In neuroscience,<unk> s refer to tiny neurons (a type of cell) that are around 10 micrometres in diameter.<unk> s are found within the<unk> r layer of the cerebellum, layer 4 of cerebral cortex, the dentate gyrus of the hippocampus, and in the olfactory bulb.
While anatomically similar,<unk> s in different brain regions are functionally diverse.  For instance, olfactory bulb<unk> s are GABAergic and axonless, while<unk> s in the dentate gyrus have glutamatergic projection axons.  Interestingly, these two populations of<unk> s are also the only major neuronal populations that undergo adult neurogenesis, while cerebellar and cortical<unk> s do not.
Cerebellar<unk> s account for nearly half of the neurons in the central nervous system.<unk> s receive excitatory input from mossy fibers originating from pontine nuclei. Cerebellar<unk> s send parallel fibers up through the Purkinje layer into the molecular layer where they branch out and spread through Purkinje cell dendritic arbors. These parallel fibers form thousands of excitatory synapses with Purkinje cells.
Layer 4<unk> s of the cerebral cortex receive driving inputs from thalamus and convey driving inputs largely to supragranular layers 2-3, but also to infragranular layers of the cerebral cortex.
Granule cell
Interneuron
Neuron
Ganglion cell
Chromaffin cell
Cone cell
Oocyte
Histiocyte