### Abstract

The instantaneous frequency display of single unit discharges provides a useful measure of neuronal activities. Such a device must produce voltage outputs proportional to the reciprocal of each inter-spike interval by on-line computation of the hyperbola of V = a/t. Segment approximation of the required hyperbola can be made by a series of exponential functions which increase in time constants by a factor of m. Numerical analysis of a normalized function indicates possible error maxima of 3.4, 2.4 and 1.1% for m of 2, 1.8 and 1.5, respectively. This prediction is fully confirmed by the actual performance where m of 1.5 is adopted. The test circuit combines only readily available ICs and other components, to give a linear F-V conversion over a dynamic range of 4-600 Hz with error maxima of approximately 1%. The outputs are square pulses of approximately 1.5 ms in duration through the use of a flexible sample-hold circuit. Compared with that of earlier models, this display mode gives better photographic records with the base-line in simultaneous multi-trace display. Simple and systematic methods are described for designing a circuit to one's own specifications, and also for compensating for component variations.

Original language | English |
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Pages (from-to) | 89-98 |

Number of pages | 10 |

Journal | Journal of Neuroscience Methods |

Volume | 7 |

Issue number | 1 |

DOIs | |

Publication status | Published - 1983 Jan |

### Keywords

- instantaneous frequency
- nerve impulse
- reciprocal time-interval
- sample-hold
- segment approximation

### ASJC Scopus subject areas

- Neuroscience(all)

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## Cite this

*Journal of Neuroscience Methods*,

*7*(1), 89-98. https://doi.org/10.1016/0165-0270(83)90022-5