Skip to main content
. 2012 May 23;6:23. doi: 10.3389/fnint.2012.00023

Figure 7.

Figure 7

Learning-facilitated LTD depends on the activation of β-adrenergic receptors at mossy fiber-CA3 synapses. (A) Application of 1 Hz stimulation (sLFS: 600 pulses) without objects induces STD at mossy fiber-CA3 synapses. sLFS given to vehicle-treated animals during exploration of landmark cues led to LTD that lasted for at least 24 h. In the presence of propranolol, LTD expression is impaired during exploration of three novel cues. LTD is facilitated when the animal explores the same three cues for the second time. Changes in time scale are indicated by line breaks. (B) Re-exposure of vehicle-treated animals to the landmark cues (ca. seven days after first exposure) results in STD, whereas re-exposure to the landmark cues, of the animals that were injected with propranolol (ca. one week previously, during the “novel exposure” experiment), facilitates LTD. A further (second) re-exposure of these animals to the landmark objects (ca. one week after the first re-exposure) results in STD. Changes in time scale are indicated by line breaks. (C) Analogs recorded during experiments shown in (A), 5 min pre-sLFS (i), 5 min post-sLFS (ii) and 24 h post-sLFS (iii). Top row represents fEPSP responses obtained during application of sLFS in vehicle-treated animals in the absence of novel landmarks, middle row represent responses elicited in animals that underwent exploration of novel landmarks, and bottom row shows fEPSPs evoked in propranolol-treated animals that underwent exploration of novel landmarks. Vertical scale bar: 2 mV, horizontal scale bar: 6 msec. (D) Analog traces recorded during experiments shown in (B), 5 min pre-sLFS (i), 5 min post-sLFS (ii), and 24 h post-sLFS (iii). The top row represent analogs from a vehicle-treated animal that underwent a second exposure to the landmarks, middle row depict fEPSP responses from a first re-exposure experiment (in an animal formerly treated with propranolol) and the bottom row represent responses of fEPSPs recorded during the second re-exposure experiment (in an animal formerly treated with propranolol). Vertical scale bar: 2 mV, horizontal scale bar: 6 ms.