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Long-Term Potentiation at CA3-CA1 Hippocampal Synapses with Special Emphasis on Aging, Disease, and Stress.

Kumar A - Front Aging Neurosci (2011)

Bottom Line: Synaptic plasticity in the mammalian central nervous system has been the subject of intense investigation for the past four decades.LTP is regarded as a principal candidate for the cellular mechanisms involved in learning and offers an attractive hypothesis of how memories are constructed.There are a number of exceptional full-length reviews published on LTP; the current review intends to present an overview of the research findings regarding hippocampal LTP with special emphasis on aging, diseases, and psychological insults.

View Article: PubMed Central - PubMed

Affiliation: Department of Neuroscience, McKnight Brain Institute, University of Florida Gainesville, FL, USA.

ABSTRACT
Synaptic plasticity in the mammalian central nervous system has been the subject of intense investigation for the past four decades. Long-term potentiation (LTP), a major reflection of synaptic plasticity, is an activity-driven long-lasting increase in the efficacy of excitatory synaptic transmission following the delivery of a brief, high-frequency train of electrical stimulation. LTP is regarded as a principal candidate for the cellular mechanisms involved in learning and offers an attractive hypothesis of how memories are constructed. There are a number of exceptional full-length reviews published on LTP; the current review intends to present an overview of the research findings regarding hippocampal LTP with special emphasis on aging, diseases, and psychological insults.

No MeSH data available.


Related in: MedlinePlus

Multiple episodes of theta burst stimulation (TBS) induced maximal LTP, which is of similar amplitude in young adult and aged rats. Illustration of individual excitatory postsynaptic potentials from aged (gray circle) and young adult (open circle) rats before (10 min) and after (60 min) the last episode of TBS. Bar diagram represents mean percentage change in the slope of synaptic responses during the last 10 min of recording, 60 min following the sixth TBS episode (adapted from Kumar et al., 2007).
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Figure 2: Multiple episodes of theta burst stimulation (TBS) induced maximal LTP, which is of similar amplitude in young adult and aged rats. Illustration of individual excitatory postsynaptic potentials from aged (gray circle) and young adult (open circle) rats before (10 min) and after (60 min) the last episode of TBS. Bar diagram represents mean percentage change in the slope of synaptic responses during the last 10 min of recording, 60 min following the sixth TBS episode (adapted from Kumar et al., 2007).

Mentions: In considering synaptic transmission during aging, it is important to note that the observed shift in synaptic modifiability is not due to a change in the expression mechanisms. For example, there is no age-related difference in the maximal LTP magnitude observed under conditions in which a strong burst of synaptic stimulation is delivered (Diana et al., 1994b; Norris et al., 1996; Shankar et al., 1998). In addition, significant LTP can be observed in aged animals when single pulses are combined with strong postsynaptic depolarization or weak stimulation is combined with increased Ca2+; our work, too, demonstrates that asymptotic LTP can be induced in aged animals by employing multiple episodes of TBS (Figure 2; Barnes et al., 1996; Watabe and O'Dell, 2003; Kumar et al., 2007). This suggests that signaling pathways for the induction of LTP are intact during senescence. In contrast, it has been shown that the threshold for LTP induction is increased in aged memory-impaired animals (Landfield et al., 1978; Deupree et al., 1993; Moore et al., 1993; Barnes et al., 1996; Norris et al., 1996; Foster and Kumar, 2007), due in part to impaired postsynaptic depolarization. Thus, during aging, there may be a shift in the mechanisms that regulate the induction (i.e., threshold) of synaptic plasticity rather than a loss of expression mechanisms (Kumar et al., 2007). This shift may favor synaptic weakening and could act as a functional lesion, reducing the ability for information to be transmitted through the hippocampus.


Long-Term Potentiation at CA3-CA1 Hippocampal Synapses with Special Emphasis on Aging, Disease, and Stress.

Kumar A - Front Aging Neurosci (2011)

Multiple episodes of theta burst stimulation (TBS) induced maximal LTP, which is of similar amplitude in young adult and aged rats. Illustration of individual excitatory postsynaptic potentials from aged (gray circle) and young adult (open circle) rats before (10 min) and after (60 min) the last episode of TBS. Bar diagram represents mean percentage change in the slope of synaptic responses during the last 10 min of recording, 60 min following the sixth TBS episode (adapted from Kumar et al., 2007).
© Copyright Policy - open-access
Related In: Results  -  Collection

License
Show All Figures
getmorefigures.php?uid=PMC3102214&req=5

Figure 2: Multiple episodes of theta burst stimulation (TBS) induced maximal LTP, which is of similar amplitude in young adult and aged rats. Illustration of individual excitatory postsynaptic potentials from aged (gray circle) and young adult (open circle) rats before (10 min) and after (60 min) the last episode of TBS. Bar diagram represents mean percentage change in the slope of synaptic responses during the last 10 min of recording, 60 min following the sixth TBS episode (adapted from Kumar et al., 2007).
Mentions: In considering synaptic transmission during aging, it is important to note that the observed shift in synaptic modifiability is not due to a change in the expression mechanisms. For example, there is no age-related difference in the maximal LTP magnitude observed under conditions in which a strong burst of synaptic stimulation is delivered (Diana et al., 1994b; Norris et al., 1996; Shankar et al., 1998). In addition, significant LTP can be observed in aged animals when single pulses are combined with strong postsynaptic depolarization or weak stimulation is combined with increased Ca2+; our work, too, demonstrates that asymptotic LTP can be induced in aged animals by employing multiple episodes of TBS (Figure 2; Barnes et al., 1996; Watabe and O'Dell, 2003; Kumar et al., 2007). This suggests that signaling pathways for the induction of LTP are intact during senescence. In contrast, it has been shown that the threshold for LTP induction is increased in aged memory-impaired animals (Landfield et al., 1978; Deupree et al., 1993; Moore et al., 1993; Barnes et al., 1996; Norris et al., 1996; Foster and Kumar, 2007), due in part to impaired postsynaptic depolarization. Thus, during aging, there may be a shift in the mechanisms that regulate the induction (i.e., threshold) of synaptic plasticity rather than a loss of expression mechanisms (Kumar et al., 2007). This shift may favor synaptic weakening and could act as a functional lesion, reducing the ability for information to be transmitted through the hippocampus.

Bottom Line: Synaptic plasticity in the mammalian central nervous system has been the subject of intense investigation for the past four decades.LTP is regarded as a principal candidate for the cellular mechanisms involved in learning and offers an attractive hypothesis of how memories are constructed.There are a number of exceptional full-length reviews published on LTP; the current review intends to present an overview of the research findings regarding hippocampal LTP with special emphasis on aging, diseases, and psychological insults.

View Article: PubMed Central - PubMed

Affiliation: Department of Neuroscience, McKnight Brain Institute, University of Florida Gainesville, FL, USA.

ABSTRACT
Synaptic plasticity in the mammalian central nervous system has been the subject of intense investigation for the past four decades. Long-term potentiation (LTP), a major reflection of synaptic plasticity, is an activity-driven long-lasting increase in the efficacy of excitatory synaptic transmission following the delivery of a brief, high-frequency train of electrical stimulation. LTP is regarded as a principal candidate for the cellular mechanisms involved in learning and offers an attractive hypothesis of how memories are constructed. There are a number of exceptional full-length reviews published on LTP; the current review intends to present an overview of the research findings regarding hippocampal LTP with special emphasis on aging, diseases, and psychological insults.

No MeSH data available.


Related in: MedlinePlus