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Biomedical subjects

T Ahonen

Publications and source records attributed to T Ahonen.

At least 19 recordsLinked to original sources
PubMed2001

Working memory and everyday cognition in adults with Down's syndrome.

A number of previous studies have suggested that young people with Down's syndrome (DS) have a specific deficit of the phonological loop component of the working memory. However, there have also been studies which have proposed a specific deficit of the central executive component of working memory and suggested similarities of working memory functioning with patients with Alzheimer's disease. Fifteen middle-aged people with DS were matched for their individual scores of non-verbal intelligence to 15 individuals with mixed aetiology of intellectual disability. A versatile range of tasks was used in order to evaluate the functioning of working memory components. In addition, several everyday cognition skills were assessed. The subjects with DS performed significantly more poorly in all tasks assessing the phonological loop. Performance in other working memory tasks and compound variables representing different working memory components was equal in the groups. In addition, both groups had equal everyday cognition skills. The functioning of the phonological loop seems to be clearly deficient in people with DS. Interestingly, the deficit does not seem to affect the vocabulary or other everyday cognition skills in individuals with DS. No signs of specific deficit of the central executive component of working memory were found.

Activities of Daily Living↗
PubMed2001

Treating missing data in a clinical neuropsychological dataset--data imputation.

Missing data frequently reduce the applicability of clinically collected data in research requiring multivariate statistics. In data imputation, missing values are replaced by predicted values obtained from models based on auxiliary information. Our aim was to complete a clinical child neuropsychological data set containing 5.2% of missing observations. This was to be used in research requiring multivariate statistics. We compared four data imputation methods by artificially deleting some data. A real-donor imputation method which preserved the parameter estimates and which predicted the observed values with acceptable accuracy was used to complete the data set. In addressing the lack of studies with regard to treatment of missing data in neuropsychological data sets, this study presents information on the outcomes of applying data imputation methods to such data. The imputation modeling described can be applied to a variety of clinical neuropsychological data sets.

Child↗
PubMed2001

A dominant gene for developmental dyslexia on chromosome 3.

Developmental dyslexia is a neurofunctional disorder characterised by an unexpected difficulty in learning to read and write despite adequate intelligence, motivation, and education. Previous studies have suggested mostly quantitative susceptibility loci for dyslexia on chromosomes 1, 2, 6, and 15, but no genes have been identified yet. We studied a large pedigree, ascertained from 140 families considered, segregating pronounced dyslexia in an autosomal dominant fashion. Affected status and the subtype of dyslexia were determined by neuropsychological tests. A genome scan with 320 markers showed a novel dominant locus linked to dyslexia in the pericentromeric region of chromosome 3 with a multipoint lod score of 3.84. Nineteen out of 21 affected pedigree members shared this region identical by descent (corrected p<0.001). Previously implicated genomic regions showed no evidence for linkage. Sequencing of two positional candidate genes, 5HT1F and DRD3, did not support their role in dyslexia. The new locus on chromosome 3 is associated with deficits in all three essential components involved in the reading process, namely phonological awareness, rapid naming, and verbal short term memory.

Adolescent↗
PubMed2001

Performance of Zambian children on the NEPSY: a pilot study.

Forty-five literate schoolchildren aged 9 (n = 25) and 11 (n = 20) from urban Zambia were given core and expanded tests on the NEPSY and their performance was scored according to age-equivalent norms for U.S. children. This study indicates that in urban, literate Zambian children, the NEPSY is relatively insensitive to language and cultural influences that often compromise the applicability of Western tests in the developing world. No consistent improvement in the standard scores was found as a function of educational experience. Comparison against the U.S. normative average revealed that both age groups were poorer in the domains of language and attention and executive functions, whereas their performance was better in the visuospatial processing domain. It is concluded that the NEPSY in its present form may be clinically useful, but its results should still be treated with caution, taking into account cultural, language, and personal demographic information. More studies, with divergent and larger samples of varying age ranges are required. It seems that the NEPSY could serve as the initial step in the development of neuropsychological practices in Zambia.

Child↗
PubMed2001

Developmental pathways of children with and without familial risk for dyslexia during the first years of life.

Comparisons of the developmental pathways of the first 5 years of life for children with (N = 107) and without (N = 93) familial risk for dyslexia observed in the Jyväskylä Longitudinal study of Dyslexia are reviewed. The earliest differences between groups were found at the ages of a few days and at 6 months in brain event-related potential responses to speech sounds and in head-turn responses (at 6 months), conditioned to reflect categorical perception of speech stimuli. The development of vocalization and motor behavior, based on parental report of the time of reaching significant milestones, or the growth of vocabulary (using the MacArthur Communicative Development Inventories) failed to reveal differences before age 2. Similarly, no group differences were found in cognitive and language development assessed by the Bayley Scales of Infant Development and the Reynell Developmental Language Scales before age 2.5. The earliest language measure that showed lower scores among the at-risk group was maximum sentence length at age 2. Early gross motor development had higher correlation to later language skills among the at-risk group rather than the control children. The most consistent predictor of differential development between groups was the onset of talking. Children who were identified as late talkers at age 2 were still delayed at the age 3.5 in most features of language-related skills-but only if they belonged to the group at familial risk for dyslexia. Several phonological and naming measures known to correlate with reading from preschool age differentiated the groups consistently from age 3.5. Our findings imply that a marked proportion of children at familial risk for dyslexia follow atypical neurodevelopmental paths. The signs listed previously comprise a pool of candidates for early predictors and precursors of dyslexia, which await validation.

Child↗
PubMed2001

Practice effects on visuomotor and problem-solving tests by children.

Practice effects on a visuomotor test (the Developmental Test of Visuo-Motor Integration), a timed visual discrimination test (the Underlining Test), and two problem-solving tests (the Porteus Mazes Test and the Tower of Hanoi Test) were analyzed. Children of two age groups (Ms: 7.7 and 11.6 yr.) were chosen to study the effect of age on practice effects. The tests were repeated nine times with test-retest intervals of 2 mo. The Developmental Test of Visuo-Motor Integration showed no practice effects, while the Porteus Mazes Test, the Underlining Test, and the Tower of Hanoi Test showed significant practice effects. Practice effects were larger for the older age group on all the tests, except the Developmental Test of Visuo-Motor Integration. The Developmental Test of Visuo-Motor Integration and the Underlining Test showed good reliability, but those of the problem-solving tasks were less satisfactory. The stability of all the tests, except the Tower of Hanoi Test, was good.

Child↗
PubMed2000

Working memory structure and intellectual disability.

The working memory of people with intellectual disability has been found to generally lag behind their mental age. However, studies concerning the structure of working memory or its connections to other cognitive functions are rare. The present study employs a versatile battery of tests for the evaluation of working memory structure in adults with intellectual disability of unknown aetiology. In addition, connections between working memory and cognitive skills valid for everyday functioning are evaluated. Working memory performance in the study participants was found to stem from two distinct components which could be regarded to represent phonological and general working memory. General working memory was closely related to intelligence, whereas phonological working memory was not. The subjects in the study group differed in their working memory profiles. These distinct profiles were significantly related to academic skills (e.g. reading, writing and mathematics) and sentence comprehension because the profile of the working memory predicted these abilities even when the intelligence and educational background of the participants was taken into consideration.

Achievement↗
PubMed2000

Repeated assessment of the Tower of Hanoi test: reliability and age effects.

The purpose of this research was to analyze the effects of repeating an executive function test. Three versions of the Tower of Hanoi (TOH) test were repeated three times each, with test-retest intervals of 2 months. Two groups of children participated in the research (7.7 and 11.6 years, n = 22 and n = 28). Repeating the assessment improved the performance and decreased the total performance time in both of the groups. The older participants improved their performance faster than the younger ones. The reliability of all the scores, besides the error scores, seemed to be satisfactory after the first few assessments. The stability of the scores was maintained through all the assessments. The planning time did not explain the variations of the achieved score. The reasons for the initially low reliabilities are discussed, and modifications for the test administration and scoring are suggested.

Age Factors↗
PubMed2000

Suggestions for revised scoring of the Tower of Hanoi test.

Detailed time and error analyses of the Tower of Hanoi (TOH) test was performed using four repeated assessments of eight children (ages 9-12 years), who had perceptual and problem solving deficits. The time before each move was measured. In addition to the traditionally counted time scores, new, relative time scores were computed in order to separate the planning time from the general reaction speed. New error scores were defined and sum scores of serious errors (perserative moves, illegal moves, and wrong results) and mild errors (self-corrected moves, almost performed moves, and interrupted trials) were computed. The relative planning time correlated positively with the achieved score, and negatively with the serious errors. The serious errors correlated negatively with the achieved score. The relative planning time seems to measure the quality of planning better than does the raw planning time, and it is a recommended score for TOH analysis. The value of new error scores requires additional research.

Cognition↗
PubMed1998

High-Resolution Infrared Spectrum of Monoiodoacetylene Between 2000 and 3000 cm-1.

The high-resolution infrared spectrum of monoiodoacetylene measured with a Bruker IFS 120 HR Fourier transform spectrometer in the spectral range of 2000-3000 cm-1 has been studied in detail. The strongest bands observed in the wavenumber region investigated are the C-C stretching fundamental nu2 (2034-2082 cm-1) and the accompanying hot bands of the types nu2 + nun - nun, where n = 3, 4, or 5, associated with the lowest stretching state v3 = 1 and with the low-lying bending states v4 = 1 and v5 = 1, 2, respectively. The combination bands of the types nu2 + nun, where n is as above, starting direct from the ground state have also been observed. In addition, the weak overtone band 2nu2 (4081-4121 cm-1) has been measured to study the anharmonicity of the C-C stretching mode. The new, more accurate values for the ground state rotational constants have been derived by combining the ground state combination differences calculated from our IR data available in the present work as well as in our previous investigations concerning the HCCI molecule to the accurate MW transitions from the literature. The rotational structures of the overtone level v2 = 2 and the combination levels v2 = vn = 1, where n is as above, have been investigated by analyzing the observed spectra with a model including various Fermi- and l-type resonances. As a result, the values for the harmonic frequency omega0 2 and the anharmonicity constants x22, x23, x24, and x25 are determined. Copyright 1998 Academic Press.

Journal Article↗
PubMed1998

Speech and language development of children born at < or = 32 weeks' gestation: a 5-year prospective follow-up study.

Speech and language comprehension and production were assessed at the age of 5 years in a cohort of children born preterm at < or = 32 weeks' gestational age (N=55) in comparison with children born at term and of similar age, sex, and social backgrounds. Data both including and excluding major neurological disabilities are presented. Mean performance for the entire group of preterm children was significantly lower than for the controls on most of the measures including the composite IQ scores. When the nine children who had major neurological disabilities were excluded from the preterm group, statistically significant differences were found on four of the total 12 speech and language measures. Intellectually normal preterm children without major neurological disability were slower than the controls on rapid word retrieval. In addition, difficulties in comprehending relative concepts were typical for the preterm children. The results suggest 'subtle dysnomia', which is indicative of later reading problems. On global verbal measures and on the basic speech and language aspects the study groups did not differ. Specific language impairment, defined as a discrepancy of > 1SD between Performance IQ and Verbal IQ scores, showed a tendency to be more common in the control group. Within both the study groups, the boys showed a tendency for a greater discrepancy between their Performance and Verbal IQ scores.

Child, Preschool↗
PubMed1997

Androgen-dependent expression of prolactin in rat prostate epithelium in vivo and in organ culture.

Peptide hormones and growth factors are involved in the regulation of prostatic cell proliferation, differentiation, and programmed cell death, which functions are primarily controlled by androgen. In carcinogenesis, prostatic cancer cells often lose androgen dependence and become largely dependent on local growth factors. The prostatic cancer cells able to respond to factors other than androgen by proliferation and inhibition of apoptosis are possibly able to survive. We demonstrate that prostatic epithelium expresses prolactin mRNA and protein in a characteristic manner. By using in situ hybridization, an overall distribution of prolactin mRNA was demonstrated in the epithelium of rat dorsal and lateral prostate, whereas a very specific localization of prolactin protein to single cells was observed by immunohistochemistry in the same tissues. In these cells, immunoelectron microscopy showed that prolactin was primarily localized to the secretory granules. These data demonstrate a selective regulation of prostatic prolactin at least at the level of transcript processing/translation and/or protein accumulation and secretion. In addition, the expression of prolactin protein in rat dorsal and lateral prostate was found to be androgen dependent in vivo in castrated and in castrated, testosterone-treated rats, as well as in vitro in organ cultures. Our results support the concept of an autocrine/paracrine loop of prolactin action in prostate where it could mediate some of androgen actions. Also, locally synthesized prolactin might belong to the factors that take over androgen regulation of prostatic cancer cells during the development of androgen-independent growth.

Androgens↗
PubMed1997

Trail Making Test in assessing children with reading disabilities: a test of executive functions or content information.

The speed of performance on Part A, Part B, and on an experimental version containing alphabetical series (Part A Alphabetic) of the Trail Making Test was studied with 19 children with reading disabilities and 34 controls from Grades 4 to 6. When the test was used in discriminant profile fashion, children with reading disabilities showed a deficit compared with control children on Part B relative to part A but did not relative to the new Part A Alphabetic. The results indicate that the performance of the children with reading disabilities on Part B is likely to be affected by their slowness on the alphabetical series. Based on these results we recommend that the speed of following the alphabetical series be assessed when using Part B of the Trail Making Test.

Child↗
PubMed1994

Communication deviances and clarity among the mothers of normally achieving and learning-disabled boys.

The main purpose of the study was to reexamine the association between maternal communication deviances and learning disabilities in children. In this study, we adapted and extended the procedure used by Ditton, Green, and Singer (1987). A two-part experimental task was used: one in which the child could not request any clarification of mother's instructions, and another in which the mother and child could communicate. Both communication deviances and the clarity of mothers' communication were analyzed. The subjects were 60 mother-child pairs in which half of the children had learning disabilities and the other half were normally achieving children matched for age and parents' SES. The dyads were videotaped in a laboratory setting. The mothers of learning-disabled (LD) children were found to give less exact instructions and to present more ambiguous messages to the child than the mothers of non-LD children. Despite the more inaccurate input from their mother, the LD boys did not request clarification for ambiguous statements any more than did the NLD boys.

Adult↗
PubMed1994

Mother-child teaching strategies and learning disabilities.

The teaching strategies used by mothers of sons with learning disabilities (LD) (n = 30) and normally achieving sons (NLD) (n = 30) were examined. The children were matched for age (8- to 11-year-olds) and for parents' socioeconomic status. The behavior of mother-child pairs was videotaped in a teaching task that was constructed to resemble a homework assignment. The results showed that the mothers of children with LD used fewer high-level strategies, and their total time used in teaching was less than that of the mothers of NLD children. The mothers of children with LD exhibited more dominance and less emotionality and cooperation than did the mothers of NLD children; however, the mothers did not differ in task motivation. The children with LD seemed to have more inactive learning strategies, evident in their weaker initiative and greater dependence on their mothers. Analyses concerning the variation of maternal strategies within the LD group revealed that the mothers' motivation, combined with their emotionality and proportion of high-level strategies, had a strong positive association with their children's success in learning.

Affect↗