Activity-Dependent Long-Term Depression of Electrical Synapses

Science ◽  
2011 ◽  
Vol 334 (6054) ◽  
pp. 389-393 ◽  
Author(s):  
J. S. Haas ◽  
B. Zavala ◽  
C. E. Landisman
Keyword(s):  
Long Term Depression ◽  
Electrical Synapses ◽  
Activity Dependent

scholarly journals Activity-dependent long-term potentiation of electrical synapses in the mammalian thalamus

2019 ◽  
Author(s):  
Brandon Fricker ◽  
Emily Heckman ◽  
Patrick C. Cunningham ◽  
Julie S. Haas
Keyword(s):  
Brain Area ◽  
Long Term Potentiation ◽  
Electrical Synapse ◽  
Thalamic Reticular Nucleus ◽  
Calcium Flux ◽  
Reticular Nucleus ◽  
Electrical Synapses ◽  
Term Potentiation ◽  
Activity Dependent

AbstractActivity-dependent changes of synapse strength have been extensively characterized at chemical synapses, but the relationship between physiological forms of activity and strength at electrical synapses remains poorly understood. For mammalian electrical synapses composed of hexomers of connexin36, physiological forms of neuronal activity in coupled pairs has thus far have only been linked to long-term depression; activity that results in strengthening of electrical synapses has not yet been identified. The thalamic reticular nucleus (TRN), a central brain area primarily connected by gap junctional (electrical) synapses, regulates cortical attention to the sensory surround. Bidirectional plasticity of electrical synapses may be a key mechanism underlying these processes in both healthy and diseased states. Here we show in electrically coupled TRN pairs that tonic spiking in one neuron results in long-term potentiation of electrical synapses between coupled pairs of TRN neurons. Potentiation is expressed asymmetrically, indicating that regulation of connectivity depends on the direction of use. Further, potentiation depends on calcium flux, and we thus propose a calcium-based activity rule for bidirectional plasticity of electrical synapse strength. Because electrical synapses dominate intra-TRN connectivity, these synapses and their modifications are key regulators of thalamic attention circuitry. More broadly, bidirectional modifications of electrical synapses are likely to be a widespread and powerful principle for ongoing, dynamic reorganization of neuronal circuitry across the brain.SummaryLong-term potentiation results from spiking in one cell of an electrically coupled pair. Asymmetry of synapses increases following unidirectional activity. We suggest a calcium-based rule for electrical synapse plasticity.

Long-Term Depression of Synaptic Inhibition Is Expressed Postsynaptically in the Developing Auditory System

2003 ◽  
Vol 90 (3) ◽  
pp. 1479-1488 ◽  
Author(s):  
Eric H. Chang ◽  
Vibhakar C. Kotak ◽  
Dan H. Sanes
Keyword(s):  
Release Kinetics ◽  
Mean Amplitude ◽  
Ruthenium Red ◽  
Synapse Elimination ◽  
Long Term Depression ◽  
Medial Nucleus ◽  
Auditory Brain Stem ◽  
Pulse Ratio ◽  
Activity Dependent

Inhibitory transmission is critically involved in the functional maturation of neural circuits within the brain. However, the mechanisms involved in its plasticity and development remain poorly understood. At an inhibitory synapse of the developing auditory brain stem, we used whole cell recordings to determine the site of induction and expression of long-term depression (LTD), a robust activity-dependent phenomenon that decreases inhibitory synaptic gain and is postulated to underlie synapse elimination. Recordings were obtained from lateral superior olivary (LSO) neurons, and hyperpolarizing inhibitory potentials were evoked by stimulation of the medial nucleus of the trapezoid body (MNTB). Both postsynaptic glycine and GABAA receptors could independently display LTD when isolated pharmacologically. Focal application of GABA, but not glycine, on the postsynaptic LSO neuron was sufficient to induce depression of the amino acid–evoked response, or MNTB-evoked inhibitory postsynaptic potentials. This GABA-mediated depression, in the absence of MNTB stimulation, was blocked by a GABAB receptor antagonist. To assess whether a change in neurotransmitter release is associated with the LTD, the polyvalent cation, ruthenium red, was used to increase the frequency of miniature inhibitory synaptic events. Consistent with a postsynaptic locus of expression, we found that the mean amplitude of miniature events decreased after LTD with no change in their frequency of occurrence. Furthermore, there was no change in the paired-pulse ratio or release kinetics of evoked inhibitory responses. Together, these results provide direct evidence that activity-dependent LTD of inhibition has a postsynaptic locus of induction and alteration, and that GABA but not glycine plays a pivotal role.

Evidence for common expression mechanisms underlying heterosynaptic and associative long-term depression in the dentate gyrus

1995 ◽  
Vol 74 (3) ◽  
pp. 1244-1247 ◽  
Author(s):  
B. R. Christie ◽  
D. Stellwagen ◽  
W. C. Abraham
Keyword(s):  
Dentate Gyrus ◽  
High Frequency ◽  
Granule Cells ◽  
Perforant Path ◽  
Long Term Depression ◽  
Anesthetized Rats ◽  
Data Support ◽  
Activity Dependent ◽  
Stimulation Of

1. The extent to which heterosynaptic and prime-associative stimulation protocols generate different forms of long-term depression (LTD) was assessed in the lateral perforant path synapses terminating on dentate gyrus granule cells in pentobarbital-anesthetized rats. 2. Heterosynaptic LTD was induced in the lateral path by repeated tetanization of the medial path. Prime-associative LTD of the lateral path was induced by alternating high-frequency conditioning trains to the medial path and single shocks to the lateral path at 100-ms intervals, all occurring 10 min after priming stimulation of the lateral path (5 Hz, 80 pulses). 3. Induction of LTD by one administration of the prime-associative protocol was normally greater in magnitude than the LTD induced by the heterosynaptic protocol. Saturation of LTD by repeated delivery of the prime-associative protocol completely occluded the subsequent induction of LTD by the heterosynaptic protocol. Saturation of LTD by repeated delivery of the heterosynaptic protocol produced an 80% occlusion of the LTD generated by the prime-associative protocol. 4. These data support the hypothesis that activity-dependent (associative) and activity-independent (heterosynaptic) LTD involve overlapping expression mechanisms, despite having demonstrably different induction mechanisms.

scholarly journals Activity-dependent long-term potentiation of electrical synapses in the mammalian thalamus

2020 ◽  
Author(s):  
Brandon Alexander Fricker ◽  
Emily Lauren Heckman ◽  
Patrick C Cunningham ◽  
Huaixing Wang ◽  
Julie S Haas
Keyword(s):  
Brain Area ◽  
Long Term Potentiation ◽  
Electrical Synapse ◽  
Thalamic Reticular Nucleus ◽  
Calcium Flux ◽  
Reticular Nucleus ◽  
Electrical Synapses ◽  
Term Potentiation ◽  
Activity Dependent

Activity-dependent changes of synapse strength have been extensively characterized at chemical synapses, but the relationship between physiological forms of activity and strength at electrical synapses remains poorly characterized and understood. For mammalian electrical synapses comprising hexamers of connexin36, physiological forms of neuronal activity in coupled pairs have thus far only been linked to long-term depression; activity that results in strengthening of electrical synapses has not yet been identified. The thalamic reticular nucleus (TRN), a central brain area primarily interconnected by electrical synapses, regulates cortical input from and attention to the sensory surround. Here, we show in electrically coupled TRN pairs that tonic spiking in one neuron results in long-term potentiation of electrical synapses with a magnitude of plasticity that alters the functionality of the synapse. Potentiation is expressed asymmetrically, indicating that regulation of connectivity depends on the direction of use. Further, potentiation depends on calcium flux, and we thus propose a calcium-based activity rule for bidirectional plasticity of electrical synapse strength. Because electrical synapses dominate intra-TRN connectivity, these synapses and their activity-dependent modifications are key dynamic regulators of thalamic attention circuitry. More broadly, we speculate that bidirectional modifications of electrical synapses may be a widespread and powerful principle for ongoing, dynamic reorganization of neuronal circuitry across the brain.

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