Semantic feature knowledge and picture naming in dementia of Alzheimer?s type: A new approach

Abstract

This study addresses continuing controversies concerning the nature of semantic impairment in early dementia of the Alzheimer type (DAT), and the relationship between conceptual knowledge and picture naming. A series of analyses of fine-grained feature knowledge data show that: (1) distinctive features of concepts were more vulnerable than shared; (2) the amount of attribute knowledge about a concept was associated reliably, and in a graded fashion, with the ability to name a picture of that item; (3) sensory features were differentially important in naming; and (4) the degree of disruption to different types of attribute knowledge did not vary between items from living and nonliving domains. These findings are discussed in the context of contemporary cognitive and computational models of semantic memory organisation.

The impact of time and repeated exposure on famous person knowledge in amnestic mild cognitive impairment and Alzheimer’s disease.

“…Early deterioration of distinctive attributes of semantic concepts in AD has been reported in previous studies (Garrard, Lambon Ralph, Patterson, Pratt, & Hodges, 2005;Giffard et al, 2002;Laisney et al, 2011;Rogers & Friedman, 2008). Our results show that distinctive attributes are also more vulnerable in aMCI.…”

Cross-sensory correspondences and cross talk between dimensions of connotative meaning: Visual angularity is hard, high-pitched, and bright

“…This would allow interactions among these lexical representations, rather than among semantic representations, to be responsible for any congruity effects. It is important to note, however, that pictorial stimuli seem not to access verbal representations (e.g., the names of pictured objects or their features) directly, but only indirectly via semantic representations (Garrard, Lambon Ralph, Patterson, Pratt, & Hodges, 2005;Lambon Ralph, McClelland, Patterson, Galton, & Hodges, 2001;McGregor, Friedman, Reilly, & Newman, 2002;Morton, 1985). Thus, lexical representations linked to shape angularity would need to be activated in a top-down manner by semantic representations of angularity.…”

A longitudinal study of semantic memory impairment in patients with Alzheimer’s disease

“…In this study, the patients were first asked to name pictures and subsequently to perform a "same category word to picture matching" task. There was a reliable overlap between loss of name production and name comprehension such that pictures named correctly were more likely to be chosen in a word-to-picture matching task than pictures not named correctly (see also Alathari et al, 2004;Bayles et el., 1999;Binetti et al, 1995;Garrard et al, 2005;Hodges and Patterson, 1995;Hornberger et al, 2009;Martin and Fedio, 1983;Salmon et al, 1999a for similar procedures). Several other researchers have described a breakdown in the structure and organization of semantic memory in patients with Alzheimer's disease (for review see Salmon et al, 1999b).…”

“…The access hypothesis predicts random absence of specific semantic information across tasks within one test occasion as well as across test occasions. The approach to test these hypotheses by examining item-by-item consistency across tests has been used in previous studies (e.g., Garrard et al, 2005;Hodges et al, 1996). Our longitudinal design extends this approach by examining item-by-item consistency within the same AD patients across time.…”