Spontaneous firing in primary afferent neurons of ampullary electroreceptor organs as attribute of bandwidth, threshold, and topology

2008 ◽  
Vol 58 (3) ◽  
pp. 301-312
Author(s):  
Franklin Bretschneider ◽  
Robert Peters ◽  
Lonneke Eeuwes
Keyword(s):  
Firing Rate ◽  
Carrier Frequency ◽  
Signal To Noise Ratio ◽  
Phase Locking ◽  
Spontaneous Firing ◽  
Sensory Stimuli ◽  
Firing Rates ◽  
Coefficients Of Variation ◽  
Electrical Stimuli ◽  
Spontaneous Firing Rate

AbstractSpontaneous firing of neurons plays an essential part in the detection of sensory stimuli. Spontaneous firing of primary afferents of ampullary electroreceptor organs in the catfish Ameiurus nebulosus (Lesueur, 1819) was studied in relation to the distribution, thresholds, and frequency characteristics of the electroreceptor organs. The spontaneous firing rate was correlated with the place on the skin. The mean inter-spike interval in 55 dorsal and 49 ventral ampullary organs in five specimens was 16.8 ms +/- 0.41 SEM and 20.5 ms +/- 0.48 SEM, corresponding to firing rates of 59.5 and 48.7 s-1 respectively. The concomitant coefficients of variation were 0.33 and 0.29. Approximately half of the dorsal ampullae were innervated by two fibres. The firing rates of each of the two fibres was lower than the firing rate of organs innervated by a single neuron. Responses to stimuli as weak as 10 pA could be recovered from the noisy average firing level provided the number of averaging sweeps was sufficiently large. This was equivalent to a stimulus of 0.025 μV/cm and was lower than the behavioural threshold of 1 μV/cm. The gain of the frequency response was enhanced at the carrier frequency, at twice the carrier frequency, and in the range from 75-90 Hz. The results revealed that the occurrence of spontaneous activity improved the signal to noise ratio of responses to electrical stimuli by reduction of the coefficient of variation, absence of a threshold, and phase locking.

scholarly journals Effects of Repeated Cold Stress on Activity of Hypothalamic Neurons in Rats During Performance of Operant Licking Task

2000 ◽  
Vol 84 (6) ◽  
pp. 2844-2858 ◽  
Author(s):  
Ryoi Tamura ◽  
Takashi Kondoh ◽  
Taketoshi Ono ◽  
Hisao Nishijo ◽  
Kunio Torii
Keyword(s):  
Cold Stress ◽  
Firing Rate ◽  
Inhibitory Response ◽  
Specific Pattern ◽  
Neuron Activity ◽  
Stressed Condition ◽  
Spontaneous Firing ◽  
Hypothalamic Area ◽  
Sensory Stimuli ◽  
Spontaneous Firing Rate

The present study investigated the effects of repeated cold stress on single neuron activity in the lateral hypothalamic area (LHA) and medial hypothalamic area (MHA) of behaving rats. The rats were trained to lick a protruding spout in response to one of several cue-tone stimuli (CTSs) to ingest water, or amino acid, NaCl or glucose solution. Following this training, the rats were raised under either stressed (repeated temperature changes between −3 and 24°C) or control (24°C) condition for 2 mo. During this period, neuronal activity was recorded in the LHA and MHA. For rats raised under the stressed condition, mean spontaneous firing rate of LHA neurons was significantly greater than for rats under the control condition. More LHA neurons in the stressed rats responded, with an accompanying decrease in activity (inhibitory response), to CTSs than in the control rats. During extinction learning, some LHA neurons enhanced or reversed the responses to CTSs in the stressed rats, whereas no LHA neurons showed such response changes in the control rats. In contrast to the effects of the stressed condition on LHA neuron activity, mean spontaneous firing rate of MHA neurons in the stressed rats was significantly smaller than in the control rats. Fewer MHA neurons in the stressed rats responded to CTSs and/or ingestion of sapid solutions. The preceding results suggested that repeated cold stress produces a specific pattern of changes in spontaneous activity and responses to sensory stimuli in LHA and MHA neurons; this could underlie the behavioral changes induced by repeated cold stress such as hyperphagia and hyper-reactivity to sensory stimuli.

Central representation of arrival of nutrient in the duodenum

1984 ◽  
Vol 246 (6) ◽  
pp. G750-G756 ◽  
Author(s):  
W. R. Ewart ◽  
D. L. Wingate
Keyword(s):  
Firing Rate ◽  
Nucleus Tractus Solitarius ◽  
Isotonic Saline ◽  
Gastric Distension ◽  
Spontaneous Firing ◽  
Firing Rates ◽  
Pass Perfusion ◽  
The Central Nervous System ◽  
Central Representation ◽  
Spontaneous Firing Rate

This study was carried out to assess the extent to which the appearance of a nutrient (D-glucose) in the duodenum of the anesthetized rat is signaled within the medulla. Recordings were made from single neurons in the region of the dorsal vagal nucleus and the nucleus tractus solitarius during constant single-pass perfusion of the duodenum with isotonic saline or D-glucose at 37 degrees C. In some experiments, the response of medullary neurons to acute gastric distension was also recorded. Of the 41 spontaneously firing neurons that were studied, 20 showed changes in firing rate when glucose replaced saline in the duodenal perfusate, 9 showed decreasing firing rates, and 11 showed increased firing rates. The spontaneous firing rate of glucose-sensitive neurons was significantly slower than that of glucose-insensitive neurons. In 14 neurons tested with both glucose perfusion and gastric distension, 6 responded to only one of the two stimuli, while only 2 responded to both. It is clear that the arrival of nutrient within the duodenum is rapidly signaled within the central nervous system, suggesting the possibility of neural as well as humoral modulation of the physiological changes seen on feeding.

Projection neurons of the lateral amygdaloid nucleus are virtually silent throughout the sleep--waking cycle

1996 ◽  
Vol 75 (3) ◽  
pp. 1301-1305 ◽  
Author(s):  
H. Gaudreau ◽  
D. Pare
Keyword(s):  
Firing Rate ◽  
Slow Wave Sleep ◽  
Paradoxical Sleep ◽  
Discharge Rate ◽  
Projection Neurons ◽  
Amygdaloid Nucleus ◽  
Average Firing Rate ◽  
Sensory Stimuli ◽  
Firing Rates ◽  
Lateral Nucleus

1. Amygdala neurons were recorded extracellularly during the sleep-waking cycle in chronically implanted cats. Neurons were identified as projection cells when they could be antidromically invaded from the perirhinal and/or entorhinal cortices. 2. In contrast with other nuclei of the amygdala, few spontaneously active neurons were encountered in the lateral nucleus. However, when hunting stimuli were applied to the parahippocampal cortices, we noticed the presence of numerous projection cells that would have otherwise remained undetected because they had little or no spontaneous activity. 3. In the states of waking, slow-wave sleep, and paradoxical sleep, the discharge rate of antidromically invaded neurons averaged 0.09 +/- 0.07 Hz (mean +/- SE) with 82% of cells firing at < 0.01 Hz in all states. However, they transiently increased their firing rate when cats were presented complex sensory stimuli, which apparently were specific to each cell. In contrast to projection cells, spontaneously active neurons of the lateral nucleus that could not be backfired from the parahippocampal cortices had an average firing rate of 4.34 +/- 1.15 Hz with 38% of cells firing at > or = 6 Hz in at least one state. 4. These results on the extremely low firing rates of identified projection cells suggest that previous extracellular studies of lateral amygdaloid neurons were biased toward a class of spontaneously active cells which probably includes local-circuit cells.

Spontaneous firing rate of neurones in the prefrontal cortex of the rat: evidence for a dopaminergic inhibition

1976 ◽  
Vol 116 (3) ◽  
pp. 516-522 ◽  
Author(s):  
F. Mora ◽  
K.F. Sweeney ◽  
E.T. Rolls ◽  
A.M. Sanguinetti
Keyword(s):  
Prefrontal Cortex ◽  
Firing Rate ◽  
Spontaneous Firing ◽  
Spontaneous Firing Rate

Neurodepressing Hormone (Ndh): Fact or Fiction?

Crustaceana ◽  
1996 ◽  
Vol 69 (1) ◽  
pp. 1-18 ◽  
Author(s):  
Alberto Huberman
Keyword(s):  
Molecular Weight ◽  
Firing Rate ◽  
Low Molecular Weight ◽  
Spontaneous Firing ◽  
Sinus Gland ◽  
Spontaneous Firing Rate

AbstractExtracts of the crustacean eyestalk, and particularly of the sinus gland, produce an inhibition of the spontaneous firing rate of motor and sensitive neurons in two different bioassays. This activity can be ascribed to a molecule of low molecular weight, neutral, non-peptidic, soluble in water and methanol, thermostable, different from GABA but suppressed by picrotoxin. Its nature remains to be elucidated.

scholarly journals Quantitative Properties of the Creation and Activation of a Cell-Intrinsic Engram

2020 ◽  
Author(s):  
C.R. Gallistel ◽  
Fredrik Johansson ◽  
Dan-Anders Jirenhed ◽  
Anders Rasmussen ◽  
Matthew Ricci ◽  
...  
Keyword(s):  
Interstimulus Interval ◽  
Interspike Interval ◽  
Spontaneous Firing ◽  
Eyeblink Response ◽  
Trial Analysis ◽  
Coefficients Of Variation ◽  
Single Spike ◽  
A Cell ◽  
The One ◽  
Spontaneous Firing Rate

AbstractThe conditional pause in the spontaneous firing of the cerebellar Purkinje, which determines the timing of the conditional eyeblink response, is mediated by a cell-intrinsic engram (Johansson, et al. 2014) that encodes the interstimulus interval. Our trial-by-trial analysis of the pause parameters reveals that it consists of a single unusually long interspike interval, whose onset and offset latencies are stochastically independent scalar functions of the interstimulus interval. The coefficients of variation are comparable to those observed in the timing of the overt conditional eyeblink. The onsets of the long interspike interval are step changes; there is no prior build-up of inhibition. A single spike volley in the parallel fiber input triggers the read-out of the engram into the long interspike interval; subsequent volleys have no effect on the pause. The high spontaneous firing rate on which the one-interval firing pause supervenes is markedly non-stationary (Fano factors >> 1).

scholarly journals Regulation of Neuronal Function by Choline and 4OH-GTS-21 Through α7 Nicotinic Receptors

2003 ◽  
Vol 89 (4) ◽  
pp. 1797-1806 ◽  
Author(s):  
Vladimir V. Uteshev ◽  
Edwin M. Meyer ◽  
Roger L. Papke
Keyword(s):  
Firing Rate ◽  
Direct Action ◽  
Choline Uptake ◽  
Spontaneous Firing ◽  
Α7 Nicotinic Acetylcholine Receptor ◽  
Physiological Concentration ◽  
Α7 Nachr ◽  
Synaptic Functions ◽  
Neuronal Functions ◽  
Spontaneous Firing Rate

A unique feature of α7 nicotinic acetylcholine receptor physiology is that, under normal physiological conditions, α7 receptors are constantly perfused with their natural selective agonist, choline. Studying neurons of hypothalamic tuberomammillary (TM) nucleus, we show that choline and the selective α7 receptor agonist 4OH-GTS-21 can regulate neuronal functions directly, via activation of the native α7 receptors, and indirectly, via desensitizing those receptors or transferring them into a state “primed” for desensitization. The direct action produces depolarization and thereby increases the TM neuron spontaneous firing (SF) rate. The regulation of the spontaneous firing rate is robust in a nonphysiological range of choline concentrations >200 μM. However, modest effects persist at concentrations of choline that are likely to be attained perineuronally under some conditions (20–100 μM). At high physiological concentration levels, the indirect choline action reduces or even eliminates the responsiveness of α7 receptors and their availability to other strong cholinergic inputs. Similarly to choline, 4OH-GTS-21 increases the TM neuron spontaneous firing rate via activation of α7 receptors, and this regulation is robust in the range of clinically relevant concentrations of 4OH-GTS-21. We conclude that factors that regulate choline accumulation in the brain and in experimental slices such as choline uptake, hydrolysis of ACh, membrane phosphatidylcholine catabolism, and solution perfusion rate influence α7 nAChR neuronal and synaptic functions, especially under pathological conditions such as stroke, seizures, Alzheimer's disease, and head trauma, when the choline concentration in the CSF is expected to rise.

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