Sensitivity to binaural intensity and phase difference cues in kitten inferior colliculus

1990 ◽  
Vol 64 (2) ◽  
pp. 582-597 ◽  
Author(s):  
B. J. Blatchley ◽  
J. F. Brugge
Keyword(s):  
Auditory Cortex ◽  
Inferior Colliculus ◽  
Phase Difference ◽  
Central Nucleus ◽  
Intensity Difference ◽  
Monotonic Functions ◽  
Age Related ◽  
Highly Correlated ◽  
Intensity Functions ◽  
Almost All

1. Responses of single neurons to monaural or binaural CF tones delivered through a closed and calibrated sound delivery system were studied in the central nucleus of the inferior colliculus (ICC) in ketamine and barbiturate-anesthetized kittens 4-105 days old. 2. Neurons from young kittens had elevated thresholds, some greater than 100 dB in the youngest kittens tested. Average thresholds in the ICC matched those previously measured in the auditory nerve (AN), cochlear nuclei (CN), and auditory cortex (CTX), suggesting that the drop in threshold as a function of age is primarily determined by development at the periphery. 3. Minimal first-spike latencies were relatively long in the youngest kittens, approaching adult values by the end of the third postnatal week. Latencies were distributed between values previously determined for the CN and auditory cortex and can be attributed to the centripetal development of the auditory system. 4. The range of frequencies that were effective in exciting ICC neurons was restricted in young kittens. Neurons having characteristic frequencies (CFs) greater than 7 kHz were not recorded before postnatal day 10. CF distribution matched that obtained in previous experiments from AN, CN, and CTX, reflecting the development of the cochlea. 5. Both monotonic and nonomonotonic spike count-versus-intensity functions were found in the youngest kittens. There was a tendency for monotonic functions from the youngest kittens to be steeper than those from older kittens. No age-related changes in the shapes of non-monotonic functions were found. 6. Sensitivity to interaural intensity difference (IID), tested by holding the intensity to the excitatory ear at a suprathreshold level and increasing the intensity of the stimulus to the inhibitory ear, was exhibited as early as 8 days after birth. The majority of the cells exhibiting sensitivity to IID (89.5%) were classified as EI cells, and almost all IID sensitive cells had CFs between 3 and 25 kHz. Within our sample the shapes of IID functions, as well as the operating range of the IID functions, closely resembled those obtained from the adult cat. Thresholds of excitation and of inhibition were highly correlated, suggesting that the ipsilateral and contralateral inputs to the ICC develop as a matched set. 7. Sensitivity to interaural phase difference (IPD), tested either by shifting the onset phase of a CF tone to one ear relative to the other or by presenting tones of slightly different frequency to the two ears, was present as early as 12 days after birth.(ABSTRACT TRUNCATED AT 400 WORDS)

Binaural processing of sound pressure level in the inferior colliculus

1987 ◽  
Vol 57 (4) ◽  
pp. 1130-1147 ◽  
Author(s):  
M. N. Semple ◽  
L. M. Kitzes
Keyword(s):  
Inferior Colliculus ◽  
Sound Pressure ◽  
Spatial Information ◽  
Discharge Rate ◽  
Excitatory Input ◽  
Central Nucleus ◽  
Intensity Difference ◽  
Inhibitory Input ◽  
Directional Information ◽  
Discharge Rates

The central auditory system could encode information about the location of a high-frequency sound source by comparing the sound pressure levels at the ears. Two potential computations are the interaural intensity difference (IID) and the average binaural intensity (ABI). In this study of the central nucleus of the inferior colliculus (ICC) of the anesthetized gerbil, we demonstrate that responses of 85% of the 97 single units in our sample were jointly influenced by IID and ABI. For a given ABI, discharge rate of most units is a sigmoidal function of IID, and peak rates occur at IIDs favoring the contralateral ear. Most commonly, successive increments of ABI cause successive shifts of the IID functions toward IIDs favoring the ipsilateral ear. Neurons displaying this behavior include many that would conventionally be classified EI (receiving predominantly excitatory input arising from one ear and inhibitory input from the other), many that would be classified EE (receiving predominantly excitatory input arising from each ear), and all that are responsive only to contralateral stimulation. The IID sensitivity of a very few EI neurons is unaffected by ABI, except near threshold. Such units could provide directional information that is independent of source intensity. A few EE neurons are very sensitive to ABI, but are minimally sensitive to IID. Nevertheless, our data indicate that responses of most EE units in ICC are strongly dominated by excitation of contralateral origin. For some units, discharge rate is nonmonotonically related to IID and is maximal when the stimuli at the two ears are of comparable sound pressure. This preference for zero IID is common for all binaural levels. Many EI neurons respond nonmonotonically to ABI. Discharge rates are greater for IIDs representative of contralateral space and are maximal at a single best ABI. For a subset of these neurons, the influence arising from the ipsilateral ear is comprised of a mixture of excitation and inhibition. As a consequence, discharge rates are nonmonotonically related not only to ABI but also to IID. This dual nonmonotonicity creates a clear focus of peak response at a particular ABI/IID combination. Because of their mixed monaural influences, such units would be ascribed to different classes of the conventional (EE/EI) binaural classification scheme depending on the binaural level presented. Several response classes were identified in this study, and each might contribute differently to the encoding of spatial information.(ABSTRACT TRUNCATED AT 400 WORDS)

Age-related synaptic changes in the central nucleus of the inferior colliculus of Fischer-344 rats

1999 ◽  
Vol 406 (3) ◽  
pp. 285-298 ◽  
Author(s):  
Robert H. Helfert ◽  
Teresa J. Sommer ◽  
Joshua Meeks ◽  
Phillip Hofstetter ◽  
Larry F. Hughes
Keyword(s):  
Inferior Colliculus ◽  
Central Nucleus ◽  
Fischer 344 Rats ◽  
Fischer 344 ◽  
Age Related ◽  
Synaptic Changes

Binaural interaction in high-frequency neurons in inferior colliculus of the cat: effects of variations in sound pressure level on sensitivity to interaural intensity differences

1990 ◽  
Vol 63 (3) ◽  
pp. 570-591 ◽  
Author(s):  
D. R. Irvine ◽  
G. Gago
Keyword(s):  
Inferior Colliculus ◽  
Sound Pressure Level ◽  
High Frequency ◽  
Sound Pressure ◽  
Pressure Level ◽  
Central Nucleus ◽  
Sensitivity Functions ◽  
Rate Intensity ◽  
Ipsilateral Stimulation ◽  
Intensity Functions

1. Development of models of the manner in which interaural intensity differences (IIDs), the major binaural cue for the azimuthal location of high-frequency sounds, are coded by populations of neurons requires knowledge of the extent to which the IID sensitivity of individual neurons is invariant with changes in sound pressure level (SPL) and other stimulus parameters. To examine this tissue, recordings were obtained from a large sample (n = 458) of neurons with characteristic frequency (CF) greater than 3 kHz in the central nucleus of the inferior colliculus (ICC) of anesthetized cats. The sensitivity to IIDs and the effects of changes in SPL on this sensitivity were examined in neurons receiving excitatory contralateral input and inhibitory or mixed inhibitory/facilitatory ipsilateral input (EI neurons). 2. The form of an EI neuron's IID sensitivity and the effects of changes in SPL on that sensitivity were found to be determined in part by the characteristics of the neuron's rate-intensity function for monaural contralateral stimulation, and detailed rate-intensity functions were therefore obtained for 91 neurons. Many ICC neurons have nonmonotonic rate-intensity functions, the proportion so classified depending on the criterion of nonmonotonicity employed. 3. IID sensitivity functions for CF tonal stimuli were obtained at one or more intensities for 90 neurons, using a method of generating IIDs that kept the average binaural intensity (ABI) of the stimuli at the two ears constant. In the standard ABI range in which a function was obtained for each unit, the majority of EI neurons (72%) had monotonic (sigmoidal) or near-monotonic IID sensitivity functions. The remainder had nonmonotonic (peaked) IID sensitivity functions, which were attributable either to mixed inhibitory and facilitatory ipsilateral influences or to the fact that the effects of ipsilateral stimulation were superimposed on nonmonotonic effects of changes in intensity at the excitatory ear. 4. IID sensitivity was examined at two or more ABIs (3-5 in most cases) for 40 neurons classified as having monotonic or near-monotonic functions in the standard ABI range and for 7 neurons classified as nonmonotonic. For a small proportion of neurons with monotonic IID sensitivity functions, the form of the function was relatively invariant with changes in ABI. In those monotonic neurons in which the form of the IID sensitivity function varied with changes in ABI, the most common type of variation was that the position of the sloping portion of the function shifted systematically in the direction of larger IIDs favoring the ipsilateral ear as ABI increased.(ABSTRACT TRUNCATED AT 400 WORDS)

Long delay lines for ranging are created by inhibition in the inferior colliculus of the mustached bat

1995 ◽  
Vol 74 (1) ◽  
pp. 1-11 ◽  
Author(s):  
I. Saitoh ◽  
N. Suga
Keyword(s):  
Auditory Cortex ◽  
Receptor Antagonist ◽  
Inferior Colliculus ◽  
Coincidence Detection ◽  
Central Nucleus ◽  
Gamma Aminobutyric Acid ◽  
Delay Lines ◽  
Mustached Bat ◽  
Gabaa Receptor Antagonist ◽  
Medial Geniculate

1. The central auditory system of the mustached bat has arrays of delay-tuned (FM-FM combination-sensitive) neurons in the inferior colliculus, the medial geniculate body, and the auditory cortex. These neurons are tuned to particular echo delays, i.e., target distances. The neural mechanisms for creating the delay-tuned neurons involve delay lines, coincidence detection, and amplification. We have hypothesized that delay lines longer than 4 ms are created by inhibition occurring in the anterolateral division (ALD) of the central nucleus of the inferior colliculus. If this hypothesis is correct, suppression of inhibition occurring in the ALD must shorten the best delays of the collicular, thalamic, and cortical delay-tuned neurons. The aim of the present study is to test this hypothesis. Responses of single delay-tuned neurons in the FM-FM area of the auditory cortex were recorded with a tungsten-wire microelectrode, and the effects of iontophoretic microinjections of strychnine (STR) and/or bicuculline methiodide (BMI) into the ALD were examined on the responses of these neurons. 2. STR (glycine receptor antagonist) and/or BMI [gamma-aminobutyric acid-A (GABAA) receptor antagonist] injections into the ALD shortened the best delays of delay-tuned neurons in the FM-FM area with little change in their response patterns. The longer the best delay of a delay-tuned neuron, the larger the amount of shortening. 3. Inhibition mediated by glycine receptors plays a larger role in creating delay lines than that mediated by GABAA receptors, because STR and BMI, respectively, shortened the best delay of 91 and 74% of the neurons with best delays longer than 4.5 ms. 4. BMI has no effect on the best delays of delay-tuned neurons that were tuned to echo delays shorter than 4.5 ms. 5. The present data support the hypothesis that long delay lines utilized by delay-tuned neurons are created by inhibition occurring in the ALD of the inferior colliculus. However, the amount of shortening in delay lines by STR and/or BMI was generally smaller than that predicted by a neural network model. Therefore the present study partially answers the questions of where and how long delay lines were created.

scholarly journals Antidromic Activation Reveals Tonotopically Organized Projections From Primary Auditory Cortex to the Central Nucleus of the Inferior Colliculus in Guinea Pig

2007 ◽  
Vol 97 (2) ◽  
pp. 1413-1427 ◽  
Author(s):  
Hubert H. Lim ◽  
David J. Anderson
Keyword(s):  
Auditory Cortex ◽  
Inferior Colliculus ◽  
Spatial Organization ◽  
Medial Geniculate Body ◽  
Primary Auditory Cortex ◽  
Central Nucleus ◽  
Antidromic Activation ◽  
Antidromic Stimulation ◽  
Medial Geniculate ◽  
Layer V

The inferior colliculus (IC) is highly modulated by descending projections from higher auditory and nonauditory centers. Traditionally, corticofugal fibers were believed to project mainly to the extralemniscal IC regions. However, there is some anatomical evidence suggesting that a substantial number of fibers from the primary auditory cortex (A1) project into the IC central nucleus (ICC) and appear to be tonotopically organized. In this study, we used antidromic stimulation combined with other electrophysiological techniques to further investigate the spatial organization of descending fibers from A1 to the ICC in ketamine-anesthetized guinea pigs. Based on our findings, corticofugal fibers originate predominantly from layer V of A1, are amply scattered throughout the ICC and only project to ICC neurons with a similar best frequency (BF). This strict tonotopic pattern suggests that these corticofugal projections are involved with modulating spectral features of sound. Along the isofrequency dimension of the ICC, there appears to be some differences in projection patterns that depend on BF region and possibly isofrequency location within A1 and may be indicative of different descending coding strategies. Furthermore, the success of the antidromic stimulation method in our study demonstrates that it can be used to investigate some of the functional properties associated with corticofugal projections to the ICC as well as to other regions (e.g., medial geniculate body, cochlear nucleus). Such a method can address some of the limitations with current anatomical techniques for studying the auditory corticofugal system.

Age-related changes of NADPH-diaphorase-positive neurons in the rat inferior colliculus and auditory cortex

2007 ◽  
Vol 70 (12) ◽  
pp. 1051-1059 ◽  
Author(s):  
Daniel Sánchez-Zuriaga ◽  
Nuria Martí-Gutiérrez ◽  
Maria Ángeles Pérez De La Cruz ◽  
Maria Rosa Peris-Sanchis
Keyword(s):  
Auditory Cortex ◽  
Inferior Colliculus ◽  
Nadph Diaphorase ◽  
Age Related ◽  
Age Related Changes

Response of auditory units in the barn owl's inferior colliculus to continuously varying interaural phase differences

1992 ◽  
Vol 67 (6) ◽  
pp. 1428-1436 ◽  
Author(s):  
A. Moiseff ◽  
T. Haresign
Keyword(s):  
Inferior Colliculus ◽  
Interaural Time Difference ◽  
Stimulus Onset ◽  
Central Nucleus ◽  
Intensity Difference ◽  
Phase Sensitivity ◽  
Tyto Alba ◽  
Interaural Phase ◽  
Stimulus Generation ◽  
Phase Differences

1. We studied the response of single units in the central nucleus of the inferior colliculus (ICc) of the barn owl (Tyto alba) to continuously varying interaural phase differences (IPDs) and static IPDs. Interaural phase was varied in two ways: continuously, by delivering tones to each ear that varied by a few hertz (binaural beat, Fig. 1), and discretely, by delaying in fixed steps the phase of sound delivered to one ear relative to the other (static phase). Static presentations were repeated at several IPDs to characterize interaural phase sensitivity. 2. Units sensitive to IPDs responded to the binaural beat stimulus over a broad range of delta f(Fig. 4). We selected a 3-Hz delta f for most of our comparative measurements on the basis of constraints imposed by our stimulus generation system and because it allowed us to reduce the influence of responses to stimulus onset and offset (Fig. 3A). 3. Characteristic interaural time or phase sensitivity obtained by the use of the binaural beat stimulus were comparable with those obtained by the use of the static technique (Fig. 5; r2 = 0.93, Fig. 6). 4. The binaural beat stimulus facilitated the measurement of characteristic delay (CD) and characteristic phase (CP) of auditory units. We demonstrated that units in the owl's inferior colliculus (IC) include those that are maximally excited by specific IPDs (CP = 0 or 1.0) as well as those that are maximally suppressed by specific IPDs (CP = 0.5; Figs. 7 and 8). 5. The selectivity of units sensitive to IPD or interaural time difference (ITD) were weakly influenced by interaural intensity difference (IID).(ABSTRACT TRUNCATED AT 250 WORDS)

Corticofugal Shaping of Frequency Tuning Curves in the Central Nucleus of the Inferior Colliculus of Mice

2005 ◽  
Vol 93 (1) ◽  
pp. 71-83 ◽  
Author(s):  
Jun Yan ◽  
Yunfeng Zhang ◽  
Günter Ehret
Keyword(s):  
Auditory Cortex ◽  
Inferior Colliculus ◽  
Cortical Neurons ◽  
Frequency Tuning ◽  
Tuning Curve ◽  
Primary Auditory Cortex ◽  
Nerve Fibers ◽  
Cortical Activation ◽  
Central Nucleus ◽  
Tuning Curves

Plasticity of the auditory cortex can be induced by conditioning or focal cortical stimulation. The latter was used here to measure how stimulation in the tonotopy of the mouse primary auditory cortex influences frequency tuning in the midbrain central nucleus of the inferior colliculus (ICC). Shapes of collicular frequency tuning curves (FTCs) were quantified before and after cortical activation by measuring best frequencies, FTC bandwidths at various sound levels, level tolerance, Q-values, steepness of low- and high-frequency slopes, and asymmetries. We show here that all of these measures were significantly changed by focal cortical activation. The changes were dependent not only on the relationship of physiological properties between the stimulated cortical neurons and recorded collicular neurons but also on the tuning curve class of the collicular neuron. Cortical activation assimilated collicular FTC shapes; sharp and broad FTCs were changed to the shapes comparable to those of auditory nerve fibers. Plasticity in the ICC was organized in a center (excitatory)-surround (inhibitory) way with regard to the stimulated location (i.e., the frequency) of cortical tonotopy. This ensures, together with the spatial gradients of distribution of collicular FTC shapes, a sharp spectral filtering at the core of collicular frequency-band laminae and an increase in frequency selectivity at the periphery of the laminae. Mechanisms of FTC plasticity were suggested to comprise both corticofugal and local ICC components of excitatory and inhibitory modulation leading to a temporary change of the balance between excitation and inhibition in the ICC.

scholarly journals Passive stimulation and behavioral training differentially transform temporal processing in the inferior colliculus and primary auditory cortex

2017 ◽  
Vol 117 (1) ◽  
pp. 47-64 ◽  
Author(s):  
Maike Vollmer ◽  
Ralph E. Beitel ◽  
Christoph E. Schreiner ◽  
Patricia A. Leake
Keyword(s):  
Auditory Cortex ◽  
Inferior Colliculus ◽  
Temporal Processing ◽  
Electric Stimulation ◽  
Primary Auditory Cortex ◽  
Central Nucleus ◽  
Electrophysiological Recording ◽  
Response Patterns ◽  
Behavioral Training ◽  
Auditory Midbrain

In profoundly deaf cats, behavioral training with intracochlear electric stimulation (ICES) can improve temporal processing in the primary auditory cortex (AI). To investigate whether similar effects are manifest in the auditory midbrain, ICES was initiated in neonatally deafened cats either during development after short durations of deafness (8 wk of age) or in adulthood after long durations of deafness (≥3.5 yr). All of these animals received behaviorally meaningless, “passive” ICES. Some animals also received behavioral training with ICES. Two long-deaf cats received no ICES prior to acute electrophysiological recording. After several months of passive ICES and behavioral training, animals were anesthetized, and neuronal responses to pulse trains of increasing rates were recorded in the central (ICC) and external (ICX) nuclei of the inferior colliculus. Neuronal temporal response patterns (repetition rate coding, minimum latencies, response precision) were compared with results from recordings made in the AI of the same animals (Beitel RE, Vollmer M, Raggio MW, Schreiner CE. J Neurophysiol 106: 944–959, 2011; Vollmer M, Beitel RE. J Neurophysiol 106: 2423–2436, 2011). Passive ICES in long-deaf cats remediated severely degraded temporal processing in the ICC and had no effects in the ICX. In contrast to observations in the AI, behaviorally relevant ICES had no effects on temporal processing in the ICC or ICX, with the single exception of shorter latencies in the ICC in short-deaf cats. The results suggest that independent of deafness duration passive stimulation and behavioral training differentially transform temporal processing in auditory midbrain and cortex, and primary auditory cortex emerges as a pivotal site for behaviorally driven neuronal temporal plasticity in the deaf cat. NEW & NOTEWORTHY Behaviorally relevant vs. passive electric stimulation of the auditory nerve differentially affects neuronal temporal processing in the central nucleus of the inferior colliculus (ICC) and the primary auditory cortex (AI) in profoundly short-deaf and long-deaf cats. Temporal plasticity in the ICC depends on a critical amount of electric stimulation, independent of its behavioral relevance. In contrast, the AI emerges as a pivotal site for behaviorally driven neuronal temporal plasticity in the deaf auditory system.

Response Properties of Neurons in the Inferior Colliculus of the Monaurally Deafened Ferret to Acoustic Stimulation of the Intact Ear

1997 ◽  
Vol 78 (2) ◽  
pp. 767-779 ◽  
Author(s):  
David McAlpine ◽  
Russell L. Martin ◽  
Jennifer E. Mossop ◽  
David R. Moore
Keyword(s):  
Inferior Colliculus ◽  
Single Unit ◽  
Acoustic Stimulation ◽  
Analysis Of Covariance ◽  
Central Nucleus ◽  
Spontaneous Discharge ◽  
Response Properties ◽  
Ipsilateral Stimulation ◽  
Intensity Functions ◽  
Stimulation Of

McAlpine, David, Russell L. Martin, Jennifer E. Mossop, and David R. Moore. Response properties of neurons in the inferior colliculus of the monaurally deafened ferret to acoustic stimulation of the intact ear. J. Neurophysiol. 78: 767–779, 1997. Response properties of neurons in the central nucleus of the inferior colliculus (ICC) were investigated after unilateral cochlear removal at various ages during infancy. Nineteen ferrets had the right cochlea surgically ablated, either in adulthood or on postnatal day (P) 5, 25, or 40, 3–18 mo before recording. Adult ablations were made on the same day as (“acute,” n = 3), or 2–3 mo before (“chronic,” n = 3), recording. Two ferrets were left binaurally intact. Single-unit ( n = 702) and multiunit ( n = 1,819) recordings were made in the ICC of barbiturate-anesthetized ferrets ipsilateral (all ages) or contralateral (P5 and acute adult only) to the intact ear. In binaurally intact animals, tonal stimulation of the contralateral ear evoked excitatory activity at the majority (94%) of recording loci, whereas stimulation of the ipsilateral ear evoked activity at only 33% of recording loci. In acutely ablated animals, the majority of contralateral (90%) and ipsilateral (70%) loci were excited by tonal stimulation of the intact ear. In chronically ablated animals, 80–90% of loci were excited by ipsilateral stimulation. Single-unit thresholds were generally higher for low-best frequency (BF) than for high-BF units, and higher in the ipsilateral than in the contralateral ICC. Analysis of covariance showed highly significant differences between all of the ipsilateral and contralateral groups, but no effects of age at ablation or survival time following ablation, other than that the group ablated at P25 had higher mean ipsilateral thresholds than the groups ablated at P5 or, acutely, in adulthood. Cochlear ablation at P5, 25, or 40 resulted in a significant increase in dynamic ranges of ipsilateral ICC unit rate-intensity functions relative to acutely ablated animals. Dynamic ranges of units in the contralateral ICC of P5-ablated ferrets were also significantly increased compared with those of acutely ablated animals. Cochlear ablation at P5, 25, or 40 resulted in a significant increase in single-unit spontaneous discharge rates in the ICC ipsilateral but not contralateral (P5 only) to the intact ear. These data show that unilateral cochlear removal in adult ferrets leads to a rapid and dramatic increase in the proportion of neurons in the ICC ipsilateral to the intact ear that is excited by acoustic stimulation of that ear. In addition, the data confirm that, in ferrets, cochlear removal in infancy leads to a further increase in responsiveness of individual neurons in the ipsilateral ICC. Finally, the data show that responses in the ICC contralateral to the intact ear are largely but not completely unchanged by unilateral cochlear removal.

Sign in / Sign up

Export Citation Format

Share Document