Cognitive contributions of the ventral parietal cortex: an integrative theoretical account

Abstract

Although ventral parietal cortex (VPC) activations can be found in a variety of cognitive domains, these activations have been typically attributed to cognitive operations specific to each domain. In this article, we propose a hypothesis that can account for VPC activations across all the cognitive domains reviewed. We first review VPC activations in the domains of perceptual and motor reorienting, episodic memory retrieval, language and number processing, theory of mind, and episodic memory encoding. Then, we consider the localization of VPC activations across domains and conclude that they are largely overlapping with some differences around the edges. Finally, we assess how well four different hypotheses of VPC function can explain findings in various domains and conclude that a bottom-up attention hypothesis provides the most complete and parsimonious account.

Figure 1. Perceptual reorienting and Episodic Retrieval

Examples of VPC activations during perceptual reorienting and episodic retrieval. A. Invalid>valid trials in a Posner task (from ref. ) B. Relevant > irrelevant distractors in an oddball task (from ref ). C. Confidence during recognition memory (top panel from ref. , bottom panel from ref.)

Figure 2. Language and number processing

Examples of VPC activations during language and numerical processing. A. Metaanalysis of semantic processing during word comprehension (from ref. ). B. VPC activity increases with discourse incoherence (from ref. ). D. VPC activity is greater for exact than approximate number calculation (from ref. ).

Figure 3. Encoding-Retrieval Flip

Contrasts between retrieval and encoding in the same participants show that VPC is associated with retrieval success (remembered > forgotten) but with encoding failure (forgotten > remembered) (From ref. )

Figure 4

VPC overlaps across functions. A. VPC overlap for perceptual and memory detection (from ref. ). B. In the same study, memory detection activity extends more posteriorly than memory detection. C. Functional connectivity of the overlapping left VPC region (in yellow) with visual cortex was stronger during perception than memory whereas functional connectivity with the hippocampus was stronger during memory than perception. D. Metaanalysis showing overlap in right VPC activity for perceptual reorienting and TOM (from ref. ). E. Overlap between reorienting and TOM within participants (from ref. ) VPC overlaps across functions

Figure 5. Fractionated vs. overarching views of functional organization

Fractionated vs. overaching views of functional organization across hypothetical subregions 1–4 of hypothetical Region X.