Mirror neurons in macaque area F5 fire when an animal performs an action, such as a mouth or limb movement, and also when the animal passively observes an identical or similar action performed by another individual. Brain-imaging studies... more
Mirror neurons in macaque area F5 fire when an animal performs an action, such as a mouth or limb movement, and also when the animal passively observes an identical or similar action performed by another individual. Brain-imaging studies in humans conducted over the last 20 years have repeatedly attempted to reveal analogous brain regions with mirror properties in humans, with broad and often speculative claims about their functional significance across a range of cognitive domains, from language
to social cognition. Despite such concerted efforts, the likely neural substrates of these mirror regions have remained controversial, and indeed the very existence of a distinct subcategory of human neurons with mirroring properties has been questioned. Here we used activation likelihood estimation (ALE), to provide a quantitative index of the consistency of patterns of fMRI activity measured in human studies of action observation and action execution. From an initial sample of more than 300 published works, data from 125 papers met our strict inclusion and exclusion criteria. The analysis revealed 14 separate clusters in
which activation has been consistently attributed to brain regions with mirror properties, encompassing 9 different Brodmann areas. These clusters were located in areas purported to show mirroring properties in the macaque, such as the inferior parietal lobule, inferior frontal gyrus and the adjacent ventral premotor cortex, but surprisingly also in regions such as the primary visual cortex, cerebellum and parts of the limbic system. Our findings suggest a core network of human brain regions that possess mirror
properties associated with action observation and execution, with additional areas recruited during tasks that engage non-motor functions, such as auditory, somatosensory and affective components.
The critical lesion site responsible for the syndrome of unilatera lspatial neglect has been debated for more than a decade. Here we performed an activation likelihood estimation (ALE) to provide for the first time an objective... more
The critical lesion site responsible for the syndrome of unilatera lspatial neglect has been debated for more than a decade. Here we performed an activation likelihood estimation (ALE) to provide for the first time an objective quantitative index of the consistency of lesion sites across anatomical group studies of spatial neglect. The analysis revealed several distinct regions in which damage hasc onsistently been associated with spatial neglect symptoms. Lesioned clusters were located in several cortical and subcortical regions of the right hemisphere, including the middle and superior temporal gyrus, inferior parietal lobule, intraparietal sulcus, precuneus, middle occipital gyrus, caudate nucleus, and posterior insula, as well as in the white matter pathway corresponding to the posterior part of the superior longitudinal fasciculus. Further analyses suggested that separate lesion sites are associated with impairments in different behavioral tests, such as line bisection and target cancellation. Similarly, specific subcomponents of the heterogeneous neglects yndrome, such as extinction and allocentric and personal neglect, are associated with distinct lesion sites. Future progress in delineating the neuropathological correlates of spatial neglect will depend upon the development of more refined measures of perceptual and cognitive functions than those currently available in the clinical setting.
It has been suggested that the mirror neuron system provides an important neural substrate for humans’ ability to imitate. Mirror neurons have been found during single-cell recordings in monkeys in area F5 and PF. It is believed that the... more
It has been suggested that the mirror neuron system provides an important neural substrate for humans’ ability to imitate. Mirror neurons have been found during single-cell recordings in monkeys in area F5 and PF. It is believed that the human equivalent of this mirror system in humans is the pars opercularis of the inferior frontal gyrus (area 44) and the rostral part of the inferior parietal lobule. This article critically reviews published fMRI studies that examined the role of frontal and parietal brain regions in imitation. A meta-analysis using activation likelihood estimation (ALE) revealed that the superior parietal lobule,
inferior parietal lobule, and the dorsal premotor cortex but not the inferior frontal gyrus, are all commonly involved in imitation. An additional meta-analysis using a label-based review confirmed that in the frontal lobe, the premotor cortex rather than the inferior frontal gyrus is consistently active in studies investigating imitation. In the parietal region the superior and inferior parietal lobules are equally activated during imitation. Our results suggest that parietal and frontal regions which extend beyond the classical mirror neuron network are crucial for imitation.
The material interface is tracked by solving the arbitrary Lagrangian-Eulerian (ALE) formulation during the simulation of the compressible multi-material flow. The material interface is looked upon as a Lagrangian interface which can move... more
The material interface is tracked by solving the arbitrary Lagrangian-Eulerian (ALE) formulation during the simulation of the compressible multi-material flow. The material interface is looked upon as a Lagrangian interface which can move freely and is composed of a number of edges of the unstructured grids and the state vectors of the points on the interface have two different definitions corresponding to the two different fluids. Then, Riemann problem is solved by the two-shock approximation method for general form of equation of state on both sides of the interface to track the interface accurately and the grids are moving automatically with the motion of the interface. The ID spherically symmetric underwater explosion model is computed by using ALE method and the numerical results agree well with the experimental data, which indicates that the interface tracking method is reasonable. Furthermore, interaction between shock and water surface is also simulated to show that this method is suitable for solving micro-deforming interface problem.
