whereas voltage is allowed to change freely in current clamp.
Could someone clarify what is going on here? Is this perhaps a recording convention that extends beyond LTP experiments? Many thanks in advance.
I am trying to study synaptic plasticity in hippocampus in urethane anesthetized rats (in vivo). Following are the coordinates recording electrode (Bregma −4.4, lateral 2.0–2.25, depth 2.0–2.7 mm), and the stimulation electrode (Bregma −3.4, lateral 2.5, depth 2–3 mm).
Is there any procedure to optimize the amplitude of the population spike. What are the factors to be considered for optimization.
In your experience, changes in the expression of which genes better represent synaptic growth and activity? I look for a marker of vesicular pool (quantity of synaptic vesicles, more precisely) and a marker of synaptic activity itself - whether the synapse is actively working or silent. I'm thinking about SV2, VAMP-associated proteins and synaptotagmin.
Do you have any suggestions?
P.S. Method - real-time PCR
Electroconvulsive therapy (ECT) as an established technique and technology in a variety of psychiatric and neurologic conditions may require reassessment with relevance to memory loss and brain damage. The therapeutic benefit of ECT will depend on heat stress induction and inactivation of the heat shock gene Sirtuin 1 (Sirt 1) with relevance to mitochondrial apoptosis and neuron death. ECT and neurostimulation in diabetes and neurodegenerative diseases should allow intact suprachiasmatic nucleus (SCN) function and activation to avoid sleep/ wake disturbances, heat shock response dysregulation and induction of circadian abnormalities. ECT technology should be used with caution (dose/frequency) in psychiatric individuals with synaptic plasticity defects with relevance to unhealthy diets and core body temperature dysregulation. ECT application may now involve plasma tests for various Sirt 1 regulated protein hormones with relevance to SCN function and circadian signals.
Electroconvulsive therapy; Mental disorders; Screening tests; Heat shock gene; Neurodegenerative diseases; Suprachiasmatic nucleus; Sirtuin 1; Diabetes; Circadian rhythm
REFERENCE: Electroconvulsive Therapy and Heat Shock Gene Inactivation in Neurodegenerative Diseases. Ann Neurodegener Dis 3(1): (2018). 1028.
Hi dear colleagues I need to record AMPA and NMDA currents of CA1 neurons in p21-p32 mice but I do not know what internal solution to prepare. There are papers that use CsCl, other Cs-Glu and other K-Gluc and differ in the use of QX314 (besides that they use different reactants). I really do not know what internal solution is better for this type of records and I am starting in the patch-clamp world. Also, is it possible that you can recommend a publication that supports the use of your internal solution? What care should I have when preparing the internal solution (ATP / GTP) and during the electrophysiological record? I appreciate your help very much
The latest antidepressant vortioxetine has a new mechanism of action that combines direct 5-HT receptor modulation and SERT inhibition. In fact it is a 5-HT3, 5-HT7 and 5-HT1D receptor antagonist, 5-HT1B receptor partial agonist, 5-HT1A receptor agonist and serotonin (5-HT) transporter (SERT) inhibitor. The result of this target profile seems to be the modulated control of neuronal activity in key areas of the brain involved in MDD but also the enhancing of synaptic plasticity and cognitive function.
Any clinical experience of effectiveness in the treatment of cognitive disorders?
I currently perform fEPSPs recordings in the stratum radiatum of dorsal CA1 while stimulating Schaffer collaterals in mouse hippocampal brain slices. I cut 300 micrometers thicks sections at 45 degrees angle from the coronal/sagittal plane, in order to preserve the fibers in the dorsal hippocampus. The cutting speed is 0.06 mm/s. I use cold choline for both cardiac perfusion and cutting and at 32 degrees for recovery (10 min). I then move them in normal aCSF.
Unfortunately, the amplitude of my fEPSPs is only as large as the fiber volley.
I am afraid that this is mainly due to the survival of my slices (from decapitation until the last slice it takes me more than 30 min) but I've been suggested also to use bicuculline to increase the excitatory events. Could this be helpfull?
Does anyone know of any intracellular solutions or methods for reducing or preventing LTP washout after going whole cell? Canoncial thinking suggests that after 5 minutes dyalisis of the cell resulting from the pippette solution starts to "washout" key molecular components of LTP. I would like to extend this time window if at all possible to give drugs in my pippette solution time to diffuse throughout as much of the cell as possible. Along with this, are there any studies that have measured the diffusion kinetics of drugs introduced into cells via patch pipettes? This would be in pyramidal neurons, area CA1. I'm sure people have done this with florescent labels etc. just not sure if the kinetics would be the same for a drug of interest.
Here we are working to get consistent results in rats hippocampal LTP in-vivo following some of the research articles. But we are facing some trouble shooting issues like we could able to find fEPSP and we could achieve steady state Population spike for at least 10 min.
And the problem is that we couldnt induce LTP with theta-burst of the Schaffer collateral pathway in every rat we tested where we could see only in 1 out of ten tested rats, so what could be the reason.
Can you use 4-AP to assess excitability in dendritic FIELD POTENTIAL recordings from medial perforant path to dentate granule cell pathway?
I am trying to assess excitability of MPP-DGC (medial perforant path-dentate granule cell) synapses and have 4-AP available in lab. I am already doing other field experiments animals and therefore cannot do whole-cell yet to answer this question. I was wondering if I could get some prelim data in the mean-time by getting a baseline field recording at MPP-DGG (1 stim, every 30 sec, 100us duration) and then apply 4-AP (100 uM) to assess changes in excitability when Kv channels are blocked.
Just need to know if I am even in the ballpark for assessing excitability at these synapses in each group.
I am already doing separate experiments with picrotoxin and therefore am already looking at inhibitory transmission in this regard.
Usually, quantal size and release probability were determined from the amplitude and frequency miniature EPSCs(mEPSC), I wonder why does NMDAR-mediated EPSCs by MK-801 can be used to examine basal release probability?And what is the mechanism?
We are working on acute hippocampal slice preparations for electrophysiological studies using MEAs' (P28 Wistar rats).
We are getting good viable slices with spontaneous and evoked signals.
We wish to know various drug testing protocols using acute hippocampal slice preparations for electrophysiological studies in view of increase in spike rate, amplitude, burst analysis, LTP, LTD etc.
Would you please share your expertise with any standardised drug testing protocols using MEAs'
Dr. Grandhi V Ramalingayya
Under a blue light stimulation on ChR2-expressed interneurons, which is not decided whether through a pre- or post- synaptic mechanism modulating the neurotransmission of a disynaptic transmission close to it, the first phase of the EPSC was reduced, and PPR was found increased compared to without the light stimulation on those interneurons.
I am looking for a genetic or pharmacological tool that allows me to block the occurrence of synaptic plasticity in a specific class of neurons. Any ideas? Thanks
is this theory right?
Pathway 1: the fast increase of intercellular [K+] produced by the spiking activity of the postsynaptic neuron.
Pathway 2: the slow production of a mediator (Glutamat) triggered by the synaptic activity.
I have read a lot of papers from neuroscience ... psychology ... Biological sciences... they talk about the roles of astrocytes in synaptic plasticity? Is there any evidence to consider astrocytes as the main player of plasticity not the neurons?..is it possible that the plasticity definition based on changing of astrocytic strength by synapses, as well as altering synaptic strength by asrtrocytes?
If, and eventually, when, the model of neural spikes and synaptic strengthening will be undermined and replaced by the Aur and Yog Neuro-Electro-Dynamics?
Are there new studies/experiments confirming the neural memory stimulus in the form of deformation and conformation of synaptic proteins, dendrites and axons under the influence of local electrical fields?
Aur and Yog pointed to the possibility of developing a new paradigm of memory stimuli reaching neural synaptic fields. These stimuli are in the form of distributions of micro-electric fields interacting with the local micro-fields of peptide chains constituting the protein structure of each neuron. Short- and long lasting deformation of these proteins may underlie of short- and long-term memory. This mechanism called Neuro-Electro-Dynamics, helps us browse processing sufficient amount of information in the process of pattern recognition, planning, decision making and other higher mental functions. This revolutionary hypothesis could be verified experimentally. However, it seems that it does not raise much interest of experimenters, which means that the neural spike model and synaptic strengthening continues to function as a current paradigm.
I am doing BLA LTP field potential measurements, and I use one time 100 Hz stimulation.
I guess I should leave it out, as this might affect the measurement, but it is also bad to just leave out data. What is the best solution?
Right now, I am doing transverse hippocampal slices. The acsf I use is: 11mM glucose; 120mM nacl; 26mM NaHCo3-; 3mM KCL; 1mM NH2PO4; 1.2 MgSo4; 2mM 147.01. I cut the slice in calcium free ACSF and put them in Ca containing acsf. I use mice 3-6 weeks old. The basal response I am getting is stable (at least for 30 minutes). I stimulate at 40% of maximum response. I stimulate from the schaffer collateral and record from the CA1 (not a population spike). The experiments are done in room temperature.
The problem is that I cannot induce a decent LTP. I've tried theta burst and multiple trains of high frequency protocols (100hz for 1second; 20 second intervals between trains). I only get 20% increases in fEPSP not like the huge 50% in papers. I also checked the protocols and they were correct.
Does anybody have any idea? This has been driving me crazy....
While working on acute hippocampal slice electrophysiology using non perforated MEAs, we have used self made grids using washer type (metal alloy rings) and cotton threading as mesh.We have used McILwain tissue chopper for making hippocampal slices. We are not getting the spontaneous activity at all.
Will the metal alloy have a great impact on recordings using MEAs? Please help us in using the grids for non perforated MEAs.
I am a very new user on IGOR and neuromatic and wish to know how one can do NSFA in there.
The biological question I am interested in is to estimate whether there is increase in AMPAR number or AMPAR conductivity that underlies the synaptic potentiation I am looking at in the hippocampus??
I have time dependent practical data of neuron system. This is a spiking data. I like to calculate synaptic weight with time between two neuron. I have input signal and output signal, which are experimentally measure with time. Any one can suggest that how i can calculate synaptic weight and is there any way that can tell me about synaptic plasticity?
Dear fellow researchers,
I just started doing field stimulation in the CA3 region of wild-type (WT) SVE129 mice (2-4 month old) to record long-term potentiation in the CA1 region. However, I have major problems seeing LTP in young sve129 mice slices. Instead of an instant excitatory postsynaptic potential (EPSP) elevation, which is maintained at least 30min (typical LTP), I see a slow incline over 5 to 10 min. I already tried to improve my slicing, double checked my solutions and changed batteries in the stimulator. I would be grateful for your help and advice how to fix it.
In our scenario, we let an Axon grow in Vitro over a distance of 500µm before it will find Dendrites to connect to.
How many Synapses are formed by that Axon when coming in contact with those Dendrites?
- The elapsed time will be 7 Days
- The Cells are embryonic Hippocampal cells from Rats
A second Question would be related: What would be the spatial spreading of the most distant Synapses?
I need to know this to solve a problem we have when connecting single Neurons to Clusters.
What could be the reason behind synaptic enhancement by altered testosterone levels? I found increased level of testosterone by pre-treating rats with Danazol alters the post synaptic calcium release which finally alter the plasticity of the synaptic neurons and increases the glutamate release in synapse. Is there any possible role of testosterone in learning and memory function?
Is there a way to interpret an increased frequency of mEPSC while both presynaptic vesicle number and dendritic spine density are decreased?
One of the most accepted theories for synaptic plasticity is STDP, but it fails when the frequency of neural firing is very high or very low, since it works in medium rates , my question is: is there any model for plasticity that consider more than one factor?
The redox signaling and the activation/nactivation of proteins by specific oxidation is a currently hot topic of research. Nox2 KO mice, resembling the human chronic granulomatous disorder, are available and present some plasticity modifications and mild cognitive decline in addition to the immune problems.
However, I was not able to find any pathways relating LTD and LTP to redox signaling cascades, with elucidation of the envolved pathways etc.
Do you know any work that has been done on this or anyone who is currently working with that?
Thanks for your time!
I am trying to understand how depolarisation induced with KCl or glutamate/ NMDA or any such stimuli leads to the balance of actin polymerization: actin depolymerization in neurons. Is it possible that actin depolymerization precedes actin polymerization as an immediate step post depolarization. How does it fit the spine dynamics post depolarization. This relates to temporal dynamics of actin organization in the neurons post depolarization. I think if actin depolymerization precedes polymerization for few minutes (30-1 hr) post depolarization it will help the spines to be flexible and let the movement of receptors and function of other spine machinery possible. It might also help to let the new dendritic mRNA and newly synthesized proteins to enter the spines and take their appropriate functions. Does this concept sound logical? Or are there other possibilities?
I am recording in vivo, from anaesthetised rats, trying to assess changes in synaptic plasticity or at least cortical excitability.
The logistics of these experiments requires that I use metal electrodes, which can be bent out of the way to have a clear skull surface for later stimulation via another method.
Currently I am stimulating primary motor (M1) cortex and recording contralateral M1. The necessity of bendable metal wires means I have had to rely on field excitatory postsynaptic potentials to measure any changes in excitability/efficacy.
My question is which component of the field response would be best to measure for cortical fEPSPs? I am measuring the initial slope, the second slope and the peak-to-peak amplitude.
Additionally, if anyone thinks this is a fools errand or has advice on another method (single unit perhaps?) I should pursue, I would be greatly appreciative. Cheers.
I have seen through publications that some labs have been routinaly able to induce very long-lasting in vitro LTD in young and adult animals. I would like to ask you if you can give me some details of the methods to achieve it.
I am trying to get LTD in my hippocampal slices from ~10 weeks old mice, but so far it has been almost impossible. I have been using both electrical stimulation (single 900 pulses at 1 Hz) or the application of mGluR2/3 agonist LY354740. I am stimulating the medial perforant path and recording fEPSPs in the dentate gyrus, at room temperature.
Does anybody have some advice to get stable LTD?
Thank you very much in advance for your contributions.
I am planning to perform a pharmacological study to assess hippocampal neurogenesis via IGF-1 receptor inhibitor. But most studies were performed in vitro or in vivo (systemic). So whether this inhibitor of IGF-1R (such as AG-1024 or picropodophyllin) can be intracranially injected by stereotaxic localization and what is the optimal dose? Thank you!
The question is based on the wide use of neuronal activity markers including Arc to dissect neuronal circuits activated in certain behavior or to certain stimuli. Does anyone have any idea of whether changes in these markers indicate changes in synaptic activity (i.e. short term or long term synaptic potentiation) or intrinsic neuronal activity (i.e. up-regulation of hyperpolarization-activated current, Ih)? Any litterature on this topic are welcome! :)
I am having trouble to replicate one of the main postulates about the expression of late LTP, concerning its dependence on de novo protein synthesis. I performe fEPSP recordings on the Schaffer collateral to CA1 synapse in rat hippocampal slices. Stimulate with 4xHFS (100 Hz, 1 sec), every five minutes. However, I cannot see an effect using anisomycin 30 µM on late LTP, even if I preincubate the slices in anisomycin for 2 hours before the experiment.
Villers et al. (PLoS One. 2012;7) already reported no effect of anisomycin or cycloheximide on late LTP. In this paper they argue that the protein-synthesis hypothesis for development of late LTP should be reconsidered.
What do you think? Do you have any idea about why these experiments are not working?
Thank you in advance for your help!
I am looking for a trans-synaptic anterograde tracer - does anyone know if wheat germ agglutinin conjugated to an alexa fluor is able to cross synapses?
I would like to do an in vivo injection into the ventral Hippocampus and expect to see labeling in the mPFC... I know that this is a distance, but I only truly need WGA to get to the second order neuron, so I feel like a viral system (such as HSV129) is overkill.
Has anyone tried WGA-fluor for a similar application? Thanks in advance!
I am treating dissociated hippocampal neurons at 10DIV with 30 uM glutamate and 1 uM glycine for 10 min before washout and the aim is to look at plasticity events (up/downregulation of receptors).
However, I am concerned that this treatment might lead to excitotoxicity and cell death although it is my impression from the litterature that excitotoxicity protocols usually use concentrations and treatment durations that are much higher/longer i.e. high uM to mM range and hours. What are your opinions on this? And if it is too harsh is there a better way to go?
Many thanks and best wishes,
Traditional golgi cox stain method can be used in brain tissue slice. However, I did not see in cell culture. Thus, does it need any modifications before applying to cell culture?
NOTE: This is a continuation from a previous post regarding the issue of fEPSP depression upon induction of LTP. (https://www.researchgate.net/post/Why_is_fEPSP_depressed_upon_induction_of_LTP)
I have an additional query with regards to this issue of fEPSP depression.
Sometimes, a 1st attempt at LTP leads to immediate fEPSP depression. However after some time, the fEPSP returns back to baseline, and I redo the I-O and successfully manage to induce LTP on this 2nd attempt on the same slice. Is LTP valid in this instance?
In another scenario, I manage to induce LTP on the 1st attempt, but I wait until it falls back to baseline, then I repulsed the slice with HFS for a 2nd LTP induction, which similarly exhibits robust LTP (that drops gradually just like the 1st LTP). Is this 2nd LTP induction also valid for inclusion?
I am aware that LTP induction leads to the synthesis of plasticity-related proteins, hence, I have a hypothesis that it is easier to re-induce LTP on slices that have successfully had a 1st LTP.
Here are also some additional queries I hope to seek for your help in.
- Should the electrodes be placed within stratum radiatum or stratum moleculare (as both have Schaffer Collaterals) in CA1? I was also told that both the recording and stimulating electrode should be on the same Schaffer Collateral pathway (but there's no way to confirm for that visually when lowering the electrodes onto the slices isn't it?)
- What is the physiological mechanism behind this LTP induction-induced fEPSP 'depression'? Discussions with my lab mates suggest either stimulation of inhibitory interneurons or overstimulation of glutaminergic neurons, but I don't find them convincing.
- Has anyone compared how the use of Morris ACSF (for slice recordings) vs Sucrose ACSF (protective cutting method with supposed better preservation of neurons, used in my lab only for patch clamping brain slices) would affect their findings?
I'am using a planar multielectrode array system to record field potentials in acute hippocampal slices. In particular I am trying to study synaptic plasticity, but I encountered several problems.
After having setted my baseline (30-50% of max), I start a protocol, usally 1 train of HFS ( 100hz in 1 second, duration 200 micr-second). After I , unfortunately, find out that LTP goes in rundown. Very often. It is very disappointing.
3 point more in the story:
1) without induction protocol my baseline seems stable for about 2 h.
2) I obtain some LTP with plateau or slow( acceptable) deacay. I mean, it seems that in some conditions ( but I don't konw why ) the induction protocol works.
3) My conditions : about 30 °C; 3,5-4 mil/min ( but often a little bit less beacuse lower flows seem to prolong slices viability); titanium electrodes (64 channels, interdistance 200 micromt. , diameter 30 micromt.) with standard chamber ( electrodes are placed on the bottom of chamber and the slice is over them, submerged, so could be some problems of oxigenations) ; amplifier 1060 series. (Multy channel system ); I use a light mesh to hold the slices and my solution is the same that has working for years for synaptic plasticity .
I hope that somebody could help me. In particular I refer to those people used my planar MEA system.
Thanks in advance
I am planing some experiments to study difference in basal synaptic transmission accross different animal conditions. I am thinking about producing a fiber volley vs fEPSP slope curve, but I haven't done this before.
Can anyone advise me for this exercise?
Regarding the x-axis of this putative curve, should I give fixed increasing steps for the stimulation intensity (for me this option seems easier) or should I try to find representative FV values (e.g. 0.05, 0.1, 0.15, 0.2, etc...; for me this option seems harder, since the FV size changes among preparations).
It would be great if you can help me.
It is said that dendritic spines can naturally occur among primary mouse neurons and their density or morphology can be thoroughly assayed. So can anybody provide any information?
At the moment we want to evaluate effect of some chemicals at synaptic level, but we wonder how valid such effect on cultured spines is, given that synapses need extra modulation in vivo.
Thanks a lot if you could help!
I want to perform a small intervention study with magnesium supplementation on cognitive functioning in patients with eating disorders. In addition to erythrocyte magnesium levels, I want to assess protein levels, epigenetic variation and gene expression levels of genes/pathways that are associated with magnesium.
Animal studies have shown that magnesium enhances synaptic plasticity and cognitive functioning through blocking the NMDA receptor, but this takes place in the brain. I can only get blood samples. Are there any relevant markers or variants that can be measured in blood for this process?
I'd be interested to know how subthreshold oscillations and noise of the inputs of a neuron are related. In particular, I would like to understand if there is some compensatory mechanism that may lead to neglect subthreshold oscillations with respect to the noise affecting synaptic inputs. This seems to me relevant to know in view of a simplified neuron model implementation for applications using very large spiking neural networks.
I am looking for a reliable and powerful compound to validate a positive effect enhancing LTP in Schaffer collateral-CA1 experiments (rat hippocampal slices).<br /><br />
I am performing both E-LTP (HFS 100 Hz, 20 stimulations) and L-LTP (4 times HFS 100 Hz, 100 stimulations) experiments at room temperature. However, so far I could not find a compound clearly increasing LTP. I have used nicotine 100 µM and an alpha 7 nAChR agonist. I put the compound half hour before HFS, and wash-out half hour after. However, the slices in presence of the compounds do not seem to be different from the controls.<br />
I am trying to find a suitable model to study certain questions.
A. Dynamics of molecular subcellular localisation under different conditions.
B. Calcium Dynamics.
To study these two objectives under live- imaging conditions, I would like to know which system will be better. Hippocampal organotypic slice cultures or hippcampal dissociated neuronal cultures from embryonic stage.
If hippocampal organotypic slice cultures are good model for these objectives, is it easy to observe such subcellular localisation dynamics of molecules under live imaging/ after PFA fixation and immunostaining in slice cultures. I am just doubtful because of the tangling and very close positioning of the neurites in the slices which might be a problem for analysis in slices if there is any change in subcellular localisation of the molecules after certain treatments.
Anyone with experience with this line of work, please help.
Good Afternoon, I’m doing in vivo electrophysiology in anesthetized mice. I’m recording evoked field excitatory postsynaptic potentials (fEPSP) in the CA1 stratum radiatum after the electrical stimulation of CA3 axons. Since I moved a couple of weeks ago to a new setup I’m experiencing a weird response. Basically, after setting the electrodes in the place where it is possible to find a clear evoked response, this response tends to decrease over the time without inducing any specific protocol (Recordings of 120 minutes; evoked response corresponds to 1 pulse each 15seconds). In this experiment I use Isoflurane (5% during induction, 1.5-1.25% during the recording, Iso delivered with compressed air at a rate of 1L/min). I use also concentric bipolar stimulation electrodes (I get a clear response with a minimal electrical artifact with an intensity of 300-500μA and duration of 20-40 μseconds). To record I use glass microelectrodes with a tip of 1-2 μm diameter filled with Pontamine sky blue in sodium acetate. Since this is a limitation to my work, I’m trying to find a possible explanation or issue in my procedure/setup. All the possible hints are very welcome. If you need more details I can send right away. Thank you very much.
I need help with some aspects the extracellular recordings. I use mouse hippocampal slices (350microm) and mainly my experiments consist of stimulating CA3 shaffer collaterals and record from dentrides of CA1 pyramidal neuron. I have a problem when I try to induce LTP in particular when i try to stabilize the signal for ten minutes for the baseline, sometimes the field potential continues to increase. I try to reduce the stimulation but in some slices there is no way to obtain a stable baseline, (increases or decreases in other cases). Do you think that the problem could be the stimulator? Or do you have some other suggestion? Thank you very much
According the effects of astrocyte in synaptic plasticity and neural function, it's not out of mind that astrocyte may play an important roles in formation and retrieval of spatial memory. But I’m looking for the related mechanism(s).I'll be appreciate who help me to finding my answer.
Tripartite synapse was studied and modeled by many researchers such as Pereira, Hydon, Nadkarni, and Postnov, but how is the network really structured?
What is the ratio of neurons to astrocytes in this network?
How do astrocytes connect with each other using connexins (Cx43,26,30)?
'Plastic' as defined, is a irreversible property of a material. One form once attained, can not come back to original form. On the contrary, synapses not only get Strengthen but also get weakened depending upon the processes going on.It means they are highly flexible system. So why do we use word Plastic to define this bidirectional property of synapses?
I am trying to validate LTP experiments in 7 weeks C57BL mice.
Hippocampal slices (400 µm). Measurements of the slope of the fEPSP (Schaffer collateral-CA1 synapse).
I am not sure about how well I am performing these experiments.
Maybe you could give me some feedback?
I attach a PDF where I show selected signals for 6 slices and the global result for the experiment.
Three of these slices (1, 2 and 5) were potentiated after 3 hours.. and the other 3 are almost back to baseline. Do you see anything wrong with the signals which can account for these inconsistencies?
In each slide, the signals in the top show selected examples of the input-output (the one in the right is the maximal response I got). I set the 30% of this maximal for the LTP experiment. Do you think they are overstimulated?
In the bottom line I show a selected example for the signal before HFS (control), just after HFS, and 1 and 3 hours after HFS.
Now, I am also trying experiments to get early LTP (using 20 stimulations instead of 100).. but after 1 hour the difference with the baseline is not significant. The problem is that if I try more stimulations... I use to have late LTP in many of the slices (I already tried 25, 30 and 50 stimulations).
ACFS composition (mM): D-glucose 10, NaHCO3 25.6, NaCl 124, KCl 2.45, KH2PO4 1.2, CaCl2 2.25 and MgSO4 1.2. Recordings are made at room temperature.
Thank you very much for your help!
PTP is normally considered to be dependent on pre-synaptic activity (result of calcium accumulation pre-synaptically as a result of the stimulation). How can the drug cause changes in PTP values in one protocol (200Hz LTP) while no change in another (theta burst LTP)? What does this mean? Please help me with this query. Thanks a lot in advance.
I am making coronal slices and stimulating at 30% of the maximum response of my field potential.
I got confused when reading the mechanism of Synaptic plasticity - (Glutamate neurotransmitter Physiological role) - necessary of learning & memory.
In some literature, they are telling that NMDA will get activated, leads to Ca2+ entry, which phophorylate the AMPA receptor. AMPA removes the Blackade of Mg2+ from NMDA & thus more NMDA will activated which multiplies the response - LTP - synaptic plasticity. As well as for the activation of AMPA, NMDA activation is must required.
While other material suggests that, During resting potential AMPA are in active stage while NMDA are blocked by Mg2+.
So can anybody suggest me the exact mechanism of synaptic plasticity???
According to the standard model of spike timing-dependent plasticity (STDP), when presynaptic spiking precedes postsynaptic spiking, the synapse undergoes potentiation, and when presynaptic spiking follows postsynaptic spiking, it undergoes depression.
Have people studied what is the effect of variability in the pre-post delay time? In other words, for the same mean pre-post delay, is a narrower delay distribution more effective in driving synaptic modification than a wider one? I would be mostly interested in experimental results, but theoretical studies would be welcome as well.
Thanks much in advance.
I'm a bit reluctant to toss this out there, but I could really use some insight. I have researched and found both quantitative and qualitative studies to support chemical and physical changes (increase in oxytocin, brain structural changes viewed by MRIs, for example) in both animals and humans during animal-assisted therapy and training, but I have yet to find any research that supports a possible relationship between HAB/AAT and cognition and memory.
My ultimate goal is to discover whether use of the HAB and AAT can positively increase brain plasticity, and use this form of teaching for elderly, and those who may have suffered brain injuries, to increase memory capabilities. I've included some of the references I've gathered, so far.
Insight, anyone? Thoughts?
I am performing fEPSP recordings (Schaffer collateral-CA1) in slices from rat hippocampus, and I find so much difference in the PPF ratio from one experiment to another. Why is that?
Sometimes I do not see PPF, or even a weak PPD. But normally my PPF ratio values range from 1.50 until 3.00, with a average of 1.87±0.05 (n = 80).
Moreover, in some of my experiments, after having a stable baseline, when I evoke PPF protocols, the baseline somehow starts to potentiate. Is this usual?
It is known that OGD supresses fEPSPs in CA1 region, and some reports demonstrated that presynaptic A1 (A2 or A3 in another way) and Ca++ flow regulation underlined this suppression. Intracellular signaling such as PKC was also suggested. Some researchers showed that the fEPSPs suppression is irreversible if OGD for more than 10 or 30 minutes (on acute brain slices). However, in my hand, fEPSPs still can be recovered to 60% of baseline level after 45 minutes OGD insult (completely recovered if it is 30 min OGD). Any opinion for this difference? In addition, some transgenic/mutant mice generated in our lab have shown either beneficial or deleterious effect, but I did not know much about the mechanisms that accounts for fEPSPs suppression. Can anyone provide advice?
I was wondering if anyone has any suggestions for antibodies that they have used to stain for glutamatergic cell bodies (and preferably not terminals) via IHC in tissue slices?
I'm doing in vivo electrophysiology (LTP protocol - 3 strains, 100Hz*1s) in CA3-CA1 synapses in mutant mice. In an electrophysiology experiment, sometimes (1 in 5 times) I fail to induce LTP in WT littermates and this results in considerable changes in my final results (when compared with the KO). Before changing the approach to induce LTP, I would really appreciate some feedback concerning this issue. How can I reliably exclude an animal? Is it valid to exclude a WT littermate that doesn't induce LTP by the protocol that I use?
Accumulating evidences indicated that synaptic plasticity underlies the mechanism of neuropathic pain. I want to use fluorescence stain and confocal microscope to separate the synapses undergoing plasticity from the ones not, so I need a tag of synaptic plasticity locating at the synapse. although I have done some research about this issue, but i do not decide which one should be choose .Do you think which one is reasonable?
F-actin(or the ratio of F-actin/G-actin);p-CaMKalpha/beta;the ratio of PSA-NCAM/NCAM;arc/arg3.1
Can temperature (especially high temperature) play a role in this phenomena of neurotransmitter binding, internalization or receptor dynamics?