Convergence of cortical types and functional motifs in the human mesiotemporal lobe

Abstract

The mesiotemporal lobe (MTL) is implicated in many cognitive processes, is compromised in numerous brain disorders, and exhibits a gradual cytoarchitectural transition from six-layered parahippocampal isocortex to three-layered hippocampal allocortex. Leveraging an ultra-high-resolution histological reconstruction of a human brain, our study showed that the dominant axis of MTL cytoarchitectural differentiation follows the iso-to-allocortical transition and depth-specific variations in neuronal density. Projecting the histology-derived MTL model to in-vivo functional MRI, we furthermore determined how its cytoarchitecture underpins its intrinsic effective connectivity and association to large-scale networks. Here, the cytoarchitectural gradient was found to underpin intrinsic effective connectivity of the MTL, but patterns differed along the anterior-posterior axis. Moreover, while the iso-to-allocortical gradient parametrically represented the multiple-demand relative to task-negative networks, anterior-posterior gradients represented transmodal versus unimodal networks. Our findings establish that the combination of micro- and macrostructural features allow the MTL to represent dominant motifs of whole-brain functional organization.

Topographic connectivity reveals task-dependent retinotopic processing throughout the human brain

“…The most striking feature in the hippocampus is a gradient of movie-watching vs. resting-state RC preference along both the medial/lateral and the long, anterior/posterior axes of the hippocampus. This RC gradient corresponds in detail to previously found microstructural and functional connectivity gradients ( 24 – 26 ). The high power, quality, and spatial resolution of both functional and anatomical HCP images allow the quantification of cognitive state-dependent RC per hippocampal subfield.…”

“…2 and 3 ) aligns surprisingly well with a combination of functional connectivity gradients found previously in the resting state. Specifically, resting-state–movie-watching preferences behave as a combination of the primary sensory-transmodal and the multiple-demand gradients ( 24 )—both in cortex and within the hippocampus ( 26 ). These large-scale gradients result from the push–pull between sensory and attentional brain systems on the one hand and the DMN on the other ( 28 ).…”

An expanding manifold in transmodal regions characterizes adolescent reconfiguration of structural connectome organization

“…The structural connectome was built by mapping the reconstructed cross-section streamlines onto the Schaefer 7-network based atlas with 200 parcels (Schaefer et al, 2018) then log-transformed to adjust for the scale (Fornito et al, 2016). We opted for this atlas as it (i) allows contextualization of our findings within macroscale intrinsic functional communities (Yeo et al, 2011), (ii) incorporates the option to assess results across different granularities, and (iii) aligns the current study with previous work from our group (Benkarim et al, 2020; Paquola et al, 2020; Park et al, 2021, 2020a; Rodríguez-Cruces et al, 2020) and others (Baum et al, 2020; Betzel et al, 2019; Osmanlıoğlu et al, 2019).…”

Functional and microstructural plasticity following social and interoceptive mental training

“…The default mode network is placed at the apex of the functional hierarchy (Margulies et al, 2016). Its broad functional role might be to integrate multiple streams of information (Margulies et al, 2016; Paquola et al, 2020a) and to orchestrate cognitive processes decoupled from external information (Frith and Frith, 2003; Murphy et al, 2018; Murphy et al, 2019; Schurz et al, 2020b) and of its potential ability to engage in high level predictive processing (Chanes and Barrett, 2016). While G2 commonly dissociates visual and somatosensory systems, G3 juxtaposes the multiple demand network known to engage in externally oriented tasks on the one hand, and sensory-motor and transmodal systems on the other hand.…”

“…Hippocampus and thalamus contribute to various aspects of emotional processing (Kober et al, 2008; Lindquist et al, 2012; Wager et al, 2008). Specifically, the hippocampus is associated with the encoding of salient stimuli (Lindquist et al, 2012) and its anatomy is at the nexus of various processing streams integrating the multiple demand and default mode cortical networks (Paquola et al, 2020a; Vos de Wael et al, 2018). Conversely, the thalamus is an integrative hub region that is known to contribute to overall cortico-cortical network organization (Hwang et al, 2017; Shine et al, 2019b), cortical excitability (Wang et al, 2019; Weng et al, 2020), as well as homeostatic processes and the endocrine system (Kober et al, 2008; Muller et al, 2020; Shine et al, 2019b).…”