Actions Speak Louder Than Functions: The Importance of Manipulability and Action in Tool Representation

Abstract

PET was used to investigate the neural correlates of action knowledge in object representations, particularly the left lateralized network of activations previously implicated in the processing of tools and their associated actions: ventral premotor cortex (VPMCx), posterior middle temporal gyrus (PMTG), and intraparietal sulcus (IPS). Judgments were made about the actions and functions associated with manipulable man-made objects (e.g., hammer); this enabled us to measure activations in response to both explicit and implicit retrieval of knowledge about actions associated with manipulable tools. Function judgments were also made about nonmanipulable artifacts (e.g., traffic light) providing a direct comparison for manipulable objects. Although neither the left VPMCx nor the left PMTG were selective for tool stimuli (nonmanipulable objects also activated these areas relative to a visual control condition), both regions responded more strongly to manipulable objects, suggesting a role for these cortical areas in the processing of knowledge associated with tools. Furthermore, these activations were insensitive to retrieval task, suggesting that visually presented tools automatically recruit both left VPMCx and left PMTG in response to action features that are inherent in tool representations. In contrast, the IPS showed clear selectivity for explicit retrieval of action information about manipulable objects. No regions of cortex were more activated by function relative to action judgments about artifacts. These results are consistent with the brain's preferential responsiveness to how we interact with objects, rather than what they are used for.

Memory for pantomimed actions versus actions with real objects

“…More recent studies have suggested that this activity is not about tools per se, but instead appears when participants make judgments about manipulable objects (including fruits and vegetables) as compared to objects that are typically viewed without motoric engagement (Gerlach et al, 2002;Kellenbach et al, 2003). The left ventral premotor locus in these hemodynamic studies is also considered to be the human analogue of monkey area F5, in which neurons respond during both performance and observation of actions (Murata et al, 1997;see Grezes and Decety, 2001 for review of human studies suggesting a parallel result).…”

“…In a positron emission tomography experiment, Kellenbach et al (2003) presented photos of objects and asked participants answer a question about an object's function (e.g., "Is it used to attach or hold objects together?") or how one would use it (e.g., "Does using the object involve a twisting or turning motion?").…”

Context-dependent interpretation of words: Evidence for interactive neural processes

“…Words referring to tools and manipulable objects such as hammer automatically activate sensory-motor aspects of tool use in regions also implicated in perceiving, imagining, executing and planning actions with tools (Martin & Chao, 2001;Chao & Martin, 2000;Kellenbach et al, 2003;Beauchamp et al, 2002;Johnson-Frey et al, 2005). Such regions include two areas encoding motor schemas for interacting with objects -the intraparietal sulcus (IPS) and ventral pre-motor cortex (PMv) (cf.…”

Perceptual decisions regarding object manipulation are selectively impaired in apraxia or when tDCS is applied over the left IPL

“…Further, it provides converging evidence for a wealth of neuroimaging data demonstrating increased left IPL activity when generating internal representations of movement, in particular when perceiving object related action (Kellenbach et al, 2003;Boronat et al, 2005;Buxbaum et al, 2006;Canessa et al, 2008), and observation or pantomime of object-use (Chao & Martin, 2000;Mozaz et al, 2002;Rumiati et al, 2004;Frey, 2007;Vingerhoets, 2008;Króliczak & Frey, 2009;Vingerhoets et al, 2009;Caspers et al, 2010). Unlike the correlational link between left IPL and manipulation perception provided by neuroimaging, the effects of tDCS support a causal relationship between left IPL integrity and object manipulation perception.…”

“…Neuroimaging studies exploring the neural correlates of object knowledge indicates that the left IPL is consistently and selectively activated during motoric elements of object-use including object manipulation perception, and when participants observe, imagine or pantomime object-use (Chao & Martin, 2000;Mozaz, Rothi, Anderson, Crucian, & Heilman, 2002;Rumiati et al, 2004;Boronat et al, 2005;Frey, 2007;Vingerhoets, 2008;Króliczak & Frey, 2009;Vingerhoets, Acke, Vandemaele, & Achten, 2009;Caspers et al, 2010). Non-motoric decisions about object function on the other hand show more temporal activation (Kellenbach et al, 2003;Rumiati et al, 2004;Buxbaum et al, 2006;Lewis, 2006;Frey, 2007;Canessa et al, 2008;Vingerhoets et al, 2008;Chen, Garcea, & Mahon, 2015).…”