Axon Diameters in Relation to the Spike Dimensions and the Conduction Velocity in Mammalian a Fibers

Gasser, Herbert S.; Grundfest, Harry

doi:10.1152/ajplegacy.1939.127.2.393

Cited by 440 publications

(166 citation statements)

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“…axons of the rat is 1.1 pm2 at a level equivalent to that of the present study. This area corresponds to an equivalent diameter of 1.2 pm (Price & Sprich, 1975 (Gasser & Grundfest, 1939;Waxman & Bennett, 1972 Richards & Sercombe, 1968;1970). When pentobarbitone (0.…”

Section: Resultsmentioning

confidence: 99%

The Actions of Pentobarbitone, Procaine and Tetrodotoxin on Synaptic Transmission in the Olfactory Cortex of the Guinea‐pig

Richards

1982

British J Pharmacology

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1 It has been suggested that the depression of excitatory synaptic potentials produced by general anaesthetics can be attributed to°la partial blockade of impulse conduction in the terminal branches of axons. This hypothesis has been tested by comparing the actions of pentobarbitone, procaine and tetrodotoxin (TTX) on synaptic transmission in the guinea-pig olfactory cortex. 2 Pentobarbitone (0.1-0.3 mM) depressed the evoked synaptic potentials without any significant depression of impulse conduction in the afferent fibres of the lateral olfactory tract (l.o.t.). It had no effect on the electrical excitability of either the l.o.

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Section: Resultsmentioning

confidence: 99%

The Actions of Pentobarbitone, Procaine and Tetrodotoxin on Synaptic Transmission in the Olfactory Cortex of the Guinea‐pig

Richards

1982

British J Pharmacology

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“…The extracellular current flow does indeed vary from one recording site to another as a direct function of neuronal size (Nelson 1966), and the magnitude of axonal spikes directly correlates with the size of the transmitting axon (Gasser & Grundfest 1939;Hunt 1951). Furthermore, it has been shown that fast activity (i.e.…”

Section: (Iv) Origin Of Lfp and Mua: Experimental Evidencementioning

confidence: 99%

The neural basis of the blood–oxygen–level–dependent functional magnetic resonance imaging signal

Logothetis

2002

Phil. Trans. R. Soc. Lond. B

819

516

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Magnetic resonance imaging (MRI) has rapidly become an important tool in clinical medicine and biological research. Its functional variant (functional magnetic resonance imaging; fMRI) is currently the most widely used method for brain mapping and studying the neural basis of human cognition. While the method is widespread, there is insufficient knowledge of the physiological basis of the fMRI signal to interpret the data confidently with respect to neural activity. This paper reviews the basic principles of MRI and fMRI, and subsequently discusses in some detail the relationship between the blood-oxygenlevel-dependent (BOLD) fMRI signal and the neural activity elicited during sensory stimulation. To examine this relationship, we conducted the first simultaneous intracortical recordings of neural signals and BOLD responses. Depending on the temporal characteristics of the stimulus, a moderate to strong correlation was found between the neural activity measured with microelectrodes and the BOLD signal averaged over a small area around the microelectrode tips. However, the BOLD signal had significantly higher variability than the neural activity, indicating that human fMRI combined with traditional statistical methods underestimates the reliability of the neuronal activity. To understand the relative contribution of several types of neuronal signals to the haemodynamic response, we compared local field potentials (LFPs), single-and multi-unit activity (MUA) with high spatio-temporal fMRI responses recorded simultaneously in monkey visual cortex. At recording sites characterized by transient responses, only the LFP signal was significantly correlated with the haemodynamic response. Furthermore, the LFPs had the largest magnitude signal and linear systems analysis showed that the LFPs were better than the MUAs at predicting the fMRI responses. These findings, together with an analysis of the neural signals, indicate that the BOLD signal primarily measures the input and processing of neuronal information within a region and not the output signal transmitted to other brain regions.

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“…Spikes produced by the synchronous firings of many cells can, in principle, be enhanced by summation and thus detected over a larger distance (Arezzo et al 1979;Huang and Buchwald 1977). In general, experiments have shown that large-amplitude signal variations in the MUA range reflect large-amplitude extracellular potentials and that small-amplitude fast activity is correlated with small ones (Buchwald and Grover 1970;Gasser and Grundfest 1939;Grover and Buchwald 1970;Hunt 1951;Nelson 1966).…”

Section: Introductionmentioning

confidence: 99%

Inferring Spike Trains From Local Field Potentials

Rasch¹,

Gretton²,

Murayama³

et al. 2008

Journal of Neurophysiology

205

200

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We investigated whether it is possible to infer spike trains solely on the basis of the underlying local field potentials (LFPs). Using support vector machines and linear regression models, we found that in the primary visual cortex (V1) of monkeys, spikes can indeed be inferred from LFPs, at least with moderate success. Although there is a considerable degree of variation across electrodes, the low-frequency structure in spike trains (in the 100-ms range) can be inferred with reasonable accuracy, whereas exact spike positions are not reliably predicted. Two kinds of features of the LFP are exploited for prediction: the frequency power of bands in the high ␥-range (40 -90 Hz) and information contained in lowfrequency oscillations (Ͻ10 Hz), where both phase and power modulations are informative. Information analysis revealed that both features code (mainly) independent aspects of the spike-to-LFP relationship, with the low-frequency LFP phase coding for temporally clustered spiking activity. Although both features and prediction quality are similar during seminatural movie stimuli and spontaneous activity, prediction performance during spontaneous activity degrades much more slowly with increasing electrode distance. The general trend of data obtained with anesthetized animals is qualitatively mirrored in that of a more limited data set recorded in V1 of non-anesthetized monkeys. In contrast to the cortical field potentials, thalamic LFPs (e.g., LFPs derived from recordings in the dorsal lateral geniculate nucleus) hold no useful information for predicting spiking activity.

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Axon Diameters in Relation to the Spike Dimensions and the Conduction Velocity in Mammalian a Fibers

Cited by 440 publications

References 1 publication

The Actions of Pentobarbitone, Procaine and Tetrodotoxin on Synaptic Transmission in the Olfactory Cortex of the Guinea‐pig

The Actions of Pentobarbitone, Procaine and Tetrodotoxin on Synaptic Transmission in the Olfactory Cortex of the Guinea‐pig

The neural basis of the blood–oxygen–level–dependent functional magnetic resonance imaging signal

Inferring Spike Trains From Local Field Potentials

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