Parietal maps of visual signals for bodily action planning

Abstract

The posterior parietal cortex (PPC) has long been understood as a high-level integrative station for computing motor commands for the body based on sensory (i.e., mostly tactile and visual) input from the outside world. In the last decade, accumulating evidence has shown that the parietal areas not only extract the pragmatic features of manipulable objects, but also subserve sensorimotor processing of others’ actions. A paradigmatic case is that of the anterior intraparietal area (AIP), which encodes the identity of observed manipulative actions that afford potential motor actions the observer could perform in response to them. On these bases, we propose an AIP manipulative action-based template of the general planning functions of the PPC and review existing evidence supporting the extension of this model to other PPC regions and to a wider set of actions: defensive and locomotor actions. In our model, a hallmark of PPC functioning is the processing of information about the physical and social world to encode potential bodily actions appropriate for the current context. We further extend the model to actions performed with man-made objects (e.g., tools) and artifacts, because they become integral parts of the subject’s body schema and motor repertoire. Finally, we conclude that existing evidence supports a generally conserved neural circuitry that transforms integrated sensory signals into the variety of bodily actions that primates are capable of preparing and performing to interact with their physical and social world.

Thalamocortical and corticothalamic connections of multiple functional domains in posterior parietal cortex of galagos

“…Recently, Graziano and colleagues proposed an alternative organizing principle of the primate motor cortex beyond the traditional view of the somatotopically arranged “body map” that motor cortex contained small functional zones, each of which associated with an ethologically relevant action (Graziano, 2016; Graziano & Aflalo, 2007). The existence of the “action map” appears to be general, supported by studies with various methods in humans and nonhuman primates (e.g., Ejaz et al., 2015; Huber et al., 2020; Orban et al., 2021). We adopted the approach initiated by Graziano et al.…”

“…with various methods in humans and nonhuman primates (e.g., Ejaz et al, 2015;Huber et al, 2020;Orban et al, 2021). We adopted the approach initiated by Graziano et al (2002), using 500 ms trains of electrical pulses to evoke complex movements from motor cortex of macaques and extended the use of this approach successfully on PPC.…”

Do graspable objects always leave a motor signature? A study on memory traces

“…In categorization tasks like the one mentioned above, Tucker and Ellis ( 2001 ) reported comparable effects when stimuli appeared in the near (15 cm) and far space (2 m), i.e., independently from whether a direct interaction with the object was physically possible. Although this observation suggests that some motor properties could be integral to object representations, more recent findings rather describe a context-dependent effect of object affordances (Costantini et al 2010 , 2011 ; Ranganathan et al 2011 ; Borghi and Riggio 2009 , 2015 ; Wokke et al 2016 ; Orban et al 2021a ). For example, in a task requiring healthy participants to reproduce a seen grip, a compatibility effect emerged between the moving hand and the handle of the object used as go-signal, but only if the object was presented within the reaching space.…”

HD-tDCS of primary and higher-order motor cortex affects action word processing

“…On the other hand, if these regions play a role only in the context of explicit task demands, then an effect would be seen only in the similarity judgment task. Moreover, it is possible that effects of HMA stimulation would be marginally stronger for action verbs due to their direct-action associations, while aIPL would show a preference for manipulable nouns due to aIPL being especially involved in higher-order action planning and object processing (Orban and Caruana, 2014 ; Orban et al, 2021 ).…”