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PubMed1993

Memory in patients with cerebellar degeneration.

Eleven patients with relatively selective cerebellar degeneration and 11 normal control subjects underwent a comprehensive neurologic and neuropsychological examination. The neuropsychological tests assessed general intellectual ability, different aspects of memory (effortful, automatic, and implicit memory processes), speed of information processing, and verbal fluency (using both category and letter fluency tasks). The results indicated that cerebellar patients were significantly impaired only on tasks requiring the use of executive functions, such as the initiation/perseveration subtest of the Mattis Dementia Rating Scale or the fluency tests, and on memory measures requiring greater processing effort. They performed normally on automatic and implicit measures of memory. Performance on the effortful memory and executive measures was not associated with neurologic variables or mood state. After controlling for the initiation/perseveration deficit, the effortful memory scores of the cerebellar patients were no longer different from those of controls. The present study suggests that memory in patients with relatively pure cerebellar dysfunction is only partially compromised and that the impairment is secondary to a deficit in executive functions.

Adult↗

PubMed1999

Relationship between choice reaction time and the Tower of Hanoi test.

The aim of this study was to examine a possible relation between the speed of information processing, as measured by simple and choice visual RT, and problem-solving, as measured by the Tower of Hanoi test. For 20 normal teenagers, performing all tests, significant correlations were found between choice RT and both measures of performance on the Tower of Hanoi, number of disk moves, and time taken to complete the task. Simple RT was correlated with Completion time but not with the number of moves, while the reverse pattern was discerned for decision time. Choice movement time was also associated with both measures, but simple movement time was not. These results are consistent with the hypothesis of a common neurobiological basis to information-processing speed and executive functions.

Adolescent↗

PubMed1987

E-speed dental films processed with rapid chemistry: a comparison with D-speed film.

Image quality of E-speed film processed in four rapid chemistry solutions was evaluated and compared to that of D-speed film. One-hundred-twenty films (60 E-speed and 60 D-speed) were exposed with the use of a quality-control phantom and processed in four different rapid solutions. The images were evaluated for speed, contrast, fog and base, resolution, and granularity, and the useful lifetime of the solutions was determined. E-speed film processed with rapid chemistry produced images equal in quality to D-speed film in the range tested (70 to 90 kVp). Fog and base levels of E-speed film were greater than those of D-speed film. The resolution and granularity of the images were equal and were judged adequate in both film types, regardless of the chemistry used. Rapid processing solutions were found to have a 10% to 15% shorter useful lifetime with E-speed film than with D-speed film. The processing of E-speed film in rapid chemistry is recommended for emergency care and endodontics.

Densitometry↗

PubMed1996

Attention deficits and dual task demands after mild traumatic brain injury.

Attention deficits are a prominent aspect of cognitive dysfunction after mild traumatic brain injury (MTBI). Patients frequently complain of distractibility and difficulty attending to more than one thing at a time, and several neuropsychological studies have found evidence for a specific attention deficit without general neuropsychological impairment. The present study examined the nature of attentional disturbance after MTBI using an extended version of the 2 and 7 Test, which introduced two conditions reflecting patients' subjective complaints: the ability to perform with background 'noise', and while simultaneously attending to a secondary task. The dual task demands produced a significant slowing in processing speed for both the MTBI patients and control subjects. However, the relative decline in processing speed appeared much greater for the patients with MTBI, and they differed from control subjects only in this condition. The results are consistent with findings that patients with MTBI exhibit relatively subtle cognitive deficits which are apparent primarily under conditions which require effortful or controlled cognitive processing and exceed their available cognitive resources. Thus, the attentional deficits apparent during dual task demands may represent decreased cognitive, and perhaps neural, efficiency which reflects MTBI patients' subjective complaints and functional impairments.

Adult↗

PubMed2026

Beyond Glycaemia: Fear of Hypoglycaemia, Cognition and Functional Mobility After Advanced Hybrid Closed-Loop Therapy in Older Adults With Type 1 Diabetes: A Prespecified Secondary Analysis of a Randomised, Single-Centre Study.

BACKGROUND: Evidence on psychological, cognitive and functional outcomes of advanced diabetes technologies in older adults with long-standing type 1 diabetes (T1D) remains limited. We evaluated whether initiation of advanced hybrid closed-loop (AHCL) therapy was associated with changes in fear of hypoglycaemia, diabetes distress, psychological well-being, cognition, frailty-related measures and mobility-related function in adults aged ≥ 65 years with T1D. METHODS: This prespecified, exploratory secondary analysis was conducted within a single-centre, open-label, randomised, controlled, parallel-group trial including adults aged ≥ 65 years with long-standing T1D. Participants were randomly assigned (1:1) to initiate AHCL therapy using the MiniMed 780G system or to continue standard diabetes treatment. The secondary outcomes included WHO-5, the 17-item Diabetes Distress Scale (DDS), Hypoglycemia Fear Survey-II (HFS-II), Montreal Cognitive Assessment, Digit Symbol Substitution Test, Fried frailty phenotype and performance-based functional measures. No formal sample-size calculation was performed for these secondary outcomes. RESULTS: Thirty-one participants were randomised and 29 completed 12 months of follow-up and were included in the treatment-effect analyses. In the baseline-adjusted primary analysis, AHCL therapy was associated with a lower HFS-II score than standard treatment (adjusted mean difference -18.9; 95% CI: -32.4 to -5.4; nominal p = 0.008), although this finding did not remain statistically significant after Holm correction (adjusted p = 0.104) or in an exploratory model additionally adjusted for sex (difference -13.6; 95% CI: -32.2 to 5.0; p = 0.145). Diabetes distress, psychological well-being, global cognition and processing speed did not differ between groups. In sex-adjusted sensitivity analyses, the between-group differences remained statistically significant for 6-min walk distance (92.6 m; 95% CI: 36.8 to 148.3; p = 0.002) and Timed Up and Go performance (-2.27 s; 95% CI: -4.28 to -0.27; p = 0.028), but not for gait speed (0.27 m/s; 95% CI: -0.05 to 0.59; p = 0.099). At 12 months, 12 of 14 AHCL participants were robust and 2 were pre-frail; in the control group, 11 of 15 were robust and 4 were pre-frail. No participant was classified as frail at follow-up. CONCLUSIONS: In this small, selected cohort, AHCL therapy was associated with a nominally lower fear-of-hypoglycaemia score and better performance on selected mobility-related tests over 12 months. The fear-of-hypoglycaemia finding did not remain statistically significant after correction for multiple comparisons or additional adjustment for sex. Six-minute walk distance and Timed Up and Go remained statistically significant in the exploratory sex-adjusted sensitivity analyses, whereas the gait-speed difference did not. No measurable between-group deterioration in global cognition or processing speed was observed. These exploratory findings require confirmation in larger studies with balanced representation by sex and direct measurement of physical activity. These findings also support a person-centred clinical message: older age alone should not be regarded as a barrier to AHCL when treatment is introduced with individualised education and appropriate ongoing support.

Humans↗

PubMed1998

Neural dynamics of motion processing and speed discrimination.

A neural network model of visual motion perception and speed discrimination is presented. The model shows how a distributed population code of speed tuning, that realizes a size-speed correlation, can be derived from the simplest mechanisms whereby activations of multiple spatially short-range filters of different size are transformed into speed-turned cell responses. These mechanisms use transient cell responses to moving stimuli, output thresholds that covary with filter size, and competition. These mechanisms are proposed to occur in the V1-->MT cortical processing stream. The model reproduces empirically derived speed discrimination curves and simulates data showing how visual speed perception and discrimination can be affected by stimulus contrast, duration, dot density and spatial frequency. Model motion mechanisms are analogous to mechanisms that have been used to model 3-D form and figure-ground perception. The model forms the front end of a larger motion processing system that has been used to simulate how global motion capture occurs, and how spatial attention is drawn to moving forms. It provides a computational foundation for an emerging neural theory of 3-D form and motion perception.

Form Perception↗

PubMed2002

Mediators of age-related differences in recollective experience in recognition memory.

This study examined states of awareness with the Remember/Know paradigm during verbal recognition memory in young and old adults. Following the presentation of a word list, subjects undertook a recognition test and indicated whether they could consciously recollect its prior occurrence (R) or recognize it on some other basis, without conscious recollection (K). In this individual-difference approach we also incorporated various processing-speed and working-memory measures to study the link between aging, states of awareness and processing resources. The results revealed that, compared to younger adults, older adults exhibited a decline in the amount of R responses during the recognition test whereas the amount of K responses did not change. Structural equation modeling indicated that a slower processing speed associated with a limited working-memory capacity is a key to explaining age-related variance in conscious recollection. The findings offer further support for the distinction between remembering and knowing and for the processing-resources hypothesis of aging.

Adult↗

PubMed1996

The relationship between articulation time and memory performance in verbal and visuospatial tasks.

The number of verbal items which can be recalled immediately is related to the rate at which an individual can speak. Subvocal rehearsal, or articulatory recoding in working memory, has been assumed to mediate this relation. For spatial items recalled in order there is also a relationship with articulation rate, which is not related to verbal rehearsal of the items. One reason for this might be that the relationship is mediated by speed of memory scanning for serial position tags in a memory set, which is related to processing speed. Subjects were asked to perform visuospatial memory tasks which involved serial position and visuospatial memory tasks in which serial position was not involved. They also performed a digit span task. The results indicated that the visuospatial memory tasks were highly related, that they were only weakly related to digit span, and that articulation rate was correlated with every measure of memory performance used, whether serial position was involved or not. There is no support for the hypothesis that speed of scanning for serial position information in immediate spatial memory leads to a relationship with articulation rate, nor is there any support for the view that memory span tasks in different domains share resources for dealing with serial order. The results are discussed in relation to Cowan, Keller, Hulme, Roodenrys, McDougall & Rack's (1994) suggestion that the relationship between articulation rate and memory span may be mediated by general processing speed.

Adult↗

PubMed2026

Role of Polygenic Risk Scores in Predicting Cognitive Functioning after Mild Traumatic Brain Injury: A TRACK-TBI Study.

Patients with traumatic brain injury (TBI) and Glasgow Coma Scale scores of 13-15 (historically called mild TBI [mTBI]) commonly experience changes in cognitive functioning, including processing speed, memory, and executive functioning. In a prospective sample (N = 523) of individuals of European descent who had been treated in a U.S. level 1 trauma center for mTBI, we examined the prognostic value of four polygenic risk scores (PRS) for cognitive outcomes at 6-months postinjury. To estimate the impact of mTBI on cognition, primary cognitive outcomes were scaled as z-scores reflecting changes in performance relative to predicted preinjury performance. The PRS examined were previously developed and validated to predict cognition-related outcomes of educational attainment (Education-PRS), intelligence (Intelligence-PRS), and Alzheimer's disease (AD-mild traumatic brain injury (APOE)-PRS and AD + APOE-PRS). Both the Education-PRS and Intelligence-PRS displayed bivariate associations with all four cognitive outcomes (β = 0.19-0.32), whereas neither Alzheimer's disease PRS was significantly associated with any outcome. After controlling for other factors known to predict cognitive outcomes of TBI (e.g., sex, education, mTBI severity defined by a combination of Glasgow Coma Scale scores and the presence/absence of acute intracranial findings on clinical neuroimaging), the Education-PRS and Intelligence-PRS remained independently predictive of verbal episodic memory (β = 0.10-0.16), whereas their associations with processing speed and executive functioning were mostly nonsignificant and were mediated through educational attainment. Looking across primary z-score and secondary raw score outcomes, cognitive outcomes 6 months post-mTBI were good on average, and PRS made small independent contributions to outcome prediction. The mediation model findings may support theories of cognitive reserve, which propose that individuals with stronger preinjury cognitive processing abilities (often estimated by educational history) can better compensate for TBI. Moreover, findings indicate that PRS may contribute modestly to multivariable models predicting cognitive function after TBI.

Humans↗

PubMed2001

Effect of copper sulfate addition on nitrous-oxide emission in high speed dentrification process using macro-porous cellulose carrier.

Nitrous oxide emission from the immobilized denitrification process was investigated under copper-added and copper-free conditions to realize high-speed denitrification with minimum nitrous oxide emission. Nitrous oxide emission was found to be smaller in culture using immobilized cells acclimatized under copper-added condition. Transient phenomena of nitrous oxide emission, nitrate reduction and nitrite accumulation were then investigated in repeated batch experiments by transferring immobilized cells acclimatized in copper-free conditions into copper-added medium. Nitrous oxide emission obviously decreased, and maximum nitrous oxide concentration of seventh batch culture was about 1/40,000 of that of first batch culture. Nitrate reduction gradually decreased from second batch to fourth batch culture and it turned to increase from fifth batch culture to seventh batch culture. At seventh batch culture, nitrate reduction rate was restored up to 80% of the initial speed. This repeated batch experiment clarified that nitrous oxide emission was repressed by copper sulfate addition. The effect of pH and temperature on nitrous oxide emission were also investigated in a continuous denitrification experiment under copper added conditions. Nitrous oxide emission was increased by lowering pH and lowering temperature. At optimum operating condition (pH8.0, 30 degrees C), nitrogen removal efficiency of 99.9%, nitrous-oxide concentration in the emitted gas of 3.1ppm(v/v) and conversion ratio to nitrous oxide of 0.000316% were obtained when 280mg-Nl(-1) nitrate containing medium was treated at 6 hours of hydraulic retention time.

Cells, Cultured↗

PubMed2000

Organization and components of psychomotor ability.

We investigated the organization and components of psychomotor abilities by administering a diverse set of cognitive and psychomotor tasks to a group of recent high school graduates (N = 161). Confirmatory factor analyses identified two psychomotor factors: a general factor associated with all psychomotor tests and an orthogonal psychomotor learning factor associated exclusively with practiced psychomotor tests. Path analyses suggested that the general psychomotor factor could be largely accounted for by two cognitive factors, general working-memory capacity (r = .67) and an orthogonal time estimation factor (r = .32). Most of the psychomotor learning factor variance was unique, but psychomotor learning was somewhat related to processing speed (r = .49). We conclude that initial psychomotor performance is constrained by working-memory limits and the ability to keep track of time. Practiced psychomotor skill is additionally limited by processing speed, consistent with the literature on the development of process automaticity. The Discussion addresses (a) the small dimensionality of the psychomotor abilities space, (b) our discovery of the importance of time estimation and other cognitive factors in psychomotor learning, and (c) the changing nature of psychomotor skill with practice.

Adolescent↗

PubMed2000

Does the Conners' Continuous Performance Test aid in ADHD diagnosis?

The performance of clinic-referred children aged 6-11 (N = 100) was examined using the Conners' Continuous Performance Test (CPT) and measures of auditory attention (Auditory Continuous Performance Test; ACPT), phonological awareness, visual processing speed, and visual-motor competence. The Conners' CPT overall index was unrelated to measures of visual processing speed or visual-motor competence. Although the Conners' CPT converged with the ACPT, the latter demonstrated age and order effects. Significant variance in Conners' CPT parameters was predicted by phonological awareness measures, suggesting that Reading Disordered (RD) children could be "false positives" on the Conners' CPT. The Conners' CPT overall index, phonological awareness, and visual-motor measures were submitted to a 2 x 2 MANCOVA (ADHD vs. RD, covarying for age and socioeconomic status): a main effect for RD status was found. Children with ADHD did not have higher Conners' CPT scores than did clinical controls; however, children with Reading Disorders did. Phonological measures distinguished RD children from ADHD children and other clinical controls. ADHD children who failed the Conners' CPT were rated by teachers as more hyperactive. Despite the strengths of the Conners' CPT, its utility for differential diagnosis of ADHD is questioned.

Attention↗

PubMed2001

Sensorimotor adaptation to violations of temporal contiguity.

Most events are processed by a number of neural pathways. These pathways often differ considerably in processing speed. Thus, coherent perception requires some form of synchronization mechanism. Moreover, this mechanism must be flexible, because neural processing speed changes over the life of an organism. Here we provide behavioral evidence that humans can adapt to a new intersensory temporal relationship (which was artificially produced by delaying visual feedback). The conflict between these results and previous work that failed to find such improvements can be explained by considering the present results as a form of sensorimotor adaptation.

Adult↗

PubMed2002

Cognitive associations of subcortical white matter lesions in older people.

Hyperintense lesions (HL), as visualized on T2-weighted or FLAIR MRI, are a common finding in older people, but their clinical significance and influence on cognitive function remain to be clarified. We investigated the relationship between HL in deep white and gray matter structures and cognition in older subjects. We recruited 154 nondemented (Mini-Mental State Examination > 24) subjects (79 males) over the age of 70 from primary care (103 subjects with mild hypertension and 51 normotensive subjects). All subjects underwent FLAIR and proton density and T2-weighted axial 1.5-tesla MRI scans (slice thickness: 5 mm). The scans were rated for the presence and distribution of HL in the subcortical gray matter (caudate, putamen, globus pallidus, thalamus) and associated white matter tracts (internal/external capsule). Subjects (n = 149) underwent a comprehensive cognitive assessment involving tests of attention, processing speed, episodic memory, working memory, and executive function. Partial correlations (correcting for age, systolic blood pressure, and New Adult Reading Test [NART] score) were performed to investigate the relationship between cognition and white matter change. HL were found in 49% of subjects. HL in both the gray (thalamus and caudate) and white matter were significantly associated with impaired cognitive function in tasks involving processing speed and/or executive function, but showed no associations with episodic or working memory. HL in both subcortical gray matter structures and associated fiber tracts correlate with impairments in attention, executive function and processing, and memory retrieval speed in nondemented older community-dwelling subjects. Such lesions may be an important cause of age-related attentional and executive dysfunction in the elderly, as well as temporal lobe and hippocampal changes that have previously been reported to be associated with impairments to the ability to actually store and retrieve information from memory.

Aged↗

PubMed1993

Prenatal alcohol exposure and infant information processing ability.

403 black, inner-city infants born to women recruited prenatally on the basis of their alcohol consumption during pregnancy were assessed on a battery focusing on information processing and complexity of play. Prenatal alcohol exposure was not related to visual recognition memory or cross-modal transfer of information but was associated with longer fixation duration, a measure indicative of slower, less efficient information processing; lower scores on elicited play; and longer periods of toy exploration, possibly also due to slower cognitive processing. The effects on processing speed and elicited play were dose-dependent and not attributable to maternal depression, parental intellectual stimulation, other prenatal drug exposure, or postpartum maternal drinking. The processing speed deficit is consistent with deficits in older children prenatally exposed to alcohol; the present study is the first to identify slower cognitive processing in infancy and in tasks not dependent on motoric proficiency.

Adolescent↗

PubMed1992

Visual expectation and dimensions of infant information processing.

Visual expectation was assessed in 103 black 6.5-month-olds using Haith, Hazan, and Goodman's paradigm and related to performance on standard developmental assessments and tests of information processing skill. As expected, percent anticipations was higher and RT lower than in 3.0-month-olds previously tested. Split-half and left-right correlations for the RT measures were moderate and similar to those previously reported, as was split-half reliability for percent anticipations. The 2 RT measures were related to fixation duration on both visual recognition memory (VRM) and cross-modal transfer, suggesting moderate cross-task and cross-age consistency in processing speed. Percent anticipations and baseline RT each contributed independently to the prediction of VRM novelty preference. Data from a factor analysis suggested 3 dimensions of cognitive function: processing speed, developmental level, and memory/attention. These findings suggest that the visual expectation paradigm provides a reliable new approach for assessing cognitive processing efficiency and attention during infancy.

Black or African American↗

PubMedDate not supplied

Two-year decline in vision but not hearing is associated with memory decline in very old adults in a population-based sample.

BACKGROUND: Recent cross-sectional research in cognitive aging has demonstrated a robust association between visual acuity, auditory thresholds and cognitive performance in old age. However, the nature of the association is still unclear, particularly with respect to whether sensory and cognitive function are causally related. OBJECTIVE: This study aimed to determine whether marked declines in performance on screening measures of either visual acuity or auditory thresholds have an effect on cognitive decline over 2 years. METHODS: The sample from the Australian Longitudinal Study of Ageing (n = 2,087) were assessed in 1992 and 1994 on measures of sensory and cognitive function as part of a larger clinical assessment. A quasi-experimental design involving comparison of extreme groups using repeated measures MANCOVA with age as a covariate was used. RESULTS: Group performance on measures of hearing, memory, verbal ability and processing speed declined significantly. Decline in visual acuity had a significant effect on memory decline, but not on decline in verbal ability or processing speed. Decline in hearing was not associated with decline in any cognitive domain. CONCLUSION: The common association between visual acuity, auditory thresholds and cognitive function observed in cross-sectional studies appears to be disassociated in longitudinal studies.

Aged↗

PubMedDate not supplied

Cross-cultural similarities in the predictors of reading acquisition.

Measures of Chinese character/English word recognition, phonological awareness, speeded naming, visual-spatial skill, and processing speed were administered to 190 kindergarten students in Hong Kong and 128 kindergarten and grade 1 students in the United States. Across groups, the strongest predictor of reading itself was phonological awareness; visual processing did not predict reading. For both groups, speed of processing strongly predicted speeded naming, visual processing, and phonological awareness. Despite diversities of culture, language, and orthography to be learned, models of early reading development were remarkably similar across cultures and first and second language orthographies.

Child↗