Fine-Grained Topography and Modularity of the Macaque Frontal Pole Cortex Revealed by Anatomical Connectivity Profiles

Abstract

The frontal pole cortex (FPC) plays key roles in various higher-order functions and is highly developed in non-human primates. An essential missing piece of information is the detailed anatomical connections for finer parcellation of the macaque FPC than provided by the previous tracer results. This is important for understanding the functional architecture of the cerebral cortex. Here, combining cross-validation and principal component analysis, we formed a tractography-based parcellation scheme that applied a machine learning algorithm to divide the macaque FPC (2 males and 6 females) into eight subareas using high-resolution diffusion magnetic resonance imaging with the 9.4T Bruker system, and then revealed their subregional connections. Furthermore, we applied improved hierarchical clustering to the obtained parcels to probe the modular structure of the subregions, and found that the dorsolateral FPC, which contains an extension to the medial FPC, was mainly connected to regions of the default-mode network. The ventral FPC was mainly involved in the social-interaction network and the dorsal FPC in the metacognitive network. These results enhance our understanding of the anatomy and circuitry of the macaque brain, and contribute to FPC-related clinical research.

Goal setting and attaining: Neural correlates of positive coping style and hope

“…Second, according to Snyder's hope theory, hope is a general disposition through which one engages in a conscious effort to achieve goals and which includes their ability to create feasible routes toward aspirations and their belief that they are motivated to initiate or maintain progress toward a goal (Snyder, 2002). Evidence from the literature has indicated that FPC contributes to many aspects of cognition (e.g., goal‐directed cognition) (He et al., 2020; Hosoda et al., 2020). FPC's signal could promote learning on which types of goals and goal‐generating processes produce particular benefits, thereby improving future choices (Tsujimoto et al., 2011); this aspect corresponds to the planning function of trait hope.…”

“…Thus, this study argues that hope is linked to amplitude of low‐frequency fluctuation (ALFF)/fractional ALFF (fALFF) in FPC, a subdivision of the prefrontal cortex (PFC) associated with problem‐solving, planning, and executive functions (Hosoda et al., 2020; Raju et al., 2021). Evidence from previous research has supported that the FPC plays a key role in several higher order functions, including goal‐directed persistence, prospection of future events, and decision‐making (He et al., 2020; Hosoda et al., 2020), corresponding to the hope theory of planning to meet goals (Snyder, 2002). Further, the extant literature has proposed that the FPC is inversely associated with decision impulsivity and risky decision‐making (Lv et al., 2020), which are negatively correlated with an individual's achievement of long‐term goals.…”

Striatonigrostriatal connectivity‐based cross‐species parcellation of human and macaque substantia nigra

“…In line with the conventional parcellation scheme (Li et al, 2017 ; He et al, 2020 ; see Figure 1b ), TCst of all voxels of SN were used to calculate a connection matrix (number of voxels of SN, VNsn × number of voxels of striatum and thalamus, VNst) and then a cross‐correlation matrix (VNsn × VNsn). The ( i , j )th element of the cross‐correlation matrix denotes the correlation between TCst maps of voxel i and j (i.e., lines i and j in the connection matrix).…”

Structural connectivity gradient associated with a dichotomy reveals the topographic organization of the macaque insular cortex

“…For each subject, the connectivity profile of one component or subregion was only focused on the ipsilateral hemisphere and transformed into the CIVM space. To further reduce the false positive connections, 3.08  10 -5 for the samples (He et al 2020) was used to binarize the connectivity profile. We averaged connectivity profiles of the subregion across the subjects to get the probabilistic connectivity profile, and the threshold 0.5 was used to obtain the group-level connectivity profile for the given subregion.…”