Origins of afferents to visual suprageniculate nucleus of the cat

Hicks, T.P.; Stark, Christian; Fletcher, William A.

doi:10.1002/cne.902460410

Cited by 57 publications

(24 citation statements)

References 76 publications

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“…In this respect, our results agree well with those reported by Abramson and Chalupa (1988) and with the study of Hicks et al (1986). Earlier reports on SC efferents to other areas, such as the dorsal and ventral lateral genicu-late nucleus (Harrel et al, 1982), the superioriinferior olive Weber et al, 1978), and the pontine and other reticular structures (Hashikawa and Kawamura, 1977;Kawamura and Hashikawa, 19781, describe cells with the same size as was found in our study.…”

Section: Size and Morphological Characteristics Of Labeled Cellssupporting

confidence: 95%

“…In four of the five cats used in this study , the HRP injection site was located graphic and HRP studies showing that fibers from the SC terminate in the Sg (Graham, 1977;Hicks et al, 1986;Abramson and Chalupa, 1988). In addition, however, we also found labeled neurons in the contralateral SC and in the external nuclei of the inferior colliculus (IC) on both sides.…”

Section: Resultsmentioning

confidence: 90%

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Organization of the colliculo‐suprageniculate pathway in the cat: A wheat germ agglutinin‐horseradish peroxidase study

Katoh

Benedek

1995

J of Comparative Neurology

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A wheat germ-agglutinated horseradish peroxidase (WGA-HRP) tracing technique was used to label the cell bodies of neurons in the superior colliculus that send projections into the visually sensitive region of the suprageniculate nucleus (Sg) in the feline thalamus. After determination of the position of the Sg by detecting characteristic single-unit responses to moving visual stimuli, WGA-HRP was injected into the Sg in five pentobarbital-anesthetized cats. The animals were than sacrificed, and serial frozen sections of the midbrain were processed for the demonstration of peroxidase activity. A total of 2,736 WGA-HRP-stained neurons were located within the ipsilateral superior colliculus (SC), and a few labeled cells were consistently found bilaterally in the external nuclei of the inferior colliculus. In each cat, a small but significant fraction of the labeled cells were encountered contralateral to the injection. Medial SC neurons tended to project to the posterior Sg, and lateral SC neurons tended to project to more rostral Sg. However, labeled cells were distributed homogeneously along the rostrocaudal extent of the SC, indicating the absence of a well defined topographic relationship. Nor was the Sg injection site location related to the laminar distribution of SC projection neurons. In all cases, the majority of the labeled cells were found in layer IV (49.0%), with fewer cells in layers III (17.5%) layer V (20.0%), and layer VI (11.8%). No labeled cells were located in layer I, although a few were located in the deep part of layer II. Five types of SC projection cells were distinguished morphologically. Of the 258 labeled cells that could be characterized, 25% were stellate cells, 25% vertical cells, 20% granular cells, 17% triangular cells, and 12% horizontal cells. The average diameter of 226 cells ranged between 8 and 47 microns. We conclude that a mixed population of SC cells projects to the Sg; the morphological heterogeneity and the distribution of these cells suggests that several functionally different pathways may be involved in the colliculothalamic pathway and in the processing of visual input in the SC.

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Section: Size and Morphological Characteristics Of Labeled Cellssupporting

confidence: 95%

Section: Resultsmentioning

confidence: 90%

Organization of the colliculo‐suprageniculate pathway in the cat: A wheat germ agglutinin‐horseradish peroxidase study

Katoh

Benedek

1995

J of Comparative Neurology

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“…There have been several reports of somatosensory or visual influences on neuronal activity in subcortical auditory structures (Aitkin et al 1981;Young et al 1992;Doubell et al 2003;Komura et al 2005;Shore and Simic 2005;Musacchia et al 2006). Moreover, following tracer injections in auditory cortex, we observed retrograde labeling in the suprageniculate nucleus of the thalamus, which is known to receive auditory, somatosensory, and visual inputs (Hicks et al 1986;Benedek et al 1997;Eo¨rdegh et al 2005). Local field potential recordings from monkey auditory belt areas have shown that somatosensory responses have a similar feedforward profile to the auditory responses, that is, beginning in layer IV and then spreading to extragranular layers (Schroeder et al 2001).…”

Section: Discussionsupporting

confidence: 51%

Physiological and Anatomical Evidence for Multisensory Interactions in Auditory Cortex

et al. 2006

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Recent studies, conducted almost exclusively in primates, have shown that several cortical areas usually associated with modalityspecific sensory processing are subject to influences from other senses. Here we demonstrate using single-unit recordings and estimates of mutual information that visual stimuli can influence the activity of units in the auditory cortex of anesthetized ferrets. In many cases, these units were also acoustically responsive and frequently transmitted more information in their spike discharge patterns in response to paired visual--auditory stimulation than when either modality was presented by itself. For each stimulus, this information was conveyed by a combination of spike count and spike timing. Even in primary auditory areas (primary auditory cortex [A1] and anterior auditory field [AAF]),~15% of recorded units were found to have nonauditory input. This proportion increased in the higher level fields that lie ventral to A1/AAF and was highest in the anterior ventral field, where nearly 50% of the units were found to be responsive to visual stimuli only and a further quarter to both visual and auditory stimuli. Within each field, the pure-tone response properties of neurons sensitive to visual stimuli did not differ in any systematic way from those of visually unresponsive neurons. Neural tracer injections revealed direct inputs from visual cortex into auditory cortex, indicating a potential source of origin for the visual responses. Primary visual cortex projects sparsely to A1, whereas higher visual areas innervate auditory areas in a field-specific manner. These data indicate that multisensory convergence and integration are features common to all auditory cortical areas but are especially prevalent in higher areas.

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“…Previous studies have distinguished the MGsg based on connections with other regions of the brainstem, especially regarding strong projections to the MGsg from the superior colliculus (Tanaka et al, 1985; Hicks et al, 1986; Hoshino et al, 2010) and the sagulum (Morest, 1965). Examination of these regions in our experiments suggests that the MGsg in guinea pigs receives similar inputs.…”

Section: Discussionmentioning

confidence: 99%

Excitatory and inhibitory projections in parallel pathways from the inferior colliculus to the auditory thalamus

Mellott¹,

Foster²,

Ohl³

et al. 2014

Front. Neuroanat.

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Individual subdivisions of the medial geniculate body (MG) receive a majority of their ascending inputs from 1 or 2 subdivisions of the inferior colliculus (IC). This establishes parallel pathways that provide a model for understanding auditory projections from the IC through the MG and on to auditory cortex. A striking discovery about the tectothalamic circuit was identification of a substantial GABAergic component. Whether GABAergic projections match the parallel pathway organization has not been examined. We asked whether the parallel pathway concept is reflected in guinea pig tectothalamic pathways and to what degree GABAergic cells contribute to each pathway. We deposited retrograde tracers into individual MG subdivisions (ventral, MGv; medial, MGm; dorsal, MGd; suprageniculate, MGsg) to label tectothalamic cells and used immunochemistry to identify GABAergic cells. The MGv receives most of its IC input (~75%) from the IC central nucleus (ICc); MGd and MGsg receive most of their input (~70%) from IC dorsal cortex (ICd); and MGm receives substantial input from both ICc (~40%) and IC lateral cortex (~40%). Each MG subdivision receives additional input (up to 32%) from non-dominant IC subdivisions, suggesting cross-talk between the pathways. The proportion of GABAergic cells in each pathway depended on the MG subdivision. GABAergic cells formed ~20% of IC inputs to MGv or MGm, ~11% of inputs to MGd, and 4% of inputs to MGsg. Thus, non-GABAergic (i.e., glutamatergic) cells are most numerous in each pathway with GABAergic cells contributing to different extents. Despite smaller numbers of GABAergic cells, their distributions across IC subdivisions mimicked the parallel pathways. Projections outside the dominant pathways suggest opportunities for excitatory and inhibitory crosstalk. The results demonstrate parallel tectothalamic pathways in guinea pigs and suggest numerous opportunities for excitatory and inhibitory interactions within and between pathways.

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Origins of afferents to visual suprageniculate nucleus of the cat

Cited by 57 publications

References 76 publications

Organization of the colliculo‐suprageniculate pathway in the cat: A wheat germ agglutinin‐horseradish peroxidase study

Organization of the colliculo‐suprageniculate pathway in the cat: A wheat germ agglutinin‐horseradish peroxidase study

Physiological and Anatomical Evidence for Multisensory Interactions in Auditory Cortex

Excitatory and inhibitory projections in parallel pathways from the inferior colliculus to the auditory thalamus

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