Does sustained ERP activity in posterior lexico-semantic processing areas during short-term memory tasks only reflect activated long-term memory?

in Behavioral and Brain Sciences (2003), 26(6), 746-747

We challenge Ruchkin et al.'s claim in reducing short-term memory (STM) to the active part of long-term memory (LTM), by showing that their data cannot rule out the possibility that activation of ... [more ▼]

We challenge Ruchkin et al.'s claim in reducing short-term memory (STM) to the active part of long-term memory (LTM), by showing that their data cannot rule out the possibility that activation of posterior brain regions could also reflect the contribution of a verbal STM buffer. [less ▲]

Phonological short-term memory networks following recovery from Landau and Kleffner syndrome

in Human Brain Mapping (2003), 19(3), 133-144

Landau-Kleffner syndrome (LKS) is a rare acquired aphasia occurring in otherwise healthy children, together with spike-wave discharges predominating over superior temporal regions and activated by sleep ... [more ▼]

Landau-Kleffner syndrome (LKS) is a rare acquired aphasia occurring in otherwise healthy children, together with spike-wave discharges predominating over superior temporal regions and activated by sleep. Although the outcome of language abilities is variable, a residual impairment in verbal short-term memory (STM) is frequent. This STM deficit might be related to the persistent dysfunction of those temporal lobe regions where epileptic discharges were observed during the active phase of the disorder. We tested this hypothesis by measuring brain activation during immediate serial recall of lists of 4 words, compared to single word repetition, using H(2) (15)O positron emission tomography (PET), in 3 LKS patients after recovery and in 14 healthy controls. The patients (TG, JPH, and DC) had shown abnormally increased or decreased glucose metabolism in left or right superior temporal gyrus (STG) at different stages during the active phase of their disease. At the time of this study, the patients were 6-10 years from the active phase of LKS. Results showed that Patients JPH and DC had impaired performance in the STM condition, whereas TG showed near normal performance. PET data showed that JPH and DC activated significantly less than controls left and right posterior STG. TG, having near normal STM performance, showed increased activity in the posterior part of the right STG. These data suggest that impaired verbal STM at late outcome of LKS might indeed be related to a persistent decrease of activity in those posterior superior temporal gyri that were involved in the epileptic focus during the active phase. [less ▲]

Perception and short-term memory for verbal information in children with specific language impairment : further evidence for impaired short-term memory capacities

in Brain & Language (2003), 87(1), 160-161

Functional neuroimaging of auditory processing

in Acta Oto-Rhino-Laryngologica Belgica (2003), 57(4), 267-273

There is a complex functional organization of the central auditory system from the brainstem to primary and associative auditory cortices. Functional neuroimaging has been used to visualize and confirm ... [more ▼]

There is a complex functional organization of the central auditory system from the brainstem to primary and associative auditory cortices. Functional neuroimaging has been used to visualize and confirm the spatial distribution of brain activation in temporal areas for the processing of simple acoustic stimuli. Brain activity is much more complex for words, and different networks can be recruited when phonological, lexical and semantic levels of processing are engaged. [less ▲]

A PET investigation of lexicality and phonotactic frequency in oral language processing

in Cognitive Neuropsychology (2002), 19(4), 343-360

Lexicality and phonotactic frequency effects are observed in many cognitive studies on language processing, but little is known about their underlying neural substrates, especially with regard to ... [more ▼]

Lexicality and phonotactic frequency effects are observed in many cognitive studies on language processing, but little is known about their underlying neural substrates, especially with regard to phonotactic frequency effects. Here, we conducted a positron emission tomography (PET) study in which 11 right-handed volunteers had either to repeat or to listen to lists of words, high phonotactic frequency nonwords, and low phonotactic frequency nonwords. The comparison of word versus nonword processing consistently confirmed previous findings of left temporal and prefrontal activations classically ascribed to lexicosemantic processing. Higher activation was found in the right posterior superior temporal gyrus when comparing high phonotactic frequency nonwords to words, but not when comparing low phonotactic frequency nonwords to words. We propose that this region is implicated in the formation of temporary phonological representations for high-probability phonological events, which may support processing of high phonotactic frequency nonwords [less ▲]

Deep dysphasia : Further evidence on the relationship between phonological short-term memory and language processing impairments

in Cognitive Neuropsychology (2001), 18(5), 385-410

We report a cognitive investigation of a case of deep dysphasia appearing in the context of primary progressive aphasia. Over a period of 5 years, patient CO presented progressive difficulties in word ... [more ▼]

We report a cognitive investigation of a case of deep dysphasia appearing in the context of primary progressive aphasia. Over a period of 5 years, patient CO presented progressive difficulties in word finding and in oral comprehension, while nonverbal cognitive functions remained preserved. As in other deep dysphasic patients, CO's repetition performance showed marked imageability and lexicality effects, and semantic paraphasias. The same effects were observed in writing-to-dictation. Regularisation errors occurred in word reading. CO's short-term memory span was less than two words. A cognitive analysis of language processing revealed difficulties in phoneme identification and rhyme judgement, in detecting grammatical class for orally presented words, and in oral and written naming. The interpretation of CO's deep dysphasic symptoms within interactive models of language processing confirmed the importance of a phonological short-term storage impairment as an explanatory factor of deep dysphasia. [less ▲]

Mémoire à court terme et pathologies du langage

in Rééducation Orthophonique (2001), 208

La rééducation des patients amnésiques : exploitation des capacités mnésiques préservées

in Azouvi, P. (Ed.) La rééducation en neuropsychologie : étude de cas (1999)