Pyramidal cell
Pyramidal cells, or pyramidal neurons, are a type of multipolar neuron found in areas of the brain including the cerebral cortex, the hippocampus, and the amygdala. Pyramidal cells are the primary excitation units of the mammalian prefrontal cortex and the corticospinal tract. Pyramidal neurons are also one of two cell types where the characteristic sign, Negri bodies, are found in post-mortem rabies infection. Pyramidal neurons were first discovered and studied by Santiago Ramón y Cajal. Since then, studies on pyramidal neurons have focused on topics ranging from neuroplasticity to cognition. File:GFPneuron.png|Pyramidal neuron visualized by [[green fluorescent protein]] (gfp) File:Hippocampal-pyramidal-cell.png|A hippocampal pyramidal cell One of the main structural features of the pyramidal neuron is the conic shaped soma, or cell body, after which the neuron is named. Other key structural features of the pyramidal cell are a single axon, a large apical dendrite, multiple basal dendrites, and the presence of dendritic spines. The apical dendrite rises from the apex of the pyramidal cell's soma. The apical dendrite is a single, long, thick dendrite that branches several times as distance from the soma increases and extends towards the cortical surface. Basal dendrites arise from the base of the soma. The basal dendritic tree consists of three to five primary dendrites. As distance increases from the soma, the basal dendrites branch profusely. Pyramidal cells are among the largest neurons in the brain. Both in humans and rodents, pyramidal cell bodies (somas) average around 20 μm in length. Pyramidal dendrites typically range in diameter from half a micrometer to several micrometers. The length of a single dendrite is usually several hundred micrometers. Due to branching, the total dendritic length of a pyramidal cell may reach several centimeters. The pyramidal cell's axon is often even longer and extensively branched, reaching many centimeters in total length. Dendritic spines receive most of the excitatory impulses (EPSPs) that enter a pyramidal cell.
