CA1 pyramidal neuron
The CA1 Pyramidal Neuron is a neuron in the CA1 region of the mammalian hippocampus.
The CA1 Pyramidal Neuron is found in the CA1 region of the mammalian hippocampus in the medial temporal lobe. "CA" refers to cornu Ammon, latin for Ammon's horn (so named for the shape of the hippocampus). The neurons in the CA1 region provide a significant output pathway from the hippocampus, which plays an important role in long-term memory and spatially related tasks. CA1 pyramidal neurons, in particular, are thought to be critical to object differentiation in long-term memory. Their relationship with Schaffer collaterals in the CA3 region of the hippocampus leads to long-term potentiation (LTP) which is a critical component of information storage.
Neuronal Type: Projection neuron
- The cell body of the CA1 pyramidal neuron is located amidst a thick set of dendritic branches and one projecting axon. The dendrites bind together in a thick band called the stratum radiatum.
- The axons of pyramidal cells in the CA1 region project mostly to the entorhinal cortex layer V and to the subiculum.
- CA1 contains approximately 250,000 pyramidal neurons.
- Neurotransmitter: Glutamate, which is the primary excitatory neurotransmitter in the mammalian brain.
- CA1 pyramidal cells receive inputs from the pyramidal cells in the CA3 region called Schaffer collaterals, and also from the superficial entorhinal cortex and the nucleus reuniens of the thalamus. Unlike other regions of the hippocampus, the CA1 region does not contain many recurrent pathways. Input is received both from dendrites and backpropagation in the axon.
- CA1 pyramidal cells project to the entorhinal cortex layer V and also to the subiculum, which is at the end of the hippocampus.
- The relationship between CA1 pyramidal neurons and Schaffer collateral cells have been implicated in LTP (the strengthening of a synapse due to recent activity). Malinow et al. (1989) found that brief, high-frequency stimulation of the Schaffer collaterals causes LTP in the CA1-Schaffer collateral synapse. LTP is input specific, the effects of LTP on one synapse do not occur in other, inactive synapses. This is key for information storage. In LTP, CA1 pyramidal neurons reach their maximum output, and thus for further information to be encoded in these neurons, long-term depression (LTD) needs to occur along other synapses.
- Changes in dendritic density are thought to be associated with neuronal damage inflicted by ischemia (restricted blood supply) (Ruan YW, Lei Z, Fan Y, Zou B, Xu ZC (2008)).
- Although controversy lingers, Golding, Nace L., William L. Kath, and Nelson Spruston (2001), as well as others, have argued that backpropagation occurs in the dendrites of the cell, which may be critical to understanding their plasticity.
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- Ruan YW, Lei Z, Fan Y, Zou B, Xu ZC (2008). “Diversity and fluctuation of spine morphology in CA1 pyramidal neurons after transient global ischemia.” Neurosci Res J, Aug. 15.