![]() ![]() It is difficult to firmly establish a causal relationship between computations that occur in dendritic branches and properties at the soma. L2/3 pyramidal neurons are also a good model system for studying the relative roles of apical and basal dendrites: while basal dendrites primarily receive feedforward input from L4 and nearby L2/3 neurons 7, 8, apical dendrites receive cortico-cortical feedback that may refine orientation selectivity 9, 10 as well as orientation-tuned thalamo-cortical input from layer 1 4, 11, 12, 13. Indeed, recent evidence suggests that apical tuft dendritic spikes serve to narrow the orientation tuning function, increasing orientation selectivity of area V1 L2/3 pyramidal neurons 6. Mouse primary visual cortex (V1) L2/3 pyramidal neurons generate action potentials in response to a narrow range of orientations 5 despite receiving highly heterogeneous input and poorly tuned subthreshold responses 4, making them ideal for studying the relationship between dendritic input and functional selectivity. Inputs are functionally heterogeneous across dendrites and even within individual dendritic branches 3, 4. Each dendritic-tree of a mouse layer 2/3 (L2/3) pyramidal neuron arborizes in a different cortical map sub-region (e.g., retinotopic region) and/or cortical layer, thereby sampling largely non-overlapping axonal inputs coming in from different brain areas 2. Neocortical pyramidal neurons ramify several basal dendritic arbors laterally and one apical dendritic arbor superficially to receive and integrate synaptic inputs 1. In conclusion, neuronal orientation-tuning appears remarkably robust to loss of dendritic input. Computational modeling corroborated our results and put limits on how orientation preferences among basal dendrites differ in order to reproduce the post-ablation data. Furthermore, orientation-tuning curves were remarkably robust to the removal of basal dendrites: ablation of 2 basal dendrites was needed to cause a small shift in orientation preference, without significantly altering tuning width. We found that removing the apical dendritic tuft did not alter orientation-tuning. We performed 2-photon dendritic micro-dissection on layer-2/3 pyramidal neurons in mouse primary visual cortex. However, how a neuron’s dendritic domains relate to its functional selectivity has not been demonstrated experimentally. It has been proposed that feed-forward inputs to basal dendrites drive a neuron’s stimulus preference, while feedback inputs to apical dendrites sharpen selectivity. Multipolar neurons, the most common type, have one axon and two or more dendrites.Pyramidal neurons integrate synaptic inputs from basal and apical dendrites to generate stimulus-specific responses. Bipolar neurons have two processes, an axon and a dendrite, that extend from opposite ends of the soma. Unipolar neurons have a single short process that emerges from the cell body and divides T-like into proximal and distal branches. Three major neuron groups make up this classification: multipolar, bipolar, and unipolar. Neurons can generally be grouped according to the number of processes extending from their cell bodies. Neurotransmission at a Chemical Synapse: A signal propagating down an axon to the cell body and dendrites of the next cell Interneurons act as relays between neurons in close proximity to one another. Motor neurons receive signals from the brain and spinal cord to initiate muscle contractions and affect glands. For example, sensory neurons respond to touch, sound, light, and other sensory inputs. The cell body is the focal point for the outgrowth of neuronal process during embryonic development.Ī number of anatomically distinct types of neurons have evolved to participate in different organismal functions. It contains neurotransmitters and other organelles needed to synthesize proteins and chemicals. The cell body is the major biosynthetic center of the neuron. Nerve impulses are generated in the axon and transmitted away from the cell body towards the synapse. These extensions are the conducting region of the neuron. Axons arise from a cone-shaped area of the cell body called axon hillock. The dendrites are short, tapering extensions that are the receptive regions and help in conveying incoming messages towards the cell body. A typical neuron consists of a cell body and neuronal processes such as dendrites and axon. Neurons are electrically excitable cells that are the structural unit of the nervous system. Axons: The conducting region of the neuron.dendrites: Short, tapering extensions that convey incoming messages toward the body of the neuron.Neurons: Electrically excitable cells that are the structural unit of the nervous system.
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