Ascending Projections from the Cochlear Nucleus to the Inferior Colliculus and their Interactions with Projections from the Superior Olivary Complex

1993 ◽  
pp. 335-347 ◽  
Author(s):  
Douglas L. Oliver ◽  
Gretchen E. Beckius
Keyword(s):  
Inferior Colliculus ◽  
Cochlear Nucleus ◽  
Superior Olivary Complex

Serotonin and Serotonin Receptors in the Central Auditory System

1994 ◽  
Vol 110 (1) ◽  
pp. 93-102 ◽  
Author(s):  
Glenn C. Thompson ◽  
Ann M. Thompson ◽  
Kennon M. Garrett ◽  
B. Hill Britton
Keyword(s):  
Ligand Binding ◽  
Inferior Colliculus ◽  
Auditory System ◽  
Auditory Processing ◽  
Cochlear Nucleus ◽  
Serotonin Receptors ◽  
Superior Olivary Complex ◽  
Receptor Subtype ◽  
Central Auditory Processing ◽  
Serotonergic Cell

Immunohistochemical and ligand-binding techniques were used to visualize the neurotransmitter serotonin and one of its receptors, the 5-HT1A subtype, in auditory nuclei of the brainstem. Serotonergic fibers and terminal endings were found in all auditory nuclei extending from the cochlear nucleus to the inferior colliculus, including the superior olivary complex and the nuclei of the lateral lemniscus. The density of the innervation varied between and within each nucleus. All serotonergic cell bodies were located outside the auditory nuclei. The 5-HT1A receptor subtype was found in the cochlear nucleus as well as in the inferior colliculus. With no serotonergic cell bodies present in the auditory nuclei, the present neuroanatomic and neurochemical findings support behavioral and neurophysiologic findings that the serotonergic system may modulate central auditory processing.

Responses of single units in cerebellar vermis of the cat to monaural and binaural stimuli

1975 ◽  
Vol 38 (2) ◽  
pp. 418-429 ◽  
Author(s):  
L. M. Aitkin ◽  
J. Boyd
Keyword(s):  
Inferior Colliculus ◽  
Cochlear Nucleus ◽  
Single Units ◽  
Intensity Difference ◽  
Cerebellar Neurons ◽  
Monaural Stimulation ◽  
Sustained Responses ◽  
Maximal Discharge ◽  
Onset Responses ◽  
Stimulation Of

The responses of 146 cerebellar neurons to tone stimuli were studied in 29 cats anesthetized with chloralose-urethan and in 7 decerebrate preparations. Units were classified as onset or sustained firing. Onset spikes occurred on stimulation of either ear and showed binaural facilitation, while sustained discharges were frequently only excited by monaural stimulation. The latent periods of sustained discharges appeared to be shorter than those of onset responses, and sustained discharges were also more sharply tuned than the onset units. Evidence was presented suggesting that onset responses reflected input from the inferior colliculus and sustained responses, the cochlear nucleus. The sterotyped facilitatory behavior of onset units suggested that a maximal discharge might occur if sounds were of equal intensity at each ear; 26 neurons were examined with variable interaural time or intensity differences and 10 of these exhibited maximal firing when the interaural time and intensity difference was zero--i.e., if the sound was located directly in front of the head.

Effects of L-Baclofen and D-Baclofen on the Auditory System: A Study of Click-Evoked Potentials from the Inferior Colliculus in the Rat

1995 ◽  
Vol 104 (5) ◽  
pp. 399-404 ◽  
Author(s):  
William S. Szczepaniak ◽  
Aage R. Møller
Keyword(s):  
Inferior Colliculus ◽  
Cochlear Nucleus ◽  
Auditory Pathway ◽  
Detectable Effect ◽  
Potential Treatment ◽  
Racemic Form ◽  
System A ◽  
Auditory Disorders ◽  
Severe Tinnitus ◽  
Second Peak

The drug baclofen is a potential treatment for severe tinnitus, but its action in relieving tinnitus is not known. Baclofen is available as an approved drug only in racemic form with about equal content of the two enantiomers. In the present paper we show that l-baclofen causes a considerable (40.7%) suppression of the amplitude of the second peak in the click-evoked response from the cochlear nucleus. Bipolar recordings from the external nucleus of the inferior colliculus showed that l-baclofen caused a reduction in the amplitude of three or four distinct peaks in this response. d-Baclofen had no detectable effect on the response from the cochlear nucleus, and had only a slight effect on one component of the response from the external nucleus of the inferior colliculus. The demonstrated effect of l-baclofen on excitation in the ascending auditory pathway indicates that this drug may be a potential treatment for hyperactive auditory disorders such as tinnitus and hyperacusis.

Separate projections from the inferior colliculus to the cochlear nucleus and thalamus in guinea pigs

2004 ◽  
Vol 191 (1-2) ◽  
pp. 67-78 ◽  
Author(s):  
Diana L. Coomes ◽  
Brett R. Schofield
Keyword(s):  
Inferior Colliculus ◽  
Cochlear Nucleus ◽  
Guinea Pigs

Spinohypothalamic Tract Neurons in the Cervical Enlargement of Rats: Locations of Antidromically Identified Ascending Axons and Their Collateral Branches in the Contralateral Brain

1997 ◽  
Vol 77 (1) ◽  
pp. 435-451 ◽  
Author(s):  
Ewa Kostarczyk ◽  
Xijing Zhang ◽  
Glenn J. Giesler
Keyword(s):  
Inferior Colliculus ◽  
Nucleus Ambiguus ◽  
Reticular Nucleus ◽  
Superior Olivary Complex ◽  
Lateral Reticular Nucleus ◽  
Antidromic Activation ◽  
Posterior Thalamus ◽  
Gigantocellular Reticular Nucleus ◽  
Medial Geniculate ◽  
Low Threshold

Kostarczyk, Ewa, Xijing Zhang, and Glenn J. Giesler, Jr. Spinohypothalamic tract neurons in the cervical enlargement of rats: locations of antidromically identified ascending axons and their collateral branches in the contralateral brain. J. Neurophysiol. 77: 435–451, 1997. Antidromic activation was used to determine the locations of ascending spinohypothalamic tract (SHT) axons and their collateral projections within C1, medulla, pons, midbrain, and caudal thalamus. Sixty-four neurons in the cervical enlargement were antidromically activated initially by stimulation within the contralateral hypothalamus. All but one of the examined SHT neurons responded either preferentially or specifically to noxious mechanical stimuli. A total of 239 low-threshold points was classified as originating from 64 ascending (or parent) SHT axons. Within C1, 38 ascending SHT axons were antidromically activated. These were located primarily in the dorsal half of the lateral funiculus. Within the medulla, the 29 examined ascending SHT axons were located ventrolaterally, within or adjacent to the lateral reticular nucleus or nucleus ambiguus. Within the pons, the 25 examined ascending SHT axons were located primarily surrounding the facial nucleus and the superior olivary complex. Within the caudal midbrain, the 23 examined SHT ascending axons coursed dorsally in a position adjacent to the lateral lemniscus. Within the anterior midbrain, SHT axons traveled rostrally near the brachium of the inferior colliculus. Within the posterior thalamus, all 17 examined SHT axons coursed rostrally through the posterior nucleus of thalamus. A total of 114 low-threshold points was classified as collateral branch points. Sixteen collateral branches were seen in C1; these were located primarily in the deep dorsal horn. Forty-five collateral branches were located in the medulla. These were primarily in or near the medullary reticular nucleus, nucleus ambiguus, lateral reticular nucleus, parvocellular reticular nucleus, gigantocellular reticular nucleus, cuneate nucleus, and the nucleus of the solitary tract. Twenty-six collateral branches from SHT axons were located in the pons. These were in the pontine reticular nucleus caudalis, gigantocellular reticular nucleus, parvocellular reticular nucleus, and superior olivary complex. Twenty-three collateral branches were located in the midbrain. These were in or near the mesencephalic reticular nucleus, brachium of the inferior colliculus, cuneiform nucleus, superior colliculus, central gray, and substantia nigra. In the caudal thalamus, two branches were in the posterior thalamic nucleus and two were in the medial geniculate. These results indicate that SHT axons ascend toward the hypothalamus in a clearly circumscribed projection in the lateral brain stem and posterior thalamus. In addition, large numbers of collaterals from SHT axons appear to project to a variety of targets in C1, the medulla, pons, midbrain, and caudal thalamus. Through its widespread collateral projections, the SHT appears to be capable of providing nociceptive input to many areas that are involved in the production of multifaceted responses to noxious stimuli.

Spectral Shape Sensitivity Contributes to the Azimuth Tuning of Neurons in the Cat's Inferior Colliculus

2003 ◽  
Vol 89 (5) ◽  
pp. 2760-2777 ◽  
Author(s):  
Pierre Poirier ◽  
Frank K. Samson ◽  
Thomas J. Imig
Keyword(s):  
Inferior Colliculus ◽  
Cochlear Nucleus ◽  
Single Unit ◽  
Free Field ◽  
Spectral Shape ◽  
Shape Sensitivity ◽  
Side Band ◽  
Inhibition Model ◽  
Frequency Domains ◽  
Field Noise

We recorded high-best-frequency single-unit responses to free-field noise bursts that varied in intensity and azimuth to determine whether inferior colliculus (IC) neurons derive directionality from monaural spectral-shape. Sixty-nine percent of the sample was directional (much more responsive at some azimuths than others). One hundred twenty-nine directional units were recorded under monaural conditions (unilateral ear plugging). Binaural directional (BD) cells showed weak monaural directionality. Monaural directional (MD) cells showed strong monaural directionality, i.e., were much more responsive at some directions than others. Some MD cells were sensitive to both monaural and binaural directional cues. MD cells were monaurally nondirectional in response to tone bursts that lack direction-dependent variation in spectral shape. MD cells were unresponsive to noise bursts at certain azimuths even at high intensities showing that particular spectral shapes inhibit their responses. Two-tone inhibition was stronger where MD cells were unresponsive to noise stimulation than at directions where they were responsive. According to the side-band inhibition model, MD cells derive monaural directionality by comparing energy in excitatory and inhibitory frequency domains and thus should have stronger inhibitory side-bands than BD cells. MD and BD cells showed differences in breadth of excitatory frequency domains, strength of nonmonotonic level tuning, and responsiveness to tones and noise that were consistent with this prediction. Comparison of these data with previous findings shows that strength of spectral inhibition increases greatly between the level of the cochlear nucleus and the IC, and there is relatively little change in strength of spectral inhibition among the IC, auditory thalamus, and cortex.

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