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A new measure for the strength of electrical synapses.

Haas JS - Front Cell Neurosci (2015)

Bottom Line: Electrical synapses are typically quantified by subthreshold measurements of coupling, which fall short in describing their impact on spiking activity in coupled neighbors.This method, also applicable to neurotransmitter-based synapses, communicates the considerable strength of electrical synapses.For electrical synapses measured in rodent slices of the thalamic reticular nucleus and in simple model neurons, spike timing is modulated by tens of ms by activity in a coupled neighbor.

View Article: PubMed Central - PubMed

Affiliation: Department of Biological Sciences, Lehigh University Bethlehem, PA, USA.

ABSTRACT
Electrical synapses, like chemical synapses, mediate intraneuronal communication. Electrical synapses are typically quantified by subthreshold measurements of coupling, which fall short in describing their impact on spiking activity in coupled neighbors. Here, we describe a novel measurement for electrical synapse strength that directly evaluates the effect of synaptically transmitted activity on spike timing. This method, also applicable to neurotransmitter-based synapses, communicates the considerable strength of electrical synapses. For electrical synapses measured in rodent slices of the thalamic reticular nucleus and in simple model neurons, spike timing is modulated by tens of ms by activity in a coupled neighbor.

No MeSH data available.


Related in: MedlinePlus

Measuring δL, latency modulation. (A) Spiking in one cell of a coupled pair (blue) in response to current pulses of increasing amplitude (lower, shown in gray). Scale bar 25 ms, 20 mV. The coupled cell was quiet and is not shown. (B) Spiking in the same cell (light blue) for the same current pulses as in (A) (lower, shown in gray), with the coupled neighbor also spiking (lower, shown in green). Responses from (A) are repeated, vertically offset for clarity (darker blue). (C) Latency of spiking in (A) (pulse alone) and (B) (pulse + GJ input) plotted against input amplitude. For peri-threshold inputs (100 pA) in this cell, δL, the percentage change in perithreshold spike latency, was 50%.
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Figure 2: Measuring δL, latency modulation. (A) Spiking in one cell of a coupled pair (blue) in response to current pulses of increasing amplitude (lower, shown in gray). Scale bar 25 ms, 20 mV. The coupled cell was quiet and is not shown. (B) Spiking in the same cell (light blue) for the same current pulses as in (A) (lower, shown in gray), with the coupled neighbor also spiking (lower, shown in green). Responses from (A) are repeated, vertically offset for clarity (darker blue). (C) Latency of spiking in (A) (pulse alone) and (B) (pulse + GJ input) plotted against input amplitude. For peri-threshold inputs (100 pA) in this cell, δL, the percentage change in perithreshold spike latency, was 50%.

Mentions: In all experiments, both cells were held near their resting voltage, at −70 mV. We used a set of 10 current steps with maximum amplitude of approximately 1 pA per MΩ of input resistance, delivered to one cell of a coupled pair through the recording electrode. Thus, for a cell of input resistance 250 MΩ, we delivered ten current pulses between 25 and 250 pA. We measured latency of spiking in that cell in two conditions: alone (Figure 2A), and with a suprathreshold input (~2× perithreshold) applied to the coupled neighbor (Figure 2B), driving it to spike before the first cell. Comparing the two sets of responses, we found that latency decreased when the synapse provided additional input (Figure 2C). We used this comparison to quantify the strength of the electrical synapse, for the smallest current step that consistently drove a spike in each cell. For the cell in Figure 2, the smallest input that reliably drove spiking was 100 pA; the cell did not spike for 75 pA of input without GJ input and δL was not calculable. Over 36 neurons, peri-threshold inputs were 93.5 ± 6.6 pA (mean ± SEM). This value was chosen for latency comparison in order to provide a realistic measurement of peri-threshold spike time modulation during synaptic input barrages in vivo.


A new measure for the strength of electrical synapses.

Haas JS - Front Cell Neurosci (2015)

Measuring δL, latency modulation. (A) Spiking in one cell of a coupled pair (blue) in response to current pulses of increasing amplitude (lower, shown in gray). Scale bar 25 ms, 20 mV. The coupled cell was quiet and is not shown. (B) Spiking in the same cell (light blue) for the same current pulses as in (A) (lower, shown in gray), with the coupled neighbor also spiking (lower, shown in green). Responses from (A) are repeated, vertically offset for clarity (darker blue). (C) Latency of spiking in (A) (pulse alone) and (B) (pulse + GJ input) plotted against input amplitude. For peri-threshold inputs (100 pA) in this cell, δL, the percentage change in perithreshold spike latency, was 50%.
© Copyright Policy
Related In: Results  -  Collection

License
Show All Figures
getmorefigures.php?uid=PMC4585165&req=5

Figure 2: Measuring δL, latency modulation. (A) Spiking in one cell of a coupled pair (blue) in response to current pulses of increasing amplitude (lower, shown in gray). Scale bar 25 ms, 20 mV. The coupled cell was quiet and is not shown. (B) Spiking in the same cell (light blue) for the same current pulses as in (A) (lower, shown in gray), with the coupled neighbor also spiking (lower, shown in green). Responses from (A) are repeated, vertically offset for clarity (darker blue). (C) Latency of spiking in (A) (pulse alone) and (B) (pulse + GJ input) plotted against input amplitude. For peri-threshold inputs (100 pA) in this cell, δL, the percentage change in perithreshold spike latency, was 50%.
Mentions: In all experiments, both cells were held near their resting voltage, at −70 mV. We used a set of 10 current steps with maximum amplitude of approximately 1 pA per MΩ of input resistance, delivered to one cell of a coupled pair through the recording electrode. Thus, for a cell of input resistance 250 MΩ, we delivered ten current pulses between 25 and 250 pA. We measured latency of spiking in that cell in two conditions: alone (Figure 2A), and with a suprathreshold input (~2× perithreshold) applied to the coupled neighbor (Figure 2B), driving it to spike before the first cell. Comparing the two sets of responses, we found that latency decreased when the synapse provided additional input (Figure 2C). We used this comparison to quantify the strength of the electrical synapse, for the smallest current step that consistently drove a spike in each cell. For the cell in Figure 2, the smallest input that reliably drove spiking was 100 pA; the cell did not spike for 75 pA of input without GJ input and δL was not calculable. Over 36 neurons, peri-threshold inputs were 93.5 ± 6.6 pA (mean ± SEM). This value was chosen for latency comparison in order to provide a realistic measurement of peri-threshold spike time modulation during synaptic input barrages in vivo.

Bottom Line: Electrical synapses are typically quantified by subthreshold measurements of coupling, which fall short in describing their impact on spiking activity in coupled neighbors.This method, also applicable to neurotransmitter-based synapses, communicates the considerable strength of electrical synapses.For electrical synapses measured in rodent slices of the thalamic reticular nucleus and in simple model neurons, spike timing is modulated by tens of ms by activity in a coupled neighbor.

View Article: PubMed Central - PubMed

Affiliation: Department of Biological Sciences, Lehigh University Bethlehem, PA, USA.

ABSTRACT
Electrical synapses, like chemical synapses, mediate intraneuronal communication. Electrical synapses are typically quantified by subthreshold measurements of coupling, which fall short in describing their impact on spiking activity in coupled neighbors. Here, we describe a novel measurement for electrical synapse strength that directly evaluates the effect of synaptically transmitted activity on spike timing. This method, also applicable to neurotransmitter-based synapses, communicates the considerable strength of electrical synapses. For electrical synapses measured in rodent slices of the thalamic reticular nucleus and in simple model neurons, spike timing is modulated by tens of ms by activity in a coupled neighbor.

No MeSH data available.


Related in: MedlinePlus