Map of types of neurons [x.com](https://twitter.com/burny_tech/status/1772844107582279954) DALL·E 2024-03-27 05.32.18 - Imagine an intricate illustration that showcases a vast network of neurons and brains interconnected to form a meta neural network. This network encom.webp 1. Sensory Neurons a. Mechanoreceptors i. Pacinian corpuscles - Rapidly adapting - Detect high-frequency vibrations and pressure changes ii. Meissner's corpuscles - Rapidly adapting - Detect low-frequency vibrations and light touch iii. Merkel's discs - Slowly adapting - Detect sustained pressure and texture iv. Ruffini endings - Slowly adapting - Detect skin stretch and joint position b. Nociceptors i. Thermal nociceptors - Detect noxious heat or cold ii. Mechanical nociceptors - Detect noxious mechanical stimuli iii. Polymodal nociceptors - Respond to multiple noxious stimuli (thermal, mechanical, chemical) iv. Silent nociceptors - Normally unresponsive but become active during inflammation c. Thermoreceptors i. Cold receptors - Detect decreases in temperature ii. Warm receptors - Detect increases in temperature d. Photoreceptors i. Rods - Sensitive to low light levels - Responsible for scotopic vision ii. Cones - Sensitive to color and high light levels - Responsible for photopic vision - L-cones (red), M-cones (green), S-cones (blue) e. Chemoreceptors i. Olfactory receptors - Detect odors - Expressed by olfactory sensory neurons ii. Taste receptors - Detect taste stimuli (sweet, salty, sour, bitter, umami) - Expressed by taste receptor cells f. Proprioceptors i. Muscle spindles - Detect muscle length and stretch - Contain intrafusal muscle fibers and sensory endings ii. Golgi tendon organs - Detect muscle tension - Located at the junction of muscle fibers and tendons 2. Motor Neurons a. Somatic motor neurons i. Alpha motor neurons - Innervate extrafusal muscle fibers - Responsible for muscle contraction and movement ii. Gamma motor neurons - Innervate intrafusal muscle fibers of muscle spindles - Regulate muscle spindle sensitivity b. Autonomic motor neurons i. Sympathetic neurons - Originate from thoracolumbar spinal cord - Innervate smooth muscles, cardiac muscle, and glands - Involved in "fight or flight" response ii. Parasympathetic neurons - Originate from brainstem and sacral spinal cord - Innervate smooth muscles, cardiac muscle, and glands - Involved in "rest and digest" functions 3. Interneurons a. Spinal cord interneurons i. Renshaw cells - Provide recurrent inhibition to alpha motor neurons ii. Ia inhibitory interneurons - Mediate reciprocal inhibition between antagonistic muscles iii. Ib inhibitory interneurons - Receive input from Golgi tendon organs and inhibit homonymous motor neurons iv. Propriospinal neurons - Connect different spinal cord segments - Involved in coordinating limb movements b. Cortical interneurons i. Basket cells - Form perisomatic synapses on pyramidal cells - Provide strong inhibition to pyramidal cells ii. Chandelier cells - Form axo-axonic synapses on the initial segment of pyramidal cell axons - Provide powerful inhibitory control over pyramidal cell output iii. Martinotti cells - Have ascending axons that arborize in layer 1 - Provide feedback inhibition to pyramidal cells iv. Double bouquet cells - Have vertically oriented axons that span multiple layers - Provide columnar inhibition in the cortex v. Neurogliaform cells - Have small, round somata and short, highly branched dendrites - Provide slow, sustained inhibition via volume transmission c. Hippocampal interneurons i. Axo-axonic cells - Target the initial segment of pyramidal cell axons - Provide strong inhibitory control over pyramidal cell output ii. Bistratified cells - Have axons that arborize in stratum oriens and stratum radiatum - Provide dendritic inhibition to pyramidal cells iii. Ivy cells - Located in stratum radiatum and stratum lacunosum-moleculare - Provide feedback inhibition to pyramidal cells iv. O-LM cells - Have axons that project to stratum lacunosum-moleculare - Provide feedback inhibition to distal dendrites of pyramidal cells v. Perforant path-associated cells - Located in the molecular layer of the dentate gyrus - Receive input from the perforant path and provide feedforward inhibition to granule cells d. Cerebellar interneurons i. Stellate cells - Located in the molecular layer - Provide feedforward inhibition to Purkinje cells ii. Basket cells - Located in the molecular layer - Form perisomatic synapses on Purkinje cells iii. Golgi cells - Located in the granular layer - Provide feedback inhibition to granule cells iv. Lugaro cells - Located in the granular layer - Provide inhibition to Golgi cells and other interneurons v. Unipolar brush cells - Located in the granular layer - Receive mossy fiber input and provide excitation to granule cells 4. Specialized Neurons a. Purkinje cells - Located in the cerebellar cortex - Integrate input from parallel fibers and climbing fibers - Provide the sole output of the cerebellar cortex b. Pyramidal cells - Located in the cerebral cortex, hippocampus, and amygdala - Have a triangular-shaped soma and apical and basal dendrites - Serve as the primary excitatory neurons in the cortex c. Granule cells - Small, densely packed neurons - Found in the cerebellum, hippocampus, and olfactory bulb - Receive input from mossy fibers (cerebellum) or perforant path (hippocampus) d. Mitral cells - Located in the olfactory bulb - Receive input from olfactory sensory neurons - Project to the olfactory cortex e. Tufted cells - Located in the olfactory bulb - Similar to mitral cells but have different morphology and connectivity f. Medium spiny neurons - Located in the striatum (caudate nucleus and putamen) - Receive input from the cortex and thalamus - Project to the globus pallidus and substantia nigra g. Dopaminergic neurons - Located in the substantia nigra and ventral tegmental area - Synthesize and release dopamine - Involved in reward, motivation, and motor control h. Serotonergic neurons - Located in the raphe nuclei of the brainstem - Synthesize and release serotonin - Involved in mood, sleep, and appetite regulation i. Noradrenergic neurons - Located in the locus coeruleus of the brainstem - Synthesize and release norepinephrine - Involved in arousal, attention, and stress response j. Cholinergic neurons - Located in the basal forebrain and brainstem - Synthesize and release acetylcholine - Involved in attention, learning, and memory k. Amacrine cells - Located in the inner nuclear layer of the retina - Provide lateral inhibition and modulation of retinal ganglion cell activity l. Horizontal cells - Located in the inner nuclear layer of the retina - Provide lateral inhibition and modulation of photoreceptor activity m. Bipolar cells - Located in the inner nuclear layer of the retina - Receive input from photoreceptors and provide output to retinal ganglion cells n. Ganglion cells - Located in the ganglion cell layer of the retina - Receive input from bipolar cells and amacrine cells - Project to the lateral geniculate nucleus and superior colliculus o. Hair cells - Located in the organ of Corti in the inner ear - Transduce mechanical sound waves into electrical signals p. Spindle neurons (von Economo neurons) - Located in the anterior cingulate cortex and frontoinsular cortex - Have a large, spindle-shaped soma and a single apical dendrite - Hypothesized to be involved in social cognition and self-awareness q. Cajal-Retzius cells - Located in the marginal zone of the developing cortex - Secrete reelin, which guides neuronal migration and cortical layering r. Mesencephalic trigeminal neurons - Located in the mesencephalic trigeminal nucleus of the brainstem - Provide proprioceptive information from the jaw and teeth s. Purkinje-like cells - Located in the cerebellar nuclei - Resemble Purkinje cells but have different connectivity t. Unipolar brush cells - Located in the granular layer of the cerebellum - Receive mossy fiber input and provide excitation to granule cells u. Lugaro cells - Located in the granular layer of the cerebellum - Provide inhibition to Golgi cells and other interneurons v. Golgi cells - Located in the granular layer of the cerebellum - Provide feedback inhibition to granule cells w. Granule cells (cerebellum) - Located in the granular layer of the cerebellum - Receive input from mossy fibers and provide excitation to Purkinje cells via parallel fibers x. Chandelier cells (axo-axonic cells) - Located in the cortex and hippocampus - Form synapses on the initial segment of pyramidal cell axons - Provide powerful inhibitory control over pyramidal cell output y. Renshaw cells - Located in the spinal cord - Provide recurrent inhibition to alpha motor neurons z. Unipolar brush cells (cerebellum) - Located in the granular layer of the cerebellum - Receive mossy fiber input and provide excitation to granule cells