Goal Representation in Human Anterior Intraparietal Sulcus

Abstract

When a child reaches toward a cookie, the watching parent knows immediately what the child wants. The neural basis of this ability to interpret other people's actions in terms of their goals has been the subject of much speculation. Research with infants has shown that 6 month olds respond when they see an adult reach to a novel goal but habituate when an adult reaches to the same goal repeatedly. We used a similar approach in an event-related functional magnetic resonance imaging experiment. Adult participants observed a series of movies depicting goal-directed actions, with the sequence controlled so that some goals were novel and others repeated relative to the previous movie. Repeated presentation of the same goal caused a suppression of the blood oxygen level-dependent response in two regions of the left intraparietal sulcus. These regions were not sensitive to the trajectory taken by the actor's hand. This result demonstrates that the anterior intraparietal sulcus represents the goal of an observed action.

Repetition suppression for performed hand gestures revealed by fMRI

“…First, the data demonstrate that RS is a robust and broad phenomenon which likely applies across the entire motor system of the brain. In conjunction with previous data showing RS for visual, linguistic, number, motor and other tasks [Dehaene et al, 1998;Dinstein et al, 2007;Hamilton and Grafton, 2006Kroliczak et al, 2008;Naccache and Dehaene, 2001;Noppeney and Price, 2004;Shmuelof and Zohary, 2005], this implies that RS may be ubiquitous across the cortex. This means that future fMRI studies should take into account the likely existence of RS and optimize stimulus sequences to either measures RS effects, or avoid them as confounds for other contrasts.…”

“…Our own interpretation of RS focuses on patterns of neuronal activity at the population level. Specifically, we suggest that repetition of a stimulus causes a decrease in population activity, and a change to a new stimulus activates a different neural population that fires robustly Hamilton and Grafton, 2006. This interpretation does not require a strict concordance between RSdefined selectivity of the population response and the selectivity of single neurons [Grill-Spector et al, 2006;Sawamura et al, 2006].…”

“…Recently, we and others have used the RS method to dissociate neural substrates for decoding different levels of action perception and action understanding. For example, we have demonstrate RS in anterior intraparietal sulcus when participants repeatedly observe the same action goal [Hamilton and Grafton, 2006], and RS in inferior frontal gyrus when participants repeatedly observe grasps with the same hand aperture . These results indicate that neural populations in aIPS selectively encode the goal of an action, while populations in IFG encode the kinematic features .…”

Object words modulate the activity of the mirror neuron system during action imitation

“…Similar to the IFG, there is also evidence that the IPL serves as a neuronal substrate underlying the action outcome representation or intention understanding (Bonini et al., 2010; Fogassi et al., 2005; A. F. Hamilton & Grafton, 2008; A. F. D. Hamilton & Grafton, 2006). Strong evidence from Desmurget et al.…”

“…From the shared brain function perspective, body parts (i.e., subject words) and action words (i.e., verbs) have been shown to activate action observation areas (Buccino et al., 2001, 2005; Hauk et al., 2004). While for object words, a large range of empirical data has provided evidence for the intention or goal representations over the MNS (Binkofski & Buccino, 2006; A. F. D. Hamilton & Grafton, 2006; Iacoboni et al., 2005a; Jarvelainen, Schurmann, & Hari, 2004; Muthukumaraswamy, Johnson, & McNair, 2004; Ocampo & Kritikos, 2011; Ogawa & Inui, 2012). Since object words induce overlapping neural network over the MNS with action imitation, we therefore expected that compared to subject words and verbs, object words would have stronger interference effects on the imitation task.…”