![]() ![]() Typically, this “semantic anomia” occurs in conjunction with deficits of single word comprehension. In contrast to pure anomia, the pathogenesis of the word retrieval deficit in patients with more anterior left temporal lesions appears to involve degradation of semantic knowledge, manifesting in a high proportion of semantic naming errors (e.g., beaver: chipmunk) and ambiguous or inappropriate circumlocutions. ![]() Naming impairments have also been documented following damage to more anterior (BAs 38, 20/21) and medial (BAs 28/34, 35/36) temporal lobe regions resulting from a variety of lesion aetiologies, including left anterior temporal lobectomy ( Bell et al., 2001 Glosser & D’Onofrio, 2001), herpes encephalitis ( Moss, Rodd, Stamatakis, Bright, & Tyler, 2005 Pietrini, Nertempi, Vaglia, Revello, & Pinna, 1988 Schmolck, Kensinger, Corkin, & Squire, 2002 Tyler et al., 2004 Warrington & Shallice, 1984), and semantic dementia ( Davies, Graham, Xuereb, Williams, & Hodges, 2004 Hodges & Patterson, 1996 Hodges, Patterson, Oxbury, & Funnell, 1992a Lambon Ralph, McClelland, Patterson, Galton, & Hodges, 2001 Mummery et al., 1999 Mummery et al., 2000). This type of naming impairment, known as “pure anomia”, has been described as reflecting a disconnection between intact semantic knowledge and phonological word forms ( Benson, 1979, 1988 Damasio et al., 1996 Foundas et al., 1998 Raymer et al., 1997), an assertion that is supported by evidence that word retrieval can be facilitated by phonemic cueing. Typically, naming errors produced by these individuals are semantically appropriate circumlocutions, demonstrating relatively intact conceptual knowledge as well as preserved phonological abilities. Specifically, case studies documenting lesions to left posterior inferior temporal cortex (BA 37) provide evidence of anomia with preserved semantic knowledge ( Damasio et al., 1996 Foundas, Daniels, & Vasterling, 1998 Raymer et al., 1997). This variability appears to parallel the regional differences documented in neuroimaging studies. Neuropsychological studies with lesion analysis support the notion that the left inferior temporal lobe is critical for semantically guided lexical retrieval, and further suggest that there is some variability in the nature of the naming impairment as a function of lesion location ( Benson, 1979 Damasio et al., 1996 De Renzi, Zambolin, & Crisi, 1987). ![]() In contrast, activation in left anterior temporal cortex (BAs 38, 20/21, 35/36) has been implicated in amodal semantic processing ( Binder & Price, 2001 Bright, Moss, & Tyler, 2004 D’Esposito et al., 1997 Moore & Price, 1999 Vandenberghe, Price, Wise, Josephs, & Frackowiak, 1996). Activation in this region is most often attributed to processes important for accessing phonological word forms from semantic input ( Binder et al., 1997 Damasio, Grabowski, Tranel, Hichwa, & Damasio 1996). ![]() For instance, functional neuroimaging studies of neurologically intact participants have demonstrated activation in left posterior inferior temporal cortex (Brodmann Area 37) during picture-naming and verbal fluency tasks ( Freidman et al., 1998 Moore & Price, 1999 Mummery, Patterson, Hodges, & Wise, 1996 Murtha, Chertkow, Beauregard, & Evans, 1999 Price, Moore, Humphreys, Frackowiak, & Friston, 1996). There is growing evidence that extrasylvian regions of the left temporal lobe play an important role in semantically guided lexical retrieval. ![]()
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