6 research outputs found
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Pulvinar contributions to visual cortical processing in the rat
The extrageniculate visual pathway, which carries visual information from the retina through the superficial layers of the superior colliculus and the pulvinar nucleus, is poorly understood. Several studies have implicated this pathway, in particular the pulvinar, in cognitive tasks such as selective attention, but no specific mechanism or circuit has been described that could support such a function. In order to better understand what role this secondary visual pathway serves, here we examine the basic anatomical and functional properties of cells in the pulvinar, and what driving or modulating effect these cells have on visual cortex. In the first study, we made extracellular recordings in the pulvinar nucleus of lightly anesthetized rats. We identified visually responsive cells that have large receptive fields on the order of 80 degrees of visual field, fire selectively in response to low spatial frequencies, and can sometimes be selective to the direction or orientation of moving grating stimuli. We also determined that the anatomically-defined lateral subdivision encodes a greater diversity of temporal frequency stimuli than the more medial subdivision, which has better direction selectivity. In the second study, we used modified rabies viruses to retrogradely trace connections between rat pulvinar and visual cortex in order to better understand from where pulvinar receives its visual information and to which cortical areas it is best connected. We found a significantly weaker projection from pulvinar to primary visual cortex (V1) than from pulvinar to higher visual cortex (V2). In the final study, we designed and tested a new modified rabies virus to optically excite and silence populations of the more numerous projections to V2 from the rat pulvinar. We found that pulvinar modulates cortical size tuning and suppresses flash responses, but doesn’t drive activity in V2. This dissertation builds a foundational understanding of the role of the pulvinar nucleus in rodents, illustrating how pulvinar integrates spatiotemporal information from visual cortex and the superior colliculus, and regulates firing rates in rodent V2. The new rabies virus variant described here is well suited to test theories of pulvinar function, in addition to its wide potential applications in non-transgenic animals such as cats or non-human primates, where models of pulvinar are already well developed
Recommended from our members
Pulvinar contributions to visual cortical processing in the rat
The extrageniculate visual pathway, which carries visual information from the retina through the superficial layers of the superior colliculus and the pulvinar nucleus, is poorly understood. Several studies have implicated this pathway, in particular the pulvinar, in cognitive tasks such as selective attention, but no specific mechanism or circuit has been described that could support such a function. In order to better understand what role this secondary visual pathway serves, here we examine the basic anatomical and functional properties of cells in the pulvinar, and what driving or modulating effect these cells have on visual cortex. In the first study, we made extracellular recordings in the pulvinar nucleus of lightly anesthetized rats. We identified visually responsive cells that have large receptive fields on the order of 80 degrees of visual field, fire selectively in response to low spatial frequencies, and can sometimes be selective to the direction or orientation of moving grating stimuli. We also determined that the anatomically-defined lateral subdivision encodes a greater diversity of temporal frequency stimuli than the more medial subdivision, which has better direction selectivity. In the second study, we used modified rabies viruses to retrogradely trace connections between rat pulvinar and visual cortex in order to better understand from where pulvinar receives its visual information and to which cortical areas it is best connected. We found a significantly weaker projection from pulvinar to primary visual cortex (V1) than from pulvinar to higher visual cortex (V2). In the final study, we designed and tested a new modified rabies virus to optically excite and silence populations of the more numerous projections to V2 from the rat pulvinar. We found that pulvinar modulates cortical size tuning and suppresses flash responses, but doesn’t drive activity in V2. This dissertation builds a foundational understanding of the role of the pulvinar nucleus in rodents, illustrating how pulvinar integrates spatiotemporal information from visual cortex and the superior colliculus, and regulates firing rates in rodent V2. The new rabies virus variant described here is well suited to test theories of pulvinar function, in addition to its wide potential applications in non-transgenic animals such as cats or non-human primates, where models of pulvinar are already well developed
Braincharts for the human lifespan
Over the past 25 years, neuroimaging has become a ubiquitous tool in basic research and clinical studies of the human brain. However, there are no reference standards against which to anchor measures of individual differences in brain morphology, in contrast to growth charts for traits such as height and weight. Here, we built an interactive online resource (www.brainchart.io) to quantify individual differences in brain structure from any current or future magnetic resonance imaging (MRI) study, against models of expected age-related trends. With the goal of basing these on the largest and most inclusive dataset, we aggregated MRI data spanning 115 days post-conception through 100 postnatal years, totaling 122,123 scans from 100,071 individuals in over 100 studies across 6 continents. When quantified as centile scores relative to the reference models, individual differences show high validity with non-MRI brain growth estimates and high stability across longitudinal assessment. Centile scores helped identify previously unreported brain developmental milestones and demonstrated increased genetic heritability compared to non-centiled MRI phenotypes. Crucially for the study of brain disorders, centile scores provide a standardised and interpretable measure of deviation that reveals new patterns of neuroanatomical differences across neurological and psychiatric disorders emerging during development and ageing. In sum, brain charts for the human lifespan are an essential first step towards robust, standardised quantification of individual variation and for characterizing deviation from age-related trends. Our global collaborative study
A longitudinal resource for population neuroscience of school-age children and adolescents in China
During the past decade, cognitive neuroscience has been calling for population diversity to address the challenge of validity and generalizability, ushering in a new era of population neuroscience. The developing Chinese Color Nest Project (devCCNP, 2013-2022), the first ten-year stage of the lifespan CCNP (2013-2032), is a two-stages project focusing on brain-mind development. The project aims to create and share a large-scale, longitudinal and multimodal dataset of typically developing children and adolescents (ages 6.0-17.9 at enrolment) in the Chinese population. The devCCNP houses not only phenotypes measured by demographic, biophysical, psychological and behavioural, cognitive, affective, and ocular-tracking assessments but also neurotypes measured with magnetic resonance imaging (MRI) of brain morphometry, resting-state function, naturalistic viewing function and diffusion structure. This Data Descriptor introduces the first data release of devCCNP including a total of 864 visits from 479 participants. Herein, we provided details of the experimental design, sampling strategies, and technical validation of the devCCNP resource. We demonstrate and discuss the potential of a multicohort longitudinal design to depict normative brain growth curves from the perspective of developmental population neuroscience. The devCCNP resource is shared as part of the "Chinese Data-sharing Warehouse for In-vivo Imaging Brain" in the Chinese Color Nest Project (CCNP) - Lifespan Brain-Mind Development Data Community (https://ccnp.scidb.cn) at the Science Data Bank