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At least 973 records · Page 54Linked to original sources

PubMed1997

Event-related potentials in a two-choice task involving within-form comparisons of pictures and words.

Behavioral as well as electrophysiological evidence suggests that words are processed differently than pictures in a variety of tasks. In this study fifteen adult subjects were tested on a speeded "same-different" judgment task between printed names and drawings of common objects. In one condition, subjects decided on the identity between their internal image of the object that was named by S1 (word) and a subsequently presented drawing of an object (Word-Picture condition). In a second condition, comparisons were made on the basis of the name of the depicted object (Picture-Word trials). Event-related potentials (ERPs) were recorded from 12 scalp locations in response to the second item in each pair. No-match waveforms were characterized by larger N350 and P500 deflections compared to Match ERPs. The two responses could be distinguished on the basis of their lateral and anterior-posterior scalp distribution. Within-form comparisons involving pictures produced increased positivity between 150 and 600 ms poststimulus onset at posterior recording sites, whereas the opposite effect was noted at anterior sites during the early portion of the ERP. Decisions on word stimuli were associated with prolonged reaction time and longer N350 peak latency compared to decisions on pictures. These results demonstrate the existence of independent sources of ERP variability, each possibly reflecting a different aspect of cognitive comparisons. Latency and reaction time data provided valuable information regarding differences in the course of the comparison process when linguistic, as opposed to pictorial, stimuli/representations were involved.

Adolescent↗

PubMed1993

Methadone maintenance and needle/syringe sharing.

Drug users who inject drugs while in treatment share needles/syringes less often than users not in treatment. This relationship may reflect treatment processes, such as cognitive or normative change, by which treatment clients are influenced to lower their HIV infection risk. However, reduced needle/syringe sharing among treatment clients may instead be simply a collateral result of reduced injection frequency. In this sample of injection drug users, those who continued to inject while in methadone maintenance treatment reported less sharing than users not in methadone maintenance. This relationship persisted after injection frequency and drug-user background characteristics were controlled. Efforts to identify explanatory treatment processes were, however, not successful.

Adult↗

PubMed1990

A theory of phenomenal geometry and its applications.

The geometry of perceived space (phenomenal geometry) is specified in terms of three basic factors: the perception of direction, the perception of distance or depth, and the perception of the observer's own position or motion. The apparent spatial locations of stimulus points resulting from these three factors thereupon determine the derived perceptions of size, orientation, shape, and motion. Phenomenal geometry is expected to apply to both veridical and illusory perceptions. It is applied here to explain a number of representative illusions, including the illusory rotation of an inverted mask (Gregory, 1970), a trapezoidal window (Ames, 1952), and any single or multiple point stimuli in which errors in one or more of the three basic factors are present. It is concluded from phenomenal geometry that the size-distance and motion-distance invariance hypotheses are special cases of the head motion paradigm, and that proposed explanations in terms of compensation, expectation, or logical processes often are unnecessary for predicting responses to single or multiple stimuli involving head or stimulus motion. Two hypotheses are identified in applying phenomenal geometry. It is assumed that the perceptual localization of stimulus points determines the same derived perceptions, regardless of the source of perceptual information supporting the localizations. This assumption of cue equivalence or cue substitution provides considerable parsimony to the geometry. Also, it is assumed that the perceptions specified by the geometry are internally consistent. Departures from this internal consistency, such as those which occur in the size-distance paradox, are considered to often reflect the intrusion of nonperceptual (cognitive) processes into the responses. Some theoretical implications of this analysis of phenomenal geometry are discussed.

Attention↗

PubMed2001

Attentional set effects on spinal and supraspinal responses to pain.

The effects of attentional set on subjective magnitude ratings, spinal reflexes, and somatosensory evoked potentials (SEP) elicited by innocuous and painful sural nerve stimulation were investigated in 24 subjects. Cuing stimuli informed subjects as to whether a visual identification or a somatosensory rating task would follow. Twenty percent of the trials were invalidly cued, where the subjects were expecting a visual stimulus but were given a sural nerve stimulus and vice versa. Subjective magnitude ratings were lower in the invalidly cued condition than the validly cued condition. Attentional set had no effect on innocuous-related spinal or early cortical responses, nor on the spinal nociceptive withdrawal reflex. The pain-related negative difference potential (NDP) and P2 component of the SEP were largest in the invalidly cued condition. These results provide further support for our hypothesis that the NDP is generated in part by the anterior cingulate, and suggest that the anterior cingulate response to pain reflects non-pain-specific cognitive processes (e.g., orienting attention towards important stimuli in the environment and/or response competition) and not some aspect of the pain experience. The effects of attentional set on the pain-related P2 suggests that it might correspond to the P3a event-related potential. If this is the case, the pain-related P2 could serve as a useful index of neural processes involved in the cognitive-evaluative aspect of pain.

Adult↗

PubMed1991

Multi-infarct dementia, subcortical dementia, and hydrocephalus.

The diagnostic evaluation of dementia is directed toward the identification of treatable causes. It can be facilitated by classification of the dementia into one of four categories: attentional, amnestic, cognitive, and intentional. Intentional dementia reflects dysfunction of frontal lobe systems, components of which include the frontal cortex, basal ganglia, thalamus, limbic structures, and subcortical white matter. Disorders that affect one or more of these components and produce intentional dementia include Binswanger's disease, Parkinson's disease, Huntington's disease, HIV infection, closed head injury, normal pressure hydrocephalus, neoplasms, syphilis, vitamin B12 deficiency, multiple sclerosis, and a number of uncommon degenerative and acquired syndromes. Depression may resemble intentional dementia. Guidelines for diagnosis and management are discussed.

Brain↗

PubMed1990

Family practice obstetric ultrasound in an urban community health center. Birth outcomes and examination accuracy of the initial 227 cases.

The initial 227 consecutive prenatal ultrasound examinations by two family physicians in an urban community health center were compared with actual birth outcomes. Of 186 examinations for which follow-up information was available, 162 infants were represented. The sampling rate was 81%. No serious anomalies were noted by ultrasound. One placenta previa, one fetal death, and two unsuspected cases of twins were detected by ultrasound. These data represent one of the first detailed reports of outcomes reflecting family physicians' psychomotor and cognitive skill in the use of obstetric ultrasound. The high accuracy (92% to 96%) of correct ultrasound dating suggests that a short postgraduate continuing medical education course was effective for these two family physicians. The accuracy rate compares favorably to more rigorous training. This structured format utilizing the average of four direct measurements for ultrasound-estimated gestational age and three anatomy ratios for assessing proper imaging relationships or growth symmetry may be useful as other family physicians develop educational methods and quality-assurance protocols in this area.

California↗

PubMed1989

[Repetitive screams].

Nurses are challenged by the repetitive shouting of the cognitively-impaired elderly. The author reflects on the known causes of this behavior and how it affects staff members. She suggests nursing actions to discourage shouting and encourages nurses to explore new ways to cope. One way is to modify staff behavior by correcting attitudes that stereotype the elderly.

Aged↗

PubMed1984

Comparison of four opioid analgesics as supplements to nitrous oxide anesthesia.

The hemodynamic changes, plasma norepinephrine levels, pupil size, and rapidity of postoperative mental recovery were measured and compared in 72 patients randomly assigned in a double-blind manner to receive either morphine, meperidine, fentanyl, or sufentanil as supplements to nitrous oxide anesthesia. Meperidine, unlike the other opioids, which did not change heart rate, consistently increased it. Hemodynamic responses to laryngoscopy and intubation were suppressed by fentanyl and sufentanil, but not by morphine or meperidine. The sufentanil group was the only group in which median norepinephrine levels remained consistently below preinduction values. The frequency with which opioids had to be administered (doses/hr) was significantly less with sufentanil than with morphine and meperidine. Meperidine produced less constriction of the pupils than the other opioids and the duration of miosis was shorter. Fentanyl and sufentanil were associated with a more rapid return of mental function than morphine and meperidine. Meperidine caused deleterious effects on objective tests of psychomotor and cognitive skills that were not reflected by subjective evaluation of rate of recovery from anesthesia. The authors conclude that moderate doses of fentanyl and sufentanil are better supplements to nitrous oxide anesthesia than morphine or meperidine and that fentanyl and sufentanil are equally satisfactory. Subjective effects of the opioids correlated well with changes in pupil diameter.

Adjuvants, Anesthesia↗

PubMed1981

The relationship between twelve-month home stimulation and school achievement.

Home Observation for Measurement of the Environment (HOME) was designed to reflect parental support of early cognitive and socioemotional development. 12-month HOME scores were correlated with elementary school achievement, 5--9 years later. 50 low-income children were rank ordered by a weighted average of centile estimates of achievement test scores, letter grades, and curriculum levels in reading and math. 24 children were classified as having significant school achievement problems. The HOME total score correlated significantly, r = .37, with school centile scores among the low-income families. The statistically more appropriate contingency table analysis revealed a 68% correct classification rate and a significantly reduced error rate over random or blanket prediction. The results supported the predictive value of the 12-month HOME for school achievement among low-income families. In an additional sample of 21 middle-income families, there was insufficient variability among HOME scores to allow prediction. The HOME total scores were highly correlated, r = .86, among siblings tested at least 10 months apart.

Achievement↗

PubMed1994

New perspectives on biological treatment of schizophrenia.

Recent research seems to indicate that many schizophrenics suffer from a defective brain development, which is reflected by basic disturbances in cognitive, information-processing, volitional and emotional functions. Positive symptoms like hallucinations and delusions may be secondary to the more basic disturbances. Varying degrees of defective brain development places a ceiling on the functional improvement that can be obtained in this illness. However, whereas positive symptoms usually respond best to neuroleptics, even negative symptoms can be improved, for instance by clozapine. To obtain such improvement, it seems necessary, in addition to blocking dopamine D2 receptors, to influence other receptor systems, as for instance serotonergic 5HT-2 and possibly dopaminergic D1 and/or D4 receptors. Stimulation of glutamatergic NMDA receptors also seems to be a promising possibility.

Antipsychotic Agents↗

PubMed1993

Racial differences in clinical and social variables among patients evaluated in a dementia assessment center.

Despite increased interest in dementia and the concomitant creation of dementia assessment centers, there has been a paucity of reports examining racial differences in the social and clinical presentation of dementia. Such information can enhance knowledge about dementia and assist in the planning of diagnostic centers located in areas with large minority populations. This study reviewed the charts of patients evaluated at a dementia assessment center in New York City. The sample comprised 102 white and 68 black patients. There were no racial differences in types of dementia nor reported length of illness. However, bivariate analysis revealed many significant differences between the groups in social, medical, and psychiatric variables. Most notably, a stepwise discriminant analysis identified seven variables--Medicaid recipient, gender, age, sleep disturbances, delusions of stealing, hypertension, and concentration--as correctly being able to classify 75% of cases. Racial differences in cognitive and behavioral symptoms may reflect the interaction of dementia with physical health, premorbid history, environment, or some basic difference in disease course.

Aged↗

PubMed1996

[Childhood memories and adult dreams].

The present retrospective study investigated the often cited clinically relevant relationship between dreams and childhood memories. Indeed, the hypothesis was confirmed that high dream recallers remember more childhood memories than low dream recallers. Whether this is a pure cognitive relationship (memory) or could reflect general personality tendencies request further investigations. Additionally, the high incidence of childhood nightmares in a normal population was stressed.

Adolescent↗

PubMed1997

Cerebellar timing systems.

Coordinated movement requires the normal operation of a number of different brain structures. Taking a modular perspective, it is argued that these structures provide unique computations that in concert produce coordinated behavior. The coordination problems of patients with cerebellar lesions can be understood as a problem in controlling and regulating the temporal patterns of movement. The timing capabilities of the cerebellum are not limited to the motor domain, but are utilized in perceptual tasks that require the precise representation of temporal information. Patients with cerebellar lesions are impaired in judging the duration of a short auditory stimulus or the velocity of a moving visual stimulus. The timing hypothesis also provides a computational account of the role of the cerebellum in certain types of learning. In particular, the cerebellum is essential for situations in which the animal must learn the temporal relationship between successive events such as in eyeblink conditioning. Modeling and behavioral studies suggest that the cerebellar timing system is best characterized as providing a near-infinite set of interval type timers rather than as a single clock with pacemaker or oscillatory properties. Thus, the cerebellum will be invoked whenever a task requires its timing function, but the exact neural elements that will be activated vary from task to task. The multiple-timer hypothesis suggests an alternative account of neuroimaging results implicating the cerebellum in higher cognitive processes. The activation may reflect the automatic preparation of multiple responses rather than be associated with processes such as semantic analysis, error detection, attention shifting, or response selection.

Animals↗

PubMed1999

Does old age or Parkinson's disease cause bradyphrenia?

BACKGROUND: Age-related declines in intellectual functioning have been linked to slower processing of information. However, any slowness with advancing age could simply reflect slower movement rather than impaired cognition. To assess any age-related decline in cognitive speed, we used an accuracy-based task that does not require a speeded motor response and that measures the time required to acquire information (inspection time). To identify possible biological mechanisms of cognitive slowing, this task was also applied to patients with Parkinson's disease, a basal ganglia disorder that reportedly causes bradyphrenia (slower thought processes). METHODS: In one experiment, 16 young (mean age 22.4 years) and 16 older adults (mean age 71.6 years) matched for intelligence and education completed an inspection time task. The task required judgments as to order of onset of two lights, where the interval between onsets ranged from 20-250 msec. A second experiment compared 16 patients diagnosed with idiopathic Parkinson's disease and 16 age-matched controls upon the same task. RESULTS: Older adults demonstrated significant cognitive slowing compared to younger adults. Medicated nondemented Parkinsonian patients were not impaired on this task compared to age-matched controls. CONCLUSIONS: Clinical and empirical impressions of bradyphrenia in Parkinson's disease may instead reflect advancing age or slower movement, because the effects of age may be greater in some cases than the effects of basal ganglia disease once motor dysfunction has been allowed for.

Adult↗

PubMedDate not supplied

Association of pulmonary function with cognitive performance in early, middle and late adulthood.

BACKGROUND: Pulmonary function has been associated with some measures of cognitive performance, mostly in late adulthood. This study investigated whether this association is present for a range of cognitive measures, at three stages of adulthood, and whether it remains after controlling for demographic, health and lifestyle factors. METHOD: The relationship between forced expiratory volume at 1 s (FEV1), a measure of pulmonary function, and cognitive test performance was examined in three cohorts aged 20-24, 40-44 and 60-64. RESULTS: After controlling for demographic variables, smoking, physical activity, and respiratory disease, significant associations between FEV1 and cognitive test performance were evident in each age group for most cognitive measures. The association between FEV1 and measures of speed increased with age. CONCLUSION: FEV1 has a small but reliable positive association with cognitive test performance throughout adulthood, possibly reflecting a common physiological factor.

Adult↗

PubMedDate not supplied

[Context-dependent EEG spectral characteristics during performance of tasks].

Spatial and frequency EEG characteristics of two groups of healthy adult subjects were examined in two series of experiments, which differed in conditions of the second cognitive task in a trial. The first task was the same in the two series: subjects had to evaluate size relationship between two closely spaced circles. The second task successively presented in trials of the first series consisted in the recognition of words/pseudowords, and in the second series, subjects had to localize a target letter in a matrix. It was assumed that the cognitive performance in the first series predominantly involved the ventral visual system, whereas during task performance in the second series, predominant involvement of the ventral and dorsal visual systems alternated. Multichannel EEG fragments recorded prior to the presentation of the task pairs were analyzed. Analysis of variance of the EEG spectral power revealed the generalized significant effect of the factor of the second task in the pair for delta band and lower beta subband, the power being higher in the first series. Factor brain hemisphere had a significant effect for the alpha band in the occipital area, the spectral power being lower in the left hemisphere for both experimental series. The task x hemisphere interaction was significant in the temporal cortical areas for the EEG power in alpha2 band, i.e., the predominant involvement of the ventral visual system was associated with stronger asymmetry of alpha2 rhythm and lower spectral power in this band in the left temporal area. Thus, the character of the forthcoming cognitive activity was shown to be reflected in spatio-frequency characteristics of the preceding EEG.

Adult↗

PubMed1997

Cognitive impairment in the Amish: a four county survey.

BACKGROUND: The prevalence of probable dementia was determined in a rural, homogeneous community of Amish individuals in the Midwestern USA. The Amish are a genetically isolated group with a low level of formal education (< or = 8 years) and few exposures to modern life, who live in intergenerational setting and have strong social support networks. METHODS: Using community directories, trained interviewers administered the Mini Mental State Examination (MMSE) and a medical history survey to all Amish over 64 years old in a four county area. Individuals with scores < 27 (out of a maximum of 30 points) were given additional neuropsychological tests. Results were reviewed by a neuropsychologist and subjects were classified with regard to probable cognitive impairment. RESULTS: The MMSE scores were inversely related with age and directly with education. The Amish have higher MMSE scores than reported for the general US population. The overall prevalence of probable cognitive impairment for those over 64 years was 6.4%. The prevalence increased with age and lower education and was lowest among married individuals. CONCLUSIONS: The MMSE scores among the Amish were higher than the general population despite their low level of formal education. The lower level of cognitive impairment among the Amish could reflect a lack of inherited susceptibility to dementing diseases, or environmental factors characteristic of their traditional lifestyle. Even among this population with < or = 8 years of formal education, education may protect against cognitive impairment.

Age Distribution↗

PubMedDate not supplied

Habituation of P300 and reflex motor (startle blink) responses to repetitive startling stimuli in children.

Positive EEG deflections with the latency and scalp distribution of the P300 accompany startle in response to loud auditory stimuli in a non-task context. The purpose of this investigation is to determine if habituation would have effects on the P300 similar to those on the startle blink. Thirty-four normal 7 to 11-year-old boys from a startle habituation study had EEG recordings of sufficient quality to provide data for the current study. Startle was measured both as orbicularis oculi EMG and vertical EOG and P300 was recorded at Pz in response to 40,104 dB bursts of white noise presented at 23-s intervals. Both the startle response and the P300 habituated toward asymptotic levels after the first 28 trials, suggesting that both startle and the subsequent cognitive evaluation of the startling stimulus, reflected in the P300 response, are modulated by a common neurophysiological mechanism extrinsic to the direct startle pathway. A modest significant correlation between the P300 and the vertical EOG peak latencies for the initial trials suggests that the cognitive evaluation of the startling stimulus may also include evaluation of the reflex response to that stimulus. Analyses of the within-subject associations between startle and P300 initial amplitudes and rates of habituation showed that these parameters varied independently within the individual subject, suggesting that the P300 is not a component of the startle response. Rather, it reflects an evaluation of the startling stimulus, decreasing in amplitude as the surprising value of the startling stimulus decreases with habituation.

Aging↗