Distribution of corticotectal cells in macaque

Lock, Thomas M.; Baizer, Joan S.; Bender, D. B.

doi:10.1007/s00221-003-1500-y

Cited by 84 publications

(120 citation statements)

References 96 publications

Supporting

Mentioning

108

Contrasting

Order By: Relevance

“…Moreover, the saliency representation was generally limited to the superficial visual SC layers. SCi visuomotor neurons, with dominant inputs that arise from frontal-parietal cortices and the basal ganglia (23)(24)(25), did not show a significant preference for the salient oddball (Fig. 4 A and B).…”

Section: Discussionmentioning

confidence: 99%

“…The input-output structure and response characteristics of SCi neurons differ in many important ways from SCs neurons (23)(24)(25). In particular, SCi neurons receive a diverse set of inputs predominantly from frontal and parietal cortices and the basal ganglia (Fig.…”

Section: Surround Modulation Emerges Earlier and Stronger In Scs Thanmentioning

confidence: 99%

“…In particular, SCi neurons receive a diverse set of inputs predominantly from frontal and parietal cortices and the basal ganglia (Fig. 1B) and project directly to the brainstem saccade generator (23)(24)(25). Functionally, these neurons have multisensory and oculomotor responses and have been shown to play a central role in spatial attention (19,20).…”

Section: Surround Modulation Emerges Earlier and Stronger In Scs Thanmentioning

confidence: 99%

“…Recently (26), it has been shown that the activity of SCs neurons, with dominant inputs that arise from the retina and V1 (Fig. 1B) (24,25), is well-predicted by a computational saliency model that has been validated on the free viewing behavior of humans (27) and nonhuman primates (28). In addition, a recent lesion study has shown that attention guidance is preserved in the absence of V1 (29), thereby challenging the hypothesis that saliency coding depends critically on V1 (6-9) and instead, implicating a possible pathway through the SC.…”

mentioning

confidence: 99%

“…1B) is multilayered but is often described as having two dominant functional layers, a superior colliculus superficial layer (SCs) associated exclusively with visual processing and a superior colliculus multisensory-cognitive-motor intermediate layer (SCi) linked to the control of attention and gaze (19)(20)(21)(22). Because SCs is interconnected with multiple visual areas (23)(24)(25), it is in an ideal location to pool diverse visual inputs to form a feature-agnostic saliency representation. Recently (26), it has been shown that the activity of SCs neurons, with dominant inputs that arise from the retina and V1 (Fig.…”

mentioning

confidence: 99%

See 4 more Smart Citations

Superior colliculus encodes visual saliency before the primary visual cortex

White

Kan

Lévy

et al. 2017

Proc. Natl. Acad. Sci. U.S.A.

115

View full text Add to dashboard Cite

Models of visual attention postulate the existence of a bottom-up saliency map that is formed early in the visual processing stream. Although studies have reported evidence of a saliency map in various cortical brain areas, determining the contribution of phylogenetically older pathways is crucial to understanding its origin. Here, we compared saliency coding from neurons in two early gateways into the visual system: the primary visual cortex (V1) and the evolutionarily older superior colliculus (SC). We found that, while the response latency to visual stimulus onset was earlier for V1 neurons than superior colliculus superficial visual-layer neurons (SCs), the saliency representation emerged earlier in SCs than in V1. Because the dominant input to the SCs arises from V1, these relative timings are consistent with the hypothesis that SCs neurons pool the inputs from multiple V1 neurons to form a feature-agnostic saliency map, which may then be relayed to other brain areas.M ost theories and computational models of saliency postulate that visual input is transformed into a topographic representation of visual conspicuity (Fig. 1A, red), whereby certain stimuli stand out from others based on low-level features of the input image (Fig. 1A, blue) (1-3). The concept of a priority map describes a combined representation of visual saliency and behavioral relevancy (Fig. 1A, yellow), which is thought to be the core determinant of attention and gaze (4, 5). To date, most studies have reported evidence of saliency and/or priority maps in a distributed network of cortical brain areas [e.g., primary visual cortex (V1) (6-9), visual area 4 (V4) (10), lateral intraparietal area (LIP) (11-13), and frontal eye fields (14, 15)]. However, there is mounting evidence for a subcortical saliency mechanism in the premammalian optic tectum (16-18) or superior colliculus (SC) in primates (Fig. 1B). The primate SC, which has received a lot of attention for its role as an oculomotor hub, might be considered an unlikely candidate for a visual salience map, but there is a rich history of research on visual attention in the SC (a recent review is in ref. 19), which has broadened our perspective of its role in processes previously thought to be the domain of neocortex.The SC (Fig. 1B) is multilayered but is often described as having two dominant functional layers, a superior colliculus superficial layer (SCs) associated exclusively with visual processing and a superior colliculus multisensory-cognitive-motor intermediate layer (SCi) linked to the control of attention and gaze (19)(20)(21)(22). Because SCs is interconnected with multiple visual areas (23-25), it is in an ideal location to pool diverse visual inputs to form a feature-agnostic saliency representation. Recently (26), it has been shown that the activity of SCs neurons, with dominant inputs that arise from the retina and V1 (Fig. 1B) (24, 25), is well-predicted by a computational saliency model that has been validated on the free viewing behavior of humans (27) and nonhuman prima...

show abstract

Section: Discussionmentioning

confidence: 99%

Section: Surround Modulation Emerges Earlier and Stronger In Scs Thanmentioning

confidence: 99%

Section: Surround Modulation Emerges Earlier and Stronger In Scs Thanmentioning

confidence: 99%

mentioning

confidence: 99%

mentioning

confidence: 99%

See 3 more Smart Citations

Superior colliculus encodes visual saliency before the primary visual cortex

White

Kan

Lévy

et al. 2017

Proc. Natl. Acad. Sci. U.S.A.

115

View full text Add to dashboard Cite

show abstract

Distribution across cortical areas of neurons projecting to the superior colliculus in new world monkeys

2005

View full text Add to dashboard Cite

Surprisingly little is known about the proportions of projections of different areas and regions of neocortex to the superior colliculus in primates. To obtain an overview of such projection patterns, we placed a total of 10 injections of retrograde tracers in the superior colliculus of three New World monkeys (Callithrix, Callicebus, and Aotus). Because cortex was flattened and cut parallel to the surface, labeled corticotectal neurons could be accurately located relative to architectonic boundaries and surface features. While there was variability across cases and injection sites, the summed results clearly support several conclusions. One, three well-defined visual areas, V1 (18%), V2 (14%), and MT (11%), contributed nearly half of the total of labeled cells. Two, several other visual areas (V3, DL, DM, and FST) that are early in the processing hierarchy provided another fifth of the total. Three, inferior temporal visual areas of the ventral stream provided only minor projections. Four, visuomotor fields (FEF, FV, cortex in the region of SEF, and posterior parietal cortex) contained less than 10% of the labeled neurons. Five, few labeled neurons were in auditory or somatosensory areas. The results indicate that cortical inputs to the superior colliculus originate predominantly from early visual areas rather than from multimodal or visuomotor areas. © 2005 Wiley-Liss, Inc. Key words: visual cortex; frontal eye field; MT; tectumThe mammalian superior colliculus is a midbrain structure importantly involved in eye and head movements that direct gaze toward objects of interest (McPeek and Keller, 2004). This function depends on multiple sources of information. Inputs include direct retinal projections, ascending auditory and somatosensory projections, and contributions from a number of cortical areas (Huerta and Harting, 1984;Kaas and Huerta, 1988;Harting, 2004). As the number and types of subdivisions of cortex vary across mammalian taxa (Merzenich and Kaas, 1980), the sources of cortical projections to the superior colliculus also vary. In addition, as cortical areas have different functional roles, their relevance to superior colliculus functions should vary. Thus, the proportional contributions of different cortical areas must vary within a species.While there is considerable evidence that a number of cortical areas across a range of studied mammals project to the superior colliculus, there is yet little understanding of the relative strengths of these projections. One reason for this is that most studies of cortical projections to the superior colliculus have been based on placing injections of tracers into subdivisions of cortex. The projections of cortical areas are generally studied one by one. In this way, projections can be demonstrated, but it is very difficult to judge the relative contributions of different cortical areas. While injections of retrograde tracers into the superior colliculus have been used to provide a more global overview of the projection pattern to the superior colliculus, ...

show abstract

Morphology of superior colliculus‐ and middle temporal area‐projecting neurons in primate primary visual cortex

Nhan

Callaway

2011

J of Comparative Neurology

View full text Add to dashboard Cite

Layers 5 and 6 of primate primary visual cortex (V1) harbor morphologically diverse cell groups that have corticocortical and corticosubcortical projections. Layer 6 middle temporal area (MT)-projecting neurons are particularly interesting, as they are the only deep-layer cortical neurons that provide both corticocortical feed-forward inputs (to area MT) and corticosubcortical feedback projections (to superior colliculus [SC]) (Fries et al. [1985] Exp Brain Res 58:613–616). However, due to limitations in anatomical tracing techniques, little is known about the detailed morphologies of these cells. We therefore applied a genetically modified rabies virus as a retrograde tracer to fill the dendrites of projection neurons with green fluorescent protein (GFP) (Wickersham et al. [2007] Nat Methods 4:47–49). We injected virus into SC or area MT of macaque monkeys and examined labeled cells in V1. Two-thirds of labeled neurons following SC injections were found in layer 5, consisting of “tall-tufted” and “nontufted” cells; the remaining cells were layer 6 “nontufted.” Area MT injections labeled neurons in layers 4B and 6, as previously described (Shipp and Zeki [1989] Eur J Neurosci 1:309–332). The layer 6 neurons projecting to MT were remarkably similar to the layer 6 SC-projecting neurons. In contrast to the dense and focused dendritic arbors of layer 5 “tall-tufted” pyramids, all “nontufted” cells had sparse, but unusually long basal dendrites. The nontufted cells closely resemble Meynert cells (le Gros Clark [1942] J Anat 76:369–376; Winfield et al. [1983] Proc R Soc Lond B Biol Sci 217:129–139), but the full in vivo reconstructions presented here show that their basal dendrites can extend much further (up to 1.2 mm) and are less asymmetric than inferred from Golgi reconstructions. J. Comp. Neurol. 520:52–80, 2012.

show abstract

Distribution of corticotectal cells in macaque

Cited by 84 publications

References 96 publications

Superior colliculus encodes visual saliency before the primary visual cortex

Superior colliculus encodes visual saliency before the primary visual cortex

Distribution across cortical areas of neurons projecting to the superior colliculus in new world monkeys

Morphology of superior colliculus‐ and middle temporal area‐projecting neurons in primate primary visual cortex

Contact Info

Product

Resources

About