Limits...
The temporoammonic input to the hippocampal CA1 region displays distinctly different synaptic plasticity compared to the Schaffer collateral input in vivo: significance for synaptic information processing.

Aksoy-Aksel A, Manahan-Vaughan D - Front Synaptic Neurosci (2013)

Bottom Line: We observed that field excitatory postsynaptic potentials at the pp-CA1 synapse have longer onset latencies and a shorter time-to-peak compared to the Sc-CA1 synapse.LTP (>24 h) was successfully evoked by tetanic afferent stimulation of pp-CA1 synapses.Paired-pulse responses also showed significant differences.

View Article: PubMed Central - PubMed

Affiliation: Department of Neurophysiology, Medical Faculty, Ruhr University Bochum Bochum, Germany ; International Graduate School for Neuroscience, Ruhr University Bochum Bochum, Germany.

ABSTRACT
In terms of its sub-regional differentiation, the hippocampal CA1 region receives cortical information directly via the perforant (temporoammonic) path (pp-CA1 synapse) and indirectly via the tri-synaptic pathway where the last relay station is the Schaffer collateral-CA1 synapse (Sc-CA1 synapse). Research to date on pp-CA1 synapses has been conducted predominantly in vitro and never in awake animals, but these studies hint that information processing at this synapse might be distinct to processing at the Sc-CA1 synapse. Here, we characterized synaptic properties and synaptic plasticity at the pp-CA1 synapse of freely behaving adult rats. We observed that field excitatory postsynaptic potentials at the pp-CA1 synapse have longer onset latencies and a shorter time-to-peak compared to the Sc-CA1 synapse. LTP (>24 h) was successfully evoked by tetanic afferent stimulation of pp-CA1 synapses. Low frequency stimulation evoked synaptic depression at Sc-CA1 synapses, but did not elicit LTD at pp-CA1 synapses unless the Schaffer collateral afferents to the CA1 region had been severed. Paired-pulse responses also showed significant differences. Our data suggest that synaptic plasticity at the pp-CA1 synapse is distinct from the Sc-CA1 synapse and that this may reflect its specific role in hippocampal information processing.

No MeSH data available.


Related in: MedlinePlus

The paired-pulse ratio is different for pp-CA1 and Sc-CA1 synapse depending on stimulus intensity. (A) Left: Paired-pulse ratio profiles for pp-CA1 and Sc-CA1 synapses at low-intensity stimulation (corresponding to the intensity necessary to evoke 40% of the maximum). Right: Example of fEPSPs evoked from corresponding synapse and interstimulus interval (Vertical scale bar: 4 mV, horizontal scale bar: 5 ms for all) (B) Left: Paired-pulse ratio profiles for pp-CA1 synapses and for the Sc-CA1 synapses at high-intensity levels (double the low-intensity or maximum of 400 μA). Increasing the stimulation intensity did not result in a significant change for the pp-CA1 synapse but led to paired-pulse depression at all interstimulus intervals for the Sc-CA1 synapse. The paired-pulse intervals used were: 20, 25, 40, 50, and 100 ms for both groups. All the recordings were collected from awake unrestrained but stationary animals. *indicates p < 0.05 (Student's t-test). Right: Example of fEPSPs evoked from corresponding synapse and interstimulus interval (Vertical scale bar: 4 mV, horizontal scale bar: 5 ms).
© Copyright Policy - open-access
Related In: Results  -  Collection

License
getmorefigures.php?uid=PMC3750210&req=5

Figure 4: The paired-pulse ratio is different for pp-CA1 and Sc-CA1 synapse depending on stimulus intensity. (A) Left: Paired-pulse ratio profiles for pp-CA1 and Sc-CA1 synapses at low-intensity stimulation (corresponding to the intensity necessary to evoke 40% of the maximum). Right: Example of fEPSPs evoked from corresponding synapse and interstimulus interval (Vertical scale bar: 4 mV, horizontal scale bar: 5 ms for all) (B) Left: Paired-pulse ratio profiles for pp-CA1 synapses and for the Sc-CA1 synapses at high-intensity levels (double the low-intensity or maximum of 400 μA). Increasing the stimulation intensity did not result in a significant change for the pp-CA1 synapse but led to paired-pulse depression at all interstimulus intervals for the Sc-CA1 synapse. The paired-pulse intervals used were: 20, 25, 40, 50, and 100 ms for both groups. All the recordings were collected from awake unrestrained but stationary animals. *indicates p < 0.05 (Student's t-test). Right: Example of fEPSPs evoked from corresponding synapse and interstimulus interval (Vertical scale bar: 4 mV, horizontal scale bar: 5 ms).

Mentions: Low- intensity stimulation revealed a similar profile of the paired pulse ratio for both the pp-CA1 and the Sc-CA1 synapse (Figure 4A). At high-intensity stimulation, 50 ms inter-pulse intervals resulted in a significant difference between the Sc-CA1 and pp-CA1 animals (p < 0.05; n = 7 for Sc-CA1, n = 6 for pp-CA1) (Figure 4B). Increasing the intensity of stimulation drastically changed the paired-pulse ratio profile for the Sc-CA1 synapse for all inter-pulse intervals (p < 0.05; n = 7) but not for the pp-CA1 synapse (no significant difference at different intensities for all inter-pulse intervals, p > 0.05). High-intensity stimulation complicated the evoked responses from pp-CA1 synapse and resulted in a high variability within the group.


The temporoammonic input to the hippocampal CA1 region displays distinctly different synaptic plasticity compared to the Schaffer collateral input in vivo: significance for synaptic information processing.

Aksoy-Aksel A, Manahan-Vaughan D - Front Synaptic Neurosci (2013)

The paired-pulse ratio is different for pp-CA1 and Sc-CA1 synapse depending on stimulus intensity. (A) Left: Paired-pulse ratio profiles for pp-CA1 and Sc-CA1 synapses at low-intensity stimulation (corresponding to the intensity necessary to evoke 40% of the maximum). Right: Example of fEPSPs evoked from corresponding synapse and interstimulus interval (Vertical scale bar: 4 mV, horizontal scale bar: 5 ms for all) (B) Left: Paired-pulse ratio profiles for pp-CA1 synapses and for the Sc-CA1 synapses at high-intensity levels (double the low-intensity or maximum of 400 μA). Increasing the stimulation intensity did not result in a significant change for the pp-CA1 synapse but led to paired-pulse depression at all interstimulus intervals for the Sc-CA1 synapse. The paired-pulse intervals used were: 20, 25, 40, 50, and 100 ms for both groups. All the recordings were collected from awake unrestrained but stationary animals. *indicates p < 0.05 (Student's t-test). Right: Example of fEPSPs evoked from corresponding synapse and interstimulus interval (Vertical scale bar: 4 mV, horizontal scale bar: 5 ms).
© Copyright Policy - open-access
Related In: Results  -  Collection

License
Show All Figures
getmorefigures.php?uid=PMC3750210&req=5

Figure 4: The paired-pulse ratio is different for pp-CA1 and Sc-CA1 synapse depending on stimulus intensity. (A) Left: Paired-pulse ratio profiles for pp-CA1 and Sc-CA1 synapses at low-intensity stimulation (corresponding to the intensity necessary to evoke 40% of the maximum). Right: Example of fEPSPs evoked from corresponding synapse and interstimulus interval (Vertical scale bar: 4 mV, horizontal scale bar: 5 ms for all) (B) Left: Paired-pulse ratio profiles for pp-CA1 synapses and for the Sc-CA1 synapses at high-intensity levels (double the low-intensity or maximum of 400 μA). Increasing the stimulation intensity did not result in a significant change for the pp-CA1 synapse but led to paired-pulse depression at all interstimulus intervals for the Sc-CA1 synapse. The paired-pulse intervals used were: 20, 25, 40, 50, and 100 ms for both groups. All the recordings were collected from awake unrestrained but stationary animals. *indicates p < 0.05 (Student's t-test). Right: Example of fEPSPs evoked from corresponding synapse and interstimulus interval (Vertical scale bar: 4 mV, horizontal scale bar: 5 ms).
Mentions: Low- intensity stimulation revealed a similar profile of the paired pulse ratio for both the pp-CA1 and the Sc-CA1 synapse (Figure 4A). At high-intensity stimulation, 50 ms inter-pulse intervals resulted in a significant difference between the Sc-CA1 and pp-CA1 animals (p < 0.05; n = 7 for Sc-CA1, n = 6 for pp-CA1) (Figure 4B). Increasing the intensity of stimulation drastically changed the paired-pulse ratio profile for the Sc-CA1 synapse for all inter-pulse intervals (p < 0.05; n = 7) but not for the pp-CA1 synapse (no significant difference at different intensities for all inter-pulse intervals, p > 0.05). High-intensity stimulation complicated the evoked responses from pp-CA1 synapse and resulted in a high variability within the group.

Bottom Line: We observed that field excitatory postsynaptic potentials at the pp-CA1 synapse have longer onset latencies and a shorter time-to-peak compared to the Sc-CA1 synapse.LTP (>24 h) was successfully evoked by tetanic afferent stimulation of pp-CA1 synapses.Paired-pulse responses also showed significant differences.

View Article: PubMed Central - PubMed

Affiliation: Department of Neurophysiology, Medical Faculty, Ruhr University Bochum Bochum, Germany ; International Graduate School for Neuroscience, Ruhr University Bochum Bochum, Germany.

ABSTRACT
In terms of its sub-regional differentiation, the hippocampal CA1 region receives cortical information directly via the perforant (temporoammonic) path (pp-CA1 synapse) and indirectly via the tri-synaptic pathway where the last relay station is the Schaffer collateral-CA1 synapse (Sc-CA1 synapse). Research to date on pp-CA1 synapses has been conducted predominantly in vitro and never in awake animals, but these studies hint that information processing at this synapse might be distinct to processing at the Sc-CA1 synapse. Here, we characterized synaptic properties and synaptic plasticity at the pp-CA1 synapse of freely behaving adult rats. We observed that field excitatory postsynaptic potentials at the pp-CA1 synapse have longer onset latencies and a shorter time-to-peak compared to the Sc-CA1 synapse. LTP (>24 h) was successfully evoked by tetanic afferent stimulation of pp-CA1 synapses. Low frequency stimulation evoked synaptic depression at Sc-CA1 synapses, but did not elicit LTD at pp-CA1 synapses unless the Schaffer collateral afferents to the CA1 region had been severed. Paired-pulse responses also showed significant differences. Our data suggest that synaptic plasticity at the pp-CA1 synapse is distinct from the Sc-CA1 synapse and that this may reflect its specific role in hippocampal information processing.

No MeSH data available.


Related in: MedlinePlus