102,102 research outputs found
Controversies over the mechanisms underlying the crucial role of the left fronto-parietal areas in the representation of tools
No full textAnatomo-clinical and neuroimaging data show that the left fronto-parietal areas play an important role in representing tools. As manipulation is an important source of knowledge about tools, it has been assumed that motor activity explains the link between tool knowledge and the left fronto-parietal areas. However, controversies exist over the exact mechanisms underlying this relationship. According to a strong version of the "embodied cognition theory," activation of a tool concept necessarily involves re-enactment of the corresponding kind of action. Impairment of the ability to use tools should, therefore, lead to impairment of tool knowledge. Both the "domains of knowledge hypothesis" and the "sensory-motor model of conceptual knowledge" refute the strong version of the "embodied cognition hypothesis" but acknowledge that manipulation and other action schemata play an important role in our knowledge of tools. The basic difference between these two models is that the former is based on an innate model and the latter holds that the brain's organization of categories is experience dependent. Data supporting and arguing against each of these models are briefly reviewed. In particular, the following lines of research, which argue against the innate nature of the brain's categorical organization, are discussed: (1) the observation that in patients with category-specific disorders the semantic impairment does not respect the boundaries between biological entities and artifact items; (2) data showing that experience-driven neuroplasticity in musicians is not confined to alterations of perceptual and motor maps but also leads to the establishment of higher-level semantic representations for musical instruments; (3) results of experiments using previously unfamiliar materials showing that the history of our sensory-motor experience with an object significantly affects its neural representation. © 2013 Gainotti
The Role of Body-Related and Environmental Sources of Knowledge in the Construction of Different Conceptual Categories
No full textControversies exist regarding: (a) the relationships between perceptual and conceptual activities and (b) the format and neuro-anatomical substrates of concepts. Some authors maintain that concepts are represented in the brain in a propositional, abstract way, which is totally unrelated to the sensory-motor functions of the brain. Other authors argue that concepts are represented in the same format in which they are constructed by the sensory-motor system and can be considered as activity patterns distributed across different perceptual and motor domains. The present paper examines two groups of investigations that support the second view. Particular attention is given to the role of body movements and somatosensory inputs in the representation of artifacts and, respectively, of visual and other perceptual sources of knowledge in the construction of biological categories. The first group of studies aimed to assess the weight of various kinds of information in the representation of different conceptual categories by asking normal subjects to subjectively evaluate the role of various perceptual, motor, and encyclopedic sources of knowledge in the construction of different semantic categories.The second group of studies investigated the neuro-anatomical correlates of various types of categorical disorders.These last inves-tigations showed that the cortical areas damaged in patients with a disorder selectively affecting a given category have a critical role in processing the information that has con-tributed most to constructing the affected category. Both lines of research suggest that body movements and somatosensory information have a major role in the representation of actions and artifacts mainly known through manipulations and other actions, whereas visual and other perceptual information has a dominant role in the representation of animals and other living things. © 2012 Gainotti
Italian neuropsychology in the second half of the twentieth century.
No full textSince the early 1960s, human neuropsychology, the study of brain-behavior interrelations, mainly based on the analysis of their pathological variations, brought about by brain damage, has had a remarkable systematical development in Italy. All this started in Milan, with the neurologist Ennio de Renzi, and his collaborators (Luigi Vignolo, then Anna Basso, Pietro Faglioni, Hans Spinnler, François Boller, and, more autonomously, Edoardo Bisiach), in the Clinic of Nervous and Mental Diseases. Scientists of the “Milan group” investigated several neuropsychological deficits caused by focal hemispheric lesions in large series of left- and right-brain-damaged patients, and control participants, comparable for cultural and demographic variables. Standardized tests and advanced statistical methods were used, which also applied to the diagnosis and rehabilitation of aphasia. Subsequently, neuropsychology developed in Italy extensively, reaching high international reputation. Leading neuropsychologists have been the neurologists Guido Gainotti (Rome), and Franco Denes (Padua), the physicians and psychologists Luigi Pizzamiglio (Rome), and Carlo Umiltà (Parma, with fruitful interactions with the neurophysiologists Giovanni Berlucchi, Giacomo Rizzolatti, and Carlo Marzi, from the school of Giuseppe Moruzzi in Pisa) A second scientific generation of neuropsychologists has then developed in the 1970s, trained by the abovementioned scientists, further boosting and spreading high-level basic and applied research (diagnosis and rehabilitation of neuropsychological deficits of patients with brain damage or dysfunction throughout the life span, from childhood to the elderly). Available techniques include structural and functional imaging (CT, PET, SPET, MRI and fMRI Scans, DTI), electrophysiological recording (EEG, ERPs), non-invasive brain stimulation (TMS, tES), and their combined use
The Differential Contributions of Conceptual Representation Format and Language Structure to Levels of Semantic Abstraction Capacity
No full textThis paper reviews some controversies concerning the original and revised versions of the 'hub-and-spoke' model of conceptual representations and their implication for abstraction capacity levels. The 'hub-and-spoke' model, which is based on data gathered in patients with semantic dementia (SD), is the most authoritative model of conceptual knowledge. Patterson et al.'s (Nature Reviews Neuroscience, 8(12), 976-987, 2007) classical version of this model maintained that conceptual representations are stored in a unitary 'amodal' format in the right and left anterior temporal lobes (ATLs), because in SD the semantic disorder cuts across modalities and categories. Several authors questioned the unitary nature of these representations. They showed that the semantic impairment is 'multi-modal'only in the advanced stages of SD, when atrophy affects the ATLs bilaterally, but that impariments can be modality-specific in lateralised (early) stages of the disease. In these cases, SD mainly affects lexical-semantic knowledge when atrophy predominates on the left side and pictorial representations when atrophy prevails on the right side. Some aspects of the model (i.e. the importance of spokes, the multimodal format of representations and the graded convergence of modalities within the ATLs), which had already been outlined by Rogers et al. (Psychological Review, 111(1), 205-235, 2004) in a computational model of SD, were strengthened by these results. The relevance of these theoretical problems and of empirical data concerning the neural substrate of concrete and abstract words is discussed critically. The conclusion of the review is that the highest levels of abstraction are due more to the structuring influence of language than to the format of representations
The anterior temporal lobes: New frontiers opened to neuropsychological research by changes in health care and disease epidemiology
No full textChanges in health care and disease epidemiology have shifted the attention of neuropsychologists and cognitive neuroscientists fromvascular lesions to degenerative diseases or other bilateral brain lesions. This displacement of attention from vascular patients to patients with degenerative brain diseases allowed the discovery of hitherto unexplored and unheralded aspects of the neural substrates of human cognition. Three aspects of research on the anterior parts of the temporal lobes (ATLs) are the focus of the present review. The first aspect is category-specific semantic disorders, including current accounts of categorical brain organization, the anatomical substrate of different categories (stressing the role of the ATLs with respect to the biological categories), and the “sources of knowledge” that contribute to construction of those categories. The second aspect is the role of the ATLs in conceptual knowledge, including the “hub-and-spokes” model of semantic representation and semantic control. The third aspect is the role of the right ATL in recognition of familiar people, including the distinction made between associative prosopagnosia and multimodal disorders of person recognition. Consistencies and inconsistencies of results obtained across these different domains are discussed, and the clinical implications of these findings are considered
Why Are the Right and Left Hemisphere Conceptual Representations Different?
No full textThe present survey develops a previous position paper, in which I suggested that the multimodal semantic impairment observed in advanced stages of semantic dementia is due to the joint disruption of pictorial and verbal representations, subtended by the right and left anterior temporal lobes, rather than to the loss of a unitary, amodal semantic system. The main goals of the present review are (a) to survey a larger set of data, in order to confirm the differences in conceptual representations at the level of the right and left hemispheres, (b) to examine if language-mediated information plays a greater role in left hemisphere semantic knowledge than sensory-motor information in right hemisphere conceptual knowledge, and (c) to discuss the models that could explain both the differences in conceptual representations at the hemispheric level and the prevalence of the left hemisphere language-mediated semantic knowledge over the right hemisphere perceptually based conceptual representations
Old and recent approaches to the problem of non-verbal conceptual disorders in aphasic patients
No full textFrom the first research on aphasia, it has been shown that, in addition to verbal communication disorders, aphasic patients often have difficulty on non-verbal cognitive tasks, which can actually be solved without the use of language. In this survey, I will discuss in a historical perspective the different interpretations provided by classical and contemporary authors to explain this puzzling observation. First, I will take into account the different positions of classical authorities on this topic, starting from the first debates (mainly based on anatomo-clinical observations) on the organisation of language in the brain. Then, I will attempt to summarize the work of authors who have tackled this complex issue more recently, in systematic investigations using methods drawn from experimental psychology, to clarify the meaning of non-verbal cognitive disorders in aphasia. Finally, in the last part of the survey, I will discuss the interpretation of proponents of the 'semantic hub' hypothesis who have tried to analyse and explain the differences between the non-verbal semantic defects of patients with semantic dementia and aphasic stroke patients. The hypothesis which assumes that most non-verbal cognitive disorders observed in aphasic patients are due to a preverbal conceptual disorder, which cannot be attributed to a loss of semantic representations but rather to a defect in their controlled retrieval, seems substantially confirmed. Nevertheless, two main issues must still be clarified. The first is that some of the non-verbal cognitive defects of aphasic patients seem due to the negative influence of language disturbances on abstract non-verbal cognitive activities, rather than to a preverbal conceptual disorder. The second issue concerns the exact nature and the neuroanatomical correlates of the defective controlled retrieval of unimpaired conceptual representations, which should subsume most of the non-verbal cognitive disorders of aphasic patients. © 2014 Elsevier Ltd
Is the difference between right and left ATLs due to the distinction between general and social cognition or between verbal and non-verbal representations?
No full textThe present review aimed to check two proposals alternative to the original version of the 'semantic hub' hypothesis, based on semantic dementia (SD) data, which assumed that left and right anterior temporal lobes (ATLs) store in a unitary, amodal format all kinds of semantic representations.The first alternative proposal is that the right ATL might subsume non-verbal representations and the left ATL lexical-semantic representations and that only in the advanced stages of SD, when atrophy affects the ATLs bilaterally, the semantic impairment becomes 'multi-modal'.The second alternative suggestion is that right and left ATLs might underlie two different domains of knowledge, because general conceptual knowledge might be supported by the left ATL, and social cognition by the right ATL.Results of the review substantially support the first proposal, showing that the right ATL subsumes non-verbal representations and the left ATL lexical-semantic representations. They are less conclusive about the second suggestion, because the right ATL seems to play a more important role in behavioral and emotional functions than in higher level social cognition
Anosognosia in degenerative brain diseases: The role of the right hemisphere and of its dominance for emotions
No full textEarlier studies, which suggested that anosognosia of hemiplegia might be related to right hemisphere (RH) lesions did not control for the influence of confounding variables, such as aphasia, in patients with left-hemisphere lesions and unilateral neglect in those with RH lesions. These confounding variables are absent in patients with degenerative brain disease, where a prevalence of right-sided lesions is often associated with emotional and behavioural disturbances. This review, which can be considered a ‘qualitative synthesis’ aimed, therefore, to determine whether the unawareness phenomena observed in degenerative brain diseases are linked to the RH dominance for emotions. Results of the review confirmed that the neural correlates of anosognosia are often right lateralised in patients with degenerative brain diseases and that emotional disturbances are associated with right frontal lesions and anosognosia in the behavioural variant, i.e., frontotemporal dementia (bvFTD). However, they also showed that anosognosia is a heterogeneous phenomenon and that the role of right frontal lesions is much greater when the loss of insight concerns emotion-linked aspects of personality or behaviour than when it concerns particular aspects of cognition or memory
Brain structures playing a crucial role in the representation of tools in humans and non-human primates
No full textThe cortical representation of concepts varies according to the information critical for their development. Living categories, being mainly based upon visual information, are bilaterally represented in the rostral parts of the ventral stream of visual processing; whereas tools, being mainly based upon action data, are unilaterally represented in a left-sided fronto-parietal network. The unilateral representation of tools results from involvement in actions of the right side of the body
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