142. Randall AD and Collingridge GL. (1992) Amino acid receptor-mediated synaptic currents in the CA1 region of the hippocampus. Ion Channels 3:63-81.

NeuronCompartmentPropertyConnectivityNotes
Hippocampus CA1 pyramidal cellDistal apical dendriteGlutamatePerforant pathway entorhinal pyramidal neuron terminals (T)Glutamate is commonly believed to be the primary excitatory neurotransmitter in the hippocampal formation generally (reviewed in Cotman et al., 1995), and in CA1 in particular (Storm-Mathisen J, 1977141 , Randall AD and Collingridge GL, 1992142 ). CA1 pyramidal neurons increase their firing (recorded extracellularly) in response to ionophoresed Glu within their apical dendritic fields or in the cell body layer (Dudar 1974 PMID#4437726). Magee JC and Cook EP, 2000183
Hippocampus CA1 pyramidal cellMiddle apical dendriteNMDA.The way that different parts of a neuron carry out multiple information processing roles is illustrated by the CA1 pyramidal cell in the hippocampus. The authors used 2-photon microscopy to obtain high resolution images of calcium signals in the apical dendrites while activating Schaffer collateral inputs to induce long-term potentiation (LTP) of different durations. Short-duration LTP (LTP 1) was associated with Ca increase in dendritic spines, due to activation of NMDA receptors and local ryanodine receptors (RyRs). Intermediate duration LTP (LTP 2) was associated with Ca increase in dendritic branches, due to activation of NMDA receptors and local IP3 receptors (IP3Rs). For Ca increase in long duration LTP (LTP3), see Ca channels in CA1 pyramidal cell apical dendrite. The authors conclude that "selective induction of different forms of LTP is achieved via spatial segregation of functionally distinct calcium signals"(Raymond CR and Redman SJ, 2006540 ). The Schaeffer collateral/commissural pathway elicits EPSPs in CA1 that have an NMDA-receptor mediated component that can be blocked by APV under certain experimental circumstances (such as low bath Mg+ levels). Many authors have suggested that NMDA receptors may be involved in long-term potentiation in this region. (Reviewed in Randall AD and Collingridge GL, 1992142 ). EM showed colocalization at axodendritic asymmetric synapses within the CA1 subfield of rat hippocampus. AMPA/NMDA receptor colocalization was found in non-GABAergic dendritic shafts as well as dendritic spines, suggesting that excitatory neuronal transmission in CA1 neurons may generally involve activation of both NMDA and AMPA receptor subunits at a single synapse (He Y et al, 1998250 ).
Hippocampus CA1 pyramidal cellMiddle apical dendriteAMPA.The Schaeffer collateral/commissural pathway elicits EPSPs in CA1 that have a large AMPA receptor-mediated component that can be blocked by CNQX (Honoré T et al, 1988 [rat ]145 ). (Reviewed in Randall AD and Collingridge GL, 1992142 ).EM showed colocalization at axodendritic asymmetric synapses within the CA1 subfield of rat hippocampus. AMPA/NMDA receptor colocalization was found in non-GABAergic dendritic shafts as well as dendritic spines, suggesting that excitatory neuronal transmission in CA1 neurons may generally involve activation of both NMDA and AMPA receptor subunits at a single synapse (He Y et al, 1998250 ). Using outside-out patches and a fast application system the properties and distribution of synaptic glutamate receptors an approximately twofold increase in AMPA-mediated current was observed in the dendritic region that receives a uniform density of Schaffer collateral input (100-250um from soma) (Andrasfalvy BK and Magee JC, 2001299 ).

References
141. Storm-Mathisen J. (1977) Localization of transmitter candidates in the brain: the hippocampal formation as a model. Prog Neurobiol 8:119-81.
142. Randall AD and Collingridge GL. (1992) Amino acid receptor-mediated synaptic currents in the CA1 region of the hippocampus. Ion Channels 3:63-81.
183. Magee JC and Cook EP. (2000) Somatic EPSP amplitude is independent of synapse location in hippocampal pyramidal neurons. Nat Neurosci 3:895-903.
540. Raymond CR and Redman SJ. (2006) Spatial segregation of neuronal calcium signals encodes different forms of LTP in rat hippocampus. J Physiol 570:97-111 [Journal] .
250. He Y, Janssen WG and Morrison JH. (1998) Synaptic coexistence of AMPA and NMDA receptors in the rat hippocampus: a postembedding immunogold study. J Neurosci Res 54:444-9 [Journal] .
145. Honoré T, Davies SN, Drejer J, Fletcher EJ, Jacobsen P, Lodge D and Nielsen FE. (1988) Quinoxalinediones: potent competitive non-NMDA glutamate receptor antagonists. Science 241:701-3.
299. Andrasfalvy BK and Magee JC. (2001) Distance-dependent increase in AMPA receptor number in the dendrites of adult hippocampal CA1 pyramidal neurons. J Neurosci 21:9151-9.
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