Place Representation within Hippocampal Networks Is Modified by Long-Term Potentiation

Abstract

In the brain, information is encoded by the firing patterns of neuronal ensembles and the strength of synaptic connections between individual neurons. We report here that representation of the environment by "place" cells is altered by changing synaptic weights within hippocampal networks. Long-term potentiation (LTP) of intrinsic hippocampal pathways abolished existing place fields, created new place fields, and rearranged the temporal relationship within the affected population. The effect of LTP on neuron discharge was rate and context dependent. The LTP-induced "remapping" occurred without affecting the global firing rate of the network. The findings support the view that learned place representation can be accomplished by LTP-like synaptic plasticity within intrahippocampal networks.

Vestibular stimulation enhances hippocampal long-term potentiation via activation of cholinergic septohippocampal cells

“…Passive rotation has been shown to modulate the activity of place cells [62,63] while bilateral vestibular inactivation or damage abolished location-specific firing of place cells [64,65]. We suggest here that vestibular stimulation enhanced hippocampal LTP, which may be necessary for the formation of place fields [66][67][68]. Degradation of hippocampal place fields during walking by cholinergic blockade [69] suggests that acetylcholine in the hippocampus is involved in place field formation, perhaps by enhancing LTP.…”

Dopamine D1Receptor Modulates Hippocampal Representation Plasticity to Spatial Novelty

“…The hippocampal representation can be altered by modification of long-term potentiation (LTP) (Rotenberg et al, 2000;Dragoi et al, 2003), and this synaptic plasticity can be modulated by dopamine (Otmakhova and Lisman, 1996; Matthies et al, 4 (Figure legend continued. ) C, A place cell had a place field that followed the change of both the distal cues (1-2) and proximal cues (3-4) in the familiar environment.…”

“…In addition, the HF appears to provide a neural representation of physical space, although broader functions have also been suggested (Maguire et al, 1998;Eichenbaum et al, 1999). The place-cell representation of space is thought to underlie certain forms of spatial learning (McHugh et al, 1996(McHugh et al, , 2007Cho et al, 1998;Kentros et al, 1998;Eichenbaum et al, 1999;Rotenberg et al, 2000;Dragoi et al, 2003). It was found that dopamine D 1 receptor knock-out (D1R-KO) mice had impaired spatial learning and altered spatial activity in the nucleus accumbens (El-Ghundi et al, 1999, Tran et al, 2005.…”

Involvement of the CA3–CA1 Synapse in the Acquisition of Associative Learning in Behaving Mice

“…The experimental induction of LTP will surely disturb the synaptic changes taking place during associative learning in selected neural sites. Indeed, it is known that LTP saturation of hippocampal circuits disrupts spatial learning (Barnes et al, 1994), and that place representation in hippocampal networks can be modified experimentally by LTP (Dragoi et al, 2003).…”