Functional organization of lateral cell groups of cat superior olivary complex

1977 ◽  
Vol 40 (2) ◽  
pp. 296-318 ◽  
Author(s):  
C. Tsuchitani
Keyword(s):  
Superior Olivary Complex ◽  
Maximum Output ◽  
Medial Superior Olive ◽  
Superior Olive ◽  
Response Characteristics ◽  
Cell Groups ◽  
Discharge Patterns ◽  
Intensity Functions ◽  
Contralateral Stimulus ◽  
Stimulation Of

1. Single-unit discharges to auditory stimuli were recorded extracellularly from superior olivary complex (SOC) units located lateral to the medial superior olive. Stimuli consisted of monaurally or binaurally presented tone bursts. The response measures obtained were effective ear, nature of effect, stimulus-frequency representation, maximum output, latency of response, and temporal pattern of tone burst-elicited discharges. Electrolytic marks were made at the unit studied or at the end of the electrode tract and in the medial superior olive. Following each experiment the locations of the units studied were determined histologically. An atlas of the laterally located SOC cell groups was developed to permit classification of units on the basis of localization within cell groups. Units were also classified according to the effects of stimulating the two ears. 2. All SOC units located lateral to the medial superior olive were excited by stimulation of the ipsilateral ear. Stimulation of the contralateral ear either excited, inhibited, had no effect, or had a potentiating effect on the discharges elicited by stimulating the ipsilateral ear. 3. Most lateral superior olivary (LSO) units were inhibited by contralateral stimulation, were narrowly tuned, produced low to high levels of maximum output, had short latencies, and produced regular discharge patterns characterized by chopper PST histograms with narrow initial peaks. 4. Most units within the caudal margins of the LSO (pLSO) were not affected or were inhibited by a contralateral stimulus; many were broadly tuned and exhibited intensity functions with large dynamic range and low slope. These units also had long latencies and produced chopper PST histograms with wide initial peaks. 5. Most units located dorsal to the LSO (DPO and DLPO) were not affected by the contralateral stimulus, were narrowly tuned, produced moderate levels of maximum discharge, had long latencies, and produced chopper PST histograms with wide initial peaks. 6. Units located ventral to the LSO appeared to have response characteristics related to unit location. Most units below the ventral hilum of the LSO (VLPO) were inhibited by the contralateral stimulus and many were broadly tuned VLPO units produced wide or poorly defined narrow-chopper discharge patterns and intensity functions with high maximum output. Most units located ventral to the lateral loop of the LSO (LNTB) were not affected by the contralateral stimulus and had response characteristics that may be related to the rostrocaudal location of the unit. 7. The cell groups located dorsal and ventral to the LSO were tonotopically organized with low-frequency-sensitive units located laterally and high-frequency-sensitive units located medially. The units located along the caudal margins of the LSO had a tonotopic organization similar to that of the LSO.

Binaural properties of single units in the superior olivary complex of the mustached bat

1991 ◽  
Vol 66 (3) ◽  
pp. 1080-1094 ◽  
Author(s):  
E. Covey ◽  
M. Vater ◽  
J. H. Casseday
Keyword(s):  
Frequency Tuning ◽  
Stimulus Frequency ◽  
Frequency Component ◽  
Sound Level ◽  
Single Units ◽  
Superior Olivary Complex ◽  
Medial Superior Olive ◽  
Superior Olive ◽  
Response Characteristics ◽  
Contralateral Ear

1. Previous studies of the superior olive of echolocating bats suggest that the lateral superior olive (LSO) retains the same structure and function as in other mammals but that the medial superior olive (MSO) is different in structure and possibly also in function. The present study is an examination of this idea in Pteronotus parnellii, a bat that has a large and well-defined MSO. 2. Using pure tones presented via earphones, we obtained data on frequency tuning for 60 single units and 96 multiunits in LSO and 94 single units and 154 multiunits in MSO. Of these we also obtained binaural response characteristics from 55 single units in LSO and 72 single units in MSO. 3. LSO and MSO each have a complete tonotopic representation, arranged in a sequence similar to that of other mammals studied. However, in both LSO and MSO there is an expanded representation of the frequencies around 60 kHz, the main frequency component of the bat's echolocation call; there is another expanded representation of the range around 90 kHz, the third harmonic of the call. The expansion of these frequency ranges suggests that the functions of LSO and MSO in Pteronotus are related to echolocation behavior. 4. The binaural characteristics of cells in LSO were essentially the same as those seen in other mammals. Most LSO units (93%) were excited by the ipsilateral ear and inhibited by the contralateral ear. The responses of nearly all LSO units were completely suppressed when the sound level at the two ears was equal. 5. The binaural characteristics of cells in MSO were different from those in nonecholocating mammals. Most MSO units (72%) were excited by the contralateral ear but were neither excited nor inhibited by the ipsilateral ear. Of the remaining units, 21% were excited by the contralateral ear and inhibited by the ipsilateral ear, and only 6% were excited by both ears. 6. The temporal discharge patterns of units in MSO differed from the tonic response pattern seen in LSO. Most MSO units had phasic response patterns, with a few spikes at the onset or offset of the stimulus; the response often changed from ON to OFF depending on stimulus frequency. 7. The results support the idea that in evolution LSO has remained unchanged, whereas MSO has undergone adaptation. The function of LSO in Pteronotus seems to be identical to that in other mammals, i.e., analysis of interaural sound level differences to derive azimuthal location. The function of MSO in Pteronotus must be different from that in nonecholocating mammals.(ABSTRACT TRUNCATED AT 400 WORDS)

Frequency-dependent interaural delays in the medial superior olive: implications for interaural cochlear delays

2011 ◽  
Vol 106 (4) ◽  
pp. 1985-1999 ◽  
Author(s):  
Mitchell L. Day ◽  
Malcolm N. Semple
Keyword(s):  
Interaural Time Difference ◽  
Superior Olivary Complex ◽  
Medial Superior Olive ◽  
Biophysical Parameters ◽  
Tone Frequency ◽  
Frequency Dependent ◽  
Superior Olive ◽  
Interaural Phase ◽  
Cochlear Delays ◽  
Delay Component

Neurons in the medial superior olive (MSO) are tuned to the interaural time difference (ITD) of sound arriving at the two ears. MSO neurons evoke a strongest response at their best delay (BD), at which the internal delay between bilateral inputs to MSO matches the external ITD. We performed extracellular recordings in the superior olivary complex of the anesthetized gerbil and found a majority of single units localized to the MSO to exhibit BDs that shifted with tone frequency. The relation of best interaural phase difference to tone frequency revealed nonlinearities in some MSO units and others with linear relations with characteristic phase between 0.4 and 0.6 cycles. The latter is usually associated with the interaction of ipsilateral excitation and contralateral inhibition, as in the lateral superior olive, yet all MSO units exhibited evidence of bilateral excitation. Interaural cochlear delays and phase-locked contralateral inhibition are two mechanisms of internal delay that have been suggested to create frequency-dependent delays. Best interaural phase-frequency relations were compared with a cross-correlation model of MSO that incorporated interaural cochlear delays and an additional frequency-independent delay component. The model with interaural cochlear delay fit phase-frequency relations exhibiting frequency-dependent delays with precision. Another model of MSO incorporating inhibition based on realistic biophysical parameters could not reproduce observed frequency-dependent delays.

scholarly journals Physiological and anatomical investigation of the auditory brainstem in the Fat-tailed Dunnart (Sminthopsis crassicaudata)

2019 ◽  
Author(s):  
Andrew Garrett ◽  
Virginia Lannigan ◽  
Nathanael Yates ◽  
Jennifer Rodger ◽  
Wilhelmina Mulders
Keyword(s):  
Auditory System ◽  
Mammalian Species ◽  
Auditory Brainstem ◽  
Auditory Brainstem Responses ◽  
Superior Olivary Complex ◽  
Medial Superior Olive ◽  
Superior Olive ◽  
Medial Nucleus ◽  
Sminthopsis Crassicaudata ◽  
Nissl Stain

The fat-tailed Dunnart (Sminthopsis crassicaudata) is a small (10-20g) native marsupial endemic to the south west of Western Australia. Currently little is known about the auditory capabilities of the dunnart, and of marsupials in general. Consequently, this study sought to investigate several electrophysiological and anatomical properties of the dunnart auditory system. Auditory brainstem responses (ABR) were recorded to brief (5ms) tone pips at a range of frequencies (4-47.5 kHz) and intensities to determine auditory brainstem thresholds. The dunnart ABR displayed multiple distinct peaks at all test frequencies, similar to other mammalian species. ABR showed the dunnart is most sensitive to higher frequencies increasing up to 47.5 kHz. Morphological observations (Nissl stain) revealed that the auditory structures thought to contribute to the first peaks of the ABR were all distinguishable in the dunnart. Structures identified include the dorsal and ventral subdivisions of the cochlear nucleus, including a cochlear nerve root nucleus as well as several distinct nuclei in the superior olivary complex, such as the medial nucleus of the trapezoid body, lateral superior olive and medial superior olive. This study is the first to show functional and anatomical aspects of the lower part of the auditory system in the Fat-tailed Dunnart.

Interaural time and intensity coding in superior olivary complex and inferior colliculus of the echolocating bat Molossus ater

1985 ◽  
Vol 53 (1) ◽  
pp. 89-109 ◽  
Author(s):  
G. Harnischfeger ◽  
G. Neuweiler ◽  
P. Schlegel
Keyword(s):  
Inferior Colliculus ◽  
Stimulus Frequency ◽  
Stimulus Onset ◽  
Time Difference ◽  
Superior Olivary Complex ◽  
Inhibitory Input ◽  
Medial Superior Olive ◽  
Transient Time ◽  
Interaural Time Differences ◽  
Superior Olive

Single-unit responses to tonal stimulation with interaural disparities were recorded in the nuclei of the superior olivary complex (SOC) and the central nucleus of the inferior colliculus (ICC) of the echolocating bat, Molossus ater. Seventy-six units were recorded from the ICC and 74 from the SOC; of the SOC units, 31 were histologically verified in the medial superior olive (MSO), 10 in the lateral superior olive (LSO), and 33 in unidentified areas of the SOC. Best frequencies (BFs) of the units ranged from 10.3 to 89.6 kHz, and Q10 dB values ranged from 2 to 70 dB. Most ICC neurons responded phasically to stimulus onset and were either inhibitory/excitatory [I/E; (53)] or excitatory/excitatory [E/E; (21)] units. In the MSO, 23 units responded tonically and 7 phasically on, 18 were E/E or E/OF (facilitatory for other input) units, and 11 were I/E neurons. All LSO neurons responded in a "chopper" fashion, and the binaural neurons were E/I units. In E/E units the excitatory response to binaural stimulation was frequently larger than the sum of the monaurally evoked responses. Many neurons with E/I or I/E inputs had very steep binaural impulse-count functions and were sensitive to small interaural intensity differences. Twenty-eight units (24%) responded with a change in firing rate of at least 20% to interaural time differences of +/- 500 microseconds. Within this sample, 11 units (8 from ICC, 2 from MSO, and 1 from SOC) were sensitive to interaural time differences of only +/- 50 microseconds. Of these 11 units, 10 were I/E units responding phasically only to stimulus onset and were also sensitive to intensity differences (delta I), being suppressed completely by the inhibitory input over a delta I range of 20 dB or less. Of 117 units tested in the ICC and SOC nuclei, 86 units (76%) were not sensitive to interaural time disparities within +/- 500 microseconds. Because the BFs of these units sensitive to interaural transient time differences (delta t) ranged between 18 and 90 kHz, responses were elicited by pure tones, and responses did not change periodically with the period equal to that of the stimulus frequency, we conclude that the neurons reacted to interaural differences of stimulus-onset time (transient time difference) but not to phase differences (ongoing time difference). Sensitivity to interaural time differences was also correlated with interaural intensity differences.(ABSTRACT TRUNCATED AT 400 WORDS)

Binaural Response Properties of Low-Frequency Neurons in the Gerbil Dorsal Nucleus of the Lateral Lemniscus

2006 ◽  
Vol 96 (3) ◽  
pp. 1425-1440 ◽  
Author(s):  
Ida Siveke ◽  
Michael Pecka ◽  
Armin H. Seidl ◽  
Sylvie Baudoux ◽  
Benedikt Grothe
Keyword(s):  
Low Frequency ◽  
Superior Olivary Complex ◽  
Suitable Model ◽  
Medial Superior Olive ◽  
Lateral Lemniscus ◽  
Auditory Midbrain ◽  
Response Properties ◽  
Superior Olive ◽  
Dorsal Nucleus ◽  
Anatomical Evidence

Differences in intensity and arrival time of sounds at the two ears, interaural intensity and time differences (IID, ITD), are the chief cues for sound localization. Both cues are initially processed in the superior olivary complex (SOC), which projects to the dorsal nucleus of the lateral lemniscus (DNLL) and the auditory midbrain. Here we present basic response properties of low-frequency (<2 kHz) DNLL neurons and their binaural sensitivity to ITDs and IIDs in the anesthetized gerbil. We found many neurons showing binaural properties similar to those reported for SOC neurons. IID-properties were similar to that of the contralateral lateral superior olive (LSO). A majority of cells had an ITD sensitivity resembling that of either the ipsilateral medial superior olive (MSO) or the contralateral LSO. A smaller number of cells displayed intermediate types of ITD sensitivity. In neurons with MSO-like response ITDs that evoked maximal discharges were mostly outside of the range of ITDs the gerbil naturally experiences. The maxima of the first derivative of their ITD-functions (steepest slope), however, were well within the physiological range of ITDs. This finding is consistent with the concept of a population rather than a place code for ITDs. Moreover, we describe several other binaural properties as well as physiological and anatomical evidence for a small but significant input from the contralateral MSO. The large number of ITD-sensitive low-frequency neurons implicates a substantial role for the DNLL in ITD processing and promotes this nucleus as a suitable model for further studies on ITD-coding.

Low-frequency neurons in the lateral superior olive exhibit phase-sensitive binaural inhibition

1991 ◽  
Vol 65 (3) ◽  
pp. 598-605 ◽  
Author(s):  
P. G. Finlayson ◽  
D. M. Caspary
Keyword(s):  
Discharge Rate ◽  
Low Frequency ◽  
Lateral Superior Olive ◽  
Superior Olive ◽  
Total Inhibition ◽  
Interaural Phase ◽  
Phase Sensitive ◽  
Evoked Activity ◽  
Discharge Patterns ◽  
Contralateral Stimulus

1. Responses of low characteristic frequency (CF) neurons in the lateral limb of the lateral superior olive (LSO) of chinchilla and rat to binaural stimuli at various interaural phase and intensity differences were examined and compared to responses from previous studies of high CF neurons. 2. Ninety-six LSO neurons from chinchillas and 10 LSO neurons from rats with CFs less than 1,200 Hz were characterized. The majority of these neurons displayed phase-locked tone-evoked temporal discharge patterns to ipsilateral CF stimuli. 3. Similar to high-CF LSO neurons, low-CF LSO neurons were excited by ipsilateral stimuli and inhibited by contralateral stimuli, with discharge rate sensitive to interaural intensity differences (IID). Discharge rate increased as ipsilateral intensity was increased and decreased as contralateral stimulus intensity was increased. 4. Binaural inhibition, inhibition of ipsilaterally evoked activity by contralateral stimuli, was dependent on interaural phase differences (IPD) in the majority of low-CF LSO neurons. Responses of phase-sensitive neurons to binaural stimuli often varied with 90 or 180 degrees changes in IPD from total inhibition to a facilitated response when compared to responses to control ipsilateral stimuli alone. 5. In summary, like high-CF LSO neurons, LSO neurons with low CFs (less than 1,200 Hz) were ipsilaterally excited and contralaterally inhibited (EI) and were sensitive to IID. Unlike most high-CF EI LSO neurons, which are not responsive when the azimuth of the stimulus is directly in front of or directly behind the animal, many low-CF LSO neurons are responsive to these stimuli.(ABSTRACT TRUNCATED AT 400 WORDS)

scholarly journals Physiological and anatomical investigation of the auditory brainstem in the Fat-tailed Dunnart (Sminthopsis crassicaudata)

2019 ◽  
Author(s):  
Andrew Garrett ◽  
Virginia Lannigan ◽  
Nathanael Yates ◽  
Jennifer Rodger ◽  
Wilhelmina Mulders
Keyword(s):  
Auditory System ◽  
Mammalian Species ◽  
Auditory Brainstem ◽  
Auditory Brainstem Responses ◽  
Superior Olivary Complex ◽  
Medial Superior Olive ◽  
Superior Olive ◽  
Medial Nucleus ◽  
Sminthopsis Crassicaudata ◽  
Nissl Stain

The fat-tailed Dunnart (Sminthopsis crassicaudata) is a small (10-20g) native marsupial endemic to the south west of Western Australia. Currently little is known about the auditory capabilities of the dunnart, and of marsupials in general. Consequently, this study sought to investigate several electrophysiological and anatomical properties of the dunnart auditory system. Auditory brainstem responses (ABR) were recorded to brief (5ms) tone pips at a range of frequencies (4-47.5 kHz) and intensities to determine auditory brainstem thresholds. The dunnart ABR displayed multiple distinct peaks at all test frequencies, similar to other mammalian species. ABR showed the dunnart is most sensitive to higher frequencies increasing up to 47.5 kHz. Morphological observations (Nissl stain) revealed that the auditory structures thought to contribute to the first peaks of the ABR were all distinguishable in the dunnart. Structures identified include the dorsal and ventral subdivisions of the cochlear nucleus, including a cochlear nerve root nucleus as well as several distinct nuclei in the superior olivary complex, such as the medial nucleus of the trapezoid body, lateral superior olive and medial superior olive. This study is the first to show functional and anatomical aspects of the lower part of the auditory system in the Fat-tailed Dunnart.

Binaural interaction in the lateral superior olive: time difference sensitivity studied in mouse brain slice

1992 ◽  
Vol 68 (4) ◽  
pp. 1151-1159 ◽  
Author(s):  
S. H. Wu ◽  
J. B. Kelly
Keyword(s):  
Brain Slice ◽  
Response Probability ◽  
Interpulse Interval ◽  
Superior Olivary Complex ◽  
Lead Times ◽  
Complete Suppression ◽  
Lateral Superior Olive ◽  
Superior Olive ◽  
Trapezoid Body ◽  
Stimulation Of

1. The sensitivity of lateral superior olive (LSO) neurons to interaural time differences was examined in an in vitro brain slice preparation. Brain slices, 400-500 microns, were taken through the superior olivary complex of C57 BL/6J mice and were maintained in an oxygenated saline solution for single-unit recording. Both extracellular and intracellular recordings were made with glass pipettes filled with 4 M potassium acetate. Responses were elicited by applying current pulses to the trapezoid body through bipolar stimulating electrodes located ipsilateral or contralateral to the olivary complex. Binaural interactions were studied by manipulating the timing and intensity of paired ipsilateral and contralateral pulses. 2. In extracellular recordings, stimulation of the ipsilateral trapezoid body usually elicited a single action potential, whereas stimulation of the contralateral trapezoid body failed to produce a spike response. Bilateral stimulation resulted in the complete suppression of the evoked spike, indicating the presence of a contralateral inhibitory effect. The degree of inhibition depended on the interpulse interval between ipsilateral and contralateral stimulation. With sufficiently large ipsilateral lead times, the probability of eliciting an extracellular spike was 1.0. As the interpulse interval was gradually shifted to reduce the ipsilateral lead time, the response probability precipitously dropped to 0.0. Most neurons could be completely suppressed by simultaneous stimulation. The dynamic range, defined as the range of interpulse intervals over which response probability changed from 0.9 to 0.1, was between 125 and 225 microseconds for most cells tested. 3. With increasing contralateral lead times, the extracellularly recorded spike was eventually released from inhibition.(ABSTRACT TRUNCATED AT 250 WORDS)

scholarly journals Interaction of excitation and inhibition in processing of pure tone and amplitude-modulated stimuli in the medial superior olive of the mustached bat

1994 ◽  
Vol 71 (2) ◽  
pp. 706-721 ◽  
Author(s):  
B. Grothe
Keyword(s):  
Discharge Rate ◽  
Stimulus Frequency ◽  
Spontaneous Discharge ◽  
Band Pass Filter ◽  
Response Patterns ◽  
Medial Superior Olive ◽  
Pass Filter ◽  
Superior Olive ◽  
Mustached Bat ◽  
Discharge Patterns

1. In mammals with good low-frequency hearing, the medial superior olive (MSO) processes interaural time or phase differences that are important cues for sound localization. Its cells receive excitatory projections from both cochlear nuclei and are thought to function as coincidence detectors. The response patterns of MSO neurons in most mammals are predominantly sustained. In contrast, the MSO in the mustached bat is a monaural nucleus containing neurons with phasic discharge patterns. These neurons receive projections from the contralateral anteroventral cochlear nucleus (AVCN) and the ipsilateral medial nucleus of the trapezoid body (MNTB). 2. To further investigate the role of the MSO in the bat, the responses of 252 single units in the MSO to pure tones and sinusoidal amplitude-modulated (SAM) stimuli were recorded. The results confirmed that the MSO in the mustached bat is tonotopically organized, with low frequencies in the dorsal part and high frequencies in the ventral part. The 61-kHz region is overrepresented. Most neurons tested (88%) were monaural and discharged only in response to contralateral stimuli. Their response could not be influenced by stimulation of the ipsilateral ear. 3. Only 11% of all MSO neurons were spontaneously active. In these neurons the spontaneous discharge rate was suppressed during the stimulus presentation. 4. The majority of cells (85%) responded with a phasic discharge pattern. About one-half (51%) responded with a level-independent phasic ON response. Other phasic response patterns included phasic OFF or phasic ON-OFF, depending on the stimulus frequency. Neurons with ON-OFF discharge patterns were most common in the 61-kHz region and absent in the high-frequency region. 5. Double tone experiments showed that at short intertone intervals the ON response to the second stimulus or the OFF response to the first stimulus was inhibited. 6. In neuropharmacological experiments, glycine applied to MSO neurons (n = 71) inhibited any tone-evoked response. In the presence of the glycine antagonist strychnine the response patterns changed from phasic to sustained (n = 35) and the neurons responded to both tones presented in double tone experiments independent of the intertone interval (n = 5). The effects of strychnine were reversible. 7. Twenty of 21 neurons tested with sinusoidally amplitude-modulated (SAM) signals exhibited low-pass or band-pass filter characteristics. Tests with SAM signals also revealed a weak temporal summation of inhibition in 13 of the 21 cells tested.(ABSTRACT TRUNCATED AT 400 WORDS)

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