Biomedical subjects

Patricia L Davies

Publications and source records attributed to Patricia L Davies.

6 recordsLinked to original sources

PubMed2004

Charting the maturation of the frontal lobe: an electrophysiological strategy.

Tracking the functional development of specific regions of the prefrontal cortex in children using event-related potentials (ERPs) is challenging for both technical and conceptual reasons. In this paper we outline our strategy for studying frontal lobe development and present preliminary results from children aged 7-17 years and young adults using ERPs functionally associated with anterior cingulate and prefrontal cortex, especially the orbitofrontal, ventral, and medial portions. Our analysis of contingent negative variation, error-related negativity, and novelty P300 data show that the ERPs associated with these regions are still maturing into late adolescence, and that their amplitude has significant correlations with behavioral capacities.

Adolescent↗

PubMed2004

Development of error-monitoring event-related potentials in adolescents.

In order to study the maturation of neurobehavioral systems involved in affect regulation and behavioral choices during adolescence, we examined brain activity associated with response monitoring and error detection using event-related potentials (ERPs). In a visual flanker test, trials with incorrect responses elicit ERP components including an error-related negativity (ERN) and a later error-positivity (Pe). We examined the amplitude and latency of the ERN and Pe of incorrect responses in 124 children from 7 to 18 years of age. The ERN amplitude in error trials increased with age although this was qualified by a nonlinear change. The quadratic distribution of the ERN indicated an initial drop in amplitude (lowest at age 10 for girls; age 13 for boys) with a subsequent rise through adolescence. The Pe amplitude did not change with age. Results are discussed with respect to continued maturation of the anterior cingulate cortex and possible influences on adolescent behaviors.

Adolescent↗

PubMed2004

Development of response-monitoring ERPs in 7- to 25-year-olds.

In a target discrimination task, trials with incorrect responses elicit event-related potentials (ERPs) that include an error-related negativity (ERN or Ne) and a later error-positivity (Pe). Substantial evidence points to the anterior cingulate cortex as the source generator of the ERN. We examined the development of ERP component morphology, amplitude and latency to processing of correct and incorrect responses in 124 children, 7 to 18 years of age, and 27 adults, 19 through 25 years of age. The ERN and Pe were recorded during a standard 480-trial visual flanker task. As expected, response times decreased significantly with age. The ERN amplitude in error trials increased with age, although this was qualified by a nonlinear change as well. The Pe amplitude did not change with age. In correct trials, most participants produced a small negativity corresponding to the timing of the ERN in error trials. This correct-response negativity (CRN) amplitude was larger in children than in adults. Results are discussed with respect to continued maturation of the anterior cingulate cortex and prefrontal cortex into young adulthood.

Adolescent↗

PubMed2004

Validity and reliability of the school function assessment in elementary school students with disabilities.

This study examined validity of the School Function Assessment (SFA) and interrater reliability of occupational therapist and teacher ratings of students' school function. The validity of the SFA was examined using the known-group method in 35 participants in kindergarten through 7th grade attending elementary schools; 15 students with learning disabilities (LD), 11 students with autism, and 9 students with traumatic brain injury (TBI). The SFA criterion scores for the 23 individual scales were clustered into five distinct parts for the validity analyses. Significant differences in SFA scores among the 3 groups of students were found using Kruskal-Wallis analyses (Chi2 ranged from 9.28 to 20.55, p <.01). Two discriminant analyses demonstrated high correct classification of students with autism and LD, but showed less accurate classification of students with TBI, indicating that the SFA scores of students with TBI did not fall into a systematic pattern for classification. For the interrater reliability study, 16 students' ratings by their teacher and occupational therapist were analyzed. Intraclass correlations resulted in moderate relationships between teacher and occupational therapist ratings for the average criterion scores for the three main sections of the SFA: participation,.70; task supports,.68; and activity performance,.73. Results of this study are discussed in terms of validity of score interpretation and the reliability of different team members completing the SFA questionnaire.

Analysis of Variance↗

PubMed2002

Error negativity and response control.

Error trials are associated with faster responses than correct trials in simple discrimination tasks suggesting that errors result from impulsive responding. We investigated the relationship between error negativity (Ne/ERN), an event-related potential associated with error detection, and two behavioral indices of response control: response time (RT) differences between incorrect and correct trials (an index of impulsivity) and percentage of errors. Response-locked ERPs were collected from 17 young adults during a visual flanker task. Consistent with previous findings, participants were significantly faster on error trials. However, participants who exhibited larger Ne/ERN peak amplitudes had significantly smaller RT differences, suggesting a more controlled response strategy. Furthermore, Ne/ERN latencies were positively associated with percentage of errors. These findings are consistent with the view that the Ne/ERN reflects the activity of a monitoring system that is closely linked to remedial systems responsible for individual differences in response control or impulsive behavior.

Adult↗

PubMedDate not supplied

Occupational therapy effects on visual-motor skills in preschool children.

OBJECTIVE: The purpose of this study was to evaluate the assumption that preschool children who receive occupational therapy will demonstrate significant improvement in their visual-motor skills as measured on the Developmental Test of Visual-Motor Integration (VMI) and the two supplemental Visual Perception and Motor Coordination tests. METHOD: Preschool children with developmental delays (n = 12) received occupational therapy a minimum of one individual 30-minute session, and one group 30-minute session per week for 1 school year. Their performance was compared to that of two control groups; preschool students without disabilities who received occupational therapy (n = 16) for one 30-minute group session per week and students without disabilities (n = 15) who received no occupational therapy. The VMI and two supplemental tests were administered three times to each student, at the beginning, middle, and end of school year. RESULTS: Planned comparison tests showed that students with developmental delays demonstrated statistically significant improvement in visual-motor skills and developed skills at a rate faster than expected when compared to typically developing peers on the VMI. The effect size for preschool students without disabilities who received occupational therapy exceeded the effect size for the VMI and Visual Perception supplemental test for the preschool students without disabilities who received no therapy, although, the difference in the post-test performance of these two groups was not statistically significant. DISCUSSION: The results of this study demonstrate that intervention, including occupational therapy, can effectively improve visual-motor skills in preschool-aged children.

Child↗