S07 → N400
The Spike of Fascinating & Unexpected
SPIKE 09
→ NEURON.
© 1. Simon Pieraut/SfN — Projection neurons from the entorhinal cortex labeled with an antibody against mCherry (cyan) / 2. S. Karimi-Abdolrezaee/S. Mojtaba Hosseini/SfN — Confocal image showing that human caudalized directly reprogrammed neural precursor cells, marked with nestin (grey), express LAR (green) and PTPσ (red) receptors / 3. Dr. Yadan Li/SfN — Representative inverted contrast and immunofluorescent staining of IBA1 and NLRP3 in primary cultured microglia co-cultured with naïve neurons / 4. Sreeja Kumari Dhanya/SfN — Confocal image shows Purkinje neurons in a mouse cerebellar section. Purkinje neurons that express tdTomato fluorescence are immunostained with calbindin (green) / 5. Derek H. Oakley/SfN — Tau-reporter aggregation induced by exposure to misfolded tau seeds in neurons derived from induced pluripotent stem cells / 6. Luis Carrillo-Reid/SfN — Active neurons (red) in layer 2/3 of mouse primary visual cortex, along with functional connections (red lines) between the neurons / 7. Nguyen Tan Tin/SfN — Neurons in the visual cortex of a mouse magnified 40 times / 8. Danielle Stanton-Turcotte/SfN — Mouse fetal neocortex stained for the expression for Satb2 (red), a marker for upper-layer pyramidal cells, Tbr1 (green), a marker of deep-layer pyramidal cells, neurofilament (fushia), a marker of white matter, and nuclei were counterstained with DAPI (blue) / 9. Atsushi Sugie/SfN — Axonal projections of R7 photoreceptors in the Drosophila medulla (axons in blue, axonal terminals in green) / 10. Tingting Wang/SfN — Perineurial glia (red) are a subset of glia (green) in the peripheral nervous system (neuronal membranes in blue) of Drosophila / 11. Cajal Institute (CSIC) — Santiago Ramón y Cajal, Calyces of Held in the nucleus of the trapezoid body (1934).
-100
-400
The concept of neurons as individual cells was first proposed by Santiago Ramón y Cajal in the late 19th century. Before his groundbreaking work, it was widely believed that the nervous system was a continuous network, not composed of discrete cells. Ramón y Cajal’s use of the Golgi staining method allowed him to visualise individual neurons and map their intricate connections, revolutionising our understanding of the nervous system.
Neurons consist of three main parts: the cell body (soma), dendrites, and axon. The cell body contains the nucleus and other organelles essential for the cell’s metabolic functions. Dendrites are branching extensions that receive signals from other neurons or sensory receptors. The axon is a long, slender projection that carries electrical impulses away from the cell body and transmits them to other neurons or target cells. Neurons communicate with one another through synapses, specialised junctions where neurotransmitters are released from the axon terminals of one neuron and received by receptors on the dendrites or cell body of another neuron. This process allows for transmitting and integrating information within the nervous system. The longest axon in the human body belongs to a single neuron. This neuron, called the sciatic nerve, can extend all the way from the base of the spine down to the big toe and can be over a meter (about 3 feet) long. This remarkable length allows it to efficiently transmit signals between the spinal cord and the muscles of the lower leg and foot, playing a crucial role in movement and sensation.
As mentioned, neurons use both electrical and chemical signals to communicate. The fastest signals in the human nervous system can travel at speeds of up to 120 metres per second (about 268 miles per hour). These rapid signals are due to a special type of neuron known as a myelinated neuron. The myelin sheath, a fatty layer that wraps around the axon of the neuron, acts like insulation around an electrical wire, allowing the signal to “jump” between gaps in the sheath (called nodes of Ranvier) and speed up the transmission. This process, known as saltatory conduction, enables swift and efficient communication within the nervous system. The neurons’ electrical impulses used to communicate are called action potentials. They follow an “all-or-nothing” principle. This means that once a neuron’s threshold is reached, it will fire an action potential at full strength. This ensures that signals are transmitted with consistency and reliability throughout the nervous system.
Neurons also have a remarkable ability to change and adapt, a property known as neuroplasticity. This means that the connections between neurons can strengthen, weaken, or even form new connections in response to learning, experience, or injury. For example, when you learn a new skill, such as playing a musical instrument, your brain forms new neural pathways and strengthens existing ones to accommodate the new information. This ability to reorganise and adapt is crucial for memory, learning, and recovery from brain injuries. Neuroplasticity demonstrates the brain’s incredible capacity for growth and change throughout a person’s life.
—
→ Sourced from: SYSTEM 01 (BD/WT) / SYSTEM 08 (AofAP)
→ Stored online: N400 Spikes Repository
—
→ Search log: Google images
—
© If you are the owner of a picture and want it removed, please contact us.