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Lateral asymmetry in perceptual judgments of reading disabled, hyperactive and control children.

Three groups of 11 year old boys, classified as reading-disabled/hyperactive, hyperactive, and normal controls, made same-different judgments to pairs of verbal or visuospatial stimuli presented simultaneously to the right or left side of a fixation point. Two experimental paradigms were used, one emphasizing comparison judgments from memory, the other, new comparison judgments. Reading-disabled boys made more errors of judgment than did controls. All subjects exhibited faster reaction times for different judgments of pairs appearing in the left visual field. Reaction times were longer and errors more numerous for judgments made when two stimuli were presented simultaneously, one to each visual field. Differences in performance for the two halves of the visual field are attributed to memory storage effects for overlearned stimuli. The deficiency in interhemispheric comparisons is attributed to immaturity of the cerebral commissures. The reading-disabled group appears to encompass two subgroups with differing modes of information processing.

Child↗

The lateralization of arithmetic and number processing: a review.

Calculation and number processing require ideographic and semantic operations which may involve the right as well as the left hemisphere. There is often also present a spatial component, whether overt as with column-addition or multiplication procedures, or covert if numbers are recoded into continuously varying analog quantities or magnitudes of a psychophysical or imaginal nature, to facilitate numerical comparison. Again right hemisphere mechanisms may be partly responsible. Evidence for such a minor hemisphere contribution is reviewed in the light of studies with clinical and commissurotomy cases, and normal subjects. Calculation itself is hard to define, as it often seems to reduce to the operation of overlearn, associative, tabular look-up functions and algorithms. Indeed alphabetic comparisons analogous to numerical tasks should generate similar laterality effects in clinical and normal populations.

Brain Damage, Chronic↗

Spatial aspects of letter cancellation performance in Arabic readers.

Studies of visuospatial and directed attention that used subjects drawn from cultures with left-to-right reading patterns have suggested a slight performance bias toward left space. This pattern could reflect an intrinsic, organic, bias in spatial processing or the confounding effect of overlearned reading patterns. We studied the spatial distribution of errors on random array letter cancellation tasks obtained from 128 healthy Syrians who were native readers of Arabic. Fifty-eight of the 128 subjects (45.3%) made a total of 91 errors in which they omitted cancelling a target. The distribution of errors was not spatially biased. This differs from the error pattern reported for native readers of English on a similar task. The findings, consistent with results of other approaches, suggest that reading patterns influence visuospatial attention, but are not the sole cause of spatial biases observed in readers of Indo-European languages.

Adult↗

Effect of uncertainty on the time course for selection of verbal name codes.

Response selection takes time. Hick's law (Hick, 1952) predicts that the time course of response selection is a logarithmic function of the number of equally likely response alternatives. However, recent work has shown that oculomotor responses constitute noteworthy exceptions in that the latencies of saccades (Kveraga, Boucher, & Hughes, 2002) and smooth pursuit movements (Berryhill, Kveraga, Boucher, & Hughes, 2004) are completely independent of response uncertainty. This finding extends to the case in which the required response was known in advance (i.e., simple reaction times [RTs] were equivalent to choice RTs). In view of these results, we reevaluated reports that latencies to name visually presented digits (Experiment 1) and/or repeat aurally presented digits (Experiment 2) are similarly independent of the size of the response set. We found that naming latencies were equivalent for response set sizes from one to eight, but simple RTs (response set of one) were faster. Thus, the overlearned task of digit naming is indeed highly automatic but has not reached the level of automaticity characteristic of the oculomotor system.

Adolescent↗

Moving the eyes along the mental number line: comparing SNARC effects with saccadic and manual responses.

Bimanual parityjudgments about numerically small (large) digits are faster with the left (right) hand, even though parity is unrelated to numerical magnitude per se (the SNARC effect; Dehaene, Bossini, & Giraux, 1993). According to one model, this effect reflects a space-related representation of numerical magnitudes (mental number line) with a genuine left-to-right orientation. Alternatively, it may simply reflect an overlearned motor association between numbers and manual responses--as, for example, on typewriters or computer keyboards--in which case it should be weaker or absent with effectors whose horizontal response component is less systematically associated with individual numbers. Two experiments involving comparisons of saccadic and manual parity judgment tasks clearly support the first view; they also establish a vertical SNARC effect, suggesting that our magnitude representation resembles a number map, rather than a number line.

Adolescent↗

Cognitive processing speed in Lyme disease.

OBJECTIVE: The goal of this study was to more precisely define the nature of the cognitive processing deficits in the patients with Lyme disease. BACKGROUND: Lyme disease has been associated with cognitive disturbances. METHOD: Sixteen patients who met the Centers for Disease Control's case definition for Lyme disease and 15 age- and education-matched control subjects completed two computerized assessments. The first was a matching procedure that assessed perceptual/motor speed. The second task was an alphabet-arithmetic (AA) test that measured the speed of mental arithmetic. On the matching task, subjects judged as true or false simple identity equations (e.g., B + 0 = B). On the AA task, subjects indicated the veracity of equations of the same form as those of the matching task but which required mental arithmetic (e.g., A + 3 = D). The use of this paradigm permits sensory or motor slowing to be distinguished from slowed cognitive processing speed. Also, the tests do not involve automated or overlearned responses. RESULTS: Lyme disease patients and healthy controls did not differ in perceptual/motor speed. However, Lyme disease patients' response times were significantly longer than those of healthy controls during the AA task, demonstrating specific impairments in mental activation speed. CONCLUSIONS: These results suggest that Lyme disease patients show specific deficits when initiating a cognitive process. These impairments are independent of sensory, perceptual, or motor deficits.

Adult↗

Ventromedial prefrontal cortex lesions in humans eliminate implicit gender stereotyping.

Patients with prefrontal cortex lesions and controls were administered an implicit association task (IAT) that measured the degree of association between male and female names and their stereotypical attributes of strength and weakness. They also completed three questionnaires measuring their explicit judgment regarding gender-related stereotypical attributes. There were no between-group differences on the explicit measures. On the IAT, patients with dorsolateral lesions and controls showed a strong association, whereas patients with ventromedial prefrontal cortex lesions had a significantly lower association, between the stereotypical attributes of men and women and their concepts of gender. This finding provides support for the hypothesis that patients with ventromedial prefrontal lesions have a deficit in automatically accessing certain aspects of overlearned associated social knowledge.

Analysis of Variance↗

Script knowledge after severe traumatic brain injury.

Severe diffuse traumatic brain injury (TBI) may impair the performance of daily-life complex activities. The aim of the present study was to assess whether these difficulties are related to a representational impairment of action knowledge. Two tasks requiring the manipulation of scripts were used. The first (script reconstitution) required subjects to sort cards describing actions belonging to 4 different scripts, presented in a random order. The second (script generation) required subjects to generate actions belonging to a given script. The results showed that TBI patients had preserved access to goal representation and action knowledge. However, they demonstrated (1) significant impairments when they had to deal with simultaneous competing sources of information and (2) a lack of inhibitory control on routine overlearned skills. Patients' performance was significantly correlated with behavioral modifications in everyday life. These data suggest that action impairment in severe TBI patients cannot be attributed to an impairment of action knowledge per se. As previously suggested by Schwartz et al., a restriction of limited-capacity processing resources may account for the observed deficits.

Activities of Daily Living↗

Paired associate learning: form 1 and form 2 of the Wechsler Memory Scale.

Despite its popularity as a clinical measure, the paired Associate Learning (PAL) subtest of Wechsler's Memory Scale (WMS) still remains relatively undocumented for its psychometric properties. This article reports on the performance of 500 (form 1) and 600 (form 2) general medical patients hospitalized for other than neuropsychiatric conditions across five (20-69) and six (20-79) ten-year age bands respectively. In both alternate forms of PAL, strong age effects emerged while sex differences were more marked in form 2. Temporal reliability, assessed in separate student samples, proved adequate for either form. Parallel form correlations also indicated a moderate relationship between them. When easy and hard associates were analysed as separate measures with MANOVA the two forms were found to differ. Some possible reasons for these results are explored with respect to current information processing concepts postulated to affect verbal learning performance, and their utility in helping distinguish between pseudodementia and mild Alzheimer type dementia. Separate factor analyses also showed the two equivalent forms to diverge somewhat in their structural pattern with form 1 demonstrating clear clusterings of the pairs along a continuum ranging from very easy (overlearned) and mediate (superordinate) to hard associates.

Journal Article↗

Validation of a new technique to detect malingering of cognitive symptoms: the b Test.

We administered the b Test, a new measure to identify malingering requiring recognition of overlearned information, to 34 suspected malingerers and to 161 subjects in various clinical groups (moderate to severe head injury, elderly depressed, learning disability, schizophrenia, right and left CVA, and elderly normals). Comparisons of groups revealed more commission and omission errors in the suspected malingerers relative to all groups except the right stroke patients. In addition, suspected malingerers took longer to complete the task than all groups except right and left stroke patients and normal elderly. A cutoff of >2 commission errors produced a sensitivity of 76.5% and specificity for all comparison groups combined of 82.6%. Lower sensitivity rates were documented for omissions (58.8 using cutoff of >40) and time (57.6% using cutoff of >12 minutes), but specificity remained high at 85.1% and 83.9%, respectively. Thus, the b Test shows considerable potential as a malingering detection tool.

Journal Article↗

[Preserved ability to read aloud kanji idioms in left handed alexia].

We report a 69-year-old left-handed man, who developed alexia after a right medial occipito-temporal lobe infarction. On admission to the rehabilitation department two months after the onset, neurological examination showed left hemianopia, left hemiparesis, decreased deep sensation on the left side, and alexia. A brain MRI demonstrated infarcts in the right medial occipito-temporal lobe and the splenium of the corpus callosum. Detailed neuropsychological examination was performed two months after the onset. The patient was alert and cooperative. His speech was fluent with some word-finding difficulty. Comprehension for spoken materials, repetition, and naming abilities were all preserved. Systematic examination for reading revealed that reading aloud was disturbed in both kanji and kana words. Reading comprehension was significantly better for kanji words than kana words. First, we examined the effects of number of characters in a word. The number of characters in a word didn't affect his reading performance. Second, his performance on reading aloud of usual kanji words was compared with that of kanji words representing idioms. A kanji idiom is different from usual kanji words, in which pronunciation of each character is selected from several options. Reading aloud kanji idioms was significantly better than usual kanji words. In addition, reaction time to complete reading a word was much shorter for kanji idioms than usual kanji. An analysis of qualitative features of errors revealed that most errors in kanji idiom reading were semantically similar to the correct answers, while many errors in usual kanji word reading were classified into "don't know" responses. These findings suggested that a kanji idiom was tightly connected to its pronunciation, which resulted in his much better performance for kanji idiom reading. Overlearning of a unique relationship between a kanji idiom and its pronunciation might modify neuronal organization for reading.

Aged↗

[Individual typological features reflected in different stages of learning and related changes in dopamine transport in the mesolimbic brain].

A hypothesis is proposed according to which there is a strong similarity between the individual typological features of animals (humans) and different stages of learning processes. The hypothesis is supported by the results of comparisons of psychophysiological and neurochemical indices of different stages of conditioning and various typologies of higher nervous activity. Such comparisons reveal a high similarity between the generalization phase and impulsivity, the phase a learned conditioned reflex and self-controlled behaviour, and overlearned CR and a state of "psychosis". Functional states close to pathology and possibilities of development and manifestation of several psychotic states depending on psychophysiological and neurochemical organization of learning processes are also considered.

Animals↗

[Attention deficits and schizophrenia. Multidisciplinary approaches and the Stroop's test].

Since McGhie & Chapman's (1961) pioneering work, there have been continual attempts to clarify the link between attentional disturbances observable in schizophrenics and their schizophrenic symptoms. Venables (1964, 1977) claims that this diminution is a consequence of a badly controlled arousal, resulting in an inadequate filtering at the level of sensory input. Although the notion of a faulty sensory filter is simple and intellectually satisfying, this idea rapidly met with articulate opposition. Broadbent himself, in 1971, revised his model to take into account the way in which semantic aspects influence selective attention, and proposed the existence of a second stage of information processing, coming after the sensory filter. It became increasingly clear that progress in understanding selective attention would depend upon more centrally-directed approaches. In 1935, Stroop developed an ingenious way of studying selective attention. In his task, an "automatic", overlearned task (reading short words aloud) is put into conflict with a slightly more difficult task (colour-naming): the subject has to name the colour of the ink in which a word is printed, but the word itself is the name of a different colour. For instance, when the word "blue" is written in red ink, the correct response is "red". Typically, subjects find it difficult to inhibit the reading response, and take significantly more time to name a colour that forms an incompatible word than take to name the colour of a row of letters "x". This increased reaction time for the incompatible condition is attributed to an "interference" caused by the verbal information contained in the double stimulus.(ABSTRACT TRUNCATED AT 250 WORDS)

Attention↗

Syndromes in developmental dysphasia and adult aphasia.

We have attempted to draw some parallels between syndromes of adult acquired aphasia and of childhood developmental dysphasia. There appear to be two syndromes that are almost exact duplicates in the adults and the children: (a) pure word deafness and verbal auditory agnosia, and (b) aphemia and verbal dyspraxia. Two other syndromes seem to have rather close but not exact counterparts: Broca's aphasia and the phonologic-syntactic deficit syndrome, and transcortical sensory aphasia and the semantic-pragmatic deficit syndrome. There are two dysphasic syndromes, the phonologic production deficit syndrome and the lexical-syntactic deficit syndrome, that do not seem to have close adult counterparts. Neither of these dysphasic syndromes has been defined in adequate linguistic detail, and it is possible that their description may have to be modified when more data become available. Whether these comparisons between dysphasias and aphasias have heuristic value for guiding external validation studies of the clinically defined dysphasic syndromes of preschool children remains to be determined. Our purpose was to formulate hypotheses as to which cerebral systems are likely to be dysfunctional in children with clinically defined dysphasic syndromes. We recognize that the disorders of language acquisition and those of overlearned adult language have fundamental differences, and that plasticity of the child's developing brain introduces further complexities. Nevertheless, it seems reasonable to think that there are constants in brain organization that span all ages. Looking for language deficits common to aphasic adults (whose lesions can usually be delineated with contemporary neuroimaging techniques) and to dysphasic children (in whom there are rarely any neurologic clues) may be a fruitful way to begin to define the cerebral correlates of the children's deficits.

Adult↗

Cognitive deficits in adolescents who developed diabetes early in life.

A comprehensive battery of neuropsychological tests was administered to 125 adolescents with a history of insulin-dependent diabetes, and to 83 demographically similar nondiabetic control subjects. To test the hypothesis that developing this disease early in life greatly increases the risk of manifesting significant cognitive impairments, diabetic subjects were assigned to an "early-onset" (diagnosis before age 5 years) or a "later-onset" subgroup. Results showed that subjects with early onset of diabetes performed more poorly than either subjects with later onset of diabetes or nondiabetic control subjects on virtually all tests, including measures of intelligence, school achievement, visuospatial ability, memory, motor speed, and eye-hand coordination. Moreover, multiple regression analyses demonstrated that the age at onset and the duration of diabetes seem to affect neuropsychological functioning in very different ways. The duration of the disease best predicted performance on those tests requiring highly overlearned, primarily verbal, skills whereas the age at onset best predicted scores on tests requiring the ability to process relatively unfamiliar, typically nonverbal, information in novel ways. Although the etiology of these deficits remains unclear, there is a possibility that they are secondary to mild brain damage that develops as a consequence of multiple episodes of serious hypoglycemia early in life.

Adolescent↗

The role of tone height, melodic contour, and tone chroma in melody recognition.

The present experiments assessed the contribution of tone height, melodic contour, and tone chroma to melody recognition. Rather than using highly familiar folk songs as in earlier studies, subjects were taught new melodies. Novel melodies were used to (a) more precisely control potential cues (e.g., rhythm) that are not of present interest, (b) eliminate unison intervals that cannot be transformed appropriately, (c) provide a direct analysis of the nature of confusion errors, (d) test whether recently learned melodies are recognized differently than highly overlearned melodies, and (e) evaluate the extent to which practice in the experimental task alters the process of recognition. The results replicate previous studies using familiar folk songs. Transformations of the original melodies were accurately recognized when tone height was violated, but both melodic contour and tone chroma were maintained. Violating both tone height and contour while maintaining chroma produced extremely poor recognition. Performance was intermediate when just melodic contour was preserved. There is now good evidence to support the idea that melodic contour and tone chroma, in addition to tone height, contribute to recognition of both highly familiar and recently learned melodies.

Humans↗

Mental acuity of the normal elderly.

The elderly are persons over age 65, now comprising 12% of our population. The normal elderly function normally both in their self care, and also in their social activities of daily living, which we tabulate. The current terms for the normally functioning elderly who show only mild psychological deficits are age-associated memory impairment and age-related cognitive decline, which we define, criticize and tabulate. The psychological deficits of the elderly consist of mild generalized slowing and inaccuracies compared to normal young persons. These deficits are measured by objective psychological tests which mimic real daily living situations--the name-face test, fire alarm test, two delayed recall tests, misplaced objects test, shopping list test, and digit symbol test, which we describe. A longer early formal education is preventive of mental dulling during normal aging. Treating using overlearning, by cognitive training, is significantly beneficial.

Activities of Daily Living↗

Motor sequence learning: a study with positron emission tomography.

We have used positron emission tomography to study the functional anatomy of motor sequence learning. Subjects learned sequences of keypresses by trial and error using auditory feedback. They were scanned with eyes closed under three conditions: at rest, while performing a sequence that was practiced before scanning until overlearned, and while learning new sequences at the same rate of performance. Compared with rest, both sequence tasks activated the contralateral sensorimotor cortex to the same extent. Comparing new learning with performance of the prelearned sequence, differences in activation were identified in other areas. (1) Prefrontal cortex was only activated during new sequence learning. (2) Lateral premotor cortex was significantly more activated during new learning, whereas the supplementary motor area was more activated during performance of the prelearned sequence. (3) Activation of parietal association cortex was present during both motor tasks, but was significantly greater during new learning. (4) The putamen was equally activated by both conditions. (5) The cerebellum was activated by both conditions, but the activation was more extensive and greater in degree during new learning. There was an extensive decrease in the activity of prestriate cortex, inferotemporal cortex, and the hippocampus in both active conditions, when compared with rest. These decreases were significantly greater during new learning. We draw three main conclusions. (1) The cerebellum is involved in the process by which motor tasks become automatic, whereas the putamen is equally activated by sequence learning and retrieval, and may play a similar role in both. (2) When subjects learn new sequences of motor actions, prefrontal cortex is activated. This may reflect the need to generate new responses. (3) Reduced activity of areas concerned with visual processing, particularly during new learning, suggests that selective attention may involve depressing the activity of cells in modalities that are not engaged by the task.

Adult↗