ArticleJournal of neurophysiology2014
Axon diameters and conduction velocities in the macaque pyramidal tract.
Article in Journal of neurophysiology, 2014. The graph could read no effect estimate from its abstract, so it casts no vote on the map. Cited by 59 papers.
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Who cites it
59 citing papers in PubMed, 114 citations in OpenAlex.
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- Histologically Informed Multiscale Modeling of the Neuronal Elements Activated by TMS.bioRxiv : the preprint server for biology · 2026Article
- Axon Diameter Mapping in the Living Human Brain with Ultra-High-Gradient Diffusion MRI at 500 mT/m Gradient Strength.Human brain mapping · 2026Article
- Self-assembling scaffolds epigenetically reactivate and electroactively guide neuronal regeneration to restore central neural circuits.Nature communications · 2026Article
- Clinical utility of evoked potentials for programming subthalamic deep brain stimulation in Parkinsons disease.NPJ Parkinson's disease · 2026Review
- Gender Differences in Nerve Conduction Parameters of Upper Limb Nerves in Healthy Adults: A Comparative Study.Journal of pharmacy & bioallied sciences · 2025Article
- Neurons Are Not All the Same: Diversity in Neuronal Populations and Their Intrinsic Responses to Spinal Cord Injury.ASN neuro · 2025Review
- Revisiting Glutamate Excitotoxicity in Amyotrophic Lateral Sclerosis and Age-Related Neurodegeneration.International journal of molecular sciences · 2024Review
- Visual Corticotectal Neurons in Awake Rabbits: Receptive Fields and Driving Monosynaptic Thalamocortical Inputs.The Journal of neuroscience : the official journal of the Society for Neuroscience · 2024Article
- Subcallosal cingulate deep brain stimulation evokes two distinct cortical responses via differential white matter activation.Proceedings of the National Academy of Sciences of the United States of America · 2024Article
- Coupled Activation of the Hyperdirect and Cerebellothalamic Pathways with Zona Incerta Deep Brain Stimulation.Movement disorders : official journal of the Movement Disorder Society · 2024Article
- Terminal organization of the corticospinal projection from the arm/hand region of the rostral primary motor cortex (M1r or old M1) to the cervical enlargement (C5-T1) in rhesus monkey.The Journal of comparative neurology · 2023Article
- Identifying spinal tracts transmitting distant effects of trans-spinal magnetic stimulation.Journal of neurophysiology · 2023Article
- Causally informed activity flow models provide mechanistic insight into network-generated cognitive activations.NeuroImage · 2023Article
- The evidence against somatotopic organization of function in the primate corticospinal tract.Brain : a journal of neurology · 2023Review
- Evolving characterization of the human hyperdirect pathway.Brain structure & function · 2023Review
- Linking cortex and contraction-Integrating models along the corticomuscular pathway.Frontiers in physiology · 2023Article
- The Existence of the StartReact Effect Implies Reticulospinal, Not Corticospinal, Inputs Dominate Drive to Motoneurons during Voluntary Movement.The Journal of neuroscience : the official journal of the Society for Neuroscience · 2022Article
- The periodic axon membrane skeleton leads to Na nanodomains but does not impact action potentials.Biophysical journal · 2022Article
- Stability and Effect of Parkinsonian State on Deep Brain Stimulation Cortical Evoked Potentials.Neuromodulation : journal of the International Neuromodulation Society · 2022Article
Corrections and comments
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Authors and funding
8 authors at 4 institutions in 3 countries.
Funding
Abstract
Small axons far outnumber larger fibers in the corticospinal tract, but the function of these small axons remains poorly understood. This is because they are difficult to identify, and therefore their physiology remains obscure. To assess the extent of the mismatch between anatomic and physiological measures, we compared conduction time and velocity in a large number of macaque corticospinal neurons with the distribution of axon diameters at the level of the medullary pyramid, using both light and electron microscopy. At the electron microscopic level, a total of 4,172 axons were sampled from 2 adult male macaque monkeys. We confirmed that there were virtually no unmyelinated fibers in the pyramidal tract. About 14% of pyramidal tract axons had a diameter smaller than 0.50 μm (including myelin sheath), most of these remaining undetected using light microscopy, and 52% were smaller than 1 μm. In the electrophysiological study, we determined the distribution of antidromic latencies of pyramidal tract neurons, recorded in primary motor cortex, ventral premotor cortex, and supplementary motor area and identified by pyramidal tract stimulation (799 pyramidal tract neurons, 7 adult awake macaques) or orthodromically from corticospinal axons recorded at the mid-cervical spinal level (192 axons, 5 adult anesthetized macaques). The distribution of antidromic and orthodromic latencies of corticospinal neurons was strongly biased toward those with large, fast-conducting axons. Axons smaller than 3 μm and with a conduction velocity below 18 m/s were grossly underrepresented in our electrophysiological recordings, and those below 1 μm (6 m/s) were probably not represented at all. The identity, location, and function of the majority of corticospinal neurons with small, slowly conducting axons remains unknown.
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Registered trials
Read under generation 80e0d062 · epoch 390. Bibliography from PubMed, PubMed Central and OpenAlex; grants from NIH RePORTER; trial links from ClinicalTrials.gov; estimates, votes and beliefs from the OpenQuestion graph.