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Updated: May 28, 2026
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Ballistic Labeling of Pyramidal Neurons in Brain Slices and in Primary Cell Culture
Published on: April 2, 2020
Large identified pyramidal cells in macaque motor and premotor cortex exhibit "thin spikes": implications for cell
Ganesh Vigneswaran1, Alexander Kraskov, Roger N Lemon
1Sobell Department of Motor Neuroscience and Movement Disorders, UCL Institute of Neurology, London WC1N 3BG, United Kingdom.
Summary
Cortical pyramidal tract neurons (PTNs) exhibit varied spike durations, challenging their use as a sole cell type identifier. Shorter spikes correlate with faster axon conduction, not necessarily interneuron identity.
Area of Science:
- Neuroscience
- Cellular Electrophysiology
Background:
- Extracellular recordings suggest distinct spike durations differentiate cortical interneurons from pyramidal neurons.
- This distinction has been proposed as a method for identifying cortical cell types in awake monkey recordings.
Purpose of the Study:
- To investigate the relationship between antidromic latency and spike duration in pyramidal tract neurons (PTNs).
- To determine if spike duration alone is a reliable indicator of cortical cell type.
Main Methods:
- Extracellular recordings of antidromically identified PTNs from primary motor cortex (M1) and ventral premotor cortex (area F5) in 4 awake macaque monkeys.
- Measurement of spike duration from negative trough to positive peak, with a high-pass filter of 300 Hz.
- Analysis of antidromic latencies (ADLs) and their correlation with spike duration.
Main Results:
- PTN ADLs differed significantly between M1 (median 1.1 ms) and F5 (median 2.6 ms).
- Spike durations ranged from 0.15 to 0.71 ms.
- A significant positive linear correlation was found between ADL and spike duration in both M1 (R² = 0.40) and F5 (R² = 0.57), indicating faster-conducting axons correlate with briefer spikes.
Conclusions:
- Pyramidal tract neurons display a wide spectrum of spike durations.
- Spike duration alone is not a reliable indicator for distinguishing cortical cell types, as short durations overlap with those of putative interneurons.
