Intrinsic frequency response patterns in mechano-sensory neurons of the leech.

Linda Fischer,Felix Felmy,Frank Scherbarth,Boris Chagnaud

doi:10.1242/bio.023960

Linda Fischer, Felix Felmy + Show 2 more

Open Access

https://doi.org/10.1242/bio.023960

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Abstract

ABSTRACTAnimals employ mechano-sensory systems to detect and explore their environment. Mechano-sensation encompasses stimuli such as constant pressure, surface movement or vibrations at various intensities that need to be segregated in the central nervous system. Besides different receptor structures, sensory filtering via intrinsic response properties could provide a convenient way to solve this problem. In leech, three major mechano-sensory cell types can be distinguished, according to their stimulus sensitivity, as nociceptive, pressure and touch cells. Using intracellular recordings, we show that the different mechano-sensory neuron classes in Hirudo medicinalis differentially respond supra-threshold to distinct frequencies of sinusoidal current injections between 0.2 and 20 Hz. Nociceptive cells responded with a low-pass filter characteristic, pressure cells as high-pass filters and touch cells as an intermediate band-pass filter. Each class of mechano-sensory neurons is thus intrinsically tuned to a specific frequency range of voltage oscillation that could help segregate mechano-sensory information centrally.

Highlights

Mechano-sensory systems inform animals about the physical nature of their surroundings
Stimulation frequency is obtained (Fig. 1E). This analysis showed that N-cells only responded with multiple action potentials to sinestimulations
The P cell response dropped by only 25% (Fig. 3G) at a stimulation frequency of 20 Hz. These results indicated that P cell membrane properties can be regarded as acting as an intrinsic high-pass filter

Summary

Introduction

Mechano-sensory systems inform animals about the physical nature of their surroundings. 2016) the different mechanical stimulation intensities potentially generate overlapping activity within the leech central neuronal network and, especially for N and P cells, it is unclear how activity is segregated. RESULTS AND DISCUSSION The intrinsic response characteristics of the three main types of mechano-sensory neuron to sinusoidal current injections at frequencies between 0.2 and 20 Hz were investigated in Hirudo medicinalis.

Results

Conclusion