4,026 research outputs found
Damage to the prefrontal cortex increases utilitarian moral judgements
The psychological and neurobiological processes underlying moral judgement have been the focus of many recent empirical studies1–11. Of central interest is whether emotions play a causal role in moral judgement, and, in parallel, how emotion-related areas of the brain contribute to moral judgement. Here we show that six patients with focal bilateral damage to the ventromedial prefrontal cortex (VMPC), a brain region necessary for the normal generation of emotions and, in particular, social emotions12–14, produce an abnor- mally ‘utilitarian’ pattern of judgements on moral dilemmas that pit compelling considerations of aggregate welfare against highly emotionally aversive behaviours (for example, having to sacrifice one person’s life to save a number of other lives)7,8. In contrast, the VMPC patients’ judgements were normal in other classes of moral dilemmas. These findings indicate that, for a selective set of moral dilemmas, the VMPC is critical for normal judgements of right and wrong. The findings support a necessary role for emotion in the generation of those judgements
A role for left temporal pole in the retrieval of words for unique entities
r r Abstract: Both lesion and functional imaging studies have implicated sectors of high-order association cortices of the left temporal lobe in the retrieval of words for objects belonging to varied conceptual categories. In particular, the cortices located in the left temporal pole have been associated with naming unique persons from faces. Because this neuroanatomical-behavioral association might be related to either the specificity of the task (retrieving a name at unique level) or to the possible preferential processing of faces by anterior temporal cortices, we performed a PET imaging experiment to test the hypothesis that the effect is related to the specificity of the word retrieval task. Normal subjects were asked to name at unique level entities from two conceptual categories: famous landmarks and famous faces. In support of the hypothesis, naming entities in both categories was associated with increases in activity in the left temporal pole. No main effect of category (faces vs. landmarks/buildings) or interaction of task and category was found in the left temporal pole. Retrieving names for unique persons and for names for unique landmarks activate the same brain region. These findings are consistent with the notion that activity in the left temporal pole is linked to the level of specificity of word retrieval rather than the conceptual class to which the stimulus belongs. Hum. Brain Mapping 13:199–212, 2001. © 2001 Wiley-Liss, Inc. Key words: left temporal pole; language; word retrieval; functional imaging; face processing; naming r
The scope of preserved procedural memory in amnesia
The finding that patients with amnesia retain the ability to
learn certain procedural skills has provided compelling
evidence of multiple memory systems in the human
brain, but the scope, defining features and ecological significance
of the preserved mnemonic abilities have not yet
been explored. Here, we tested the hypothesis that subjects
with amnesia would be able to learn and retain a broad
range of procedural skills, by examining their acquisition
and retention performance on five novel experimental
tasks. The tasks are based on real-world activities and
encompass a broad range of perceptual–motor demands:
(i) the weaving task involves weaving pieces of fabric from
woollen strings, using a manual weaver’s loom; (ii) the
geometric figures task consists of tracing geometric figures
with a stylus as they move horizontally across a touch
screen monitor; (iii) the control stick task involves tracking
a sequence of visual target locations using a joystick control;
(iv) the pouring task consists of pouring 200 ml of
water from a watering can into a series of graduated cylinders,
from a point 20 cm above the cylinders; and (v) the
spatial sequence task involves learning an ordered
sequence of pushing five spatially distributed buttons without
visual guidance. Ten chronic and stable amnesic subjects
(nine with bilateral medial temporal lobe damage due
to herpes simplex encephalitis or anoxia, and one with thalamic
stroke) and 25 matching normal comparison subjects
were tested on three occasions: initial learning at time 1;
retention at time 2 (24 h later); and retention at time
3 (2 months later). Despite impaired declarative memory
for the tasks, the amnesic subjects demonstrated acquisition
and retention of the five skills; their learning slopes
over repeated trials were comparable with those of comparison
subjects. These findings indicate that preserved
learning of complex perceptual–motor skills in patients
with amnesia is a robust phenomenon, and that it can be
demonstrated across a variety of conditions and perceptual–
motor demands. The comparability of the tasks
employed in this study with real-world activities highlights
the potential application of this memory dissociation in the
rehabilitation of patients with amnesi
Providing Self-Aware Systems with Reflexivity
We propose a new type of self-aware systems inspired by ideas from
higher-order theories of consciousness. First, we discussed the crucial
distinction between introspection and reflexion. Then, we focus on
computational reflexion as a mechanism by which a computer program can inspect
its own code at every stage of the computation. Finally, we provide a formal
definition and a proof-of-concept implementation of computational reflexion,
viewed as an enriched form of program interpretation and a way to dynamically
"augment" a computational process.Comment: 12 pages plus bibliography, appendices with code description, code of
the proof-of-concept implementation, and examples of executio
A Robot Model of OC-Spectrum Disorders : Design Framework, Implementation and First Experiments
© 2019 Massachusetts Institute of TechnologyComputational psychiatry is increasingly establishing itself as valuable discipline for understanding human mental disorders. However, robot models and their potential for investigating embodied and contextual aspects of mental health have been, to date, largely unexplored. In this paper, we present an initial robot model of obsessive-compulsive (OC) spectrum disorders based on an embodied motivation-based control architecture for decision making in autonomous robots. The OC family of conditions is chiefly characterized by obsessions (recurrent, invasive thoughts) and/or compulsions (an urge to carry out certain repetitive or ritualized behaviors). The design of our robot model follows and illustrates a general design framework that we have proposed to ground research in robot models of mental disorders, and to link it with existing methodologies in psychiatry, and notably in the design of animal models. To test and validate our model, we present and discuss initial experiments, results and quantitative and qualitative analysis regarding the compulsive and obsessive elements of OC-spectrum disorders. While this initial stage of development only models basic elements of such disorders, our results already shed light on aspects of the underlying theoretical model that are not obvious simply from consideration of the model.Peer reviewe
Disgusting but harmless moral violations are perceived as harmful due to the negative emotions they elicit
Harmless but disgusting moral violations can be justified as harmful to others due to the negative emotions they elicit. The relationship between the emotions of anger and disgust and the harm associated to these emotions as a result of a moral violation was investigated. Results showed that a disgusting moral violation (taboo violation) described as harmless to others is more related to disgust than to anger. Such violation created a presumption of harm of three different types: to the community, nature, and the individual. Disgust was a mediator between the taboo violation and the presumption of harm to nature, whereas anger was a mediator between the taboo violation and the presumption of harm to the individual. In general, results also showed that in moral violations that are harmless to others, the emotions of anger and disgust allow people to presume harm to symbolic entities such as nature and the community as a result of such violations
Distributed neural system for general intelligence revealed by lesion mapping
General intelligence (g) captures the performance variance shared across cognitive tasks and correlates with real-world success. Yet it remains debated whether g reflects the combined performance of brain systems involved in these tasks or draws on specialized systems mediating their interactions. Here we investigated the neural substrates of g in 241 patients with focal brain damage using voxel-based lesion–symptom mapping. A hierarchical factor analysis across multiple cognitive tasks was used to derive a robust measure of g. Statistically significant associations were found between g and damage to a remarkably circumscribed albeit distributed network in frontal and parietal cortex, critically including white matter association tracts and frontopolar cortex. We suggest that general intelligence draws on connections between regions that integrate verbal, visuospatial, working memory, and executive processes
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Decreased Neuroautonomic Complexity in Men during an Acute Major Depressive Episode: Analysis of Heart Rate Dynamics
Major depression affects multiple physiologic systems. Therefore, analysis of signals that reflect integrated function may be useful in probing dynamical changes in this syndrome. Increasing evidence supports the conceptual framework that complex variability is a marker of healthy, adaptive control mechanisms and that dynamical complexity decreases with aging and disease. We tested the hypothesis that heart rate (HR) dynamics in non-medicated, young to middle-aged males during an acute major depressive episode would exhibit lower complexity compared with healthy counterparts. We analyzed HR time series, a neuroautonomically regulated signal, during sleep, using the multiscale entropy method. Our results show that the complexity of the HR dynamics is significantly lower for depressed than for non-depressed subjects for the entire night (P<0.02) and combined sleep stages 1 and 2 (P<0.02). These findings raise the possibility of using the complexity of physiologic signals as the basis of novel dynamical biomarkers of depression
Oscillator neural network model with distributed native frequencies
We study associative memory of an oscillator neural network with distributed
native frequencies. The model is based on the use of the Hebb learning rule
with random patterns (), and the distribution function of
native frequencies is assumed to be symmetric with respect to its average.
Although the system with an extensive number of stored patterns is not allowed
to get entirely synchronized, long time behaviors of the macroscopic order
parameters describing partial synchronization phenomena can be obtained by
discarding the contribution from the desynchronized part of the system. The
oscillator network is shown to work as associative memory accompanied by
synchronized oscillations. A phase diagram representing properties of memory
retrieval is presented in terms of the parameters characterizing the native
frequency distribution. Our analytical calculations based on the
self-consistent signal-to-noise analysis are shown to be in excellent agreement
with numerical simulations, confirming the validity of our theoretical
treatment.Comment: 9 pages, revtex, 6 postscript figures, to be published in J. Phys.
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