Abstract
Neural substrates of action to the object or this specific direct route, however, remain unclear, especially for the connection from the visual pathway to the motor cortex. The study examined this issue by conducting an fMRI experiment, in which two action generation tasks involving pictures of real objects (PA) and the object's nouns (NA) were used, with pictures naming (PN) and covert noun reading (NR) being the control tasks. The result showed that the model predefined for the PCC and precuneus connecting IPL to the posterior-medial frontal cortex dominated over the others (with 0.45 probability), suggesting that the PCC and the precuneus locate at the neural substrates of action to the object. Furthermore, a feasibility study suggests that the neural pathway composed of the V3/MT, precuneus, PCC, and PM (premotor cortex) forms the direct route from perception to action, which also links to the dorsal pathway so that the perception of objects bypasses the semantic ventral pathway and then directly cues actions via the affordance.
Highlights
Motor system in the brain is activated during observing the manipulable objects and the relationship between an object and potential actions associated with the object that is called as “affordance” [1,2]
Neural mechanisms that underlie the direct visual route are still unknown. In this fMRI study, by involving both object pictures and nouns in the tasks of object naming, noun reading and action generation, we investigated the similarities and differences in the neural substrates that mediate action generation from object pictures and corresponding nouns to identify cortical regions that are crucial to the direct route from vision to action [7]
A direct comparison between pictures of real objects (PA)-pictures naming (PN) and NA-noun reading (NR) was conducted to locate the locations of significant different activities, and it was calculated by T contrasts (p < .0005 at voxel level) and cluster-level family-wise error (FWE) correction (p < .05, corrected)
Summary
Motor system in the brain is activated during observing the manipulable objects and the relationship between an object and potential actions associated with the object that is called as “affordance” [1,2]. Riddoch [7] pointed out that a patient with lesions in the left parietal cortex was not able to generate appropriate right-hand actions toward an object even though his semantic knowledge was preserved, which was attributed to the deficit in the direct visual route, but he was able to perform hand gestures when he was given the object’s nouns. Their result suggested that the direct visual route contributed to actions related to objects and wasnot critical to retrieving actions for nouns, while visual features of an object may be necessary for activating the “direct. By building DCM models for different connection hypotheses and comparing them, the best hypothesis can be selected as evidence
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