Around April every year artists attempt a 100 day challenge. This year I will be creating embroidery hoops of 100 different types of neurons! I hope you’ll join me in learning how different neurons look in different animals and brain areas!
Day 1 of the #100NeuronProject! I wanted to start with a classic: the pyramidal cell. This one specifically comes from the hippocampus, but you can also find pyramidal cells in the cortex! When you see a cartoon rendition of a neuron you are probably seeing a caricature of a pyramidal cells. These cells are pretty common and are considered to be the main type of cell found in the cortex! The stereotyped morphology or shape of pyramidal cells allow them to be great for showing the different parts of the neuron. I couldn’t help adding in my brand new Two Photon pin!
Day 2: Inferior Olivary Neuron You can find these neurons in the superior olive, this brain structure is where climbing fibers start heading towards the cerebellum. Inferior olivary neurons also have absolutely wild dendrites that extend off the cell body in as many directions as possible! Groups of these neurons communicate with each other using special connections called gap junctions. Gap junctions are electrical synapses where electrical activity can pass directly from one cell to another. They’re quite fast! Which is one of the benefits of having electrical synapses!
Day 3: The Oriens-Lacunosum Moleculare Cell or the OLM! OLM neurons are one of the many (like MANY) inhibitory interneurons of the hippocampus! This OLM neuron is particularly special to me because it’s one that I recorded from myself! I study these cells in the lab and I’m trying to figure out how they contribute to keeping the hippocampus up and running. The hardest part is that OLMs only make up about 0.5% of all the neurons in the area of hippocampus I study (YIKES at those odds) Even though there aren’t a large number of them, OLM cells still do a very important job and orchestrate the movement of activity through the hippocampus.
Day 4: Chandelier Cell These cells are another type of inhibitory interneuron, BUT they live in the cortex instead of the hippocampus. Chandelier cells are super interesting in that they have cool processes called ‘cartridges’ that specifically target the output portion of other cells, the axon. I used a pretty metallic gold thread here for the cartridges to make the cell look a little more like a chandelier! Chandelier cells have been shown to exhibit very dramatic changes during development by drastically increasing their number of cartridges to mirror the development of their excitatory neuron counter parts.
Day 5: Retinal Ganglion Cell These cells are a part of the visual pathway. They vary GREATLY in what they look like, here I’m only showing one example, but in reality there are at least five different classes of retinal ganglion cells! However, all of the different types of retinal ganglion cells have long axons that extend away from the cell body and form the optic nerve, optic chiasm, and optic tract. A very small number of retinal ganglion cells contribute to the resizing of the pupil, also called the pupillary light reflex. This is when the pupil diameter will shrink in a high light intensity environment or grow in a low light environment.
Day 6: Bipolar Cells These neurons are found along the visual pathway and are a part of the circuitry of the retina, much like the Day 5 retinal ganglion cells. Bipolar cells have a very interesting way of communicating with their connected counter parts. Instead of firing action potentials, which is a pretty typical way for cells to signal to each other, bipolar cells use graded potentials. A graded potential signals changes over a period of time, where as action potentials are an all or none phenomena and can signal only at one point in time.
Day 7: Hippocampal Basket Cell. There are actually a few different cells that are named ‘basket cells’ in the brain. This one comes from the hippocampus, the area of the brain that I study and contributes a lot to our understanding of learning and memory. Basket cells in the hippocampus strongly inhibit up to 2,500 pyramidal cells, that’s A LOT! These cells are also quite famous for their very expansive axon, which allows them to connect with so many of the excitatory pyramidal cells.
Day 8: Horizontal Cell This neuron is another part of the visual pathway in the brain and makes up some of the key cells in the retina. Horizontal cells integrate information from rods and cones. The rods and cones are known as photoreceptors and have specialized properties that allow rods to sense light and cones to sense color.
Day 9: Stellate Cell These beautiful cells are inhibitory interneurons that are found in the cerebellum. Stellate cells derive their name from star shaped dendritic processes that radiate out from the cell body. There are actually multiple cells that have the name Stellate Cell (neuroscientists are super clever when it comes to names obviously) These particular cells happen to be the most common stellate cell. I’m so happy with how lovely this one came out!
Day 10: Unipolar Brush Cell These cells are not considered the most beautiful neuron ever, but they do have some interesting characteristics. Unipolar brush cells are found in the granular layer of the cerebellum. They get their name from the ‘brush-like’ dendritic process that can be seen on the right side of the neuron. ??♀️ I chose to include the axon, the output portion of the cell, for this neuron to show a super neat feature of UBCs. The axon is the long winding process that extends to the left off of the cell body. Unipolar brush cells have special ‘blebs’ on their axon, also known as rosettes. They form large connections with cerebellar granule cells and other UBCs