The Neural Basis for Spatial Relations

Studies in semantics traditionally focus on knowledge of objects. By contrast, less is known about how objects relate to each other. In an fMRI study, we tested the hypothesis that the neural processing of categorical spatial relations between objects is distinct from the processing of the identity of objects. Attending to the categorical spatial relations compared with attending to the identity of objects resulted in greater activity in superior and inferior parietal cortices (especially on the left) and posterior middle frontal cortices bilaterally. In an accompanying lesion study, we tested the hypothesis that comparable areas would be necessary to represent categorical spatial relations and that the hemispheres differ in their biases to process categorical or coordinate spatial relations. Voxelbased lesion symptom mapping results were consistent with the fMRI observations. Damage to a network comprising left inferior frontal, supramarginal, and angular gyri resulted in behavioral impairment on categorical spatial judgments. Homologous right brain damage also produced such deficits, albeit less severely. The reverse pattern was observed for coordinate spatial processing. Right brain damage to the middle temporal gyrus produced more severe deficits than left hemisphere damage. Additional analyses suggested that some areas process both kinds of spatial relations conjointly and others distinctly. The left angular and inferior frontal gyrus processes coordinate spatial information over and above the categorical processing. The anterior superior temporal gyrus appears to process categorical spatial information uniquely. No areas within the right hemisphere processed categorical spatial information uniquely. Taken together, these findings suggest that the functional neuroanatomy of categorical and coordinate processing is more nuanced than implied by a simple hemispheric dichotomy

The Right Hemisphere in Esthetic Perception

Little about the neuropsychology of art perception and evaluation is known. Most neuropsychological approaches to art have focused on art production and have been anecdotal and qualitative. The field is in desperate need of quantitative methods if it is to advance. Here, we combine a quantitative approach to the assessment of art with modern voxel-lesion-symptom-mapping methods to determine brain–behavior relationships in art perception. We hypothesized that perception of different attributes of art are likely to be disrupted by damage to different regions of the brain. Twenty participants with right hemisphere damage were given the Assessment of Art Attributes, which is designed to quantify judgments of descriptive attributes of visual art. Each participant rated 24 paintings on 6 conceptual attributes (depictive accuracy, abstractness, emotion, symbolism, realism, and animacy) and 6 perceptual attributes (depth, color temperature, color saturation, balance, stroke, and simplicity) and their interest in and preference for these paintings. Deviation scores were obtained for each brain-damaged participant for each attribute based on correlations with group average ratings from 30 age-matched healthy participants. Right hemisphere damage affected participants’ judgments of abstractness, accuracy, and stroke quality. Damage to areas within different parts of the frontal parietal and lateral temporal cortices produced deviation in judgments in four of six conceptual attributes (abstractness, symbolism, realism, and animacy). Of the formal attributes, only depth was affected by inferior prefrontal damage. No areas of brain damage were associated with deviations in interestingness or preference judgments. The perception of conceptual and formal attributes in artwork may in part dissociate from each other and from evaluative judgments. More generally, this approach demonstrates the feasibility of quantitative approaches to the neuropsychology of art

Artistic Production Following Brain Damage: A Study of Three Artists

We know little about the neurologic bases of art production. The idea that the right brain hemisphere is the “artistic brain” is widely held, despite the lack of evidence for this claim. Artists with brain damage can offer insight into these laterality questions. The authors used an instrument called the Assessment of Art Attributes to examine the work of two individuals with left-brain damage and one with right-hemisphere damage. In each case, their art became more abstract and distorted and less realistic. They also painted with looser strokes, less depth and more vibrant colors. No unique pattern was observed following right-brain damage. However, art produced after left-brain damage also became more symbolic. These results show that the neural basis of art production is distributed across both hemispheres in the human brain

Not all analogies are created equal: Associative and categorical analogy processing following brain damage

Current research on analogy processing assumes that different conceptual relations are treated similarly. However, just as words and concepts are related in distinct ways, different kinds of analogies may employ distinct types of relationships. An important distinction in how words are related is the difference between associative (dog-bone) and categorical (dog-cat) relations. To test the hypothesis that analogical mapping of different types of relations would have different neural instantiations, we tested patients with left and right hemisphere lesions on their ability to understand two types of analogies, ones expressing an associative relationship and others expressing a categorical relationship. Voxel-based lesion-symptom mapping (VLSM) and behavioral analyses revealed that associative analogies relied on a large left-lateralized language network while categorical analogies relied on both left and right hemispheres. The verbal nature of the task could account for the left hemisphere findings. We argue that categorical relations additionally rely on the right hemisphere because they are more difficult, abstract, and fragile, and contain more distant relationships. (C) 2012 Elsevier Ltd. All rights reserved

Language, perception, and the schematic representation of spatial relations

Schemas are abstract nonverbal representations that parsimoniously depict spatial relations. Despite their ubiquitous use in maps and diagrams, little is known about their neural instantiation. We sought to determine the extent to which schematic representations are neurally distinguished from language on the one hand, and from rich perceptual representations on the other. In patients with either left hemisphere damage or right hemisphere damage, a battery of matching tasks depicting categorical spatial relations was used to probe for the comprehension of basic spatial concepts across distinct representational formats (words, pictures, and schemas). Left hemisphere patients underperformed right hemisphere patients across all tasks. However, focused residual analyses using voxel-based lesion-symptom mapping (VLSM) suggest that (1) left hemisphere deficits in the representation of categorical spatial relations are difficult to distinguish from deficits in naming these relations and (2) the right hemisphere plays a special role in extracting schematic representations from richly textured pictures. © 2011 Elsevier Inc

Tumor Treating Fields for Ovarian Carcinoma: A Modeling Study

Purpose: Since the inception of tumor treating fields (TTFields) therapy as a Food and Drug Administration–approved treatment with known clinical efficacy against recurrent and newly diagnosed glioblastoma, various in silico modeling studies have been performed in an effort to better understand the distribution of applied electric fields throughout the human body for various malignancies or metastases. Methods and Materials: Postacquisition attenuation-corrected positron emission tomography–computed tomography image data sets from 2 patients with ovarian carcinoma were used to fully segment various intrapelvic and intra-abdominal gross anatomic structures. A 3-dimensional finite element mesh model was generated and then solved for the distribution of applied electric fields, rate of energy deposition, and current density at the clinical target volumes (CTVs) and other intrapelvic and intra-abdominal structures. Electric field-volume histograms, specific absorption rate–volume histograms, and current density-volume histograms were generated, by which plan quality metrics were derived from and used to evaluate relative differences in field coverage between models under various conditions. Results: TTFields therapy distribution throughout the pelvis and abdomen was largely heterogeneous, where specifically the field intensity at the CTV was heavily influenced by surrounding anatomic structures as well as its shape and location. The electric conductivity of the CTV had a direct effect on the field strength within itself, as did the position of the arrays on the surface of the pelvis and/or abdomen. Conclusion: The combined use of electric field-volume histograms, specific absorption rate-volume histograms, current density-volume histograms, and plan quality metrics enables a personalized method to dosimetrically evaluate patients receiving TTFields therapy for ovarian carcinoma when certain patient- and tumor-specific factors are integrated with the treatment plan

Language, perception, and the schematic representation of spatial relations

Schemas are abstract nonverbal representations that parsimoniously depict spatial relations. Despite their ubiquitous use in maps and diagrams, little is known about their neural instantiation. We sought to determine the extent to which schematic representations are neurally distinguished from language on the one hand, and from rich perceptual representations on the other. In patients with either left hemisphere damage or right hemisphere damage, a battery of matching tasks depicting categorical spatial relations was used to probe for the comprehension of basic spatial concepts across distinct representational formats (words, pictures, and schemas). Left hemisphere patients underperformed right hemisphere patients across all tasks. However, focused residual analyses using VLSM (voxel-based lesion-symptom mapping) suggest that (1) left hemisphere deficits in the representation of categorical spatial relations are difficult to distinguish from deficits in naming these relations and (2) the right hemisphere plays a special role in extracting schematic representations from richly textured pictures