Understanding actions of conspecifics is a fundamental social ability depending largely on the activation of a parieto-frontal network. Using functional MRI (fMRI), we studied how goal-directed movements (i.e., motor acts) performed by others are coded within this network. In the first experiment, we presented volunteers with video clips showing four different motor acts (dragging, dropping, grasping, and pushing) performed with different effectors (foot, hand, and mouth). We found that the coding of observed motor acts differed between premotor and parietal cortex. In the premotor cortex, they clustered according to the effector used, and in the inferior parietal lobule (IPL), they clustered according to the type of the observed motor act, regardless of the effector. Two subsequent experiments in which we directly contrasted these four motor acts indicated that, in IPL, the observed motor acts are coded according to the relationship between agent and object: Movements bringing the object toward the agent (grasping and dragging) activate a site corresponding approximately to the ventral part of the putative human AIP (phAIP), whereas movements moving the object away from the agent (pushing and dropping) are clustered dorsally within this area. These data provide indications that the phAIP region plays a role in categorizing motor acts according to their behavioral significance. In addition, our results suggest that in the case of motor acts typically done with the hand, the representations of such acts in phAIP are used as templates for coding motor acts executed with other effectors.

Objectives: To evaluate the impact of a revised Italian motorcycle-moped-scooter helmet law on crash brain injuries. Design: A pre-post law evaluation of helmet use and traumatic brain injury (TBI) occurrence from 1999 to 2001. Setting: Romagna region, northeastern Italy, with a 2000 resident population of 983 534 persons. Participants: Motorcycle-moped rider survey for helmet use compliance and all residents in the region admitted to the Division of Neurosurgery of the Maurizio Bufalini Hospital in Cesena, Italy for TBI. Outcome measures: Helmet use compliance and change in TBI admissions and type(s) of brain lesions. Results: Helmet use increased from an average of less than 20% to over 96%. A comparison of TBI incidence in the Romagna region shows that there was no significant variation before and after introduction of the revised helmet law, except for TBI admissions for motorcycle-moped crashes where a 66% decrease was observed. In the same area TBI admissions by age group showed that motorcycle mopeds riders aged 14–60 years sustained significantly fewer TBIs. The rate of TBI admissions to neurosurgery decreased by over 31% and epidural hematomas almost completely disappeared in crash injured moped riders. Conclusions: The revised Italian mandatory helmet law, with police enforcement, is an effective measure for TBI prevention at all ages.

People have always been fascinated by the exquisite precision and flexibility of the human hand. When hand meets object, we confront the overlapping worlds of sensorimotor and cognitive functions. The complex apparatus of the human hand is used to reach for objects, grasp and lift them, manipulate them, and use them to act on other objects. This review examines what is known about the control of the hand by the cerebral cortex. It compares and summarizes results from behavioral neuroscience, electrophysiology, and neuroimaging to provide a detailed description of the neural circuits that facilitate the formation of grip patterns in human and nonhuman primates. NEUROSCIENTIST 14(2):157—170, 2008. DOI: 10.1177/1073858407312080