Relation between the slope of the rate‐level curve, the maximum driven firing‐rate, and the neuronal dynamic range in auditory primary afferents of the cat

2001 ◽  
Vol 109 (5) ◽  
pp. 2349-2349 ◽  
Author(s):  
Lance Nizami ◽  
JoAnn McGee ◽  
Edward J. Walsh
Keyword(s):  
Firing Rate ◽  
Dynamic Range ◽  
Primary Afferents ◽  
Level Curve ◽  
Rate Level ◽  
Neuronal Dynamic

Rate-level functions of neurons in the inferior colliculus of cats measured with the use of free-field sound stimuli

1991 ◽  
Vol 65 (2) ◽  
pp. 383-392 ◽  
Author(s):  
L. Aitkin
Keyword(s):  
Firing Rate ◽  
Inferior Colliculus ◽  
Dynamic Range ◽  
Discharge Rate ◽  
Free Field ◽  
Peak Level ◽  
Stimulus Level ◽  
Sound Level ◽  
Acoustic Stimuli ◽  
Rate Level

1. The responses as a function of stimulus level of 125 single units in the inferior colliculus of anesthetized cats were studied with the use of free-field acoustic stimuli. 2. The characteristic frequency (CF; frequency at which threshold was lowest) of each unit was determined, and stimuli were presented from one of three speaker positions: 45 degrees contralateral to the midline, midline, and 45 degrees ipsilateral to the midline. 3. For each unit a variety of stimulus levels was presented at CF, and the total spike count was summed for 20 stimuli at each level. If time permitted, a similar series of levels of noise was presented. 4. Four classes of rate-level (RL) functions were observed. Monotonic increases in firing rate were observed in 10% of units stimulated with CF stimuli and 57% of units studied with noise. Nonmonotonic RL functions, for which firing first increased and then declined to less than 50% of the peak level, were observed in 61% of units responding to CF tones and in 10% responding to noise. Plateau functions, with shapes lying between these, accounted for 19% of CF responses and the remaining units excited by noise. Some very complex shapes that could not be categorized into the above groups were seen in the remaining 10% of the units responding to CF stimuli. 5. The RL functions of units studied with both noise and CF tones could belong to different classes; commonly, nonmonotonic RL functions to tones were associated with monotonic RL functions to noise. The noise thresholds averaged 10 dB, some 10-20 dB less sensitive than those to CF stimuli. 6. For the vast majority of both noise and tone responses, stimuli from the contralateral location were more effective than those from the other two positions in terms of a lower threshold, higher peak discharge rate, and, for nonmonotonic units, a lower sound level at which the function became nonmonotonic (turnover point). 7. The turnover points of nonmonotonic functions at any given CF could be spread broadly but, overall, tended to be concentrated between -6 and 44 dB. 8. The dynamic ranges (range of levels over which firing rate increased) were larger for monotonic and plateau functions than for nonmonotonic functions, which had dynamic ranges less than 45 dB. The median dynamic range for units stimulated with CF tones was 20 dB and for noise stimuli, 40 dB.(ABSTRACT TRUNCATED AT 400 WORDS)

Similarity of dynamic range adjustment in auditory nerve and cochlear nuclei

1985 ◽  
Vol 53 (4) ◽  
pp. 940-958 ◽  
Author(s):  
D. J. Gibson ◽  
E. D. Young ◽  
J. A. Costalupes
Keyword(s):  
Auditory Nerve ◽  
Dynamic Range ◽  
Mean Value ◽  
Background Intensity ◽  
Rate Level ◽  
Saturation Intensity ◽  
Type Iv ◽  
Cochlear Nuclei ◽  
The Mean ◽  
Continuous Noise

Rate versus level functions were recorded for responses to best-frequency (BF) tones of 116 cochlear nucleus units and 53 auditory-nerve fibers in the presence of interrupted tone backgrounds and continuous noise backgrounds of various intensities. The backgrounds shifted the dynamic ranges of rate-level functions to higher test intensities, so in the presence of backgrounds, rate saturation occurred at higher intensities than in quiet. The shift in saturation intensity evoked by each background was measured by comparing the rate-level function recorded with the background to one recorded without. The relation between change in saturation intensity and background intensity could be approximated by the formula (formula: see text) delta Isat is the shift in saturation intensity, I is the background intensity, theta is the threshold for evoking shift, and A is the ratio of shift to background intensity re theta. In the appendix, it is shown that A is a measure of a unit's ability to avoid saturation by the background stimulus. The optimal value of A is unity, at which point a unit's operating range is infinite. The value of A depended on BF for interrupted tone backgrounds, but not for continuous noise backgrounds. For BF less than 10 kHz, the mean value of A for tone backgrounds was 0.33 in the auditory nerve, 0.37 in the ventral cochlear nuclei (VCN), and 0.47 in the dorsal cochlear nucleus (DCN). The difference between auditory nerve and VCN was not statistically significant. For BF greater than 10 kHz, the mean A was 0.16 in auditory nerve and 0.30 in VCN. The mean value of A for noise backgrounds was 0.79 in auditory nerve, 0.86 in VCN, 0.86 in DCN units of response types II and III, and 1.04 in DCN type IV units. Only the differences between DCN type IV and the non-DCN unit groups were statistically significant. The qualitative changes produced in rate-level functions by tone and noise backgrounds were similar in auditory nerve and cochlear nuclei except for DCN type IV units. The shifts in rate functions produced by interrupted tone backgrounds did not prevent saturation of the rate response at background intensities above the dynamic range of the unit as recorded in quiet. However, the rate response to test tones was preserved in the presence of all noise background levels used (up to a 30-dB spectrum level). The shift in rate function produced by the noise was almost sufficient to allow the unit to encode test intensity relative to noise background intensity.(ABSTRACT TRUNCATED AT 400 WORDS)

Analysis of Interspike Interval of Dorsal Horn Neurons Evoked by Different Needle Manipulations at St36

2014 ◽  
Vol 32 (1) ◽  
pp. 43-50 ◽  
Author(s):  
Tao Zhou ◽  
Jiang Wang ◽  
Chun-Xiao Han ◽  
Ishida Torao ◽  
Yi Guo
Keyword(s):  
Firing Rate ◽  
Dorsal Horn ◽  
Neural Coding ◽  
Spinal Dorsal Horn ◽  
Interspike Interval ◽  
Dynamic Range ◽  
Stimulus Frequency ◽  
Electrical Signals ◽  
Spinal Dorsal ◽  
Wdr Neurons

Objectives Previous research has suggested that different manual acupuncture (MA) manipulations may have different physiological effects. Recent studies have demonstrated that neural electrical signals are generated or changed when acupuncture is administered. In order to explore the effects of different MA manipulations on the neural system, an experiment was designed to record the discharges of wide dynamic range (WDR) neurons in the spinal dorsal horn evoked by MA at different frequencies (0.5, 1, 2 and 3 Hz) at ST36. Methods Microelectrode extracellular recordings were used to record the discharges of WDR neurons evoked by different MA manipulations. Approximate firing rate and coefficient of variation of interspike interval (ISI) were used to extract the characteristic parameters of the neural electrical signals after spike sorting, and the neural coding of the evoked discharges by different MA manipulations was obtained. Results Our results indicated that the neuronal firing rate and time sequences of ISI showed distinct clustering properties for different MA manipulations, which could distinguish them effectively. Conclusions The combination of firing rate and ISI codes carries information about the acupuncture stimulus frequency. Different MA manipulations appear to change the neural coding of electrical signals in the spinal dorsal horn through WDR neurons.

Two separate inhibitory mechanisms shape the responses of dorsal cochlear nucleus type IV units to narrowband and wideband stimuli

1994 ◽  
Vol 71 (6) ◽  
pp. 2446-2462 ◽  
Author(s):  
I. Nelken ◽  
E. D. Young
Keyword(s):  
Firing Rate ◽  
Cochlear Nucleus ◽  
Inhibitory Effect ◽  
Broadband Noise ◽  
Dorsal Cochlear Nucleus ◽  
Inhibitory Input ◽  
Inhibitory Influence ◽  
Type Ii ◽  
Rate Level ◽  
Type Iv

1. The principal cells of the dorsal cochlear nucleus (DCN) are mostly inhibited by best frequency (BF) tones but are mostly excited by broadband noise (BBN), producing the so-called type IV response characteristic. The narrowband inhibitory responses can be explained by the inhibitory influence of interneurons with type II response characteristics. However, it is not clear that all the details of the type IV responses can be accounted for by this neural circuit. In particular, many type IV units are inhibited by band-reject noise (notch noise); type II units tend to be only weakly excited by these stimuli, if at all. In this paper we study the relationships between the narrowband, inhibitory and the wideband, excitatory regimens of the type IV responses and present the case for the existence of a second inhibitory source in DCN, called the wideband inhibitor (WBI) below. 2. Type IV units were studied using pure tones, noise bands arithmetically centered on BF, notch noise centered on BF, and BBN. We measured the rate-level function (response rate as function of stimulus level) for each stimulus. This paper is based on the responses of 28 type IV units. 3. Evidence for low-threshold inhibitory input to type IV units is derived from analysis of rate-level functions at sound levels just above threshold. Notch noise stimuli of the appropriate notch width produce inhibition at threshold in this regime. When BBN is presented, this inhibition appears to summate with excitation produced by energy in the band of noise centered on BF, resulting in BBN rate-level functions with decreased slope and maximum firing rate. A range of slopes and maximal firing rates is observed, but these variables are strongly correlated and they are negatively correlated with the strength of the inhibition produced by notch noise; this result supports the conclusion that a single inhibitory source is responsible for these effects. 4. By contrast, there is a weak (nonsignificant) positive correlation between the strength of the inhibitory effect of notch noise and the slope/maximal firing rate in response to narrowband stimuli, including BF tones. The contrast between this positive nonsignificant correlation and the significant negative correlation mentioned above suggests that more than one inhibitory effect operates: specifically, the type II input is responsible for inhibition by narrowband stimuli and a different inhibitory source, the WBI, produces inhibition by notch stimuli. 5. Several lines of evidence are given to show that type II units cannot produce the inhibition seen with notch noise stimuli.(ABSTRACT TRUNCATED AT 400 WORDS)

Proteinase-Activated Receptor-4 (PAR4) Activation Leads to Sensitization of Rat Joint Primary Afferents Via a Bradykinin B2 Receptor-Dependent Mechanism

2010 ◽  
Vol 103 (1) ◽  
pp. 155-163 ◽  
Author(s):  
Fiona A. Russell ◽  
Victoria E. Veldhoen ◽  
Dmitri Tchitchkan ◽  
Jason J. McDougall
Keyword(s):  
Firing Rate ◽  
Transient Receptor Potential ◽  
Receptor Potential ◽  
Receptor Activation ◽  
Primary Afferents ◽  
Knee Joints ◽  
Transient Receptor Potential Vanilloid ◽  
Mechanical Stimuli ◽  
Male Wistar Rats ◽  
Normal Rat

The G-protein-linked receptor, proteinase-activated receptor-4 (PAR4) is activated by proteinases released into the joint during inflammation. It is unclear whether PAR4 has a pro- or anti-nociceptive effect and whether it directly affects nerve activity. In this study, we examined the expression of PAR4 in joints and dorsal root ganglion (DRG) neurons and whether activation of PAR4 has an effect on nociception in normal rat knee joints. Electrophysiological recordings were made from joint primary afferents in male Wistar rats during both nonnoxious and noxious rotations of the knee. Afferent firing rate was recorded for 15 min post close intra-arterial injection of 10−9–10−5 mol of the PAR4 activating peptide, AYPGKF-NH2, or the inactive peptide, YAPGKF-NH2 (100 μl bolus). Rats were either naive or pretreated with the selective PAR4 antagonist, pepducin P4pal-10, the transient receptor potential vanilloid-1 (TRPV1) antagonist, SB366791, or the bradykinin B2 receptor antagonist, HOE140. Immunofluorescence experiments showed extensive PAR4 expression in the knee joint and in sensory neurons projecting from the joint. AYPGKF-NH2 significantly increased joint afferent firing during nonnoxious and noxious rotation of the knee. The inactive control peptide, YAPGKF-NH2 was without effect. Systemic pretreatment with the PAR4 antagonist, pepducin P4pal-10, inhibited the AYPGKF-NH2-induced increase in firing rate. Pretreatment with HOE140, but not SB366791, also blocked this increase in firing rate. These data reveal that in normal rat knee joints, PAR4 activation increases joint primary afferent activity in response to mechanical stimuli. This PAR4-induced sensitization is TRPV1-independent but involves B2 receptor activation, suggesting a role for kinins in this process.

Firing patterns and functional roles of different classes of spinal afferents in rectal nerves during colonic migrating motor complexes in mouse colon

2012 ◽  
Vol 303 (3) ◽  
pp. G404-G411 ◽  
Author(s):  
Vladimir P. Zagorodnyuk ◽  
Melinda Kyloh ◽  
Simon J. Brookes ◽  
Sarah J. Nicholas ◽  
Nick J. Spencer
Keyword(s):  
Firing Rate ◽  
Dynamic Range ◽  
Contractile Activity ◽  
Circular Muscle ◽  
Visceral Afferents ◽  
High Threshold ◽  
Wide Dynamic Range ◽  
Low Threshold ◽  
Spinal Afferents ◽  
Circumferential Stretch

The functional role of the different classes of visceral afferents that innervate the large intestine is poorly understood. Recent evidence suggests that low-threshold, wide-dynamic-range rectal afferents play an important role in the detection and transmission of visceral pain induced by noxious colorectal distension in mice. However, it is not clear which classes of spinal afferents are activated during naturally occurring colonic motor patterns or during intense contractions of the gut smooth muscle. We developed an in vitro colorectum preparation to test how the major classes of rectal afferents are activated during spontaneous colonic migrating motor complex (CMMC) or pharmacologically induced contraction. During CMMCs, circular muscle contractions increased firing in low-threshold, wide-dynamic-range muscular afferents and muscular-mucosal afferents, which generated a mean firing rate of 1.53 ± 0.23 Hz ( n = 8) under isotonic conditions and 2.52 ± 0.36 Hz ( n = 17) under isometric conditions. These low-threshold rectal afferents were reliably activated by low levels of circumferential stretch induced by increases in length (1–2 mm) or load (1–3 g). In a small proportion of cases (5 of 34 units), some low-threshold muscular and muscular-mucosal afferents decreased their firing rate during the peak of the CMMC contractions. High-threshold afferents were never activated during spontaneous CMMC contractions or tonic contractions induced by bethanechol (100 μM). High-threshold rectal afferents were only activated by intense levels of circumferential stretch (10–20 g). These results show that, in the rectal nerves of mice, low-threshold, wide-dynamic-range muscular and muscular-mucosal afferents are excited during contraction of the circular muscle that occurs during spontaneous CMMCs. No activation of high-threshold rectal afferents was detected during CMMCs or intense contractile activity in naïve mouse colorectum.

Dynamic range of neural rate responses in the ventral cochlear nucleus of awake cats

1992 ◽  
Vol 68 (5) ◽  
pp. 1589-1602 ◽  
Author(s):  
B. J. May ◽  
M. B. Sachs
Keyword(s):  
Cochlear Nucleus ◽  
Background Noise ◽  
Dynamic Range ◽  
Broad Band ◽  
Rate Level ◽  
Ventral Cochlear Nucleus ◽  
Band Noise ◽  
Level Function ◽  
Decerebrate Cats ◽  
Awake Cats

1. Response thresholds and dynamic range properties of neurons in the ventral cochlear nucleus (VCN) of awake cats were measured by fitting a computational model to rate-level functions for best frequency (BF) tone bursts and for bursts of broad-band noise. Dynamic range measurements were performed in quiet and in the presence of continuous background noise. 2. The sample of neurons obtained in the VCN of awake cats exhibited a variety of peristimulus histograms (PSTHs) and thresholds. All PSTH response types previously described in the VCN of anesthetized cats were found in awake cats. The lowest thresholds for neural responses were observed at sound pressure levels that were equivalent to behavioral thresholds of absolute auditory sensitivity. 3. When responses to BF tones or bursts of broad-band noise were recorded in quiet backgrounds, the dynamic range properties of most units in the VCN of awake cats were not significantly different from dynamic range properties of auditory nerve fibers (ANFs) in anesthetized cats or VCN units in decerebrate cats. All auditory units showed a larger dynamic range for noise bursts than for tone bursts, but VCN units with primary-like and onset PSTHs showed larger dynamic ranges for responses to noise bursts than that of ANFs and VCN chopper units. 4. When tests were performed in the presence of continuous noise, rate-level functions for BF tone bursts shifted to higher tone levels and showed a more compressed range of driven rates in comparison with data obtained in quiet. Compression of the rate-level function in noise resulted from an increase in driven rate at low tone levels and a decrease in rate at high tone levels. These changes in the rate-level function suggest that noise may reduce the range of BF tone levels that are potentially encoded by a unit's rate responses. By exhibiting larger shifts and less compression in background noise, VCN units in awake cats better preserved the dynamic range of their rate responses to BF tones than ANFs in anesthetized cats or VCN units in decerebrate cats. 5. Rate-level functions were obtained from a small sample of VCN units not only with the cat performing the behavioral task but also with the cat awake and sitting quietly in the testing apparatus. No differences in noise-induced shift or compression were noted between the two testing conditions.(ABSTRACT TRUNCATED AT 400 WORDS)

scholarly journals Response Growth With Sound Level in Auditory-Nerve Fibers After Noise-Induced Hearing Loss

2004 ◽  
Vol 91 (2) ◽  
pp. 784-795 ◽  
Author(s):  
Michael G. Heinz ◽  
Eric D. Young
Keyword(s):  
Hearing Loss ◽  
Hair Cell ◽  
Auditory Nerve ◽  
Outer Hair Cell ◽  
Dynamic Range ◽  
Nerve Fibers ◽  
Sound Level ◽  
Broadband Noise ◽  
Noise Induced Hearing Loss ◽  
Rate Level

People with sensorineural hearing loss are often constrained by a reduced acoustic dynamic range associated with loudness recruitment; however, the neural correlates of loudness and recruitment are still not well understood. The growth of auditory-nerve (AN) activity with sound level was compared in normal-hearing cats and in cats with a noise-induced hearing loss to test the hypothesis that AN-fiber rate-level functions are steeper in impaired ears. Stimuli included best-frequency and fixed-frequency tones, broadband noise, and a brief speech token. Three types of impaired responses were observed. 1) Fibers with rate-level functions that were similar across all stimuli typically had broad tuning, consistent with outer-hair-cell (OHC) damage. 2) Fibers with a wide dynamic range and shallow slope above threshold often retained sharp tuning, consistent with primarily inner-hair-cell (IHC) damage. 3) Fibers with very steep rate-level functions for all stimuli had thresholds above approximately 80 dB SPL and very broad tuning, consistent with severe IHC and OHC damage. Impaired rate-level slopes were on average shallower than normal for tones, and were steeper in only limited conditions. There was less variation in rate-level slopes across stimuli in impaired fibers, presumably attributable to the lack of suppression-induced reductions in slopes for complex stimuli relative to BF-tone slopes. Sloping saturation was observed less often in impaired fibers. These results illustrate that AN fibers do not provide a simple representation of the basilar-membrane I/O function and suggest that both OHC and IHC damage can affect AN response growth.

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