PubMed Health⌕ Search

Biomedical subjects

R E Graves

Publications and source records attributed to R E Graves.

At least 19 recordsLinked to original sources
PubMed2004

Correcting the 3MS for bias does not improve accuracy when screening for cognitive impairment or dementia.

We investigated the effects of correcting for demographic biases on the sensitivity and specificity of the Modified Mini Mental Status Exam (3MS) using a sample of English-speaking older adults (N=8901) from the Canadian Studies of Health and Aging. The sensitivity and specificity of the original 3MS were compared to the 3MS regression-adjusted for the influence of demographic variables and then to 3MS percentiles based on published normative data with age and education corrected cutoff scores. According to receiver operating characteristic curve analyses, the regression-adjusted 3MS was no more accurate than the original 3MS when screening for dementia, and it was less accurate when screening for cognitive impairment. The use of 3MS percentiles based on normative data with age and education corrected cut-off points were less accurate than the original 3MS when screening for both cognitive impairment and when screening for dementia.

Aged↗
PubMed2004

Boston naming test short forms: a comparison of previous forms with new item response theory based forms.

Two new short forms of the Boston Naming Test (BNT) were developed using item response theory (IRT) with data from 206 elderly outpatients. We evaluated the diagnostic ability of 12 short forms among the full sample and in a sub-sample of 69 patients diagnosed with mild Alzheimer's disease (AD) either alone or in combination with vascular dementia (VD). The full BNT (reliability alpha = .90) identified 44% of the AD/VD patients as abnormal on naming. Our 30 item short form (alpha = .90) also identified 44% of the AD/VD patients as abnormal, with 93% agreement with the full BNT on abnormal AD/VD patient classifications. Our 15 item short form (alpha = .84) identified 48% of the AD/VD patients as abnormal, with 90% agreement with the full BNT's abnormal classifications. An adaptive 30/15 item version equaled the performance of the full 30 item test while requiring only 15 items for 75% of the patients with normal naming ability. This study illustrates the utility of IRT for developing neuropsychological assessment tools.

Adult↗
PubMed2001

Loose but normal: a semantic association study.

An abnormal facilitation of the spreading activation within semantic networks is thought to under-lie schizophrenics' remote associations and referential ideas. In normal subjects, elevated magical ideation (MI) has also been associated with a style of thinking similar to that of schizotypal subjects. We thus wondered whether normal subjects with a higher MI score would judge "loose associations" as being more closely related than do subjects with a lower MI score. In two experiments, we investigated whether judgments of the semantic distance between stimulus words varied as a function of MI. In the first experiment, random word pairs of two word classes, animals and fruits, were presented. Subjects had to judge the semantic distance between word pairs. In the second experiment, sets of three words were presented, consisting of a pair of indirectly related, or unrelated nouns plus a third noun. Subjects had to judge the semantic distance of the third noun to the word pair The results of both experiments showed that higher MI subjects considered unrelated words as more closely associated than did lower MI subjects. We conjecture that for normal subjects high on MI "loose associations" may not be loose after all. We also note that the tendency to link uncommon, nonobvious, percepts may not only be the basis of paranormal and paranoid ideas of reference, but also a prerequisite of creative thinking.

Adult↗
PubMed2000

Accuracy of regression equation prediction across the range of estimated premorbid IQ.

Linear regression is often used to predict psychological criterion variables such as premorbid IQ. The prevailing method of evaluating the accuracy of prediction indicates poor accuracy for both high and low criterion values. These results have led to the conclusion that the equations are not applicable for predicting scores beyond about one standard deviation from the mean. The apparent inaccuracy at the extremes, however, is an artifact of inappropriate analysis. An alternative analysis method is described and used to re-analyze two sets of data. Empirical results show that both high and low WAIS-R IQ scores, predicted using versions of the NART, agree with actual measured IQ scores as accurately as do predicted scores near the mean. In addition, confidence intervals were only 5% larger for more extreme predicted values than for values near the mean, which would be of minor clinical consequence. The practical constraint on prediction of extreme values arises not from the regression technique, but from the limited range of the predictor variable(s). The two reviewed IQ prediction equations would, however, have adequate range for a high percentage of individuals.

Humans↗
PubMed1999

Visual localization in dyslexia.

Individuals with specific reading disability (SRD) may exhibit visual psychophysical abnormalities that include prolonged visual persistence, decreased luminance contrast sensitivity, lower flicker fusion thresholds, abnormal metacontrast masking, and lower motion detection sensitivity. These abnormalities could result from impairment of the magnocellular division of the visual afferent pathway to the cortex. The authors predicted that an impairment of this pathway would also cause abnormalities in ability to localize visual stimuli. This prediction was tested in 2 experiments. Results of both experiments showed that adults who reported a history of SRD and who currently had lower reading performance were less able than non-SRD participants to report the locations of small visual stimuli that were briefly flashed at positions similar to the ends of lines of text.

Adult↗
PubMed1999

Feed bunk length requirements for Holstein dairy heifers.

The objectives of this study were to determine the necessary feed bunk length per heifer and to assess the feeding behavior of heifers fed from bunks of varying sizes. Heifers in three age categories were used for three 16-wk experiments. In Experiment 1, feed bunk lengths per heifer were 15 or 31 cm, and, in Experiments 2 and 3, the lengths were 15, 31, or 47 cm per heifer. Heifers were fed a total mixed ration at restricted intakes. Within-group growth analyses showed uniform growth rates for all heifers at all feed bunk lengths. Individual heifer growth within each group did not vary significantly for either length used in Experiment 1. In Experiment 2, heifers fed from a 15-cm bunk had more variation in live weight gain than did heifers fed from 31- or 47-cm bunks. Live weight gains of heifers fed from a 31-cm bunk varied more than those of heifers fed from 15- and 47-cm bunks in Experiment 3. The mean number of eating bouts and meals and the mean meal duration showed differences between the 15-cm feed bunk length and the 31- and 47-cm feed bunk lengths in Experiments 1 and 2. In Experiment 3, this behavior was different across all lengths. Based on growth responses and feeding behavior, heifers that grow rapidly and that are fed a high quality total mixed diet in a free stall or a bedded pack group housing system require 15-, 31-, and 47-cm feed bunk lengths at 4 to 8, 11.5 to 15.5, and 17 to 21 mo of age, respectively.

Animal Feed↗
PubMed1998

Schizotypal thinking and associative processing: a response commonality analysis of verbal fluency.

OBJECTIVE: To determine whether people with high scores for schizotypal thinking generate more uncommon words in a letter fluency task than people with low scores. DESIGN: Prospective study. SETTING: University psychology department. PATIENTS: Forty healthy, right-handed students. INTERVENTIONS: Students were administered the Magical Ideation (MI) Scale and a 2-minute letter fluency task in which they named as many nouns as possible beginning with "A" or "F," in any order. OUTCOME MEASURES: Total number of words produced and percentage of unique, rare and common words (as determined by the responses of the whole group); scores on MI scale. RESULTS: Participants with high scores (above the median) on the MI scale generated as many words as those who had low scores. People in both groups also generated a comparable number of unique words (named by only 1 person) and common words (named by 6 or more people). As hypothesized, people with high scores on the MI scale generated more rare words (named by fewer than 6 people) than those with low scores. CONCLUSIONS: These findings support the view of a disinhibition of semantic network functioning as the neuropsychological basis of creative thought, magical ideation and thought disorder.

Adult↗
PubMed1997

Right hemispatial inattention and magical ideation.

In visual and tactile bisection tasks, healthy subjects have been reported to place the subjective midline towards the left of the objective midline. This phenomenon, known as "pseudoneglect", has been interpreted as a right hemispatial inattention due to hypodopaminergic activity of the left hemisphere mesocortical dopamine system. In schizophrenic patients pseudoneglect was previously found to be correlated with severity of psychotic symptoms. We administered a tactile bisection task (rod centering) to 40 healthy students (20 women and 20 men). All participants also filled in the "Megical Ideation" scale which asks for hallucination-like experiences and delusion-like beliefs. There was no significant pseudoneglect for the group as a whole. However, Magical Ideation scores were significantly correlated to the size of relative right-sided inattention for the 20 men only. On the background of the findings in patients with schizophrenia we conclude that, at least in healthy men, susceptibility to schizophrenia-like experiences and thoughts is likewise accompanied by an attentional shift towards the left hemi-space.

Adolescent↗
PubMed1997

Postdicting verbal IQ of elderly individuals.

We undertook a longitudinal crossvalidation of the Ryan and Paolo (1992) equation's ability to postdict Wechsler Adult Intelligence Scale-Revised (WAIS-R) Verbal IQ (VIQ) from National Adult Reading Test (NART) performance measured 5 years after VIQ scores were obtained, for a sample of 49 elderly normal individuals (mean age 71 years). Five-year interval postdiction accuracy agreed very well with the results of the original, concurrent study. Clinical utility is still limited, however, as VIQ must decline by 16.3 points for 95%-detection sensitivity. A new regression equation that utilizes a combination of NART errors and WAIS-R Vocabulary age-scaled scores (measured 3 years earlier) provided slightly better expected clinical sensitivity and accounted for 49% of the variance in VIQ scores.

Aged↗
PubMed1997

The legacy of the Wernicke-Lichtheim model.

Wernicke established an integrated model of the relation between higher cognitive functions and neurophysiological structure of the human brain in 1874. The previous Bouillaud/Broca view envisaged a mosiac map of centres for specific functions, each of which had no clear inter-relation with other centres or with input/output pathways, and with no theoretical explanation of how each centre operated in relation to more basic neural elements. Wernicke's model overcame these objections, and, with Lichtheim's systematization in 1885, the "Wernicke-Lichtheim model" became the standard neuropsychological theory. In this model, each normal higher function is explained in terms of an underlying neural pathway that includes the input/output systems, related functions employ portions of the pathways used for other functions, pathological syndromes are explained by reference to where in the pathway damage occurred, and previously unobserved pathological syndromes can be predicted. Development of the model at the hands of Lissauer, Dejerine, Liepmann, Geschwind, Heilman, and Ellis and Young is traced.

History, 19th Century↗
PubMed1994

From superstitious behavior to delusional thinking: the role of the hippocampus in misattributions of causality.

Nearly half a century ago B. F. Skinner proposed the hypothesis that human superstitiousness would be equivalent to the 'superstitious' behavior displayed by animals in operant situations involving response-independent reinforcement. Surprisingly, no attempt has ever been made to test this equivalence hypothesis experimentally. In the light of recent evidence for a common neurological basis of both superstitious beliefs held by normal subjects and delusional ideas of psychotic patients, Skinner's hypothesis has become topical again. We present an extension of the hypothesis which assumes dysfunction of the medial temporal lobe, in particular of the hippocampus, to be responsible for conditioned superstitions in animals, for common everyday superstitions, and for schizophrenic delusions. This hypothesis is based on (1) the observation of an enhanced 'superstitious' reactivity in hippocampectomized animals, (2) findings of an increased occurrence of popular superstitions in patients with a temporal-limbic epileptic focus, and (3) morphological and pharmacological evidence for schizophrenic delusions to be causally related to hippocampal damage.

Animals↗
PubMed1994

Singing with and without words: hemispheric asymmetries in motor control.

Singing is relatively preserved and can even improve the language production of aphasic patients who have lesions of the left hemisphere but an intact right hemisphere. In contrast, singing is impaired following lesions or anesthesia of the right hemisphere, suggesting a right hemisphere role in singing. To assess the influence of singing upon hemispheric control of articulatory output in normal subjects, we measured lip opening asymmetry by single-frame photographic analysis. Spontaneous speech, reciting the words of a song, and singing with words all showed right-side lip opening superiority, revealing a major left hemisphere role in control of verbal articulation. Singing without words, on the other hand, did not show asymmetric facial motor activation, suggesting that the right hemisphere also participates in singing. In addition, we assessed auditorily perceivable differences in articulation when lip movement on one side of the mouth was artificially restricted (hemibuccal speech). Articulation quality was higher when speaking from the right side of the mouth.

Adult↗
PubMed1990

Localization of unseen visual stimuli by humans with normal vision.

Thirty university students were shown tachistoscopically presented stimuli (half contained an open circle at one of six locations, half were blanks) at four durations. Short durations and a pattern mask reduced subjects' ability to detect the stimuli. For trials on which the subjects reported that the circle was absent, they nevertheless guessed the exact locations of the targets significantly better than chance. A signal detection theory analysis found that subjects were more sensitive for the location decision than for the detection decision. These findings show that the blindsight phenomenon of localization of "unseen" stimuli, previously reported for cortically blind patients, also occurs for humans with normal vision.

Adult↗
PubMed1990

Mouth asymmetry during speech of epileptic patients who have undergone carotid amytal testing.

Asymmetry in the opening of the two sides of the mouth during speech has been suggested as an observable correlate of lateralization of cerebral speech motor control. For 24 epileptic patients who suffered speech disturbance only during left hemisphere carotid amytal anesthetization, 22 showed the expected greater opening of the right side of the mouth during a repetition task. However, all four of the patients who suffered speech disturbance following only right hemisphere anesthetization, and 8 of the 11 "bilateral speech" patients, also showed greater opening of the right side of the mouth. The speech dominant patients may, however, have genetic left speech dominance but a pathology-forced shift of some components of language to the right hemisphere. Basic mouth asymmetry, as measured here, may primarily reflect lateralization of a component of the motor/speech/language control system that may not be shifted by pathology in epileptic patients sustaining early brain insult. Relative change in mouth asymmetry as the speech task becomes more demanding may, however, be a more sensitive indicator or cerebral asymmetries for language in pathological cases.

Adolescent↗
PubMed1990

Antidepressant effect on memory in depressed older persons.

There is evidence from the clinical and experimental literature that the elderly may be more susceptible to the anticholinergic side effects associated with antidepressant drugs. Fifty-four elderly depressed subjects participated: 27 were taking antidepressants and 27 were unmedicated controls matched for severity of depression, age, and education. The medicated subjects showed a mild, but statistically significant, deficit on a set of six measures of memory performance. However, it was unclear whether this deficit was related to anticholinergic activity. It appears that, while antidepressant medications may not be benign in terms of memory functioning in the elderly, the memory difficulties are mild and are not similar to those of Alzheimer's patients. Thus, differential diagnosis of depression and dementia should not be greatly complicated by antidepressant medication.

Aged↗
PubMed1989

Dichotic listening indices of right hemisphere semantic processing.

A new dichotic listening technique, based on a psychophysical threshold procedure and providing ordinal scale measurement of lateral asymmetry, was used to investigate variation in the size of right-ear advantage for verbal vs manual response modalities across three semantic categories of stimuli in 60 right-handed males. For manual responders, abstract words elicited a significantly greater right-ear advantage than did concrete words, while emotional words elicited a non-significant left-ear advantage. Verbal responders showed no significant difference in the size of right-ear advantage across stimuli. The results suggest that both response modality and stimulus type are important variables for dichotic listening paradigms seeking evidence of right hemisphere contributions to semantic processing.

Adult↗
PubMed1988

Is interhemispheric transfer related to handedness and gender?

Interhemispheric transfer was assessed by five motor, tactile and visual tasks which required the 48 subjects to compare stimuli presented simultaneously on both sides of the body midline. Non-right-handers performed significantly better than consistent right-handers on one motor and one tactile task. Females out-performed males on the visual task and on one tactile task. Better interhemispheric transfer performance by non-right-handers and by females may be related to the reportedly larger corpus callosum regions in these groups and also to the reportedly less strong lateralization of function.

Adult↗