scholarly journals Plastic Change in the Auditory Minimum Threshold Induced by Intercollicular Effects in Mice

2016 ◽  
Vol 2016 ◽  
pp. 1-8 ◽  
Author(s):  
Hui-Xian Mei ◽  
Jia Tang ◽  
Zi-Ying Fu ◽  
Liang Cheng ◽  
Qi-Cai Chen
Keyword(s):  
Signal Processing ◽  
Inferior Colliculus ◽  
Electric Stimulation ◽  
Auditory Pathway ◽  
Minimum Threshold ◽  
Auditory Responses ◽  
Recording Conditions ◽  
Plastic Changes ◽  
Acoustic Experience ◽  
Plastic Change

In the auditory pathway, the commissure of the inferior colliculus (IC) interconnects the two ICs on both sides of the dorsal midbrain. This interconnection could mediate an interaction between the two ICs during sound signal processing. The intercollicular effects evoked by focal electric stimulation for 30 min could inhibit or facilitate auditory responses and induce plastic changes in the response minimum threshold (MT) of IC neurons. Changes in MT are dependent on the best frequency (BF) and MT difference. The MT shift is larger in IC neurons with BF differences ≤2 kHz than in those with BF differences >2 kHz. Moreover, MTs that shift toward electrically stimulated IC neurons increase with the increasing MT difference between the two ICs. The shift in MT lasts for a certain period of time and then returns to previous levels within ~150 min. The collicular interactions are either reciprocal or unilateral under alternate stimulating and recording conditions in both ICs. Our results suggest that intercollicular effects may be involved in the acoustic experience-dependent plasticity of the MT of IC neurons.

scholarly journals Modulation of thalamic auditory neurons by the primary auditory cortex

2012 ◽  
Vol 108 (3) ◽  
pp. 935-942 ◽  
Author(s):  
Jie Tang ◽  
Weiguo Yang ◽  
Nobuo Suga
Keyword(s):  
Signal Processing ◽  
Electric Stimulation ◽  
Frequency Tuning ◽  
Primary Auditory Cortex ◽  
Auditory Signal ◽  
Tuning Curves ◽  
Auditory Responses ◽  
Auditory Signal Processing ◽  
Plastic Changes ◽  
Stimulation Of

The central auditory system consists of the lemniscal and nonlemniscal pathways or systems, which are anatomically and physiologically different from each other. In the thalamus, the ventral division of the medial geniculate body (MGBv) belongs to the lemniscal system, whereas its medial (MGBm) and dorsal (MGBd) divisions belong to the nonlemniscal system. Lemniscal neurons are sharply frequency-tuned and provide highly frequency-specific information to the primary auditory cortex (AI), whereas nonlemniscal neurons are generally broadly frequency-tuned and project widely to cortical auditory areas including AI. These two systems are presumably different not only in auditory signal processing, but also in eliciting cortical plastic changes. Electric stimulation of narrowly frequency-tuned MGBv neurons evokes the shift of the frequency-tuning curves of AI neurons toward the tuning curves of the stimulated MGBv neurons (tone-specific plasticity). In contrast, electric stimulation of broadly frequency-tuned MGBm neurons augments the auditory responses of AI neurons and broadens their frequency-tuning curves (nonspecific plasticity). In our current studies, we found that electric stimulation of AI evoked tone-specific plastic changes of the MGBv neurons, whereas it degraded the frequency tuning of MGBm neurons by inhibiting their auditory responses. AI apparently modulates the lemniscal and nonlemniscal thalamic neurons in quite different ways. High MGBm activity presumably makes AI neurons less favorable for fine auditory signal processing, whereas high MGBv activity makes AI neurons more suitable for fine processing of specific auditory signals and reduces MGBm activity.

scholarly journals Temporal Features of Spectral Integration in the Inferior Colliculus: Effects of Stimulus Duration and Rise Time

2009 ◽  
Vol 102 (1) ◽  
pp. 167-180 ◽  
Author(s):  
Donald Gans ◽  
Kianoush Sheykholeslami ◽  
Diana Coomes Peterson ◽  
Jeffrey Wenstrup
Keyword(s):  
Inferior Colliculus ◽  
Rise Time ◽  
Low Frequency ◽  
Auditory Pathway ◽  
Spectral Integration ◽  
Auditory Responses ◽  
Temporal Features ◽  
Vocal Signals ◽  
Inhibitory Interactions ◽  
Different Levels

This report examines temporal features of facilitation and suppression that underlie spectrally integrative responses to complex vocal signals. Auditory responses were recorded from 160 neurons in the inferior colliculus (IC) of awake mustached bats. Sixty-two neurons showed combination-sensitive facilitation: responses to best frequency (BF) signals were facilitated by well-timed signals at least an octave lower in frequency, in the range 16–31 kHz. Temporal features and strength of facilitation were generally unaffected by changes in duration of facilitating signals from 4 to 31 ms. Changes in stimulus rise time from 0.5 to 5.0 ms had little effect on facilitatory strength. These results suggest that low frequency facilitating inputs to high BF neurons have phasic-on temporal patterns and are responsive to stimulus rise times over the tested range. We also recorded from 98 neurons showing low-frequency (11–32 kHz) suppression of higher BF responses. Effects of changing duration were related to the frequency of suppressive signals. Signals <23 kHz usually evoked suppression sustained throughout signal duration. This and other features of such suppression are consistent with a cochlear origin that results in masking of responses to higher, near-BF signal frequencies. Signals in the 23- to 30-kHz range—frequencies in the first sonar harmonic—generally evoked phasic suppression of BF responses. This may result from neural inhibitory interactions within and below IC. In many neurons, we observed two or more forms of the spectral interactions described here. Thus IC neurons display temporally and spectrally complex responses to sound that result from multiple spectral interactions at different levels of the ascending auditory pathway.

scholarly journals Emergence of Multiplicative Auditory Responses in the Midbrain of the Barn Owl

2007 ◽  
Vol 98 (3) ◽  
pp. 1181-1193 ◽  
Author(s):  
Brian J. Fischer ◽  
José Luis Peña ◽  
Masakazu Konishi
Keyword(s):  
Inferior Colliculus ◽  
Interaural Time Difference ◽  
Extracellular Recording ◽  
Auditory Pathway ◽  
Barn Owl ◽  
Central Nucleus ◽  
Interaural Level Difference ◽  
Tyto Alba ◽  
Neural Responses ◽  
Auditory Responses

Space-specific neurons in the barn owl's auditory space map gain spatial selectivity through tuning to combinations of the interaural time difference (ITD) and interaural level difference (ILD). The combination of ITD and ILD in the subthreshold responses of space-specific neurons in the external nucleus of the inferior colliculus (ICx) is well described by a multiplication of ITD- and ILD-dependent components. It is unknown, however, how ITD and ILD are combined at the site of ITD and ILD convergence in the lateral shell of the central nucleus of the inferior colliculus (ICcl) and therefore whether ICx is the first site in the auditory pathway where multiplicative tuning to ITD- and ILD-dependent signals occurs. We used extracellular recording of single neurons to determine how ITD and ILD are combined in ICcl of the anesthetized barn owl ( Tyto alba). A comparison of additive, multiplicative, and linear-threshold models of neural responses shows that ITD and ILD are combined nonlinearly in ICcl, but the interaction of ITD and ILD is not uniformly multiplicative over the sample. A subset (61%) of the neural responses is well described by the multiplicative model, indicating that ICcl is the first site where multiplicative tuning to ITD- and ILD-dependent signals occurs. ICx, however, is the first site where multiplicative tuning is observed consistently. A network model shows that a linear combination of ICcl responses to ITD–ILD pairs is sufficient to produce the multiplicative subthreshold responses to ITD and ILD seen in ICx.

Effects of Agonists and Antagonists of NMDA and ACh Receptors on Plasticity of Bat Auditory System Elicited by Fear Conditioning

2005 ◽  
Vol 94 (2) ◽  
pp. 1199-1211 ◽  
Author(s):  
Weiqing Ji ◽  
Nobuo Suga ◽  
Enquan Gao
Keyword(s):  
Nmda Receptors ◽  
Fear Conditioning ◽  
Electric Stimulation ◽  
Short Term ◽  
Acoustic Stimuli ◽  
Auditory Responses ◽  
Big Brown Bats ◽  
Plastic Changes

In big brown bats, tone-specific plastic changes [best frequency (BF) shifts] of cortical and collicular neurons can be evoked by auditory fear conditioning, repetitive acoustic stimuli or cortical electric stimulation. It has been shown that acetylcholine (ACh) plays an important role in evoking large long-term cortical BF shifts. However, the role of N-methyl-d-aspartate (NMDA) receptors in evoking BF shifts has not yet been studied. We found 1) NMDA applied to the auditory cortex (AC) or inferior colliculus (IC) augmented the auditory responses, as ACh did, whereas 2-amino-5-phosphovalerate (APV), an antagonist of NMDA receptors, reduced the auditory responses, as atropine did; 2) although any of these four drugs did not evoke BF shifts, they influenced the development of the long-term cortical and short-term collicular BF shifts elicited by conditioning; 3) like ACh, NMDA augmented the cortical and collicular BF shifts regardless of whether it was applied to the AC or IC; 4) endogenous ACh of the AC and IC is necessary to produce the long-term cortical and short-term collicular BF shifts; 5) blockade of collicular NMDA receptors by APV abolished the development of the collicular BF shift and made the cortical BF shift small and short-term; 6) blockade of cortical NMDA receptors by APV reduced the cortical and collicular BF shifts and made the cortical BF shift short-term; and 7) conditioning with NMDA + atropine applied to the AC evoked the small, short-term cortical BF shift, whereas conditioning with APV + ACh applied to the AC evoked the small, but long-term cortical BF shift.

scholarly journals Brief and Short-Term Corticofugal Modulation of Subcortical Auditory Responses in the Big Brown Bat, Eptesicus fuscus

2000 ◽  
Vol 84 (6) ◽  
pp. 3083-3087 ◽  
Author(s):  
Xiaoming Zhou ◽  
Philip H.-S. Jen
Keyword(s):  
Signal Processing ◽  
Inferior Colliculus ◽  
Auditory System ◽  
Central Nucleus ◽  
Short Term ◽  
Auditory Responses ◽  
Big Brown Bat ◽  
Auditory Experience ◽  
Frequency Map ◽  
Corticofugal Modulation

Recent studies show that the auditory corticofugal system modulates and improves ongoing signal processing and reorganizes frequency map according to auditory experience in the central nucleus of bat inferior colliculus. However, whether all corticofugally affected collicular neurons are involved in both types of modulation has not been determined. In this study, we demonstrate that one group (51%) of collicular neurons participates only in corticofugal modulation of ongoing signal processing, while a second group (49%) of collicular neurons participates in both modulation of ongoing signal processing and in reorganization of the auditory system.

Temporal coding of envelopes and their interaural delays in the inferior colliculus of the unanesthetized rabbit

1989 ◽  
Vol 61 (2) ◽  
pp. 257-268 ◽  
Author(s):  
R. Batra ◽  
S. Kuwada ◽  
T. R. Stanford
Keyword(s):  
Inferior Colliculus ◽  
Phase Locking ◽  
Acoustic Stimulus ◽  
Low Frequency ◽  
Auditory Pathway ◽  
Temporal Coding ◽  
Time Of Arrival ◽  
Unanesthetized Rabbit ◽  
The Difference ◽  
Ipsilateral Stimulation

1. The difference in the time of arrival of a sound at the two ears can be used to locate its source along the azimuth. Traditionally, it has been thought that only the on-going interaural temporal disparities (ITDs) produced by sounds of lower frequency (approximately less than 2 kHz) could be used for this purpose. However, ongoing ITDs of low frequency are also produced by envelopes of amplitude-modulated (AM) tones. These ITDs can be detected and used to lateralize complex high-frequency sounds (1, 8, 12, 15, 22, 24, 26). Auditory neurons synchronize to the modulation envelope, but do so at progressively lower modulation frequencies at higher levels of the auditory pathway. Some neurons of the cochlear nucleus synchronize best to frequencies as high as 700 Hz, but those of the inferior colliculus (IC) exhibit their best synchrony below 200 Hz. Even though synchrony to higher modulation frequencies is reduced at higher levels of the auditory pathway, is information about ITDs retained? 2. We answered this question by extracellularly recording the responses of neurons in the IC of the unanesthetized rabbit. We used an unanesthetized preparation because anesthesia alters the responses of neurons in the IC to both monaurally presented tones and ITDs. The unanesthetized rabbit is ideal for auditory research. Recordings can be maintained for long periods, and the acoustic stimulus to each ear can be independently controlled. 3. We studied the responses of 89 units to sinusoidally AM tones presented to the contralateral ear. For each unit, we recorded the response at several modulation frequencies. The degree of phase locking to the envelope at each frequency was measured using the synchronization coefficient. Two measures were used to assess the range of modulation frequencies over which phase locking occurred. The "best AM frequency" was the frequency at which we observed the greatest phase locking. The "highest AM frequency" was the highest frequency at which significant phase locking (0.001 level) was observed. We could not assess synchrony to ipsilateral AM tones directly, because most units did not respond to ipsilateral stimulation. 4. We studied the sensitivity of 63 units to ITDs produced by the envelopes of AM tones. Sensitivity to ITDs was tested by presenting AM tones to the two ears that had the same carrier frequency, but modulation frequencies that differed by 1 Hz. Units that were sensitive to ITDs responded to this stimulus by varying their response rate cyclically at the difference frequency, i.e., 1 Hz.(ABSTRACT TRUNCATED AT 400 WORDS)

scholarly journals Abnormal development of auditory responses in the inferior colliculus of a mouse model of Fragile X Syndrome

2020 ◽  
Vol 123 (6) ◽  
pp. 2101-2121 ◽  
Author(s):  
Anna O. Nguyen ◽  
Devin K. Binder ◽  
Iryna M. Ethell ◽  
Khaleel A. Razak
Keyword(s):  
Mouse Model ◽  
Inferior Colliculus ◽  
Fragile X Syndrome ◽  
Fragile X ◽  
Autism Spectrum ◽  
Abnormal Development ◽  
Sensory Sensitivity ◽  
Auditory Responses ◽  
Underlying Mechanisms ◽  
Early Developmental

Autism spectrum disorders (ASD) are commonly associated with sensory sensitivity issues, but the underlying mechanisms are unclear. This study presents novel evidence for neural correlates of auditory hypersensitivity in the developing inferior colliculus (IC) in the Fmr1 knockout (KO) mouse, a mouse model of Fragile X Syndrome (FXS), a leading genetic cause of ASD. Responses begin to show genotype differences between postnatal days 14 and 21, suggesting an early developmental treatment window.

Roles of Inhibition in Creating Complex Auditory Responses in the Inferior Colliculus: Facilitated Combination-Sensitive Neurons

2005 ◽  
Vol 93 (6) ◽  
pp. 3294-3312 ◽  
Author(s):  
Kiran Nataraj ◽  
Jeffrey J. Wenstrup
Keyword(s):  
Brain Stem ◽  
Inferior Colliculus ◽  
Low Frequency ◽  
Auditory Responses ◽  
Auditory Brain Stem ◽  
Neural Interactions ◽  
Lower Brain Stem ◽  
Excitatory Responses ◽  
Sonar Echoes ◽  
Inhibitory Interactions

We studied roles of inhibition on temporally sensitive facilitation in combination-sensitive neurons from the mustached bat's inferior colliculus (IC). In these integrative neurons, excitatory responses to best frequency (BF) tones are enhanced by much lower frequency signals presented in a specific temporal relationship. Most facilitated neurons (76%) showed inhibition at delays earlier than or later than the delays causing facilitation. The timing of inhibition at earlier delays was closely related to the best delay of facilitation, but the inhibition had little influence on the duration or strength of the facilitatory interaction. Local iontophoretic application of antagonists to receptors for glycine (strychnine, STRY) and γ-aminobutyric acid (GABA) (bicuculline, BIC) showed that STRY abolished facilitation in 96% of tested units, but BIC eliminated facilitation in only 28%. This suggests that facilitatory interactions are created in IC and reveals a differential role for these neurotransmitters. The facilitation may be created by coincidence of a postinhibitory rebound excitation activated by the low-frequency signal with the BF-evoked excitation. Unlike facilitation, inhibition at earlier delays was not eliminated by application of antagonists, suggesting an origin in lower brain stem nuclei. However, inhibition at delays later than facilitation, like facilitation itself, appears to originate within IC and to be more dependent on glycinergic than GABAergic mechanisms. Facilitatory and inhibitory interactions displayed by these combination-sensitive neurons encode information within sonar echoes and social vocalizations. The results indicate that these complex response properties arise through a series of neural interactions in the auditory brain stem and midbrain.

Inferior colliculus. II. Development of tuning characteristics and tonotopic organization in central nucleus of the neonatal cat

1975 ◽  
Vol 38 (5) ◽  
pp. 1208-1216 ◽  
Author(s):  
L. M. Aitkin ◽  
D. R. Moore
Keyword(s):  
Inferior Colliculus ◽  
Tuning Curve ◽  
External Auditory Meatus ◽  
Auditory Pathway ◽  
Central Nucleus ◽  
Synaptic Density ◽  
Tonotopic Organization ◽  
Tuning Curves ◽  
Sharp Form ◽  
Cochlear Development

Tuning curves were measured for 65 units in the inferior colliculus of seven anesthetized kittens aged from 6 to 28 days. At 2 days of age the inferior colliculus was divisible into central, pericentral, and external nuclei. Evidence was found for broader tuning curves to occur in the pericentral nucleus compared with the central nucleus, as has been observed in the adult. The middle ear was filled with serous fluid to 6 days, while the external auditory meatus remained collapsed until 10 days. Central nucleus tuning curves in kittens were relatively flat with high thresholds. Best-frequency thresholds diminished from a mean of near 100 dB SPL at 6-11 days to near 50 dB in the adult. The marked drop in thresholds between days 22 and 21 led to the adoption of the sharp form of tuning curve common for adults. Tonotopic organization of the central nucleus was clear at day 11. Speculations were advanced about the dependence of central auditory maturations on cochlear development, axon myelination in the auditory pathway, and changes in synaptic density as a function of age.

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