The Angular Gyrus

Abstract

There is considerable interest in the structural and functional properties of the angular gyrus (AG). Located in the posterior part of the inferior parietal lobule, the AG has been shown in numerous meta-analysis reviews to be consistently activated in a variety of tasks. This review discusses the involvement of the AG in semantic processing, word reading and comprehension, number processing, default mode network, memory retrieval, attention and spatial cognition, reasoning, and social cognition. This large functional neuroimaging literature depicts a major role for the AG in processing concepts rather than percepts when interfacing perception-to-recognition-to-action. More specifically, the AG emerges as a cross-modal hub where converging multisensory information is combined and integrated to comprehend and give sense to events, manipulate mental representations, solve familiar problems, and reorient attention to relevant information. In addition, this review discusses recent findings that point to the existence of multiple subdivisions in the AG. This spatial parcellation can serve as a framework for reporting AG activations with greater definition. This review also acknowledges that the role of the AG cannot comprehensibly be identified in isolation but needs to be understood in parallel with the influence from other regions. Several interesting questions that warrant further investigations are finally emphasized.

Left Anterior Temporal Lobe and Bilateral Anterior Cingulate Cortex Are Semantic Hub Regions: Evidence from Behavior-Nodal Degree Mapping in Brain-Damaged Patients

“…This replicates the finding that the ATL is a semantic hub (Hodges et al, 1992;Garrard and Hodges, 2000;Pobric et al, 2010;Zhou et al, 2012;Rice et al, 2015a,b;Chiou and Lambon Ralph, 2016). It might suggest that the left ATL is a convergent zone of semantic memory and that its connectivity with the rest of the brain embodies semantic knowledge.…”

“…The remaining steps were also completed with DPARSFA, including (6) liner trend removal, (7) bandpass filtering (0.01-0.1 Hz), (8) spatial smoothing (Gaussian kernel of FWHM 6 mm), and (9) nuisance covariate (global signal, white-matter signal, and CSF signal) regression. Specifically, we then performed head-motion scrubbing (Power et al, 2012) to exclude brain volumes that had spikes of head motion. We set the framewise displacement threshold at 0.5 to detect the "bad" time points and scrubbed one time point before and two time points after the bad time point.…”

“…One possible reason for this seeming contradiction is that the region is primarily responsible for nonverbal rather than verbal semantic information (Rice et al, 2015a). To test this idea, we separately correlated the mean nodal degree values of this region mask with the composite scores in verbal tasks or nonverbal tasks by averaging z-transformed t scores of verbal tasks or nonverbal tasks, respectively.…”

Decoding the Cortical Dynamics of Sound-Meaning Mapping

“…These early effects of semantic competition involved the LIFG (BA 47) and spread into the LATL, followed by effects in the LAG and then the ATL again as the UP neared and the number of semantic competitors declined. The LAG is frequently associated with a variety of semantic-based processes (Binder et al, 2009) such as semantic feature integration (Price et al, 2016), whereas the LATL is thought to be a core region within the amodal semantic hub (Patterson et al, 2007). The finding that the effects of semantic competition flow between these regions over time suggests their joint sensitivity to semantic effects.…”

Deconstructing saccades : identifying the components of saccades that produce saccade-induced retrieval enhancement.

“…The AG are activated during a variety of tasks, and may relay information between different cortical regions (for review, Seghier, 2013). The AG are active during successful memory retrieval (e.g., Ciaramelli et al, 2008) and TMS knockout of the left AG is detrimental to recognition (Sestieri, Capotosto, Tosoni, Romani, & Corbetta, 2013).…”