Sint1 cell bodies are located on the medial dorsal surface just caudal to the prominent tentacular lobe that rises from the center of the pleural ganglion. 30-50 micron.
Sint1 branches in the pleural ganglion neuropil near the base of the optic lobe and projects to the ipsilateral pedal ganglion via the dorsal pleuralpedal connective, where it forms a series of arborizations.
A single sint2 is found near the dorsal midline of each pedal ganglion.
LY staining shows that sint2 branches in the pedal ganglion neuropil and sends a major process to the opposite pedal
ganglion via the circumesophageal, pedal-pedal connective.
sint1 can cause phase advance/delay.
There is reciprocal inhibition between left and right sint1 neurons, via direct IPSP.
sint1 innervates motoneurons.
sint1 and sint2 are electrically coupled.
Mutual inhibition between sint2 neurons.
Mutual inhibition between sint2 and the contralateral sint1
Activity in Sint1 and Sint2 dissociates during other locomotor behaviors.
the CPG for swimming is formed dynamically, when activity in the sint1 and sint2 cell pairs becomes bound together. When this does not occur, the same interneurons appear to function independently during the performance of other behaviors that involve the same or similar musculature, such as turning.
Thursday, December 4, 2008
Monday, November 24, 2008
Jing's CC9&10 paper (2008)
They generated rat antibody for 5-HT.
Briefly, the antigen was prepared by coupling 2 mg serotonin oxalate to 10 mg BSA (Sigma-Aldrich) in 1 ml of 50 mM NaH2PO4, pH 7.2, using 100 microL 16% paraformaldehyde (EMS). Followingovernight incubation at 4°C, coupled antigen was purified from the reaction using a Microcon-30 spinning at 13,800 x g for 30 min at 4°C. After washing the retentate four times with 0.4 ml of 50 mM NaH2PO4, it was resuspended in 0.5 ml of the same buffer and transferred to a new tube...
Tissues were fixed in 4% paraformaldehyde, 0.2% picric acid, 25% sucrose, and 0.1MNaH2PO4, pH 7.6, for either 3 h at room temperature or overnight at 4°C.
Washing buffer (WB; 2% Triton X-100, 1% BSA, 154 mM NaCl, 50 mM EDTA, 0.01% thimerosal, and 10mM Na2HPO4, pH 7.4).
Both the dorsal and the ventral surfaces of the cerebral ganglion were desheathed. The cerebral ganglion was then twisted at the commissure to make it possible to access CC9/10 on the dorsal surface and contralateral CBIs on the ventral surface.
Frequent IPSPs are observed simultaneously in both CC9/10 cells (Fig. 2B). Activation of one CC9/10 can induce polysynaptic inhibition in the other CC9/10 (Fig. 2C1).
CC9/10 responds to noxious stimulus by tonic firing.
CC9/10 firing evokes locomotion.
The locomotion can be seen very well from PPCN (para-pedal commissural nerve).
The frequency of the locomotory rhythm is different depending on whether you stimulated P9 or AT4 nerve.
The cycle frequency of locomotor activity reflects the firing frequency of CC9/10 activity.
CC9 and CC10 may act as locomotion initiators.
One function of CC9/10 is to provide excitation to serotonergic modulatory neurons of the pedal ganglion.
It enhances the induction of the locomotory response.
CC9/10 weakly excites contralateral MCC and CBI-2. MCC>CBI-2
CC9/10 increase excitability (?) of MCC, but this could be just because of depolarization.
CC9–10 are broadly activated and their responses are not site-specific.
Aplysia locomotes, and then eats.
The Journal of Neuroscience, November 19, 2008 • 28(47):12349 –12361
Neural Analog of Arousal: Persistent Conditional Activation of a Feeding Modulator by Serotonergic Initiators of Locomotion
Jian Jing, Ferdinand S. Vilim, Elizabeth C. Cropper, and Klaudiusz R. Weiss
Briefly, the antigen was prepared by coupling 2 mg serotonin oxalate to 10 mg BSA (Sigma-Aldrich) in 1 ml of 50 mM NaH2PO4, pH 7.2, using 100 microL 16% paraformaldehyde (EMS). Followingovernight incubation at 4°C, coupled antigen was purified from the reaction using a Microcon-30 spinning at 13,800 x g for 30 min at 4°C. After washing the retentate four times with 0.4 ml of 50 mM NaH2PO4, it was resuspended in 0.5 ml of the same buffer and transferred to a new tube...
Tissues were fixed in 4% paraformaldehyde, 0.2% picric acid, 25% sucrose, and 0.1MNaH2PO4, pH 7.6, for either 3 h at room temperature or overnight at 4°C.
Washing buffer (WB; 2% Triton X-100, 1% BSA, 154 mM NaCl, 50 mM EDTA, 0.01% thimerosal, and 10mM Na2HPO4, pH 7.4).
Both the dorsal and the ventral surfaces of the cerebral ganglion were desheathed. The cerebral ganglion was then twisted at the commissure to make it possible to access CC9/10 on the dorsal surface and contralateral CBIs on the ventral surface.
Frequent IPSPs are observed simultaneously in both CC9/10 cells (Fig. 2B). Activation of one CC9/10 can induce polysynaptic inhibition in the other CC9/10 (Fig. 2C1).
CC9/10 responds to noxious stimulus by tonic firing.
CC9/10 firing evokes locomotion.
The locomotion can be seen very well from PPCN (para-pedal commissural nerve).
The frequency of the locomotory rhythm is different depending on whether you stimulated P9 or AT4 nerve.
The cycle frequency of locomotor activity reflects the firing frequency of CC9/10 activity.
CC9 and CC10 may act as locomotion initiators.
One function of CC9/10 is to provide excitation to serotonergic modulatory neurons of the pedal ganglion.
It enhances the induction of the locomotory response.
CC9/10 weakly excites contralateral MCC and CBI-2. MCC>CBI-2
CC9/10 increase excitability (?) of MCC, but this could be just because of depolarization.
CC9–10 are broadly activated and their responses are not site-specific.
Aplysia locomotes, and then eats.
The Journal of Neuroscience, November 19, 2008 • 28(47):12349 –12361
Neural Analog of Arousal: Persistent Conditional Activation of a Feeding Modulator by Serotonergic Initiators of Locomotion
Jian Jing, Ferdinand S. Vilim, Elizabeth C. Cropper, and Klaudiusz R. Weiss
Xue-Ying Jiang and Tom Abrams' paper (1998)
The first EPSP and the second EPSP in a paired pulse are evoked at distinct loci.
Paired-pulse ratio decreases with repeated testing.
Paired-pulse ratio depends on the size of the initial EPSP size.
The second EPSP size does not do much in determining the PPR.
The decrease in PPR is independent from synaptic depression.
The decrease of PPR occurs even without the depression of the 1st EPSP.
The decrease of PPR develops much faster than the depression of the 1st EPSP.
The PPR is not affected by the depression of the 1st EPSP.
Depresssion reduces EPSP2 along with EPSP1
Does synaptic depression change large synapses into small synapses?
No, they are different.
The paired pulse ratio is independent from the initial synaptic strength.
Use-dependent plasticity of paired-pulse facilitation provides evidence that a separate set of release sites contributes to EPSP2
A dramatic reduction in the 2nd EPSP after a single paired-pulse trial, when there was minimal change in the first.
Post-tetanic potentiation persists through repeated testing
Facilitation is not simply a modest form of PTP.
Interaction of serotonin-induced facilitation with the paired-pulse ratio
Serotonin-induced facilitation persisted only in the 1st EPSP. The 2nd EPSP shows a transient increase.
Contribution of Ca2+ and phosphorylation to paired-pulse facilitation
Facilitation is Ca dependent, but not phosphatase-dependent.
Paired-pulse ratio decreases with repeated testing.
Paired-pulse ratio depends on the size of the initial EPSP size.
The second EPSP size does not do much in determining the PPR.
The decrease in PPR is independent from synaptic depression.
The decrease of PPR occurs even without the depression of the 1st EPSP.
The decrease of PPR develops much faster than the depression of the 1st EPSP.
The PPR is not affected by the depression of the 1st EPSP.
Depresssion reduces EPSP2 along with EPSP1
Does synaptic depression change large synapses into small synapses?
No, they are different.
The paired pulse ratio is independent from the initial synaptic strength.
Use-dependent plasticity of paired-pulse facilitation provides evidence that a separate set of release sites contributes to EPSP2
A dramatic reduction in the 2nd EPSP after a single paired-pulse trial, when there was minimal change in the first.
Post-tetanic potentiation persists through repeated testing
Facilitation is not simply a modest form of PTP.
Interaction of serotonin-induced facilitation with the paired-pulse ratio
Serotonin-induced facilitation persisted only in the 1st EPSP. The 2nd EPSP shows a transient increase.
Contribution of Ca2+ and phosphorylation to paired-pulse facilitation
Facilitation is Ca dependent, but not phosphatase-dependent.
Shakiryanova's vesicle mobility paper (2007)
It has been postulated that vesicle mobility is increased to enhance release of transmitters, its mechanism was unknown.
Ryanodine receptor mediated Ca2+-induced Ca2+ release from ER is necessary for the sustained DCV mobilization.
This RyR-receptor mediated release is short-lived, and triggers activation of CaMKII as a downstream activator.
ryanodine (high purity) and other chemicals were purchased from Calbiochem.
4-bromo-clacimycin is a Ca2+ ionophore.
cytosolic calcium sensor, Cameleon 2.1.
CaMKII activity can be blocked by a membrane-permiable version of AIP-II (Antennapedia peptide fused).
veratridine, a sodium channel opener (that results in an increase of intracellular Ca2+).
Ryanodine receptor mediated Ca2+-induced Ca2+ release from ER is necessary for the sustained DCV mobilization.
This RyR-receptor mediated release is short-lived, and triggers activation of CaMKII as a downstream activator.
ryanodine (high purity) and other chemicals were purchased from Calbiochem.
4-bromo-clacimycin is a Ca2+ ionophore.
cytosolic calcium sensor, Cameleon 2.1.
CaMKII activity can be blocked by a membrane-permiable version of AIP-II (Antennapedia peptide fused).
veratridine, a sodium channel opener (that results in an increase of intracellular Ca2+).
Two serotonin blockers in Aplysia
cinanserin, methiothepin, cyproheptadine, spiperone.
10 mM 5-HT stock solutions were made in 0.1 M acetic acid solutions and stored at 4℃.
methiothepine blocked AC-coupled 5-HT receptors.
spiperone (100microM) blocks PKC-dependent modulatory effects of 5-HT, which is the facilitation from the depressed synapse.
spiperone is a selective antagonist of PLC-coupled 5-HT receptors in Aplysia.
Staurosporine is the PKC blocker.
Serotonin Receptor Antagonists Discriminate Between PKA- and PKC-Mediated Plasticity in Aplysia Sensory Neurons
Bogdan Dumitriu, Jonathan E. Cohen, Qin Wan, Andreea M. Negroiu and Thomas W. Abrams
J Neurophysiol 95: 2713-2720, 2006. First published October 19, 2005; doi:10.1152/jn.00642.2005
10 mM 5-HT stock solutions were made in 0.1 M acetic acid solutions and stored at 4℃.
methiothepine blocked AC-coupled 5-HT receptors.
spiperone (100microM) blocks PKC-dependent modulatory effects of 5-HT, which is the facilitation from the depressed synapse.
spiperone is a selective antagonist of PLC-coupled 5-HT receptors in Aplysia.
Staurosporine is the PKC blocker.
Serotonin Receptor Antagonists Discriminate Between PKA- and PKC-Mediated Plasticity in Aplysia Sensory Neurons
Bogdan Dumitriu, Jonathan E. Cohen, Qin Wan, Andreea M. Negroiu and Thomas W. Abrams
J Neurophysiol 95: 2713-2720, 2006. First published October 19, 2005; doi:10.1152/jn.00642.2005
Thursday, November 20, 2008
Quantal release of transmitter
The amount of quantal release is determined by both the number of available synaptic vesicles as well as by the probability that an available vesicle is released.
EPSCs can be described as the product of the number of available vesicles (n), release probability of each quanta (Pr) and size of the quantal unit q (mEPSC size):
EPSC = n·Pr·q
If N is the number of release sites (= maximum number of available vesicles), and Pa is the number of available vesicles.
n = N·Pa
EPSC = N·Pa·Po·q
This is the release-site model (Vere-Jones, 1966), assuming that the number of release site is limited.
The value q can be determined by recording mEPSC, sustaining presynaptic neuron depolarized, or stimulating the presynaptic neuron in low-Ca saline.
N can be estimated by giving a depleting stimulus. N is dependent on active zone constituents and mechanisms of vesicle recycling.
EPSCs can be described as the product of the number of available vesicles (n), release probability of each quanta (Pr) and size of the quantal unit q (mEPSC size):
EPSC = n·Pr·q
If N is the number of release sites (= maximum number of available vesicles), and Pa is the number of available vesicles.
n = N·Pa
EPSC = N·Pa·Po·q
This is the release-site model (Vere-Jones, 1966), assuming that the number of release site is limited.
The value q can be determined by recording mEPSC, sustaining presynaptic neuron depolarized, or stimulating the presynaptic neuron in low-Ca saline.
N can be estimated by giving a depleting stimulus. N is dependent on active zone constituents and mechanisms of vesicle recycling.
Wednesday, September 17, 2008
A ground wire
There was an argument about the ground wire used in electrophysiological recordings.
Of course, the surface area of the ground wire should be as large as possible:
1) To minimize the junctional resistance between the electrode and the saline.
2) To let it last longer.
AgCl2 coatings on the larger ground wires last longer because of its lower current density at the surface. The ground becomes more stable with increased surface area.
Remember, the ground wire works as a current sink. It sucks up all current you apply through the microelectrodes, including those generated by zapping and by the capacitance compensation.
3) The AgC2 layer is very thin on those pellets purchased. It will go away soon after a heavy usage such as the current - and voltage-clamping.
To avoid it, one has to chloride it. Then the AgCl2 layer often gets too thick because of limited surface area.
When the AgCl2 layer gets too thick, it becomes very fragile and often flakes off by a shock, or accidentally touching it with forceps. This is why I don't like those purchased pellets.
4) The silver pellet on the market with a ridiculous price is basically a rip-off. That't the other reason why I hate it.
Of course, the surface area of the ground wire should be as large as possible:
1) To minimize the junctional resistance between the electrode and the saline.
2) To let it last longer.
AgCl2 coatings on the larger ground wires last longer because of its lower current density at the surface. The ground becomes more stable with increased surface area.
Remember, the ground wire works as a current sink. It sucks up all current you apply through the microelectrodes, including those generated by zapping and by the capacitance compensation.
3) The AgC2 layer is very thin on those pellets purchased. It will go away soon after a heavy usage such as the current - and voltage-clamping.
To avoid it, one has to chloride it. Then the AgCl2 layer often gets too thick because of limited surface area.
When the AgCl2 layer gets too thick, it becomes very fragile and often flakes off by a shock, or accidentally touching it with forceps. This is why I don't like those purchased pellets.
4) The silver pellet on the market with a ridiculous price is basically a rip-off. That't the other reason why I hate it.
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