Structure and deterioration of semantic memory: a neuropsychological and computational investigation.
The authors present a parallel distributed processing implementation of this theory, in which semantic representations emerge from mechanisms that acquire the mappings between visual representations of objects and their verbal descriptions, to understand the structure of impaired performance in patients with selective and progressive impairments of conceptual knowledge.
Age of acquisition effects depend on the mapping between representations and the frequency of occurrence: Empirical and computational evidence
In the last few years, a number of connectionist models have been described that provide an explanation for age-of-acquisition (AoA) effects in verbal and nonverbal tasks. Further simulations and an…
Prototypicality, distinctiveness, and intercorrelation: Analyses of the semantic attributes of living and nonliving concepts
- P. Garrard, M. L. Lambon Ralph, J. Hodges, K. Patterson
- PsychologyCognitive Neuropsychology
- 1 March 2001
The results demonstrate that rated prototypicality is related to both the familiarity of the concept and its distance from the average of the exemplars within the same category (the category centroid).
Generalization and Differentiation in Semantic Memory
- M. L. Lambon Ralph, K. Patterson
- Psychology, BiologyAnnals of the New York Academy of Sciences
- 1 March 2008
A comprehensive array of under‐ and overgeneralization errors by patients with SD when engaged in receptive and expressive verbal and nonverbal tasks and everyday behaviors is described.
Coherent concepts are computed in the anterior temporal lobes
- M. L. Lambon Ralph, K. Sage, Roy W Jones, Emily J. Mayberry
- PsychologyProceedings of the National Academy of Sciences
- 21 January 2010
By studying patients with semantic dementia, it is demonstrated that this aspect of semantic memory becomes compromised following atrophy of the anterior temporal lobes and, as a result, the patients become increasingly influenced by superficial rather than conceptual similarities.
Conceptual knowledge is underpinned by the temporal pole bilaterally: convergent evidence from rTMS.
Two novel experiments that used off-line, low-frequency, repetitive transcranial magnetic stimulation to disrupt neural processing temporarily in the left or right temporal poles confirm that both TPs form a critical substrate within the neural network that supports conceptual knowledge.
Neurocognitive insights on conceptual knowledge and its breakdown
- M. L. Lambon Ralph
- PsychologyPhilosophical Transactions of the Royal Society B…
- 19 January 2014
Evidence is offered that conceptualization follows from a combination of modality-specific sources of information plus a transmodal ‘hub’ representational system that is supported primarily by regions within the anterior temporal lobe, bilaterally.
Neural basis of category-specific semantic deficits for living things: evidence from semantic dementia, HSVE and a neural network model.
- M. L. Lambon Ralph, C. Lowe, T. Rogers
- Psychology, BiologyBrain : a journal of neurology
- 21 November 2006
Using a combination of neuropsychology and computational neuroscience, the possibility that category-specific deficits for living things depend not solely upon the location of damage within the cortical semantic network but also critically upon the type of impairment is tested.
The Neural Organization of Semantic Control: TMS Evidence for a Distributed Network in Left Inferior Frontal and Posterior Middle Temporal Gyrus
- C. Whitney, Marie Kirk, Jamie O'Sullivan, M. L. Lambon Ralph, E. Jefferies
- PsychologyCerebral Cortex
- 17 September 2010
Stimulation of left inferior frontal gyrus and posterior middle temporal cortex with repetitive transcranial magnetic stimulation reveals that an extended network of prefrontal and posterior temporal regions underpins semantic control.
Age of acquisition effects in adult lexical processing reflect loss of plasticity in maturing systems: insights from connectionist networks.
The authors showed that such age of acquisition effects are a natural property of connectionist models trained by back-propagation when patterns are introduced at different points into training and learning of early and late patterns is cumulative and interleaved.