Topic
Inferior colliculus
About: Inferior colliculus is a research topic. Over the lifetime, 3863 publications have been published within this topic receiving 172874 citations. The topic is also known as: inferior colliculi.
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TL;DR: Findings indicate that the magnocellular afferents work as delay lines, and the laminaris neurons work as co- incidence detectors, which suggest that interaural time differences and their phase equivalents are mapped in each frequency band along the dorsoventral axis of the nucleus laminari.
Abstract: Detection of interaural time differences underlies azimuthal sound localization in the barn owl Tyto alba. Axons of the cochlear nucleus magnocellularis, and their targets in the binaural nucleus laminaris, form the circuit responsible for encoding these interaural time differences. The nucleus laminaris receives bilateral inputs from the cochlear nucleus magnocellularis such that axons from the ipsilateral cochlear nucleus enter the nucleus laminaris dorsally, while contralateral axons enter from the ventral side. This interdigitating projection to the nucleus laminaris is tonotopic, and the afferents are both sharply tuned and matched in frequency to the neighboring afferents. Recordings of phase-locked spikes in the afferents show an orderly change in the arrival time of the spikes as a function of distance from the point of their entry into the nucleus laminaris. The same range of conduction time (160 mu sec) was found over the 700-mu m depth of the nucleus laminaris for all frequencies examined (4-7.5 kHz) and corresponds to the range of interaural time differences available to the barn owl. The estimated conduction velocity in the axons is low (3-5 m/sec) and may be regulated by short internodal distances (60 mu m) within the nucleus laminaris. Neurons of the nucleus laminaris have large somata and very short dendrites. These cells are frequency selective and phase-lock to both monaural and binaural stimuli. The arrival time of phase-locked spikes in many of these neurons differs between the ipsilateral and contralateral inputs. When this disparity is nullified by imposition of an appropriate interaural time difference, the neurons respond maximally. The number of spikes elicited in response to a favorable interaural time difference is roughly double that elicited by a monaural stimulus. Spike counts for unfavorable interaural time differences fall well below monaural response levels. These findings indicate that the magnocellular afferents work as delay lines, and the laminaris neurons work as co- incidence detectors. The orderly distribution of conduction times, the predictability of favorable interaural time differences from monaural phase responses, and the pattern of the anatomical projection from the nucleus laminaris to the central nucleus of the inferior colliculus suggest that interaural time differences and their phase equivalents are mapped in each frequency band along the dorsoventral axis of the nucleus laminaris.
837 citations
TL;DR: Short-latency evoked potentials recorded from the vertex of adult cats in response to click stimulation were analyzed in a series of lesion experiments to determine the origins of each component.
Abstract: Short-latency evoked potentials recorded from the vertex of adult cats in response to click stimulation (the far-field acoustic response) were analyzed in a series of lesion experiments to determine the origins of each component. The resultant data indicate that the primary generator of potential is the acoustic nerve; of potential 2, the cochlear nucleus; of potential 3, neurons of the superior olivary complex activated by projections crossing the midline; of potential 4, neurons of the ventral nucleus of the lateral lemniscus and preolivary region activated equally by crossed and uncrossed projections; and of potential 5, neurons of the inferior colliculus activated primarily by crossed projections.
656 citations
TL;DR: Cells that send ascending projections to the inferior Colliculus were identified following injections of horseradish peroxidase into the colliculus and all major subcollicular nuclei except the ventral nucleus of the lateral lemniscus were labelled.
Abstract: Cells that send ascending projections to the inferior colliculus were identified following injections of horseradish peroxidase into the colliculus. Labelled cells were found in all subcollicular auditory nuclei. Virtually all cells of the ipsilateral ventral nucleus of the lateral lemniscus and medial superior olive appear to project to the colliculus. Very few cells in these nuclei were labelled on the contralateral side. Heavy labelling on the contralateral side was found in the dorsal nucleus of the lateral lemniscus and cochlear nucleus, with less labelling being found ipsilaterally in these nuclei. The lateral superior olive was approximately evenly labelled on the two sides, with about half the cells from each side projecting to each colliculus. Cells in all periolivary cell groups were labelled, with most being found adjacent to the medial superior olive. An effort was made to identify individual cell types that were labelled and some 24 cell types were identified. In the cochlear nucleus there were marked differences between cell types in the extent of their labelling. Topographic projections matched previously described tonotopic organization of the colliculus and all major subcollicular nuclei except the ventral nucleus of the lateral lemniscus. A description of the cells in the nucleus is provided.
630 citations
TL;DR: Auditory hallucinations may be mediated by a distributed network of cortical and subcortical areas that is associated with activation in the inferior frontal/insular, anterior cingulate, and temporal cortex bilaterally and may have identified different components of this network.
Abstract: Background Perceptions of speech in the absence of an auditory stimulus (auditory verbal hallucinations) are a cardinal feature of schizophrenia. Functional neuroimaging provides a powerful means of measuring neural activity during auditory hallucinations, but the results from previous studies have been inconsistent. This may reflect the acquisition of small numbers of images in each subject and the confounding effects of patients actively signaling when hallucinations occur. Methods We examined 6 patients with schizophrenia who were experiencing frequent auditory hallucinations, using a novel functional magnetic resonance imaging method that permitted the measurement of spontaneous neural activity without requiring subjects to signal when hallucinations occurred. Approximately 50 individual scans were acquired at unpredictable intervals in each subject while they were intermittently hallucinating. Immediately after each scan, subjects reported whether they had been hallucinating at that instant. Neural activity when patients were and were not experiencing hallucinations was compared in each subject and the group as a whole. Results Auditory hallucinations were associated with activation in the inferior frontal/insular, anterior cingulate, and temporal cortex bilaterally (with greater responses on the right), the right thalamus and inferior colliculus, and the left hippocampus and parahippocampal cortex ( P Conclusions Auditory hallucinations may be mediated by a distributed network of cortical and subcortical areas. Previous neuroimaging studies of auditory hallucinations may have identified different components of this network.
614 citations
TL;DR: The results indicate that widely spaced electrodes can detect potentials, by means of averaging, at considerable distances from the generator of the potentialS, so that additional evidence about the location of the generator must be provided when using this recording arrangement.
593 citations