Tectopulvinar pathway

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The tectopulvinar pathway and the geniculostriate pathway are the two visual pathways that travel from the retina to the early visual cortical areas. From the optic tract, the tectopulvinar pathway sends neuronal radiations to the superior colliculus in the tectum, then to the lateral posterior-pulvinar thalamic complex. [1] . Approximately 10% of retinal ganglion cells (mostly magnocellular) project onto the tectopulvinar pathway [2] .

Contents

The tectopulvinar pathway is a phylogenetically older pathway than the geniculostriate pathway [3] , and is the only visual pathway present in fish, amphibians, and reptiles [1] . The tectopulvinar pathway terminates at the prestriate cortex (also known as the extrastriate cortex or visual area V2) [4] , which receives large feedforward input from the striate cortex; the geniculostriate pathway also converges to the same location. . At the thalamic pulvinar nucleus, visual information is routed either to the medial pulvinar, which sends connections to cingulate, posterior parietal, premotor and prefrontal cortical areas; or to the lateral pulvinar, which sends connections to the temporal lobe dorsal stream cortical areas (and in particular, to region MT – a critical region for motion perception) [5] .

Damage to the tectopulvinar pathway is most commonly characterized by visual ataxia [1] , a deficit characterized by an inability to perform visually guided hand movements in reaching and grasping objects [6] , as well as by spatial attentional deficits.

Function

The tectopulvinar pathway is a fast-acting pathway that provides the viewer with information on the absolute spatial information of objects. The pathway plays a large role in directing visual spatial attention and is particularly responsive to novel stimuli that appear or move in peripheral vision; however, because it receives mostly magnocellular visual input, the tectopulvinar pathway is not sensitive to fine detail [2] . It directs visual spatial attention most notably through guided eye movements, via cranial nerves III ( the oculomotor nerve), IV ( the trochlear nerve), and VI (the abducens nerve). Directing visual spatial attention and eye movements to salient peripheral stimuli is necessary to bring likely important visual information to center vision. Furthermore, the tectopulvinar pathway has been suggested to support residual visual perceptual abilities in blindsight patients [7] .

Superior Colliculus

Within the pathway, the superior colliculus functions to orient the viewer’s gaze and attention via eye and head movements towards objects of interest in egocentric space [2] . The superior colliculus’s role in directing eye movements is especially well-studied: multiple lines of evidence show that artificially blocking and increasing superior colliculus activity modulates (inhibits and biases, respectively) eye saccades to the affected side [8] . Recent evidence has argued that superior colliculus function is not limited to basic motor and low-level visual control, but more generally in target selection and in both covert and overt attentional control [9] . Further studies contend that superior colliculus function encompasses a wide range of behavioral responses such as in arm-reaching, and not just in eye and head movements [10] .

The superior colliculus is also a center for multisensory auditory and visual integration. Recent studies have shown that the superior colliculus responds especially strongly when auditory input arrives temporally and synchronously with visual input [2] . Superior colliculus activity was measured to be greater in these multisensory events than in single modality events [11]

Pulvinar Nucleus

Further along the pathway, the pulvinar nucleus performs similar tasks to the superior colliculus in directing visual spatial attention. Pulvinar lesions often create visuomotor deficits and neglect-like attentional deficits [5] . Lastly, the pulvinar nucleus has been implicated in guiding attention for behavioral responses: greater neuronal activity was recorded for stimuli that serve as targets or cues for active behavior than for stimuli that are not associated with active behavior [12] .

Related Research Articles

Visual cortex Region of the brain that processes visual information

The visual cortex of the brain is the area of the cerebral cortex that processes visual information. It is located in the occipital lobe. Sensory input originating from the eyes travels through the lateral geniculate nucleus in the thalamus and then reaches the visual cortex. The area of the visual cortex that receives the sensory input from the lateral geniculate nucleus is the primary visual cortex, also known as visual area 1 (V1), Brodmann area 17, or the striate cortex. The extrastriate areas consist of visual areas 2, 3, 4, and 5.

Blindsight is the ability of people who are cortically blind due to lesions in their striate cortex, also known as the primary visual cortex or V1, to respond to visual stimuli that they do not consciously see.

Lateral geniculate nucleus Relay center in thalamus

The lateral geniculate nucleus is a relay center in the thalamus for the visual pathway. It receives a major sensory input from the retina. The LGN is the main central connection for the optic nerve to the occipital lobe, particularly the primary visual cortex. In humans, each LGN has six layers of neurons alternating with optic fibers.

Parietal lobe

The parietal lobe is one of the four major lobes of the cerebral cortex in the brain of mammals. The parietal lobe is positioned above the temporal lobe and behind the frontal lobe and central sulcus.

Pulvinar nuclei

The pulvinar nuclei or nuclei of the pulvinar are the nuclei located in the thalamus. As a group they make up the collection called the pulvinar of the thalamus, usually just called the pulvinar.

Superior colliculus

The superior colliculus is a structure lying on the roof of the mammalian midbrain. In non-mammalian vertebrates, the homologous structure is known as the optic tectum, or optic lobe. The adjective form tectal is commonly used for both structures.

The pretectal area, or pretectum, is a midbrain structure composed of seven nuclei and comprises part of the subcortical visual system. Through reciprocal bilateral projections from the retina, it is involved primarily in mediating behavioral responses to acute changes in ambient light such as the pupillary light reflex, the optokinetic reflex, and temporary changes to the circadian rhythm. In addition to the pretectum's role in the visual system, the anterior pretectal nucleus has been found to mediate somatosensory and nociceptive information.

Multisensory integration, also known as multimodal integration, is the study of how information from the different sensory modalities may be integrated by the nervous system. A coherent representation of objects combining modalities enables animals to have meaningful perceptual experiences. Indeed, multisensory integration is central to adaptive behavior because it allows animals to perceive a world of coherent perceptual entities. Multisensory integration also deals with how different sensory modalities interact with one another and alter each other's processing.

Koniocellular cell

A koniocellular cell is a neuron with a small cell body that is located in the koniocellular layer of the lateral geniculate nucleus (LGN) in primates, including humans.

Thalamocortical radiations

Thalamocortical radiations are the fibers between the thalamus and the cerebral cortex.

The zona incerta (ZI) is a horizontally elongated region of gray matter in the subthalamus below the thalamus. Its connections project extensively over the brain from the cerebral cortex down into the spinal cord.

Frontal eye fields

The frontal eye fields (FEF) are a region located in the frontal cortex, more specifically in Brodmann area 8 or BA8, of the primate brain. In humans, it can be more accurately said to lie in a region around the intersection of the middle frontal gyrus with the precentral gyrus, consisting of a frontal and parietal portion. The FEF is responsible for saccadic eye movements for the purpose of visual field perception and awareness, as well as for voluntary eye movement. The FEF communicates with extraocular muscles indirectly via the paramedian pontine reticular formation. Destruction of the FEF causes deviation of the eyes to the ipsilateral side.

Supplementary eye field

Supplementary eye field (SEF) is the name for the anatomical area of the dorsal medial frontal lobe of the primate cerebral cortex that is indirectly involved in the control of saccadic eye movements. Evidence for a supplementary eye field was first shown by Schlag, and Schlag-Rey. Current research strives to explore the SEF's contribution to visual search and its role in visual salience. The SEF constitutes together with the frontal eye fields (FEF), the intraparietal sulcus (IPS), and the superior colliculus (SC) one of the most important brain areas involved in the generation and control of eye movements, particularly in the direction contralateral to their location. Its precise function is not yet fully known. Neural recordings in the SEF show signals related to both vision and saccades somewhat like the frontal eye fields and superior colliculus, but currently most investigators think that the SEF has a special role in high level aspects of saccade control, like complex spatial transformations, learned transformations, and executive cognitive functions.

Medial dorsal nucleus

The medial dorsal nucleus is a large nucleus in the thalamus.

Posterior parietal cortex

The posterior parietal cortex plays an important role in planned movements, spatial reasoning, and attention.

Inferior pulvinar nucleus

Inferior pulvinar nucleus is one of four traditionally anatomically distinguished nuclei of the pulvinar of the thalamus. The other three nuclei of the pulvinar are called lateral, anterior and medial pulvinar nuclei.

Lateral pulvinar nucleus

Lateral pulvinar nucleus is one of four traditionally anatomically distinguished nuclei of the pulvinar of the thalamus. The other three nuclei of the pulvinar are called anterior, inferior and medial pulvinar nuclei.

Medial pulvinar nucleus

Medial pulvinar nucleus is one of four traditionally anatomically distinguished nuclei of the pulvinar of the thalamus. The other three nuclei of the pulvinar are called lateral, inferior and anterior pulvinar nuclei.

Peter Schiller (neuroscientist) Neuroscientist

Peter H. Schiller is a professor emeritus of Neuroscience in the Department of Brain and Cognitive Sciences at the Massachusetts Institute of Technology (MIT). He is well known for his work on the behavioral, neurophysiological and pharmacological studies of the primate visual and oculomotor systems.

Michael E. Goldberg, also known as Mickey Goldberg, is an American neuroscientist and David Mahoney Professor at Columbia University. He is known for his work on the mechanisms of the mammalian eye in relation to brain activity. He served as president of the Society for Neuroscience from 2009 to 2010.

References

  1. 1 2 3 Whishaw, I. Q., & Kolb, B. (2015). Fundamentals of human neuropsychology. New York, NY: Worth Custom Publishing.
  2. 1 2 3 4 Banich, M. T., & Compton, R. J. (2018). Cognitive neuroscience. Cambridge, United Kingdom: Cambridge University Press.
  3. ↑ Nagel, S. M. (n.d.). Superior Colliculus. Retrieved November 20, 2019, from https://psych.athabascau.ca/html/Psych402/Biotutorials/24/colliculus.shtml
  4. ↑ Visual cortex. (n.d.). In Wikipedia. Retrieved November 20, 2019, from https://en.wikipedia.org/wiki/Visual_cortex.
  5. 1 2 Pulvinar nuclei. (n.d.). In Wikipedia. Retrieved November 20, 2019, from https://en.wikipedia.org/wiki/Pulvinar_nuclei.
  6. ↑ Swearer J. (2011) Optic Ataxia. In: Kreutzer J.S., DeLuca J., Caplan B. (eds) Encyclopedia of Clinical Neuropsychology. Springer, New York, NY
  7. ↑ Leh, S. E., Johansen-Berg, H., & Ptito, A. (2006). Unconscious vision: new insights into the neuronal correlate of blindsight using diffusion tractography. Brain, 129(7), 1822–1832. doi: 10.1093/brain/awl111
  8. ↑ Mcpeek, R. M., & Keller, E. L. (2010). Deficits in saccade target selection after temporary inactivation of superior colliculus. Journal of Vision, 2(7), 573–573. doi: 10.1167/2.7.573
  9. ↑ Krauzlis, R. J., Lovejoy, L. P., & Zénon, A. (2013). Superior Colliculus and Visual Spatial Attention. Annual Review of Neuroscience, 36(1), 165–182. doi: 10.1146/annurev-neuro-062012-170249
  10. ↑ Song, J.-H., & Mcpeek, R. M. (2015). Neural correlates of target selection for reaching movements in superior colliculus. Journal of Neurophysiology, 113(5), 1414–1422. doi: 10.1152/jn.00417.2014
  11. ↑ Ghose, D., Maier, A., Nidiffer, A., & Wallace, M. T. (2014). Multisensory Response Modulation in the Superficial Layers of the Superior Colliculus. Journal of Neuroscience, 34(12), 4332–4344. doi: 10.1523/jneurosci.3004-13.2014
  12. ↑ Petersen, S. E., Robinson, D. L., & Morris, J. (1987). Contributions of the pulvinar to visual spatial attention. Neuropsychologia, 25(1), 97–105. doi: 10.1016/0028-3932(87)90046-7
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