scholarly journals Stimulation of Perforant Path Fibers Induces LTP Concurrently in Amygdala and Hippocampus in Awake Freely Behaving Rats

2013 ◽  
Vol 2013 ◽  
pp. 1-6 ◽  
Author(s):  
J. Harry Blaise ◽  
Rachel A. Hartman
Keyword(s):  
Learning And Memory ◽  
Basolateral Amygdala ◽  
Peak Level ◽  
Long Term Potentiation ◽  
Perforant Path ◽  
Sprague Dawley ◽  
Sprague Dawley Rats ◽  
Term Potentiation ◽  
Freely Behaving ◽  
Stimulation Of

Long-term potentiation (LTP) which has long been considered a cellular model for learning and memory is defined as a lasting enhancement in synaptic transmission efficacy. This cellular mechanism has been demonstrated reliably in the hippocampus and the amygdala—two limbic structures implicated in learning and memory. Earlier studies reported on the ability of cortical stimulation of the entorhinal cortex to induce LTP simultaneously in the two sites. However, to retain a stable baseline of comparison with the majority of the LTP literature, it is important to investigate the ability of fiber stimulation such as perforant path activation to induce LTP concurrently in both structures. Therefore, in this paper we report on concurrent LTP in the basolateral amygdala (BLA) and the dentate gyrus (DG) subfield of the hippocampus induced by theta burst stimulation of perforant path fibers in freely behaving Sprague-Dawley rats. Our results indicate that while perforant path-evoked potentials in both sites exhibit similar triphasic waveforms, the latency and amplitude of BLA responses were significantly shorter and smaller than those of DG. In addition, we observed no significant differences in either the peak level or the duration of LTP between DG and BLA.

scholarly journals Forepaw Sensorimotor Deprivation in Early Life Leads to the Impairments on Spatial Memory and Synaptic Plasticity in Rats

2009 ◽  
Vol 2009 ◽  
pp. 1-9 ◽  
Author(s):  
Yuanyuan Zhang ◽  
Fei Li ◽  
Xiaohua Cao ◽  
Xingming Jin ◽  
Chonghuai Yan ◽  
...  
Keyword(s):  
Synaptic Plasticity ◽  
Spatial Memory ◽  
Learning And Memory ◽  
Early Life ◽  
Hippocampal Slices ◽  
Long Term Potentiation ◽  
Perforant Path ◽  
Sprague Dawley ◽  
Cellular Mechanisms ◽  
Spatial Reference

To investigate the influence of forepaw sensorimotor deprivation on memory and synaptic plasticity, Sprague-Dawley rats were divided into two groups: a sham-operated group and a group deprived of forepaw sensorimotor function by microsurgical operation at postnatal day 13 (PN13). Behavioral and electrophysiological studies were performed at PN25, PN35, PN45, and PN60. Open field test was used to assess the spontaneous locomotor activity. Morris water maze was used to evaluate spatial reference learning and memory. The long-term potentiation (LTP) in the medial perforant path—dentate gyrus (MPP-DG) pathway was examined with hippocampal slices. We found that forepaw sensorimotor deprivation did not affect spontaneous activity of the rats. However, spatial reference learning and memory were significantly impaired in their early life (PN25, PN35, and PN45). In accordance with the behavior results, LTP in MPP-DG pathway was significantly suppressed in their early life. These data demonstrated that forepaw sensorimotor deprivation led to the impairments on spatial memory via inducing pronounced deficits in the MPP-DG pathway to exhibit LTP, one of the major cellular mechanisms underlying learning and memory.

scholarly journals GABAergic Transmission in the Basolateral Amygdala Differentially Modulates Plasticity in the Dentate Gyrus and the CA1 Areas

2020 ◽  
Vol 21 (11) ◽  
pp. 3786 ◽  
Author(s):  
Rose-Marie Vouimba ◽  
Rachel Anunu ◽  
Gal Richter-Levin
Keyword(s):  
Dentate Gyrus ◽  
Basolateral Amygdala ◽  
Long Term Potentiation ◽  
Brain Regions ◽  
Stressful Events ◽  
Perforant Path ◽  
Tetanic Stimulation ◽  
Gabaergic Neurotransmission ◽  
Hippocampal Commissure ◽  
Stimulation Of

The term “metaplasticity” is used to describe changes in synaptic plasticity sensitivity following an electrical, biochemical, or behavioral priming stimulus. For example, priming the basolateral amygdala (BLA) enhances long-term potentiation (LTP) in the dentate gyrus (DG) but decreases LTP in the CA1. However, the mechanisms underlying these metaplastic effects are only partly understood. Here, we examined whether the mechanism underlying these effects of BLA priming involves intra-BLA GABAergic neurotransmission. Low doses of muscimol, a GABAA receptor (GABAAR) agonist, were microinfused into the rat BLA before or after BLA priming. Our findings show that BLA GABAAR activation via muscimol mimicked the previously reported effects of electrical BLA priming on LTP in the perforant path and the ventral hippocampal commissure-CA1 pathways, decreasing CA1 LTP and increasing DG LTP. Furthermore, muscimol application before or after tetanic stimulation of the ventral hippocampal commissure-CA1 pathways attenuated the BLA priming-induced decrease in CA1 LTP. In contrast, muscimol application after tetanic stimulation of the perforant path attenuated the BLA priming-induced increase in DG LTP. The data indicate that GABAAR activation mediates metaplastic effects of the BLA on plasticity in the CA1 and the DG, but that the same GABAAR activation induces an intra-BLA form of metaplasticity, which alters the way BLA priming may modulate plasticity in other brain regions. These results emphasize the need for developing a dynamic model of BLA modulation of plasticity, a model that may better capture processes underlying memory alterations associated with emotional arousing or stressful events.

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.

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