| 1. |
- Hedenius, Martina, et al.
(författare)
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Enhanced Recognition Memory after Incidental Encoding in Children with Developmental Dyslexia
- 2013
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Ingår i: PLOS ONE. - : Public Library of Science (PLoS). - 1932-6203. ; 8:5, s. e63998-
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Tidskriftsartikel (refereegranskat)abstract
- Developmental dyslexia (DD) has previously been associated with a number of cognitive deficits. Little attention has been directed to cognitive functions that remain intact in the disorder, though the investigation and identification of such strengths might be useful for developing new, and improving current, therapeutical interventions. In this study, an old/new recognition memory paradigm was used to examine previously untested aspects of declarative memory in children with DD and typically developing control children. The DD group was not only not impaired at the task, but actually showed superior recognition memory, as compared to the control children. These findings complement previous reports of enhanced cognition in other domains (e. g., visuo-spatial processing) in DD. Possible underlying mechanisms for the observed DD advantage in declarative memory, and the possibility of compensation by this system for reading deficits in dyslexia, are discussed.
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| 2. |
- Hedenius, Martina, et al.
(författare)
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Grammar predicts procedural learning and consolidation deficits in children with Specific Language Impairment
- 2011
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Ingår i: Research in Developmental Disabilities. - : Elsevier. - 0891-4222 .- 1873-3379. ; 32:6, s. 2362-2375
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Tidskriftsartikel (refereegranskat)abstract
- The Procedural Deficit Hypothesis (PDH) posits that Specific Language Impairment (SLI) can be largely explained by abnormalities of brain structures that subserve procedural memory. The PDH predicts impairments of procedural memory itself, and that such impairments underlie the grammatical deficits observed in the disorder. Previous studies have indeed reported procedural learning impairments in SLI, and have found that these are associated with grammatical difficulties. The present study extends this research by examining consolidation and longer-term procedural sequence learning in children with SLI. The Alternating Serial Reaction Time (ASRT) task was given to children with SLI and typically developing (TD) children in an initial learning session and an average of three days later to test for consolidation and longer-term learning. Although both groups showed evidence of initial sequence learning, only the TD children showed clear signs of consolidation, even though the two groups did not differ in longer-term learning. When the children were re-categorized on the basis of grammar deficits rather than broader language deficits, a clearer pattern emerged. Whereas both the grammar impaired and normal grammar groups showed evidence of initial sequence learning, only those with normal grammar showed consolidation and longer-term learning. Indeed, the grammar-impaired group appeared to lose any sequence knowledge gained during the initial testing session. These findings held even when controlling for vocabulary or a broad non-grammatical language measure, neither of which were associated with procedural memory. When grammar was examined as a continuous variable over all children, the same relationships between procedural memory and grammar, but not vocabulary or the broader language measure, were observed. Overall, the findings support and further specify the PDH. They suggest that consolidation and longer-term procedural learning are impaired in SLI, but that these impairments are specifically tied to the grammatical deficits in the disorder. The possibility that consolidation and longer-term learning are problematic in the disorder suggests a locus of potential study for therapeutic approaches. In sum, this study clarifies our understanding of the underlying deficits in SLI, and suggests avenues for further research.
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| 3. |
- Hedenius, Martina, 1970-, et al.
(författare)
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Impaired implicit sequence learning in children with developmental dyslexia
- 2013
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Ingår i: Research in Developmental Disabilities. - : Elsevier. - 0891-4222 .- 1873-3379. ; 34:11, s. 3924-3935
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Tidskriftsartikel (refereegranskat)abstract
- It has been proposed that an impairment of procedural memory underlies a range of linguistic, cognitive and motor impairments observed in developmental dyslexia (DD). However, studies designed to test this hypothesis using the implicit sequence learning paradigm have yielded inconsistent results. A fundamental aspect of procedural learning is that it takes place over an extended time-period that may be divided into distinct stages based on both behavioural characteristics and neural correlates of performance. Yet, no study of implicit sequence learning in children with DD has included learning stages beyond a single practice session. The present study was designed to fill this important gap by extending the investigation to include the effects of overnight consolidation as well as those of further practice on a subsequent day. The results suggest that the most pronounced procedural learning impairment in DD may emerge only after extended practice, in learning stages beyond a single practice session.
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| 4. |
- Hedenius, Martina
(författare)
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Procedural and Declarative Memory in Children with Developmental Disorders of Language and Literacy
- 2013
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Doktorsavhandling (övrigt vetenskapligt/konstnärligt)abstract
- The procedural deficit hypothesis (PDH) posits that a range of language, cognitive and motor impairments associated with specific language impairment (SLI) and developmental dyslexia (DD) may be explained by an underlying domain-general dysfunction of the procedural memory system. In contrast, declarative memory is hypothesized to remain intact and to play a compensatory role in the two disorders. The studies in the present thesis were designed to test this hypothesis.Study I examined non-language procedural memory, specifically implicit sequence learning, in children with SLI. It was shown that children with poor performance on tests of grammar were impaired at consolidation of procedural memory compared to children with normal grammar. These findings support the PDH and are line with previous studies suggesting a link between grammar processing and procedural memory.In Study II, the same implicit sequence learning paradigm was used to test procedural memory in children with DD. The DD group showed a learning profile that was similar to that of children with SLI in Study I, with a significant impairment emerging late in learning, after extended practice and including an overnight interval. Further analyses suggested that the DD impairment may not be related to overnight consolidation but to the effects of further practice beyond the initial practice session. In contrast to the predictions of the PDH, the sequence learning deficit was unrelated to phonological processing skills as assessed with a nonword repetition task.Study III examined declarative memory in DD. The performance of the DD group was found to be not only intact, but even enhanced, compared to that of the control children. The results encourage further studies on the potential of declarative memory to compensate for the reading problems in DD.In sum, the results lend partial support for the PDH and suggest further refinements to the theory. Collectively, the studies emphasize the importance of going beyond a narrow focus on language learning and memory functions in the characterization of the two disorders. Such a broader cognitive, motor and language approach may inform the development of future clinical and pedagogical assessment and intervention practices for SLI and DD.
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| 5. |
- Jennische, Margareta
(författare)
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Linguistic difficulties in children andadolescents after acquired brain injury : a retrospective study.
- 2010
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Ingår i: Journal of Pediatric Rehabilitation Medicine. - Amsterdam : IOS Press. - 1875-8894. ; 3:4, s. 251-258
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Tidskriftsartikel (refereegranskat)abstract
- Objective The purpose of this study was to focus on two linguistic abilities, word retrieval (expressive language) and comprehension of vocabulary and grammar (receptive language), as well as to investigate to what extent longterm problems exist in these areas in children following traumatic brain injury. Methods Two groups of children were studied retrospectively: twentyfour children with traumatic brain injury (TBI) and twenty-one children diagnosed with brain tumour. All children had been referred to the rehabilitation team for assessment. The children were between four and seventeen years old when assessed, with the assessments performed at least one year after the injury or brain tumour diagnosis. An established set of tests regarding word retrieval and comprehension of vocabulary and grammar was used, and the results were compared with normative test data. Results In both clinical groups, significantly more children scored lower than the designated “normal” score than in the normative sample on tests measuring confrontation naming and phonological word retrieval. In addition, in the brain tumour group, more children demonstrated significantly lower results than normal performance on a test for semantic word retrieval. In the TBI group, significantly more children scored below the normal value on tests of word and grammatical comprehension when compared to the normative sample. Conclusions This study confirms that word retrieval is an area of deficit in many children with acquired brain injuries one year or more after the injury occurred. The study also indicates that children with TBI may have persistent deficits in comprehension of both vocabulary and grammar.
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| 6. |
- Rejnö-Habte Selassie, Gunilla, 1947, et al.
(författare)
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Speech, language, and cognitive dysfunction in children with focal epileptiform activity : A follow-up study
- 2010
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Ingår i: Epilepsy & Behavior. - : Elsevier BV. - 1525-5050 .- 1525-5069. ; 18:3, s. 267-275
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Tidskriftsartikel (refereegranskat)abstract
- We reviewed the medical history, EEG recordings, and developmental milestones of 19 children with speech and language dysfunction and focal epileptiform activity. Speech, language, and neuropsychological assessments and EEG recordings were performed at follow-up, and prognostic indicators were analyzed. Three patterns of language development were observed: late start and slow development, late start and deterioration/regression, and normal start and later regression/deterioration. No differences in test results among these groups were seen, indicating a spectrum of related conditions including Landau-Kleffner syndrome and epileptic language disorder. More than half of the participants had speech and language dysfunction at follow-up. IQ levels, working memory, and processing speed were also affected. Dysfunction of auditory perception in noise was found in more than half of the participants, and dysfunction of auditory attention in all. Dysfunction of communication, oral motor ability, and stuttering were noted in a few. Family history of seizures and abundant epileptiform activity indicated a worse prognosis.
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