Pyramidal cell
Pyramidal cell | |
---|---|
GABA | |
Identifiers | |
MeSH | D017966 |
NeuroLex ID | sao862606388 |
TH | H1.00.01.0.00044 |
FMA | 84105 |
Anatomical terms of neuroanatomy] |
Pyramidal cells, or pyramidal neurons, are a type of
Pyramidal neurons are also one of two cell types where the
Structure
One of the main structural features of the pyramidal neuron is the conic shaped
Apical dendrite
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.[1]
Basal dendrite
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.[1]
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
Growth and development
Differentiation
Pyramidal specification occurs during early development of the cerebrum.
Early postnatal development
Pyramidal cells in rats have been shown to undergo many rapid changes during early
Signaling
Like dendrites in most other neurons, the dendrites are generally the input areas of the neuron, while the axon is the neuron's output. Both axons and dendrites are highly branched. The large amount of branching allows the neuron to send and receive signals to and from many different neurons.
Pyramidal neurons, like other neurons, have numerous voltage-gated ion channels. In pyramidal cells, there is an abundance of Na+, Ca2+, and K+ channels in the dendrites, and some channels in the soma.[9][10] Ion channels within pyramidal cell dendrites have different properties from the same ion channel type within the pyramidal cell soma.[11][12] Voltage-gated Ca2+ channels in pyramidal cell dendrites are activated by subthreshold EPSPs and by back-propagating action potentials. The extent of back-propagation of action potentials within pyramidal dendrites depends upon the K+ channels. K+ channels in pyramidal cell dendrites provide a mechanism for controlling the amplitude of action potentials.[13]
The ability of pyramidal neurons to integrate information depends on the number and distribution of the synaptic inputs they receive. A single pyramidal cell receives about 30,000 excitatory inputs and 1700 inhibitory (
Firing classifications
Pyramidal neurons have been classified into different subclasses based upon their firing responses to 400-1000 millisecond current pulses. These classification are RSad, RSna, and IB neurons.
RSad
RSad pyramidal neurons, or adapting regular spiking neurons, fire with individual action potentials (APs), which are followed by a hyperpolarizing afterpotential. The afterpotential increases in duration which creates spike frequency adaptation (SFA) in the neuron.[15]
RSna
RSna pyramidal neurons, or non-adapting regular spiking neurons, fire a train of action potentials after a pulse. These neurons show no signs of adaptation.[15]
IB
IB pyramidal neurons, or intrinsically bursting neurons, respond to threshold pulses with a burst of two to five rapid action potentials. IB pyramidal neurons show no adaptation.[15]
Molecular classifications
There are several studies showing that morphological and electric pyramidal cells properties could be deduced from gene expression measured by
Function
Corticospinal tract
Pyramidal neurons are the primary neural cell type in the corticospinal tract. Normal motor control depends on the development of connections between the axons in the corticospinal tract and the spinal cord. Pyramidal cell axons follow cues such as growth factors to make specific connections. With proper connections, pyramidal cells take part in the circuitry responsible for vision guided motor function.[20]
Cognition
Pyramidal neurons in the prefrontal cortex are implicated in cognitive ability. In mammals, the complexity of pyramidal cells increases from
Memory and learning
The hippocampus's pyramidal cells are essential for certain types of memory and learning. They form synapses that aid in the integration of synaptic voltages throughout their complex dendritic trees through interactions with mossy fibers from granule cells. Since it affects the postsynaptic voltages produced by mossy fiber activation, the placement of
See also
- Pyramidal tract
- Chandelier cells - innervate initial segments of pyramidal axons
- Rosehip neuron
References
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