Center for Computational Brain Research, Indian Institute of Technology-Madras, Chennai,Tamil Nadu 600036, IndiaIndia
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The pulvinar is a collection of thalamic nuclei which is often considered mainly with visual processing and attention. The unique thing about this thalamic brain area is that, in phylogeny, this area is considered to be much more advanced in primates and virtually absent in rodents1 , making it an important brain area to understand in human brain evolution. This editorial aims to shed light on the structure and function of the pulvinar
Keywords: thalamic; pulvinar
OpenJournal PUBLISHERS Editorial Pulvinar Complex: Relay Center or Something More?
* Jaikishan Jayakumar, PhD* Center for Computational Brain Research, Indian Institute of Technology-Madras, Chennai,Tamil Nadu 600036, India * *Corresponding author Jaikishan Jayakumar, PhD Center for Computational Brain Research, Indian Institute of Technology-Madras, Chennai,Tamil Nadu 600036, India; E-mail: Jaikishan.jayakumar@gmail.com Article information nd th th Received: July 2 , 2018; Accepted: July 26 , 2018; Published: July 30 , 2018 Cite this article Jayakumar J. Pulvinar complex: Relay center or something more? Neuro Open J. 2018; 5(1): e1-e2. doi: 10.17140/NOJ-5-e008 he pulvinar is a collection of thalamic nuclei which is often The non-visual areas of the pulvinar which is mainly the considered mainly with visual processing and attention. The medial pulvinar is involved in emotional salience estimation6 and T unique thing about this thalamic brain area is that, in phylogeny, has extensive connections with many paralimbic cortical structures this area is considered to be much more advanced in primates and and higher multisensory cortex7. In addition, this area has strong virtually absent in rodents1, making it an important brain area to connections with emotional centers such as the amygdala8. understand in human brain evolution. This editorial aims to shed light on the structure and function of the pulvinar. As mentioned before, the lateral and the inferior zones is mainly visual except for a small area called as the lateral posterior The pulvinar that is described in this article mainly pulvinar9 which is thought to be involved in motor salience. The represents the pulvinar of primates including humans as they are visual part of the pulvinar, particularly the striate cortex recipient much more defined and developed compared with lesser species. zones are topographically aligned to their inputs from visual areas Based on the cyto- and myeloarchitecture, the pulvinar can be such as V1, V2, V5 as well as higher areas across both the dorsal divided into medial, lateral, inferior and the more anterior oral visual stream and the ventral visual stream. This results in the pulvinar2. This classification, however, is purely anatomical and possibility of this area being a point of interaction between the controversial and does not represent the functional classification two streams and thus can effectively help in visual attention. The of the nuclei. It is still unclear as to how many nuclei there are in pulvinar is theorized to promote large scale synchronization across the various divisions of the pulvinar. The majority of visual zones different networks within the cortex10. In addition, the pulvinar within the pulvinar for e.g. are found in the lateral and the inferior also enhances visual processing within the cortex by synchronizing zones. Within the visual pulvinar, there is at least three subdivisions gamma band oscillations within the pulvino-cortical networks11. In 3 12 that have been named based on Calbindin staining3. In addition, addition, a more recent study by Saalmann et al.,12 shows that the the visual pulvinar is also classified into two zones depending on pulvinar demonstrates alpha band synchronization that serves as an its recipients: a striate cortical zone and a superior collicular zone4. attentional communication mechanism. Using behavioral task of visual discrimination, they were able to show the synchronization The pulvinar is unique from other sensory nuclei within of two different cortico-thalamic systems namely area 17 and the the thalamus in that it receives a majority of its inputs from the ventromedial region of the caudal part of the lateral zone of the cortical structures rather than sensory structures for e.g. lateral pulvinar and the other network being area 18 and the dorsolateral geniculate nucleus is driven by the retina. Moreover, functionally part of the same region of the pulvinar.
the pulvinar looks to “mimic” the topographical organization of the cortical structures from which it receives input. This has led to The pulvinar has also been shown to be involved 13,14 15 the name “associative nuclei” rather than sensory or motor nuclei in “distractor filtering” , contrast processing , and for this area5.
interhemispheric integration16. The dorsal aspect of the pulvinar cc Copyright 2018 by Jayakumar J. This is an open-access article distributed under Creative Commons Attribution 4.0 International License (CC BY 4.0), which Neuro Open J. 2018; 5(1): e1-e2. doi: 10.17140/NOJ-5-e008 nucleus is also a critical hub for spatial attention and selection of 120. doi: 10.1002/cne.902270112 visually guided actions17.
8. Rosenberg DS, Mauguière F, Demarquay G, Ryvlin P, Isnard J, There is also evidence18 that a subset of nuclei in the Fischer C, Guénot M, Magnin M. Involvement of medial pulvinar medial part of the inferior pulvinar act as a subcortical component thalamic nucleus in human temporal lobe seizures. Epilepsia. 2006; of the dorsal stream and another subset in the lateral part of the 47(1): 98-107. doi: 10.1111/j.1528-1167.2006.00375.x inferior pulvinar and the neighboring ventrolateral nucleus of the lateral pulvinar are part of the ventral stream of processing. 9. Sherman SM, Guillery RW. Distinct functions for direct and transthalamic corticocortical connections. J Neurophysiol. 2011; In summary, the pulvinar can be considered not as a 106(3): 1068-1077. doi: 10.1152/jn.00429.2011 simple relay center but as a thalamic brain area that serves as an integrator for most visual processing areas through possibly a 10. Shipp S. The functional logic of cortico-pulvinar connections. mechanism of intra brain oscillations. Although its function as a Philos Trans R Soc Lond B Biol Sci. 2003; 358(1438): 1605-1624. doi: visual processing area is somewhat clear how it relates to other 10.1098/rstb.2002.1213 modalities and intermodality synchronization is still unclear and why this area, in an evolutionary timeframe, has evolved in primates 11. Shumikhina S, Molotchnikoff S. Pulvinar participates in still remains a mystery.
synchronizing neural assemblies in the visual cortex, in cats. Neurosci Lett. 1999; 272(2): 135-139.