Action-Potential Modulation During Axonal Conduction

• Published in: Science (American Association for the Advancement of Science) Vol. 331; no. 6017; pp. 599 - 601
• Main Authors: Sasaki, Takuya, Matsuki, Norio, Ikegaya, Yuji
• Format: Journal Article
• Language: English
• Published: Washington, DC American Association for the Advancement of Science 04.02.2011; The American Association for the Advancement of Science
• Subjects: action potentials; Action Potentials - drug effects; adenosine; Adenosine - metabolism; Adenosine - pharmacology; Adenosine A1 Receptor Antagonists - pharmacology; Animals; antagonists; Astrocytes; Astrocytes - metabolism; Axons; Axons - drug effects; Axons - physiology; Biological and medical sciences; Boluses; Brain; CA3 Region, Hippocampal - cytology; CA3 Region, Hippocampal - physiology; Calcium; Calcium - metabolism; Cellular biology; Employee assistance programs; Excavation; Excitatory Postsynaptic Potentials; fluorescence; Fundamental and applied biological sciences. Psychology; gamma-Aminobutyric Acid - pharmacology; geometry; glutamate receptors; glutamic acid; Glutamic Acid - pharmacology; In Vitro Techniques; Neurobiology; Neurons; Neuroscience; Patch-Clamp Techniques; Pipettes; Potassium Channels - metabolism; Presynaptic Terminals - physiology; Pyramidal Cells - physiology; Rats; Rats, Wistar; Receptor, Adenosine A1 - metabolism; Receptors; Receptors, AMPA - metabolism; Synaptic Transmission; travel; Vertebrates: nervous system and sense organs; Waveforms; Xanthines - pharmacology; Waveform; Human; Conduction; Neuroglia; Central nervous system; Electrophysiology; A1 Adenosine receptor; Axon; Patch clamp method; Action potential; Glutamate receptor; Encephalon; Thought; Ex vivo; Antagonist; Pyramidal neuron; Hippocampus
• ISSN: 0036-8075; 1095-9203; 1095-9203
• DOI: 10.1126/science.1197598

Once initiated near the soma, an action potential (AP) is thought to propagate autoregeneratively and distribute uniformly over axonal arbors. We challenge this classic view by showing that APs are subject to waveform modulation while they travel down axons. Using fluorescent patch-clamp pipettes, we recorded APs from axon branches of hippocampal CA3 pyramidal neurons ex vivo. The waveforms of axonal APs increased in width in response to the local application of glutamate and an adenosine A₁ receptor antagonist to the axon shafts, but not to other unrelated axon branches. Uncaging of calcium in periaxonal astrocytes caused AP broadening through ionotropic glutamate receptor activation. The broadened APs triggered larger calcium elevations in presynaptic boutons and facilitated synaptic transmission to postsynaptic neurons. This local AP modification may enable axonal computation through the geometry of axon wiring.