No description available.

Extensive research has supported the existence of a specialized face-processing network that is distinct from the visual processing areas used for general object recognition. The majority of this work has been aimed at characterizing the response properties of the fusiform face area (FFA) and the occipital face area (OFA), which together are thought to constitute the core network of brain areas responsible for facial identification. Although accruing evidence has shown that face-selective patches in the ventral anterior temporal lobes (vATLs), within perirhinal cortex, play a necessary role in facial identification, the relative contribution of these brain areas to the core face-processing network has remained unarticulated. The current study assessed the relative sensitivity of the anterior face patch, the OFA, and the FFA, to different aspects of person information. Participants learned to associate a name and occupation label, or a name only, with different facial identities. The sensitivity of the face processing areas to facial identity, occupation, and the amount of information associated with a face was then assessed. The results of a multivoxel pattern analysis (MVPA) revealed that distributed activity patterns in the anterior face patch contained information about facial identity, occupation, and the amount of information associated with a face, with the sensitivity of the anterior face patch to occupation and amount of information being greater than the more posterior face processing regions. When a similar analysis was conducted that included all voxels in the perirhinal cortex, sensitivity to every aspect of person information increased. These results suggest that the human ventral anterior temporal lobes may be critically involved in representing social, categorical, information about individual identities. / Psychology

We investigated age-related differences in neural activation associated with recognition of familiar melodies, a process that requires retrieval from musical semantic memory and leads to a feeling of familiarity. We used sparse sampling fMRI to determine the neural correlates of melody processing and familiarity by comparing activation when listening to melodies versus signal-correlated noise, and to familiar versus unfamiliar melodies, respectively. Overall, activity in the bilateral superior temporal gyrus correlated well with melody processing. Familiarity was associated with several frontal regions (bilateral inferior frontal gyrus, superior frontal gyrus, and precentral gyrus; left insular cortex), right superior temporal gyrus; left supramarginal gyrus and cingulate gyrus; bilateral putamen and thalamus; cerebellum and brainstem. No significant differences were found between younger and older adults for either melody processing or familiarity based activation. Assessment of familiarity-related group differences using less stringent criteria identified plausible areas; greater activation was seen bilaterally in the superior temporal gyrus in younger adults and in some left parietal regions in older adults. This study adds to the knowledge of musical semantic memory with results based on a large sample (N = 40) that includes older adults. Our findings for activation associated with melody processing and familiarity support some, but not all, previous results of related studies. We were unable to find conclusive evidence of age-related differences in neural correlates of musical semantic memory, while also being the first study (to the best of our knowledge) to search for these differences. / Thesis (Master, Neuroscience Studies) -- Queen's University, 2013-09-16 12:38:10.757

We investigated age-related differences in neural activation associated with recognition of familiar melodies, a process that requires retrieval from musical semantic memory and leads to a feeling of familiarity. We used sparse sampling fMRI to determine the neural correlates of melody processing and familiarity by comparing activation when listening to melodies versus signal-correlated noise, and to familiar versus unfamiliar melodies, respectively. Overall, activity in the bilateral superior temporal gyrus correlated well with melody processing. Familiarity was associated with several frontal regions (bilateral inferior frontal gyrus, superior frontal gyrus, and precentral gyrus; left insular cortex), right superior temporal gyrus; left supramarginal gyrus and cingulate gyrus; bilateral putamen and thalamus; cerebellum and brainstem. No significant differences were found between younger and older adults for either melody processing or familiarity based activation. Assessment of familiarity-related group differences using less stringent criteria identified plausible areas; greater activation was seen bilaterally in the superior temporal gyrus in younger adults and in some left parietal regions in older adults. This study adds to the knowledge of musical semantic memory with results based on a large sample (N = 40) that includes older adults. Our findings for activation associated with melody processing and familiarity support some, but not all, previous results of related studies. We were unable to find conclusive evidence of age-related differences in neural correlates of musical semantic memory, while also being the first study (to the best of our knowledge) to search for these differences. / Thesis (Master, Neuroscience Studies) -- Queen's University, 2013-09-16 12:38:10.757

No description available.

Semantic memory includes vocabulary and word meanings, conceptual information, and general facts about the world (Tulving, 1972). According to the standard view of semantic memory in cognitive neuroscience, the hippocampus is necessary to first acquire new semantic information (Gabrieli, Cohen, & Corkin, 1988), but these representations are then consolidated in the neocortex and become independent of the hippocampus with time (McClelland, McNaughton, & O'Reilly, 1995). Remote semantic memory is considered independent of the hippocampus, and the hippocampus is not thought to play a critical role in the processing and use of such representations. The current work challenges the notion that previously acquired semantic knowledge, and its use during communication, is independent of the hippocampus. A group of patients with bilateral hippocampal damage and severe impairments in declarative memory were tested. Intact naming and word-definition matching performance in amnesia, has led to the notion that remote semantic memory is intact in patients with hippocampal amnesia. Motivated by perspectives of word learning as a protracted process where additional features and senses of a word are added over time, and by recent discoveries about the time course of hippocampal contributions to on-line relational processing, reconsolidation, and the flexible integration of information, we revisit the notion that remote semantic memory is intact in amnesia. Using measures of semantic richness and vocabulary depth from psycholinguistics and first and second language-learning studies, we examined how much information is associated with previously acquired, highly familiar words in hippocampal amnesic patients. Relative to healthy demographically matched comparison participants and a group of brain-damaged comparison participants, the patients with hippocampal amnesia performed significantly worse on both productive and receptive measures of vocabulary depth and semantic richness. In the healthy brain, semantic memory appears to get richer and deeper with time. Healthy participants of all ages were tested on these measures and strong correlations are seen with age as older healthy adults displayed richer semantic knowledge than the younger adults. The patient data provides a mechanism: hippocampal relational binding supports the deepening and enrichment of knowledge over time. These findings suggest that remote semantic memory is impoverished in patients with hippocampal amnesia and that the hippocampus supports the maintenance and updating of semantic memory beyond its initial acquisition. The use of lexical and semantic knowledge during discourse was also examined. Amnesic patients displayed significantly lower levels of lexical diversity in the speech they produced, and showed a strong trend toward producing language with reduced levels of semantic detail suggesting that patients cannot use their semantic representations as richly during communication. These results add to a growing body of work detailing a role for the hippocampus in language processing more generally. By documenting a role for the hippocampus in maintaining, updating, and using semantic knowledge, this work informs theories of semantic memory and it's neural bases, advances knowledge of the role of the hippocampus in supporting human behavior, and brings more sensitive measures to the neuroscientific study of semantic memory.

This thesis addresses the computation and organization of conceptual knowledge. Specifically, it focuses on the recruitment of concrete knowledge during single word reading using behavioural and electrophysiological methodologies. Chapters 1 and 2 assess how number of visual semantic features listed by participants as being part of a given concept influence the speed of word meaning computation, and its neural underpinnings, providing evidence for modality-specific neural organization. Chapter 3 assesses the flexibility of knowledge activation as a function of specific task constraints, suggesting a multi-faceted approach to semantic richness is needed. Chapter 4 describes a novel application of recent statistical advances to the analysis of real-time electrophysiological data, and highlights some limitations of standard analytical approaches. Chapter 5 assesses the real-time influence of several types of knowledge on the neuroelectric activity underlying concrete word meaning computation. A timecourse of sensory-based knowledge type activation is outlined. Finally, Chapter 6 describes a novel approach whereby real-time electrophysiological brain activity is used to predict the speed of semantic decision making, providing further evidence of a highly flexible, but finely structured, human semantic memory system.

This thesis addresses the computation and organization of conceptual knowledge. Specifically, it focuses on the recruitment of concrete knowledge during single word reading using behavioural and electrophysiological methodologies. Chapters 1 and 2 assess how number of visual semantic features listed by participants as being part of a given concept influence the speed of word meaning computation, and its neural underpinnings, providing evidence for modality-specific neural organization. Chapter 3 assesses the flexibility of knowledge activation as a function of specific task constraints, suggesting a multi-faceted approach to semantic richness is needed. Chapter 4 describes a novel application of recent statistical advances to the analysis of real-time electrophysiological data, and highlights some limitations of standard analytical approaches. Chapter 5 assesses the real-time influence of several types of knowledge on the neuroelectric activity underlying concrete word meaning computation. A timecourse of sensory-based knowledge type activation is outlined. Finally, Chapter 6 describes a novel approach whereby real-time electrophysiological brain activity is used to predict the speed of semantic decision making, providing further evidence of a highly flexible, but finely structured, human semantic memory system.

The aim of the present doctoral thesis was to investigate the ability of patients with Alzheimer's disease (AD) to utilize cognitive support in order to improve episodic remembering. A review of previous research indicated that most studies have failed to find beneficial effects of encoding support on memory in AD patients. The ability to utilize cognitive support (i.e., motoric activities, semantic organization, and semantic knowledge) for episodic remembering was investigated in five studies (Bäckman &amp; Herlitz, 1990; Herlitz, Adolfsson, Bäckman, &amp; Nilsson, in press; Herlitz &amp; Bäckman, 1990; Herlitz &amp; Viitanen, in press; Karlsson et al., 1989). Patients with mild, moderate, or severe AD, and normal older adults participated in the studies. On the basis of the results from these studies and the review of the literature, it was concluded that (a) AD patients, irrespective of dementia severity, perform at a lower level than normal older adults in episodic memory tasks; (b) provided that support is supplied at retrieval, AD patients may be sensitive to manipulations at encoding; (c) the strength of the encoding manipulation determines the size of the memory improvement in AD patients; and (d) depending on dementia severity, the type of encoding support also determines the magnitude of memory improvement obtained. / <p>Diss. (sammanfattning) Umeå : Umeå universitet, 1991, härtill 5 uppsatser.</p> / digitalisering@umu

Most of the work investigating the representation of concrete nouns in the brain has focused on the locations that code the information. We present a model to study the contributions of perceptual and semantic features to the neural code representing concepts over time and space. The model is evaluated using magnetoencephalography data from different paradigms and not only corroborates previous findings regarding a distributed code, but provides further details about how the encoding of different subcomponents varies in the space-time spectrum. The model also successfully generalizes to novel concepts that it has never seen during training, which argues for the combination of specific properties in forming the meaning of concrete nouns in the brain. The results across paradigms are in agreement when the main differences among the experiments (namely, the number of repetitions of the stimulus, the task the subjects performed, and the type of stimulus provided) were taken into consideration. More specifically, these results suggest that features specific to the physical properties of the stimuli, such as word length and right-diagonalness, are encoded in posterior regions of the brain in the first hundreds of milliseconds after stimulus onset. Then, properties inherent to the nouns, such as is it alive? and can you pick it up?, are represented in the signal starting at about 250 ms, focusing on more anterior parts of the cortex. The code for these different features was found to be distributed over time and space, and it was common for several regions to simultaneously code for a particular property. Moreover, most anterior regions were found to code for multiple features, and a complex temporal profile could be observed for the majority of properties. For example, some features inherent to the nouns were encoded earlier than others, and the extent of time in which these properties could be decoded varied greatly among them. These findings complement much of the work previously described in the literature, and offer new insights about the temporal aspects of the neural encoding of concrete nouns. This model provides a spatiotemporal signature of the representation of objects in the brain. Paired with data from carefully-designed paradigms, the model is an important tool with which to analyze the commonalities of the neural code across stimulus modalities and tasks performed by the subjects.