Inferior colliculus. I. Comparison of response properties of neurons in central, pericentral, and external nuclei of adult cat

1975 ◽  
Vol 38 (5) ◽  
pp. 1196-1207 ◽  
Author(s):  
L. M. Aitkin ◽  
W. R. Webster ◽  
J. L. Veale ◽  
D. C. Crosby
Keyword(s):  
Inferior Colliculus ◽  
Physiological Responses ◽  
Cell Types ◽  
Central Nucleus ◽  
Low Frequencies ◽  
High Frequencies ◽  
The Common ◽  
Adult Cat ◽  
Tonal Stimuli ◽  
Anesthetized Cat

The responses of 150 units in the central (ICC), pericentral (ICP), and external nuclei (ICX) of the inferior colliculus of the anesthetized cat were studied in relation to their tuning characteristics and binaural responses to tonal stimuli. Units in ICC were characterized by sharp tuning and binaural responses, while those in ICP and ICX were frequently very broadly tuned with a poorly defined best frequency. Nonetheless, in the latter nuclei a tendency existed for tonotopic organization to occur with high frequencies located externally and low frequencies at the margins of the central nucleus. Tuning measurements were hampered by the common occurrence of habituation in the discharges of single units in ICP and, to a lesser extend, ICX. The majority of units in ICP could be differentiated from those in ICX by their monaural input. Speculations were advanced linking anatomical cell types to physiological responses in the three nuclei and into the possible functional significance of the different behavior of units to tonal stimuli.

Representation of sound frequency and laterality by units in central nucleus of cat inferior colliculus

1979 ◽  
Vol 42 (6) ◽  
pp. 1626-1639 ◽  
Author(s):  
M. N. Semple ◽  
L. M. Aitkin
Keyword(s):  
Inferior Colliculus ◽  
Three Dimensions ◽  
Central Nucleus ◽  
Interaction Patterns ◽  
Low Frequencies ◽  
High Frequencies ◽  
Unit Classes ◽  
Heterogeneous Interaction ◽  
Phase Sensitive ◽  
Adult Cats

1. The discharges of 632 units were isolated extracellularly during 42 penetrations of the central nucleus of the inferior colliculus (ICC) in 21 adult cats lightly anesthetized with pentobarbital and ketamine. Microelectrode penetrations were directed from caudal to rostral through ICC, parallel to the Horsley-Clarke (H-C) horizontal and sagittal planes. 2. The threshold best frequency (BF) and binaural response properties were examined for each unit, with the aim of elucidating the organization of these discharge characteristics within ICC. 3. Binaural unit classes consisted of monaural (contralateral) (EO), binaurally phase-sensitive (delay), contralateral excitatory/ipsilateral inhibitory (EI), binaurally excitatory (EE), and other more heterogeneous interaction patterns (other). 4. Detailed histological reconstruction of electrode tracks allowed the recording site for each unit to be related to the three dimensions of ICC. This structure was divided into three lateromedial and three rostrocaudal blocks such that each block contained a similar number of units, enabling meaningful statistical comparisons. Low (3.2 kHz greater than BF) and high (3.2 kHz less than BF) best-frequency classes provided a correlate of dorsoventral location. 5. The arrangements of BFs within ICC were found to be compatible with a model of this structure in which units having similar BFs are organized into layers lying in the H-C horizontal plane medially and gradually tilting in both a ventrolateral and ventrorostral direction. Low frequencies are concentrated dorsally and laterally; high frequencies, ventrally and medially. A rostrocaudal BF difference arises only in lateral aspects of the ICC, where lower frequencies are encountered rostrally. 6. Binaural response classes were distributed differentially throughout ICC. Thus, EO units were concentrated caudally, ventrally, and laterally, while delay units were in greatest numbers rostrally, dorsally, and laterally--almost totally segregated from EO and EI units. The latter populations overlapped ventrally and laterally, but EI units were in greatest density rostrally. The EE class occurred throughout the nucleus, but was most common medially. 7. It is suggested that the differential distributions of binaural responses reflect a partial segregation of the afferents, arising in the superior olive and cochlear nucleus, which terminate in ICC. The central nucleus of the inferior colliculus thus may be composed of several functionally segregated subregions contained within a common tonotopic organization.

The representation of stimulus azimuth by high best-frequency azimuth-selective neurons in the central nucleus of the inferior colliculus of the cat

1987 ◽  
Vol 57 (4) ◽  
pp. 1185-1200 ◽  
Author(s):  
L. M. Aitkin ◽  
R. L. Martin
Keyword(s):  
Inferior Colliculus ◽  
Discharge Rate ◽  
Median Plane ◽  
Central Nucleus ◽  
High Discharge ◽  
Discharge Rates ◽  
Tonal Stimuli ◽  
Anesthetized Cat ◽  
The Way

The responses to changes in stimulus azimuth of 220 high best-frequency (BF) (greater than 3 kHz) units in the central nucleus of the inferior colliculus of the anesthetized cat were studied with BF tones (220 units) and noise stimuli (84 units). By this means we hoped to gain some insights into the way the azimuthal locations of high BF stimuli were represented in the inferior colliculus. For each unit the discharge rate was determined for stimuli located along a plane tilted at 20 degrees above the horizontal. This plane was chosen to optimize pinna directionality. Locations in the frontal field were sampled in 10-20 degree steps around a 170 degree arc. These measurements were repeated at a number of different stimulus intensities until the directional properties of the unit became clear. Units for which the functions relating discharge rate to azimuth for a given stimulus showed a clear feature (peak or border), the azimuthal location of which varied little with intensities between 20 and 40 dB above threshold, were defined as being azimuth selective for that stimulus. Only 13% of units were azimuth selective for BF tones, whereas 44% were selective for noise. Many azimuth functions for selective units were of the plateau-shaped type for which relatively high discharge rates occurring at most contralateral azimuths declined steeply to near zero and remained low for most ipsilateral azimuths. These plateau-shaped functions were most common for tonal stimuli. Other functions showed a fixed azimuth of maximum firing (best azimuth); these were more common for noise than for tonal stimuli. Detailed azimuth functions for both tone and noise stimuli were measured for 63 units. Some exhibited the same kind of azimuth function to both stimuli. However, 18 units were azimuth selective to noise but not to tones. The borders of plateau-shaped functions obtained using both noise and tonal stimuli were concentrated within 20 degrees of the median plane. Very few units had borders that spanned peripheral ipsilateral or contralateral azimuths. Although the best azimuths of some noise azimuth functions were observed to lie at these peripheral azimuths, the majority occurred around 20 degrees contralateral to the median plane. The recording sites for units were related to a three-by-three matrix of rostrocaudal and mediolateral locations across the central nucleus. Units that were azimuth selective to noise were distributed fairly evenly throughout the central nucleus, whereas units azimuth selective to tones formed highest proportions rostrally.(ABSTRACT TRUNCATED AT 400 WORDS)

Binaural masking and sensitivity to interaural delay in the inferior colliculus

1992 ◽  
Vol 336 (1278) ◽  
pp. 415-422 ◽  
Keyword(s):  
Inferior Colliculus ◽  
Physiological Mechanism ◽  
Central Nucleus ◽  
Neural Population ◽  
Physiological Basis ◽  
Low Frequencies ◽  
Delay Sensitive ◽  
Masking Level Difference ◽  
The Mean ◽  
Number Of Discharges

The binaural masking level difference (BMLD) is a psychophysical effect whereby signals masked by a noise at one ear become unmasked by sounds reaching the other, BMLD effects are largest at low frequencies where they depend on signal phase, suggesting that part of the physiological mechanism responsible for the BMLD resides in cells that are sensitive to interaural time disparities. We have investigated a physiological basis for unmasking in the responses of delay-sensitive cells in the central nucleus of the inferior colliculus in anaesthetized guinea pigs. The masking effects of a binaurally presented noise, as a function of the masker delay, were quantified by measuring the number of discharges synchronized to the signal, and by measuring the masked threshold. The noise level for masking was lowest at the best delay for the noise. The mean magnitude of the unmasking across our neural population was similar to the human psychophysical BMLD under the same signal and masker conditions.

Response selectivity for multiple dimensions of frequency sweeps in the pallid bat inferior colliculus

1994 ◽  
Vol 72 (3) ◽  
pp. 1061-1079 ◽  
Author(s):  
Z. M. Fuzessery
Keyword(s):  
Inferior Colliculus ◽  
High Frequency ◽  
Low Frequency ◽  
Central Nucleus ◽  
Frequency Change ◽  
Frequency Range ◽  
Low Frequencies ◽  
Response Properties ◽  
Sweep Direction ◽  
Pallid Bat

1. While hunting, the pallid bat uses passive sound localization at low frequencies to find terrestrial prey, and echolocation for general orientation. It must therefore process two different types of acoustic input at the same time. The pallid bat's echolocation pulse is a downward frequency-modulated (FM) sweep from 60 to 30 kHz. This study examined the response selectivity of single neurons in the pallid bat's central nucleus of the inferior colliculus (ICC) for FM sweeps, comparing the response properties of the high-frequency population, tuned to the biosonar pulse, with the low-frequency population, tuned below the pulse. The working hypothesis was that the high-frequency population would exhibit a response selectivity for downward FM sweeps that was not present in the low-frequency population. 2. Neurons were tested for their selectivity for FM sweep direction, duration, frequency range and bandwidth, and rate of frequency change. The extent to which they responded exclusively to tones, noise, and FM sweeps was also examined. Significant differences in the response properties of neurons in the two populations were found. In the low-frequency population, all neurons responded to tones, but only 50% responded to FM sweeps. Only 23% were selective for sweep direction. In the high-frequency population, all neurons responded to FM sweeps, but 31% did not respond to tones. Over one-half of this population was selective for sweep direction, and of those that were selective, all preferred the downward sweep direction of the biosonar pulse. A large percentage (31%) responded exclusively to downward sweeps, and not to tones or upward sweeps. None of the cells in either population responded to noise, or did so only at very high relative thresholds. 3. Both populations contained neurons that were selective for short stimulus durations that approximated the duration of the biosonar pulse, although the percentage was greater in the high-frequency population (58% vs. 20%). In the high-frequency population, 31% of the neurons tested for duration responded exclusively to both the sweep direction and duration of the biosonar pulse. 4. Downward FM-selective neurons, with one exception, were generally insensitive to the rate of frequency change of the FM sweep, as well as the frequency range and bandwidth of the sweep. They responded similarly to both the full 60- to 30-kHz sweep and to 5-kHz bandwidth portions of the full sweep.(ABSTRACT TRUNCATED AT 400 WORDS)

scholarly journals Measuring and Analyzing the Common and Idiosyncratic Cycles: An Application for Turkish Manufacturing Industry

2021 ◽  
Vol 11 (2) ◽  
pp. 279
Author(s):  
Emel Siklar ◽  
Ilyas Siklar
Keyword(s):  
Manufacturing Industry ◽  
Production Data ◽  
Low Frequencies ◽  
High Frequencies ◽  
Industrial Activities ◽  
Butterworth Filter ◽  
Leading Indicator ◽  
Production Trend ◽  
The Common

This study uses the Butterworth filter to decompose cyclical signals at low and high frequencies in the production data of the manufacturing industry and its sub-sectors. At low frequencies, the production trend exhibits considerable differences among industrial activities while most of the sub-sectors are more sensitive to common cycle than their own dynamics at high frequencies. Moreover, it is predicted that changes in the manufacture of basic metals sub-sector production can be used as a leading indicator for the expansion and contraction periods of the common cycle estimated for the manufacturing industry.

scholarly journals Simple Setup for Measuring the Response to Differential Mode Noise of Common Mode Chokes

Electronics ◽  
2020 ◽  
Vol 9 (3) ◽  
pp. 381 ◽  
Author(s):  
Pablo González-Vizuete ◽  
Carlos Domínguez-Palacios ◽  
Joaquín Bernal-Méndez ◽  
María A. Martín-Prats
Keyword(s):  
High Frequency ◽  
Electromagnetic Compatibility ◽  
Differential Mode ◽  
Common Mode ◽  
Low Frequencies ◽  
High Frequencies ◽  
Natural Modes ◽  
Magnetic Couplings ◽  
The Common ◽  
Conducted Emissions

This work presents a technique to measure the attenuation of differential mode noise provided by common mode chokes. The proposed setup is a simpler alternative to the balanced setup commonly employed to that end, and its main advantage is that it avoids the use of auxiliary circuits (baluns). We make use of a modal analysis of a high-frequency circuit model of the common mode choke to identify the natural modes actually excited both in the standard balanced setup and in the simpler alternative setup proposed here. This analysis demonstrates that both setups are equivalent at low frequencies and makes it possible to identify the key differences between them at high frequencies. To analyze the scope and interest of the proposed measurement technique we have measured several commercial common mode chokes and we have thoroughly studied the sensitivity of the measurements taken with the proposed setup to electric and magnetic couplings. We have found that the proposed setup can be useful for quick assessment of the attenuation provided by a common mode choke for differential mode noise in a frequency range that encompasses the frequencies where most electromagnetic compatibility regulations impose limits to the conducted emissions of electronic equipment.

scholarly journals Modularity in the Microcircuitry of the Mouse Inferior Colliculus Yields Dual Processing Streams for Auditory and Multisensory Information

2019 ◽  
Author(s):  
Alexandria M. H. Lesicko ◽  
Daniel A. Llano
Keyword(s):  
Inferior Colliculus ◽  
Brain Slices ◽  
Cell Types ◽  
Dorsal Column ◽  
Central Nucleus ◽  
Dual Processing ◽  
Dorsal Column Nuclei ◽  
Somatosensory Stimuli ◽  
Caged Glutamate ◽  
Multisensory Information

ABSTRACTThe lateral cortex of the inferior colliculus (LCIC) is parcellated into two neurochemical compartments: one that comprises periodic neurochemical modules rich in GABAergic and cholinergic terminals and an extramodular matrix rich in calretinin neurons. We recently found that projections from auditory structures (auditory cortex and central nucleus of the IC) target the extramodular matrix, while somatosensory structures (somatosensory cortex and dorsal column nuclei) target the modules. What is peculiar about this finding of segregated inputs is that previous work has found that many LCIC neurons respond to both auditory and somatosensory stimuli. To investigate how these pathways interact, here we use laser photostimulation of caged glutamate to interrogate local LCIC circuits in brain slices from mouse. We found that most cell types in the LCIC receive inputs only from their home domain, but that GABAergic neurons in the modules serve as a bridge between modules and extramodular space. Further, we found that residence in- or out-of a module strongly predicted the output connectivity of that cell. These data suggest that distinct processing streams are seen in the LCIC and that GABAergic cells in modules serve to link these streams.

Representation of the Temporal Envelope of Sounds in the Human Brain

2000 ◽  
Vol 84 (3) ◽  
pp. 1588-1598 ◽  
Author(s):  
Anne-Lise Giraud ◽  
Christian Lorenzi ◽  
John Ashburner ◽  
Jocelyne Wable ◽  
Ingrid Johnsrude ◽  
...  
Keyword(s):  
Inferior Colliculus ◽  
Auditory System ◽  
Medial Geniculate Body ◽  
Response Model ◽  
Response Type ◽  
Low Frequencies ◽  
High Frequencies ◽  
Temporal Envelope ◽  
Medial Geniculate ◽  
The Right

The cerebral representation of the temporal envelope of sounds was studied in five normal-hearing subjects using functional magnetic resonance imaging. The stimuli were white noise, sinusoidally amplitude-modulated at frequencies ranging from 4 to 256 Hz. This range includes low AM frequencies (up to 32 Hz) essential for the perception of the manner of articulation and syllabic rate, and high AM frequencies (above 64 Hz) essential for the perception of voicing and prosody. The right lower brainstem (superior olivary complex), the right inferior colliculus, the left medial geniculate body, Heschl's gyrus, the superior temporal gyrus, the superior temporal sulcus, and the inferior parietal lobule were specifically responsive to AM. Global tuning curves in these regions suggest that the human auditory system is organized as a hierarchical filter bank, each processing level responding preferentially to a given AM frequency, 256 Hz for the lower brainstem, 32–256 Hz for the inferior colliculus, 16 Hz for the medial geniculate body, 8 Hz for the primary auditory cortex, and 4–8 Hz for secondary regions. The time course of the hemodynamic responses showed sustained and transient components with reverse frequency dependent patterns: the lower the AM frequency the better the fit with a sustained response model, the higher the AM frequency the better the fit with a transient response model. Using cortical maps of best modulation frequency, we demonstrate that the spatial representation of AM frequencies varies according to the response type. Sustained responses yield maps of low frequencies organized in large clusters. Transient responses yield maps of high frequencies represented by a mosaic of small clusters. Very few voxels were tuned to intermediate frequencies (32–64 Hz). We did not find spatial gradients of AM frequencies associated with any response type. Our results suggest that two frequency ranges (up to 16 and 128 Hz and above) are represented in the cortex by different response types. However, the spatial segregation of these two ranges is not systematic. Most cortical regions were tuned to low frequencies and only a few to high frequencies. Yet, voxels that show a preference for low frequencies were also responsive to high frequencies. Overall, our study shows that the temporal envelope of sounds is processed by both distinct (hierarchically organized series of filters) and shared (high and low AM frequencies eliciting different responses at the same cortical locus) neural substrates. This layout suggests that the human auditory system is organized in a parallel fashion that allows a degree of separate routing for groups of AM frequencies conveying different information and preserves a possibility for integration of complementary features in cortical auditory regions.

Neural Sensitivity to Interaural Envelope Delays in the Inferior Colliculus of the Guinea Pig

2005 ◽  
Vol 93 (6) ◽  
pp. 3463-3478 ◽  
Author(s):  
Sarah J. Griffin ◽  
Leslie R. Bernstein ◽  
Neil J. Ingham ◽  
David McAlpine
Keyword(s):  
Fine Structure ◽  
Guinea Pig ◽  
Inferior Colliculus ◽  
High Frequency ◽  
Low Frequency ◽  
Nerve Fibers ◽  
Neural Firing ◽  
Low Frequencies ◽  
Interaural Time Differences ◽  
High Frequencies

Interaural time differences (ITDs) are important cues for mammalian sound localization. At high frequencies, sensitivity to ITDs, which are conveyed only by the envelope of the waveforms, has been shown to be poorer than sensitivity to ITDs at low frequencies, which are conveyed primarily by the fine structure of the waveforms. Recently, human psychophysical experiments have demonstrated that sensitivity to envelope-based ITDs in high-frequency transposed tones can be equivalent to low-frequency fine-structure–based ITD sensitivity. Transposed tones are designed to provide high-frequency auditory nerve fibers (ANFs) with similar temporal information to that provided by low-frequency tones. We investigated neural sensitivity to ITDs in high-frequency transposed and sinusoidally amplitude modulated (SAM) tones, in the inferior colliculus of the guinea pig. Neural sensitivity to ITDs in transposed tones was found to be greater than that to ITDs in SAM tones; in response to transposed tones, neural firing rates were more modulated as a function of ITD and discrimination thresholds were found to be lower than those in response to SAM tones. Similar to psychophysical findings, ITD discrimination of single neurons in response to transposed tones for rates of modulation <250 Hz was comparable to neural discrimination of ITDs in low-frequency tones. This suggests that the neural mechanisms that mediate sensitivity to ITDs at high and low frequencies are functionally equivalent, provided that the stimuli result in appropriate temporal patterns of action potentials in ANFs.

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