On the generality of the short-term memory/reading ability relationship.
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Age Factors↗
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Immediate memory functions of verbally deficient reading-disabled children.
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Age Factors↗
Counting rate, naming rate, phonological sensitivity, and memory span: major factors in dyslexia.
Children with severe dyslexia were slower in counting from memory and naming alternating digits and letters than those with milder reading impairment. The children most disabled also had poorer phonological sensitivity, shorter digit spans, and lower Verbal IQs, but these variables accounted for no additional variance in prediction of scores on the Wide Range Achievement Test-Revised (R = 0.89).
Achievement↗
Information-processing patterns in specific reading disability.
This research investigated specific processing strengths and weaknesses among three groups of readers who ranged in age from 6 through 10 years. The first-grade unsuccessful and the older unsuccessful readers had similar information-processing patterns, whereas collectively they differed significantly from the first-grade successful readers on short-term auditory/working memory and decoding/encoding. When separately compared to the controls, the age-matched high-risk group showed additional weakness in rapid automatized naming, and the reading-level-matched older disabled group showed additional weakness in phonological coding as well as visual sequential memory. Examination of second-level classifications using cluster analysis suggested the presence of three potential subtypes among the 50 poor readers. All were characterized by difficulty in what was interpreted as symbolic processing/memory (Subtype 1), which occurred in combination with visual processing deficiencies (Subtype 2) and with deficits in both visual processing and rapid automatized naming (Subtype 3).
Attention↗
Mediation or production deficiency in disabled readers.
Deficiences in disabled readers' short-term memory processing were studied. A deficit in memory capacity versus susceptibility to interference was investigated by examining performance over trials. A mediation versus production deficiency in memory processing was examined by testing the effect of instructions for rehearsal on performance of average and disabled readers in Grades 2 and 5. Contrary to prior research, facilitative effects of rehearsal graders' memory was adversely affected by overt rehearsal. Requiring children to rehearse overtly at a set rate may account for the results. A second study examined effects of covert rehearsal on the memory of average and disabled readers in Grade 2 over trials. Facilitative effects of covert rehearsal were shown when data of children who spontaneously rehearsed were removed. A deficiency in production by second graders was supported. Disabled readers who did not rehearse were more susceptible to interference.
Age Factors↗
Effect of testing procedure on Corsi's block-tapping task in normal subjects and Alzheimer-type dementia.
Corsi's block-tapping task was given to 30 normal subjects and 38 Alzheimer-type demented patients following two different procedures. The first is the most widely standardized (scoring criterion: 3 correct reproductions out of 5 sequences), while the second is more lenient since it does not require subjects to replicate a certain performance three times. Demented patients' scores were lower than those of controls in both conditions, and scores on the two tasks were significantly correlated for patients and controls. However, the requirement of replicating the visuospatial memory performances was more detrimental for demented patients than for controls so the two procedures cannot be considered equivalent.
Aged↗
Alphanumeric sequencing: a report on a brief measure of information processing used among persons with multiple sclerosis.
Alphanumeric Sequencing involves the alternating recitation of counting and the alphabet. We report data on the use of this measure with two clinical samples of persons with multiple sclerosis, having either the chronic progressive (n = 23) or relapsing-remitting form (n = 52) of the disease. Patients were administered Alphanumeric Sequencing and several other tests of information-processing speed/capacity and short-term memory. Chronic progressive MS patients performed worse than 23 healthy controls on both the speed and error components of the test, while relapsing-remitting patients were worse than 35 controls only on the total time to complete the task. The time score was correlated with several measures of information processing and short-term memory.
Adult↗
Implicit and explicit tests: evidence for dissociable motor skills in probable Alzheimer's dementia.
Previous authors reported evidence for intact implicit memories (those retrieved without conscious effort) in a serial reaction time task for both Alzheimer's subjects and age-matched controls, although performance on an explicit memory task (requiring conscious effort for retrieval) was poor. The current study assessed latencies on a puzzle-assembly task to assess implicit (procedural) memory for 23 female volunteers. Nine participants suffered from probable Alzheimer's Disease and fourteen did not. Even when subjects had no explicit memory of practicing the task, they demonstrated savings upon relearning. Implications for research on memory dissociations in Alzheimer's Disease are discussed.
Aged↗
The relationship between blood lead levels and neurobehavioral test performance in NHANES III and related occupational studies.
OBJECTIVES: The goals of this study were two-fold: (1) to assess the relationship between blood lead levels and neurobehavioral test performance in a nationally sample of adults from the third National Health and Nutrition Evaluation Survey and (2) to analyze the results from previously published studies of occupational lead exposure that used the same neurobehavioral tests as those included in the survey. METHODS: Regression models were used to test and estimate the relationships between measurements of blood lead and performance on a simple reaction time, a symbol-digit substitution, and a serial digit learning test in adults aged 20-59 years who participated the survey. Mixed models were used to analyze the data from the occupational studies. RESULTS: The blood lead levels of those participating in the survey ranged from 0.7 to 41.8 microg/dl. The estimated geometric mean was 2.51 microg/dl, and the estimated arithmetic mean was 3.30 microg/dl. In the survey, no statistically significant relationships were found between blood lead concentration and performance on the three neurobehavioral tests when adjusted for covariates. In the occupational studies, the groups exposed to lead consistently performed worse than control groups on the simple reaction time and digit-symbol substitution tests. CONCLUSIONS: The results from the survey and the occupational studies do not provide evidence for impairment of neurobehavioral test performance at levels below 25 microg/dl, the concentration that the Centers for Disease Control and Prevention define as elevated in adults. The average blood lead level of the exposed groups in the occupational studies was 41.07 microg/dl, less than 50 microg/dl, the minimum concentration that the Occupational Safety and Health Administration requires for medical removal from the workplace. Given the evidence of impaired neurobehavioral performance in these groups, the 50 microg/dl limit should be reevaluated.
Adult↗
DOM (STP), a new hallucinogenic drug: specific perceptual changes.
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Adult↗
Assessment of modafinil on attentional processes in a five-choice serial reaction time test in the rat.
It is well known that modafinil is an effective wake-promoting agent, but there is growing evidence to suggest that modafinil may also enhance some aspects of cognition. In man, modafinil has been shown to enhance vigilance in sleep-deprived and/or narcoleptic subjects and also to improve executive-type functioning (predominantly inhibitory response control processes) across a variety of human patient population groups. Preclinically, a delay-dependent improvement has been reported with modafinil in a mouse T-maze test of working memory. To investigate further the role of modafinil as a potential cognition enhancer, the effects of modafinil on attentional processes were assessed in the rat. The aim of the present study was to evaluate the potential of modafinil to enhance five-choice serial reaction time test (5-CSRT) performance. Lister Hooded rats received 32-128 mg/kg modafinil and 5-CSRT performance was assessed under standard and test parametric conditions in which the attentional load was increased, and also under conditions of scopolamine pre-treatment. Modafinil failed to significantly enhance 5-CSRT performance under standard conditions. Similarly, modafinil was unable to reverse the deficits in accuracy and/or increased omission errors induced by either parametric or pharmacological manipulations. Indeed, at higher doses, modafinil caused an increase in premature responding under certain test conditions, suggestive of increased impulsivity. The present findings suggest that, although modafinil may enhance vigilance in sleep-deprived human subjects, attentional processes in normal awake rats remain unaffected. No evidence was found to support a modafinil-induced improvement in response control; rather, under conditions of increased attentional load, modafinil appeared to facilitate impulsive responding. Finally, the failure of modafinil to improve a scopolamine-induced performance deficit suggests that modafinil does not act on the cholinergic system directly.
Animals↗
Picture and motor sequencing in Parkinson's disease.
A recent report found that the discrepancy between scaled scores on the Vocabulary and Picture Arrangement subtests of the Wechsler Adult Intelligence Scale-Revised (WAIS-R) was much larger for patients with Parkinson's disease than for healthy controls or patients with Alzheimer's disease. On this basis, it was argued that Parkinson's disease causes a specific deficit in cognitive sequencing that occurs even when the memory and speed requirements of the task are minimal. However, other work indicated that Parkinson's disease patients are almost as severely impaired on other Performance subtests from the WAIS-R that do not require sequencing. In the present study, an extremely simple, untimed test of picture sequencing and a version of the Luria three-step test of motor sequencing were employed. Parkinson's disease patients were impaired on both tasks. The extent of their impairments on picture and motor sequencing were positively correlated, and the severity of deficits on both sequencing tests was related to global mental status and to performance on the Wisconsin Card Sorting Test, but not to neurologic measures of disease severity. However, the patients' performance on the picture sequencing test but not on the motor sequencing test was related to performance on Benton's Facial Recognition Test. These results demonstrate the existence of a generalized sequencing deficit in Parkinson's disease that appears dissociable from impairment in performing simple motor acts.
Aged↗
The Brief Repeatable Battery of Neuropsychological Tests for Multiple Sclerosis: a preliminary serial study.
The Brief Repeatable Battery of Neuropsychological Tests (BRB-N) for MS consisting of the selective reminding, 10/36 spatial recall, symbol digit modalities, paced auditory serial addition (PASAT) and word list generation tests is a sensitive measure of early cognitive impairment in MS patients. We administered it to 19 chronic stable MS patients every 60 days for 120 days to examine variability. The mean coefficient of variation for the tests ranged from 18% to 22%. A significant practice effect was seen in the PASAT results (P < 0.05) using the Wilcoxon signed rank test. These results suggest that cognitive fluctuations analogous to motor fluctuations may occur in MS patients and that the BRB-N may be useful in clinical trials of agents expected to alter cognitive function in MS patients if test-retest variability and practice effects are taken into account. Further study is warranted.
Adult↗
The security implications of VeriChip cloning.
The VeriChip is a Radio-Frequency Identification (RFID) tag produced commercially for implantation in human beings. Its proposed uses include identification of medical patients, physical access control, contactless retail payment, and even the tracing of kidnapping victims. As the authors explain, the VeriChip is vulnerable to simple, over-the-air spoofing attacks. In particular, an attacker capable of scanning a VeriChip, eavesdropping on its signal, or simply learning its serial number can create a spoof device whose radio appearance is indistinguishable from the original. We explore the practical implications of this security vulnerability. The authors argue that:1 The VeriChip should serve exclusively for identification, and not authentication or access control. 2 Paradoxically, for bearer safety, a VeriChip should be easy to spoof; an attacker then has less incentive to coerce victims or extract VeriChips from victims' bodies.
Computer Security↗
Evaluation of the utility of a radioimmunoassay for serum CA 19-9 levels in patients before and after treatment of carcinoma of the pancreas.
By radioimmunoassay we determined circulating levels of a tumor-associated antigen, CA 19-9, in 47 patients with pancreatic adenocarcinoma, to learn if serial testing was useful in predicting prognosis or in detecting disease progression. Before treatment, 42 (89%) had an abnormal serum level, and 45 (96%) had an abnormal level at some time during the disease course. A pretreatment value of less than 1,000 U/mL (normal, less than or equal to 37 U/mL) was found in 38 patients; 20 (53%) had resectable disease. One of nine patients (11%) with a pretreatment value greater than 1,000 U/mL had resectable disease (P2 = .05). Among 14 patients who underwent pancreatectomy and were studied serially, the CA 19-9 level normalized in eight; seven (88%) survived greater than or equal to 18 months. Six patients whose levels did not normalize after pancreatectomy all died in less than 12 months (P2 less than .005). Greatly elevated levels occurred in 11 patients after pancreatectomy 1 to 7 months before clinically apparent recurrence. The other three patients without significant elevations remain clinically free of disease. The data suggest that serial determination of serum CA 19-9 levels are useful as a prognostic indicator and in detecting disease recurrence following pancreatectomy. Concurrent determinations of carcinoembryonic antigen (CEA) levels showed abnormal preoperative values in 28 of 46 patients tested (61%). Concurrent serial postoperative determinations of CEA were available in ten patients. Whereas CA 19-9 values clearly indicated eight recurrences, CEA was helpful in only four. In this small group of patients, CA 19-9 was a better predictor of recurrence.
Adenocarcinoma↗
Behavioral inhibition, self-regulation of motivation, and working memory in children with attention deficit hyperactivity disorder.
We examined 3 aspects of Barkley's (1997) recent model of Attention Deficit Hyperactivity Disorder (ADHD)--behavioral inhibition, self-regulation of motivation, and working memory utilizing 152 elementary school children ages 7 to 12. Seventy-six children with ADHD and 76 children without a psychiatric diagnosis completed the stop-signal task, a computerized Digit Span Task requiring concurrent storage and processing, and the Kaufman Brief Intelligence Test during a 1-hr testing session. Parent and teacher ratings were also obtained on the Conners Parent Rating Scale-Revised: Long Version (Conners, 1997), and the Conners Teacher Rating Scale-Revised: Long Version (Conners, 1997), respectively. Results indicated that children with ADHD had deficits in inhibitory control, working memory, and short-term memory relative to children without the disorder. Contrary to our prediction, the groups did not differ in their responsiveness to external reinforcement. In addition, children with and without ADHD had similar self-perceptions of their performances during the experimental session. Future directions for specifying childhood difficulties in inhibitory control and memory processes are discussed.
Arousal↗
Neurobehavioral function and tibial and chelatable lead levels in 543 former organolead workers.
OBJECTIVE: To evaluate the associations between tibial lead, dimercaptosuccinic acid (DMSA)-chelatable lead, and neurobehavioral function in former organolead manufacturing workers with past exposure to organic and inorganic lead. METHODS: Data were collected from 543 subjects with a mean age of 58 years and an average of 17.8 years since last lead exposure. Years since last exposure to lead was used to estimate tibial lead levels in the year of last occupational lead exposure, termed "peak tibial lead." Current tibial lead levels, measured by x-ray fluorescence, were extrapolated back using a clearance half-time of lead in tibia of 27 years, assuming first-order clearance from tibia. RESULTS: Peak tibial lead levels ranged from -2.2 to 105.9 microg Pb/g bone mineral, and DMSA-chelatable lead levels were between 1.2 and 136 microg. After adjustment for confounding variables, peak tibial lead was a significant negative predictor of performance on the Wechsler Adult Intelligence Scale-Revised vocabulary subtest (p = 0.02), serial digit learning test (p = 0.04), Rey Auditory-Verbal Learning Test (immediate recall and recognition, p = 0.03 for each), Trail Making Test B (p = 0.03), finger tapping (dominant hand [p = 0.02] and nondominant hand [p < 0.01]), Purdue pegboard (dominant hand, nondominant hand, both hands, and assembly, p < 0.01 for each), and Stroop Test (p < 0.01). Moreover, with one exception, average neurobehavioral test scores were poorer at higher peak tibial lead levels. DMSA-chelatable lead was only significantly associated with choice reaction time (p = 0.01). CONCLUSION: Peak tibial lead was consistently associated with poorer neurobehavioral test scores, particularly in the domains of manual dexterity, executive ability, verbal intelligence, and verbal memory.
Adult↗
Motor perseveration is an early sign of Parkinson's disease.
Perseveration in the generation of random motor behavior was examined by means of the Vienna perseverance task in groups of de novo (n = 18) and treated (n = 18) patients with early PD, and in control subjects (n = 18). In comparison with control subjects, both the de novo and treated patients with PD were relatively unable to generate random motor sequences, indicating a decreased ability to switch cortical behavioral programs in PD. An impairment of random motor generation appears to be a very early feature of PD.
Aged↗