Periodic Reporting for period 2 - CORTIGRAD (Cortical gradients of functional integration)
Reporting period: 2022-06-01 to 2023-11-30
How does the brain's structure enable and constrain our cognitive abilities? Historically, cognitive neuroscience has focused on describing discrete, mutually exclusive modules or networks; however, current network-level descriptions of brain organization fail to account for integrated features of cognition. Building on recent work describing a principal gradient in cortical connectivity that reflects how activity from primary sensory/motor areas is integrated into transmodal regions of the default-mode network, we hypothesize that coherent aspects of cognition are an emergent property of a whole brain architecture consisting of multiple zones of integration. In particular, this project investigates the hypothesis that each region of transmodal cortex is the apex of a ‘zone’ of integration that is anchored by multiple unimodal cortical regions.
To investigate the mechanism that allows abstract representations to form in transmodal systems, we implement structural studies to investigate covariance in zone geometry across healthy adults, how zones have emerged through evolution and how they change across the lifespan. We then explore the functional consequence of zones of integration for higher-order human cognition. Studies address the ways in which individual differences in cognition emerge from variation in the architecture of different zones, and how brain activity is altered based on information that needs to converge across multiple zones. Finally, we examine how the absence of input from a sensory modality (through congenital deafness or blindness) alters the structure and function of transmodal regions in a zone-specific manner.
By describing how the spatial layout of the cortex shapes its functions, this research aims to provide a novel framework for understanding the structural constraints that underpin the integrated nature of human cognition.
To investigate the mechanism that allows abstract representations to form in transmodal systems, we implement structural studies to investigate covariance in zone geometry across healthy adults, how zones have emerged through evolution and how they change across the lifespan. We then explore the functional consequence of zones of integration for higher-order human cognition. Studies address the ways in which individual differences in cognition emerge from variation in the architecture of different zones, and how brain activity is altered based on information that needs to converge across multiple zones. Finally, we examine how the absence of input from a sensory modality (through congenital deafness or blindness) alters the structure and function of transmodal regions in a zone-specific manner.
By describing how the spatial layout of the cortex shapes its functions, this research aims to provide a novel framework for understanding the structural constraints that underpin the integrated nature of human cognition.
This research project investigates the macroscale cortical architecture related to functional integration across six studies:
1. Mapping zones of integration on the individual-level: We have begun developing methods using a surface-based watershed algorithm to delineate cortical zones on the individual brain.
2. Cross-species comparative analysis of cortical zones: We plan to apply these methods to comparative anatomical studies using openly available MRI data acquired in non-human primates such as the macaque monkey and marmoset. Data sharing initiatives through the PRIME-DRE consortium have facilitated data sharing and enabled this study to be conducted by combining data from multiple sites. This work will help to establish whether zones of cortical integration are phylogenetically conserved.
3. Development of cortical zones across the lifespan: We have characterized alterations in cortical gradients during childhood and adolescent development, and plan to further investigate the organization of cortical zones beginning with infancy. This line of research will establish the relationship between early cortical development and the emergence of cognitive abilities in early childhood.
4. Functional organization using meta-analytic approaches and population-level approaches: We have developed two novel methods to (1) assess the covariation of cortical geometry and cognitive measures; and (2) project the cerebral cortex into a functionally defined polar coordinate space. These lines of work have yielded promising results confirmed the specialization of association cortex based on proximity to adjacent sensory modalities.
5. Functional localization: We have acquired an MRI dataset of 24 participants while they imagine scenes requiring different combinations of sensory imagery. Results demonstrate subtle shifts in activation patterns aligned with the core hypothesis of this study — namely, activations within the lateral parietal cortex that spatially shift with respect to the internally generate sensory representations.
6. Impact of the absence of sensory input on cortical organization: In the next phase of this project, we plan to apply our analytic approaches to investigate the alterations within association cortex in congenitally blind and early deaf individuals. We hypothesize that alterations in cortical organization will be most pronounced within association cortex proximal to the respective sensory modality, and that such differences will account for distinct cognitive capacities.
1. Mapping zones of integration on the individual-level: We have begun developing methods using a surface-based watershed algorithm to delineate cortical zones on the individual brain.
2. Cross-species comparative analysis of cortical zones: We plan to apply these methods to comparative anatomical studies using openly available MRI data acquired in non-human primates such as the macaque monkey and marmoset. Data sharing initiatives through the PRIME-DRE consortium have facilitated data sharing and enabled this study to be conducted by combining data from multiple sites. This work will help to establish whether zones of cortical integration are phylogenetically conserved.
3. Development of cortical zones across the lifespan: We have characterized alterations in cortical gradients during childhood and adolescent development, and plan to further investigate the organization of cortical zones beginning with infancy. This line of research will establish the relationship between early cortical development and the emergence of cognitive abilities in early childhood.
4. Functional organization using meta-analytic approaches and population-level approaches: We have developed two novel methods to (1) assess the covariation of cortical geometry and cognitive measures; and (2) project the cerebral cortex into a functionally defined polar coordinate space. These lines of work have yielded promising results confirmed the specialization of association cortex based on proximity to adjacent sensory modalities.
5. Functional localization: We have acquired an MRI dataset of 24 participants while they imagine scenes requiring different combinations of sensory imagery. Results demonstrate subtle shifts in activation patterns aligned with the core hypothesis of this study — namely, activations within the lateral parietal cortex that spatially shift with respect to the internally generate sensory representations.
6. Impact of the absence of sensory input on cortical organization: In the next phase of this project, we plan to apply our analytic approaches to investigate the alterations within association cortex in congenitally blind and early deaf individuals. We hypothesize that alterations in cortical organization will be most pronounced within association cortex proximal to the respective sensory modality, and that such differences will account for distinct cognitive capacities.
The hypothesis we address in this project requires the development of novel methodologies for characterizing cortical geometry. We have been developing the tools to investigate these spatial features in cortical organization. In the following period we will apply these tools to investigate how these features vary across individuals, species and the lifespan, and we will further investigate the impact of these organizational principles for cognitive function.