Why is the perceptual octave stretched? An account based on mismatched time constants within the auditory brainstem

2021 ◽  
Author(s):  
Alain de Cheveigné
Keyword(s):  
Time Constant ◽  
Auditory Brainstem ◽  
The Other ◽  
Inhibitory Synapses ◽  
Coincidence Counting ◽  
Time Constants ◽  
Direct Pathway ◽  
Lower Tone ◽  
Excitatory And Inhibitory Synapses

This paper suggests an explanation for listener’s greater tolerance to positive than negative mistuning of the higher tone within an octave pair. It hypothesizes a neu- ral circuit tuned to cancel the lower tone, that also cancels the higher tone if that tone is in tune. Imperfect cancellation is the cue to mistuning of the octave. The circuit involves two pathways, one delayed with respect to the other, that feed a coincidence-counting neuron via excitatory and inhibitory synapses. A mismatch between the time constants of these two synapses results in an asymmetry in sen- sitivity to mismatch. Specifically, if the time constant of the delayed pathway is greater than that of the direct pathway, there is a greater tolerance to positive than to negative mistuning, which can lead to a perceptual“stretch” of the octave. The model is applicable to both harmonic and – with qualification – melodic oc- taves. The paper describes the model and reviews the evidence from auditory psychophysics and physiology in favor – or against – it.

scholarly journals Inhibitory Synchronization of Bursting in Biological Neurons: Dependence on Synaptic Time Constant

2002 ◽  
Vol 88 (3) ◽  
pp. 1166-1176 ◽  
Author(s):  
Robert C. Elson ◽  
Allen I. Selverston ◽  
Henry D. I. Abarbanel ◽  
Mikhail I. Rabinovich
Keyword(s):  
Time Constant ◽  
Reciprocal Inhibition ◽  
Inhibitory Neurons ◽  
Inhibitory Synapses ◽  
Cycle Period ◽  
Phase Lag ◽  
Time Constants ◽  
Synaptic Interactions ◽  
Phase Coordination ◽  
Phase Differences

Using the dynamic clamp technique, we investigated the effects of varying the time constant of mutual synaptic inhibition on the synchronization of bursting biological neurons. For this purpose, we constructed artificial half-center circuits by inserting simulated reciprocal inhibitory synapses between identified neurons of the pyloric circuit in the lobster stomatogastric ganglion. With natural synaptic interactions blocked (but modulatory inputs retained), these neurons generated independent, repetitive bursts of spikes with cycle period durations of ∼1 s. After coupling the neurons with simulated reciprocal inhibition, we selectively varied the time constant governing the rate of synaptic activation and deactivation. At time constants ≤100 ms, bursting was coordinated in an alternating (anti-phase) rhythm. At longer time constants (>400 ms), bursts became phase-locked in a fully overlapping pattern with little or no phase lag and a shorter period. During the in-phase bursting, the higher-frequency spiking activity was not synchronized. If the circuit lacked a robust periodic burster, increasing the time constant evoked a sharp transition from out-of-phase oscillations to in-phase oscillations with associated intermittent phase-jumping. When a coupled periodic burster neuron was present (on one side of the half-center circuit), the transition was more gradual. We conclude that the magnitude and stability of phase differences between mutually inhibitory neurons varies with the ratio of burst cycle period duration to synaptic time constant and that cellular bursting (whether periodic or irregular) can adopt in-phase coordination when inhibitory synaptic currents are sufficiently slow.

Interpretation of time constant and electrotonic length estimates in multicylinder or branched neuronal structures

1992 ◽  
Vol 68 (4) ◽  
pp. 1401-1420 ◽  
Author(s):  
W. R. Holmes ◽  
I. Segev ◽  
W. Rall
Keyword(s):  
Time Constant ◽  
Algebraic Approach ◽  
Weighted Average ◽  
Analytic Solutions ◽  
The Other ◽  
Geometric Complexity ◽  
Time Constants ◽  
Voltage Transients ◽  
Branched Structures ◽  
Current Transients

1. We have investigated the theoretical and practical problems associated with the interpretation of time constants and the estimation of electrotonic length with equivalent cylinder formulas for neurons best represented as multiple cylinders or branched structures. Two analytic methods were used to compute the time constants and coefficients of passive voltage transients (and time constants of current transients under voltage clamp). One method, suitable for simple geometries, involves analytic solutions to boundary value problems. The other, suitable for neurons of any geometric complexity, is an algebraic approach based on compartmental models. Neither of these methods requires the simulation of transients. 2. We computed the time constants and coefficients of voltage transients for several hypothetical neurons and also for a spinal motoneuron whose morphology was characterized from serial reconstructions. These time constants and coefficients were used to generate voltage transients. Then exponential peeling, nonlinear regression, and transform methods were applied to these transients to test how well these procedures estimate the underlying time constants and coefficients. 3. For a serially reconstructed motoneuron with 732 compartments, we found that the theoretical and peeled tau 0 values were nearly equal, but the theoretical tau 1 was much larger than the peeled tau 1. The theoretical tau 1 could not be peeled because it was associated with a coefficient, C1, that had a very small value. In fact, there were 156 time constants between 1.0 and 6.0 ms, most of which had very small coefficients; none had a coefficient larger than 2% of the signal. The peeled value of tau 1 (called tau 1 peel) can be viewed as some sort of a weighted average of the time constants having the largest coefficients. 4. We studied simple hypothetical neurons to determine what interpretation could be applied to the multitude of theoretical time constants. We found that after tau 0, there was a group of time constants associated with eigenfunctions that were odd (or approximately odd) functions with respect to the soma. These time constants could be interpreted as "equalizing" time constants along particular paths between different pairs of dendritic terminals in the neuron. After this group of time constants, there was one that we call tau even because it was associated with an eigen-function that was approximately even with respect to the soma. This tau even could be interpreted as an equalizing time constant for charge equalization between proximal membrane (soma and proximal dendrites) and distal membrane (including all distal dendrites).4=

scholarly journals Analysis of CO2 kinetics in Na,Cs-Rho crystals using the zero length column: a case study for slow systems

2021 ◽  
Author(s):  
Enzo Mangano ◽  
Stefano Brandani
Keyword(s):  
Time Constant ◽  
Transport Process ◽  
Diffusion Path ◽  
The Other ◽  
Experimental Measurements ◽  
Time Constants ◽  
Adsorption Processes ◽  
Concentration Dependent Diffusivity

AbstractExperimental measurements of systems with slow gas transport kinetics are generally considered a relatively easier task when compared to the challenges of measurements of very fast systems. On the other hand, when the transport process goes towards time constants of the order of several hours, not only the measurements, but also the analysis and interpretation of the data offer challenges which make the assessment of the correct time constant of the process non trivial. In this work we used the measurements of CO2 diffusion in Na,Cs-Rho crystals, carried out using the zero length column (ZLC) technique, as a case study for the use of the technique for very slow adsorption processes. The system, which has a time constant of the order of 8 h, shows the importance of using the partial loading approach for the determination of an unambiguous time constant from the analysis of the ZLC desorption curves. The traditional analysis is refined by using the nonlinear ZLC model to take into account the isotherm nonlinearity that results in a concentration dependent diffusivity. Finally, the method proposed by Cavalcante is used to confirm the 3-D diffusion path of the system.

scholarly journals Individual motion perception parameters and motion sickness frequency sensitivity in fore-aft motion

2021 ◽  
Author(s):  
Tugrul Irmak ◽  
Ksander N. de Winkel ◽  
Daan M. Pool ◽  
Heinrich H. Bülthoff ◽  
Riender Happee
Keyword(s):  
Motion Sickness ◽  
Motion Perception ◽  
Time Constant ◽  
Storage Time ◽  
Velocity Storage ◽  
Strong Positive Correlation ◽  
Subjective Vertical ◽  
Time Constants ◽  
Frequency Sensitivity ◽  
Observer Model

AbstractPrevious literature suggests a relationship between individual characteristics of motion perception and the peak frequency of motion sickness sensitivity. Here, we used well-established paradigms to relate motion perception and motion sickness on an individual level. We recruited 23 participants to complete a two-part experiment. In the first part, we determined individual velocity storage time constants from perceived rotation in response to Earth Vertical Axis Rotation (EVAR) and subjective vertical time constants from perceived tilt in response to centrifugation. The cross-over frequency for resolution of the gravito-inertial ambiguity was derived from our data using the Multi Sensory Observer Model (MSOM). In the second part of the experiment, we determined individual motion sickness frequency responses. Participants were exposed to 30-minute sinusoidal fore-aft motions at frequencies of 0.15, 0.2, 0.3, 0.4 and 0.5 Hz, with a peak amplitude of 2 m/s2 in five separate sessions, approximately 1 week apart. Sickness responses were recorded using both the MIsery SCale (MISC) with 30 s intervals, and the Motion Sickness Assessment Questionnaire (MSAQ) at the end of the motion exposure. The average velocity storage and subjective vertical time constants were 17.2 s (STD = 6.8 s) and 9.2 s (STD = 7.17 s). The average cross-over frequency was 0.21 Hz (STD = 0.10 Hz). At the group level, there was no significant effect of frequency on motion sickness. However, considerable individual variability was observed in frequency sensitivities, with some participants being particularly sensitive to the lowest frequencies, whereas others were most sensitive to intermediate or higher frequencies. The frequency of peak sensitivity did not correlate with the velocity storage time constant (r = 0.32, p = 0.26) or the subjective vertical time constant (r = − 0.37, p = 0.29). Our prediction of a significant correlation between cross-over frequency and frequency sensitivity was not confirmed (r = 0.26, p = 0.44). However, we did observe a strong positive correlation between the subjective vertical time constant and general motion sickness sensitivity (r = 0.74, p = 0.0006). We conclude that frequency sensitivity is best considered a property unique to the individual. This has important consequences for existing models of motion sickness, which were fitted to group averaged sensitivities. The correlation between the subjective vertical time constant and motion sickness sensitivity supports the importance of verticality perception during exposure to translational sickness stimuli.

Diagnostic Implications of Stimulus Polarity Effects on the Auditory Brainstem Response

2002 ◽  
Vol 13 (02) ◽  
pp. 072-082 ◽  
Author(s):  
Cynthia G. Fowler ◽  
Christopher D. Bauch ◽  
Wayne O. Olsen
Keyword(s):  
Mayo Clinic ◽  
Auditory Brainstem Response ◽  
Auditory Brainstem ◽  
The Other ◽  
Intersubject Variability ◽  
Acoustic Neuromas ◽  
Full Complement ◽  
Brainstem Response ◽  
Polarity Effects ◽  
Click Polarity

The purpose of this study was to determine whether clicks presented in rarefaction or condensation modes produce more accurate diaghostic information. Subjects were 20 consecutive patients who were seen at the Mayo Clinic for unilateral acoustic neuromas. The nontumor ear served as a control to minimize intersubject variability in the latencies. A standard audio logic evaluation was followed by an auditory brainstem response (ABR) test for which the stimuli were rarefaction and condensation clicks. Responses were analyzed for the presence of waves I, III, and V; absolute latencies of waves I, III, and V; interpeak intervals I–III, III–V, and I–V; and interaurallatency difference for wave V. The results indicated that measures from both polarities were similar in this set of patients and that neither click polarity provided diagnostic advantages over the other. Recommendations are to collect ABRs to both click polarities individually to obtain the full complement of waves on which to base the diagnostic impression.

Properties of spontaneous inhibitory synaptic currents in cultured rat spinal cord and medullary neurons

1996 ◽  
Vol 76 (1) ◽  
pp. 448-460 ◽  
Author(s):  
C. A. Lewis ◽  
D. S. Faber
Keyword(s):  
Spinal Cord ◽  
Time Constant ◽  
Decay Time ◽  
Cultured Cells ◽  
Decay Time Constant ◽  
Inhibitory Synapses ◽  
Gamma Aminobutyric Acid ◽  
Postsynaptic Receptor ◽  
Decay Times ◽  
Medullary Neurons

1. To identify the type(s) and properties of inhibitory postsynaptic receptor(s) involved in synaptic transmission in cultured rat embryonic spinal cord and medullary neurons, we have used whole cell patch-clamp techniques to record miniature inhibitory postsynaptic currents (mIPSCs) in the presence of tetrodotoxin, DL-2-amino-5-phosphonovaleric acid, and 6-cyano-7-nitroquinoxaline-2,3-dione. 2. The mIPSCs recorded from both spinal cord and medullary neurons had skewed amplitude distributions. 3. The glycinergic antagonist strychnine and the GABAergic antagonist bicuculline each decreased both the frequency and mean peak amplitudes of mIPSCs. We conclude that both glycine and gamma-aminobutyric acid (GABA) are neurotransmitters at inhibitory synapses in our cultured cells. 4. Most (approximately 96-97%) mIPSCs decay with single-exponential time constants, and decay time distributions were consistently best fitted by the sum of four Gaussians with decay constants as follows: D1 = 5.8 +/- 0.1 (SE) ms (n = 63), D2 = 12.2 +/- 0.2 ms (n = 61), D3 = 23.2 +/- 0.4 ms (n = 54), and D4 = 44.7 +/- 1.0 ms (n = 57). We conclude that the four classes of decay times represent kinetically different inhibitory postsynaptic receptor populations. 5. Strychnine and bicuculline usually had one of two different effects on the mIPSC decay time constant distributions; either selective decreases in the frequency of mIPSCs with decay times in certain classes (i.e., the D1 class was reduced by bicuculline, the D2 class by strychnine, and the D3 and D4 classes by both antagonists) or a nonselective depression in the frequency of mIPSCs with decay times in all four classes. The particular effect observed in a given neuron was correlated with the presence or absence of ATP and guanosine 5'-triphosphate (GTP) in the patch pipette. Namely, in 71% of the antagonist applications where the pipette contained ATP and GTP, the result was a nonselective decrease in mIPSCs in all decay time constant classes. Conversely, in 54% of the antagonist applications in their absence, the result was a selective decrease in the frequency of mIPSCs in specific decay time constant classes. 6. In some experiments, mIPSCs reappeared in antagonist solution after an essentially complete block. Recovery from block in the continued presence of antagonist was never observed in the absence of ATP and GTP (8 neurons), and, at the same time, 5 of 9 neurons patched with ATP and GTP in the pipette did show recovery (56%).

scholarly journals Voltage-gated transient currents in bovine adrenal fasciculata cells. I. T-type Ca2+ current.

1993 ◽  
Vol 102 (2) ◽  
pp. 217-237 ◽  
Author(s):  
B Mlinar ◽  
B A Biagi ◽  
J J Enyeart
Keyword(s):  
Time Constant ◽  
Low Voltage ◽  
Zona Fasciculata ◽  
Patch Clamp Technique ◽  
Time Constants ◽  
Voltage Gated ◽  
Wide Range ◽  
Boltzmann Function ◽  
Voltage Dependent ◽  
Ca2 Channels

The whole cell version of the patch clamp technique was used to identify and characterize voltage-gated Ca2+ channels in enzymatically dissociated bovine adrenal zona fasciculata (AZF) cells. The great majority of cells (84 of 86) expressed only low voltage-activated, rapidly inactivating Ca2+ current with properties of T-type Ca2+ current described in other cells. Voltage-dependent activation of this current was fit by a Boltzmann function raised to an integer power of 4 with a midpoint at -17 mV. Independent estimates of the single channel gating charge obtained from the activation curve and using the "limiting logarithmic potential sensitivity" were 8.1 and 6.8 elementary charges, respectively. Inactivation was a steep function of voltage with a v1/2 of -49.9 mV and a slope factor K of 3.73 mV. The expression of a single Ca2+ channel subtype by AZF cells allowed the voltage-dependent gating and kinetic properties of T current to be studied over a wide range of potentials. Analysis of the gating kinetics of this Ca2+ current indicate that T channel activation, inactivation, deactivation (closing), and reactivation (recovery from inactivation) each include voltage-independent transitions that become rate limiting at extreme voltages. Ca2+ current activated with voltage-dependent sigmoidal kinetics that were described by an m4 model. The activation time constant varied exponentially at test potentials between -30 and +10 mV, approaching a voltage-independent minimum of 1.6 ms. The inactivation time constant (tau i) also decreased exponentially to a minimum of 18.3 ms at potentials positive to 0 mV. T channel closing (deactivation) was faster at more negative voltages; the deactivation time constant (tau d) decreased from 8.14 +/- 0.7 to 0.48 +/- 0.1 ms at potentials between -40 and -150 mV. T channels inactivated by depolarization returned to the closed state along pathways that included two voltage-dependent time constants. tau rec-s ranged from 8.11 to 4.80 s when the recovery potential was varied from -50 to -90 mV, while tau rec-f decreased from 1.01 to 0.372 s. At potentials negative to -70 mV, both time constants approached minimum values. The low voltage-activated Ca2+ current in AZF cells was blocked by the T channel selective antagonist Ni2+ with an IC50 of 20 microM. At similar concentrations, Ni2+ also blocked cortisol secretion stimulated by adrenocorticotropic hormone. Our results indicate that bovine AZF cells are distinctive among secretory cells in expressing primarily or exclusively T-type Ca2+ channels.(ABSTRACT TRUNCATED AT 400 WORDS)

Identification of Time-Varying Time Constants of Thermocouple Sensors and Its Application to Temperature Measurement

2008 ◽  
Vol 131 (1) ◽  
Author(s):  
Kenneth Kar ◽  
Akshya K. Swain ◽  
Robert Raine
Keyword(s):  
Kalman Filter ◽  
Least Squares ◽  
Time Constant ◽  
Identification Problem ◽  
Basis Functions ◽  
New Technique ◽  
Ratio Test ◽  
Time Varying ◽  
Time Constants ◽  
Orthogonal Least Squares

The present study addresses the problem of estimating time-varying time constants associated with thermocouple sensors by a set of basis functions. By expanding each time-varying time constant onto a finite set of basis sequences, the time-varying identification problem reduces to a parameter estimation problem of a time-invariant system. The proposed algorithm, to be called as orthogonal least-squares with basis function expansion algorithm, combines the orthogonal least-squares algorithm with an error reduction ratio test to include significant basis functions into the model, which results in a parsimonious model structure. The performance of the method was compared with a linear Kalman filter. Simulations on engine data have demonstrated that the proposed method performs satisfactorily and is better than the Kalman filter. The new technique has been applied in a Stirling cycle compressor. The sinusoidal variations in time constant are tracked properly using the new technique, but the linear Kalman filter fails to do so. Both model validation and thermodynamic laws confirm that the new technique gives unbiased estimates and that the assumed thermocouple model is adequate.

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