Results: 5

1.
Figure 5

Figure 5. Staurosporine, which blocks LTP but not LTD, has no effect on the transition between LTP and LTD. From: An experimental test of the role of postsynaptic calcium levels in determining synaptic strength using perirhinal cortex of rat.

A, LTP, induced by depolarisation to -10 mV in the presence of 0.5 mm EGTA is blocked by staurosporine n = 3. B, LTD, induced by depolarisation to -10 mV in the presence of 10 mm EGTA is not blocked by staurosporine n = 3. C, the transition between LTP and LTD is unaffected by staurosporine n = 5. D, graph showing the results from the above experiments plotted together with the plasticity curve obtained from .

K Cho, et al. J Physiol. 2001 April 15;532(Pt 2):459-466.
2.
Figure 4

Figure 4. MCPG, which blocks LTD but not LTP, has no effect on the position of the transition between LTP and LTD. From: An experimental test of the role of postsynaptic calcium levels in determining synaptic strength using perirhinal cortex of rat.

A, LTP, induced by depolarisation to -10 mV in the presence of 0.5 mm EGTA, is not blocked by MCPG n = 3. B, LTD, which is normally induced by depolarisation to -10 mV in the presence of 10 mm EGTA, is blocked by MCPG n = 3. C, the transition between LTP and LTD, observed at -10 mV in the presence of 5 mm EGTA, is not affected by MCPG n = 3. D, graph showing the results from the above experiments plotted together with the plasticity curve obtained from .

K Cho, et al. J Physiol. 2001 April 15;532(Pt 2):459-466.
3.
Figure 2

Figure 2. Altering [EGTA] appropriately can result in LTP, no change, or LTD. From: An experimental test of the role of postsynaptic calcium levels in determining synaptic strength using perirhinal cortex of rat.

LFS delivered during depolarisation to -10 mV results in LTP in the presence of 0.5 mm EGTA n = 4 (A) but LTD in 10 mm EGTA n = 4 (B). C, changes in synaptic strength are completely prevented by the inclusion of 20 mm EGTA in the whole-cell solution n = 4. D, graph showing the effect of a range of different concentrations of EGTA on synaptic strength. *Significant difference from baseline (P < 0.05).

K Cho, et al. J Physiol. 2001 April 15;532(Pt 2):459-466.
4.
Figure 1

Figure 1. The magnitude of LTD is dependent on the activity-dependent increase in intracellular calcium. From: An experimental test of the role of postsynaptic calcium levels in determining synaptic strength using perirhinal cortex of rat.

A, LTD is not induced by pairing LFS with depolarisation to -40 mV when the filling solution contains 0.2 mm EGTA n = 4. B, however, LTD is induced with 2 mm EGTA in the filling solution n = 4. C, increasing EGTA to 5 mm reduces but does not prevent the induction of LTD n = 4. In this and subsequent figures the period of LFS is indicated by the arrows. Synaptic traces are the average of 4 consecutive responses from the time points indicated. D, graph illustrating the magnitude of LTD induced in the presence of each of the 5 different concentrations of EGTA: a U-shaped relationship exists between [EGTA] and LTD when LTD is induced at either -40 mV (○) or -70 mV (•). *Significant difference from baseline (P < 0.05).

K Cho, et al. J Physiol. 2001 April 15;532(Pt 2):459-466.
5.
Figure 3

Figure 3. Possible interactions between LTD and LTP in determining the outcome of synaptic strength. From: An experimental test of the role of postsynaptic calcium levels in determining synaptic strength using perirhinal cortex of rat.

A, the change in synaptic strength () may be a function of the induction and expression of both LTD and LTP. The induction and expression of LTD (○) occurs at low concentrations of calcium and then reaches a plateau level. As calcium levels increase, the induction of LTP (•) also occurs and then reaches a maximum plateau level. The change in synaptic strength therefore describes the middle curve () due to both LTD and LTP and the transition between LTD and LTP is due to a sum of these two opposite processes. B, an alternative explanation is that LTD (○) and LTP (•) do not co-exist and that the change in synaptic strength () is a function of the selective presence of either LTD or LTP. Thus LTD is induced by low calcium concentrations. As the calcium concentration increases, LTD induction is prevented. As the calcium levels increase further the induction of LTP occurs. Therefore the two processes rely on different calcium concentrations and occur essentially independently of one another, and the transition between LTD and LTP is due to the lack of both LTD and LTP.

K Cho, et al. J Physiol. 2001 April 15;532(Pt 2):459-466.

Supplemental Content

Recent activity

Your browsing activity is empty.

Activity recording is turned off.

Turn recording back on

See more...
Write to the Help Desk