The postcentral sulcal complex and the transverse postcentral sulcus and their relation to sensorimotor functional organization

Abstract

It has been demonstrated that the postcentral sulcus, which forms the posterior boundary of the sensorimotor region, is a complex of distinct sulcal segments. Although the general somatotopic arrangement in the human sensorimotor cortex is relatively well known, we do not know whether the different segments of the postcentral sulcus relate in a systematic way to the sensorimotor functional representations. Participants were scanned with functional magnetic resonance imaging while they made movements of different body parts and the location of functional activity was examined on a subject-by-subject basis with respect to the morphological features of the postcentral sulcus. The findings demonstrate that the postcentral sulcus of each subject may be divided into five segments and there is a tight relationship between sensorimotor representations of different body parts and specific segments of the postcentral sulcus. The results also addressed the issue of the transverse postcentral sulcus, a short sulcus that is present within the ventral part of the postcentral gyrus in some brains. It was shown that, when present, this sulcus is functionally related to the oral (mouth and tongue) sensorimotor representation. When this sulcus is not present, the inferior postcentral sulcus which is also related to the oral representation is longer. Thus, the sulcal morphology provides an improved framework for functional assignments in individual subjects.

Validation of periodic fMRI signals in response to wearable tactile stimulation

“…2A), dozens of S-ROIs survive at p = 0.001 (uncorrected), including those located within and outside the primary sensorimotor cortex. Although recent fMRI studies have revealed somatotopic areas in nonprimary cortex (e.g., Huang et al, 2012; Zlatkina et al, 2016), the boundary of a broader sensorimotor network has not been established for accepting or rejecting S-ROIs solely by their anatomical locations. Some of the S-ROIs found in the posterior parietal, frontal, temporal, cingulate, and even occipital cortex could contain authentic brain activation driven by higher-level processing of tactile stimuli, while others could result from non-brain activities containing partial but strong periodic signals at the stimulus frequency from unknown sources.…”

“…Third, a data-driven approach would be helpful for labeling new somatotopic areas in humans because no generally accepted functional brain atlas can be used as a reference map to validate unknown ROIs, particularly those found outside the primary sensorimotor cortex. For example, several human neuroimaging studies have shown preliminary evidence of somatotopic areas in nonprimary sensorimotor cortex (Dresel et al, 2008; Fink et al, 1997; Huang and Sereno, 2007; Huang et al, 2012; Zlatkina et al, 2016). Taken together, there is a need to further validate and differentiate ROIs by analyzing the temporal characteristics of fMRI signals in each ROI.…”

Sulcal organization in the medial frontal cortex reveals insights into primate brain evolution

“…For instance, functional magnetic resonance imaging (fMRI) studies have shown that the primary hand motor area is always located in the central sulcus in human and non-human primates (Yousry et al, 1997;Petrides, 2014, 2018;Hopkins et al, 2014), the frontal eye field is always located in the ventral branch of the superior precentral sulcus in the human brain (Amiez et al, 2006;Petrides, 2009, 2018;Derrfuss et al, 2012) and in the genu of the arcuate sulcus in macaque (Bruce and Goldberg, 1985;Koyama et al, 2004), the face motor representation of the rostral cingulate motor area and the juice feedback-related activity during exploratory situations recruits a region located in the CGS when no PCGS is present, but in the PCGS when the CGS is present (Amiez et al, 2013;Amiez and Petrides, 2014). Comparable observations were made in other regions of the brain, such as the inferior frontal junction (Derrfuss et al, 2009(Derrfuss et al, , 2012, the orbitofrontal cortex (Li et al, 2015), the parietal somatomotor cortex (Zlatkina et al, 2016), and the angular gyrus region (Segal and Petrides, 2013). Collectively, these studies strongly suggest that the sulcal organization in primates is not random, but rather has anatomo-functional relevance that are likely associated with the evolution to increasingly sophisticated sensory, motor, and cognitive functions.…”

Spectral partitioning identifies individual heterogeneity in the functional network topography of ventral and anterior medial prefrontal cortex

“…Next, we asked if the idiosyncratic organization of the DN corresponded to patterns of sulcal morphology. Several previous studies have provided evidence that sulcal and gyral organization informs the location of functional effects (Amiez & Petrides, 2014; Amiez et al, 2013; Zlatkina et al, 2016). Recent work has suggested that DN regions in individuals lie mostly within sulci in vmPFC (Lopez-Persem et al, 2019).…”