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

Abstract

Animals 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.

Ultrasound Stimulations Induce Prolonged Depolarization and Fast Action Potentials in Leech Neurons

“…More specifically, a possible explanation to the different sensitivity to US of P and N cells could lie on the recent finding of frequency specificity of the classes of mechanosensory neurons in the leech [33] . In this work the authors find that N cells are effectively low-pass filtering voltage oscillations while P cells act as high pass filters.…”

Pharmacological or genetic inhibition ofScn9aprotects beta-cells while reducing insulin secretion in type 1 diabetes

“…It has been suggested that excitotoxicity may be a contributing factor to pancreatic β-cell failure, in both type 1 diabetes and type 2 diabetes 69,70 . Interestingly, we observed an increase in action potential frequency and a decrease in AP firing threshold in Scn9a KO β-cells, indicating that these cells have increased excitability by some definititions 72 . Elevation in the intracellular Ca 2+ concentration has been found in rat islets, exposed to prolonged high glucose 71 , and mice with dysfunctional K ATP channels exhibiting chronic, continuous action potential firing 5 .…”

The interaction between nervous and secretory functions in the integrative activity of the neurosecretory Retzius cell of the leech

“…При сильном болевом воздействии на стенку тела животного N-механочувствительные нейроны генерируют низкочастотные спайки от 0,5 до 2 Гц. Слабое давление или поглаживание вызывает активацию механосенсорных клеток T-типа, генерирующих высокочастотные разряды от 5 до 12 Гц, механосенсорные нейроны P-типа генерируют разряды средней частоты (Fischer et al 2017). Поскольку НР имеет синаптическую связь с механосенсорными нейронами (De-Miguel, Nicholls 2015;Fischer et al 2017;De-Miguel, Trueta 2005), то, следовательно, и in vivo он может получать раздражающее воздействие самой различной частоты, тесно связанной с жизнедеятельностью животного.…”