Heterosynaptic LTD and Depotentiation in the Medial Perforant Path of the Dentate Gyrus in the Freely Moving Rat

1997 ◽  
Vol 77 (2) ◽  
pp. 571-578 ◽  
Author(s):  
Valérie Doyère ◽  
Bolek Srebro ◽  
Serge Laroche
Keyword(s):  
Dentate Gyrus ◽  
High Frequency ◽  
Long Term Potentiation ◽  
Perforant Path ◽  
High Frequency Stimulation ◽  
Tetanic Stimulation ◽  
Frequency Stimulation ◽  
Freely Moving ◽  
Stimulation Of

Doyère, Valérie, Bolek Srebro, and Serge Laroche. Heterosynaptic LTD and depotentiation in the medial perforant path of the dentate gyrus in the freely moving rat. J. Neurophysiol. 77: 571–578, 1997. We examined the characteristics of heterosynaptic long-term depression (LTD) and depotentiation of previously established long-term potentiation (LTP) in the medial and lateral entorhinal afferents to the dentate gyrus in the awake rat. Rats were prepared for chronic recording of dentate gyrus evoked potentials to activation of the medial and lateral perforant paths. This study in awake rats confirms that heterosynaptic LTD can be induced at inactive medial perforant path synapses in conjunction with the induction of LTP produced by high-frequency stimulation of the lateral perforant path. This form of LTD was long lasting and reversible by tetanic stimulation delivered to the depressed pathway. In contrast, tetanic stimulation of the medial perforant path had only a small heterosynaptic effect on the lateral pathway, suggesting that the two input pathways to the dentate gyrus are not symmetrical in their ability to induce heterosynaptic LTD. We also examined the ability of high-frequency stimulation of one pathway to produce depotentiation of the other pathway. We found that when LTP was first induced in the medial perforant path, depotentiation was induced heterosynaptically by tetanization of the lateral pathway. Both newly established LTP (30 min) and LTP induced and saturated by repeated tetanic stimulation over several days can be depotentiated heterosynaptically. Moreover, depotentiation of the medial perforant path synapses was found to be linearly correlated with the magnitude of LTP induced in the lateral perforant path synapses, and subsequent tetanic stimulation of the depotentiated medial perforant path restored LTP to an extent that counterbalanced depotentiation. The saturation and repotentiation experiments provide clear support for the conclusion that the rapid reversal of LTP reflects true depotentiation of the medial input. Again, as with heterosynaptic LTD, tetanization of the medial perforant path had little effect on previously induced LTP in the lateral path. These results provide evidence that medial perforant path synapses can be depressed and depotentiated heterosynaptically. They suggest that in the intact rat synaptic changes in the afferents to the dentate gyrus from the lateral entorhinal cortex exert powerful control over ongoing or recent synaptic plasticity in the medial entorhinal afferents.

Low-frequency stimulation of the perforant path produces long-term potentiation in the dentate gyrus of unanesthetized rats

1983 ◽  
Vol 61 (10) ◽  
pp. 1156-1161 ◽  
Author(s):  
R. W. Skelton ◽  
J. J. Miller ◽  
A. G. Phillips
Keyword(s):  
Dentate Gyrus ◽  
Low Frequency ◽  
Long Term Potentiation ◽  
Perforant Path ◽  
High Frequency Stimulation ◽  
Synaptic Efficacy ◽  
Term Potentiation ◽  
Frequency Stimulation ◽  
Stimulation Of

Brief periods of high-frequency stimulation of hippocampal afferents produce long-term potentiation (LTP) of synaptic transmission, but the minimum frequency capable of inducing this alteration in synaptic efficacy has not been specified. The present study used the repeated measurement of input–output curves in the perforant path – dentate gyrus system of freely moving rats to monitor synaptic efficacy and found that stimulation at 0.2 Hz, but not 0.04 Hz produced LTP. These results suggest that the minimum stimulation frequency capable of producing LTP is lower than previously described. Possible reasons for the discrepancy between the present and previous findings are discussed, along with the implications of low-frequency potentiation.

Medial amygdala enhances synaptic transmission and synaptic plasticity in the dentate gyrus of rats in vivo

1995 ◽  
Vol 74 (5) ◽  
pp. 2201-2203 ◽  
Author(s):  
Y. Ikegaya ◽  
K. Abe ◽  
H. Saito ◽  
N. Nishiyama
Keyword(s):  
Synaptic Plasticity ◽  
Synaptic Transmission ◽  
Dentate Gyrus ◽  
High Frequency ◽  
Long Term Potentiation ◽  
Perforant Path ◽  
High Frequency Stimulation ◽  
Medial Amygdala ◽  
Frequency Stimulation ◽  
Stimulation Of

1. The present experiment was designed to test whether synaptic transmission and synaptic plasticity in the dentate gyrus were modulated by the medial amygdala (MeA). Field potentials in the dentate gyrus (DG) evoked by stimulations of the medial perforant path (PP) were extracellularly recorded in anesthetized rats. 2. Although single-pulse stimulation of the MeA augmented PP stimulation-evoked population spike amplitude in the DG transiently, high-frequency stimulation (100 Hz for 1 s) of the MeA induced long-lasting enhancement of synaptic transmission that was not occluded by PP tetanus-induced long-term potentiation (LTP). 3. When high-frequency stimulation of the MeA was applied concurrently with weak tetanus of the PP, which alone induced only marginal LTP, the magnitude of LTP increased considerably. 4. These results demonstrate that neuron activities in the MeA induce short- and long-lasting changes in the excitability of the PP-DG synapses and thereby enhance their synaptic plasticity.

Electrical high-frequency stimulation of the human thoracolumbar fascia evokes long-term potentiation-like pain amplification

Pain ◽  
2016 ◽  
Vol 157 (10) ◽  
pp. 2309-2317 ◽  
Author(s):  
Andreas Schilder ◽  
Walter Magerl ◽  
Ulrich Hoheisel ◽  
Thomas Klein ◽  
Rolf-Detlef Treede
Keyword(s):  
High Frequency ◽  
Long Term Potentiation ◽  
High Frequency Stimulation ◽  
Thoracolumbar Fascia ◽  
Term Potentiation ◽  
Frequency Stimulation ◽  
Stimulation Of

“Heterosynaptic” LTD in the Dentate Gyrus of Anesthetized Rat Requires Homosynaptic Activity

2007 ◽  
Vol 98 (2) ◽  
pp. 1048-1051 ◽  
Author(s):  
Wickliffe C. Abraham ◽  
Barbara Logan ◽  
Amy Wolff ◽  
Lubica Benuskova
Keyword(s):  
Dentate Gyrus ◽  
High Frequency ◽  
Path Following ◽  
Spike Timing ◽  
Perforant Path ◽  
High Frequency Stimulation ◽  
Frequency Stimulation ◽  
Computational Properties

Heterosynaptic long-term depression (LTD) is conventionally defined as occurring at synapses that are inactive during a time when neighboring synapses are activated by high-frequency stimulation. A new model that combines computational properties of both the Bienenstock, Cooper and Munro model and spike timing-dependent plasticity, however, suggests that such LTD actually may require presynaptic activity in the depressed pathway. We tested experimentally whether presynaptic activity is in fact necessary for previously described heterosynaptic LTD in lateral perforant path synapses in the dentate gyrus of urethane-anesthetized rats. As predicted by the model, procaine infusion into the lateral path fibers, sufficient to transiently block neural activity in this pathway, prevented the induction of LTD in the lateral path following medial path high-frequency stimulation. These data indicate that the previously described heterosynaptic LTD in the dentate gyrus in vivo is actually a form of homosynaptic LTD, requiring presynaptic activity in the depressed pathway.

Robust Changes of Afferent-Induced Excitation in the Rat Spinal Dorsal Horn After Conditioning High-Frequency Stimulation

2000 ◽  
Vol 83 (4) ◽  
pp. 2412-2420 ◽  
Author(s):  
Hiroshi Ikeda ◽  
Tatsuya Asai ◽  
Kazuyuki Murase
Keyword(s):  
Dorsal Horn ◽  
High Frequency ◽  
Low Frequency ◽  
Single Pulse ◽  
High Frequency Stimulation ◽  
Neuronal Excitation ◽  
Low Frequency Stimulation ◽  
Frequency Stimulation ◽  
Stimulation Of

We investigated the neuronal plasticity in the spinal dorsal horn and its relationship with spinal inhibitory networks using an optical-imaging method that detects neuronal excitation. High-intensity single-pulse stimulation of the dorsal root activating both A and C fibers evoked an optical response in the lamina II (the substantia gelatinosa) of the dorsal horn in transverse slices of 12- to 25-day-old rat spinal cords stained with a voltage-sensitive dye, RH-482. The optical response, reflecting the net neuronal excitation along the slice-depth, was depressed by 28% for more than 1 h after a high-frequency conditioning stimulation of A fibers in the dorsal root (3 tetani of 100 Hz for 1 s with an interval of 10 s). The depression was not induced in a perfusion solution containing an NMDA antagonist,dl-2-amino-5-phosphonovaleric acid (AP5; 30 μM). In a solution containing the inhibitory amino acid antagonists bicuculline (1 μM) and strychnine (3 μM), and also in a low Cl−solution, the excitation evoked by the single-pulse stimulation was enhanced after the high-frequency stimulation by 31 and 18%, respectively. The enhanced response after conditioning was depotentiated by a low-frequency stimulation of A fibers (0.2–1 Hz for 10 min). Furthermore, once the low-frequency stimulation was applied, the high-frequency conditioning could not potentiate the excitation. Inhibitory transmissions thus regulate the mode of synaptic plasticity in the lamina II most likely at afferent terminals. The high-frequency conditioning elicits a long-term depression (LTD) of synaptic efficacy under a greater activity of inhibitory amino acids, but it results in a long-term potentiation (LTP) when inhibition is reduced. The low-frequency preconditioning inhibits the potentiation induction and maintenance by the high-frequency conditioning. These mechanisms might underlie robust changes of nociception, such as hypersensitivity after injury or inflammation and pain relief after electrical or cutaneous stimulation.

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