The neural correlates of rhyme awareness in preliterate and literate children

ObjectiveMost rhyme awareness assessments do not encompass measures of the global similarity effect (i.e., children who are able to perform simple rhyme judgments get confused when presented with globally similar non-rhyming pairs). The present study examines the neural nature of this effect by studying the N450 rhyme effect.MethodsBehavioral and electrophysiological responses of Dutch pre-literate kindergartners and literate second graders were recorded while they made rhyme judgments of word pairs in three conditions; phonologically rhyming (e.g., wijn-pijn), overlapping non-rhyming (e.g., pen-pijn) and unrelated non-rhyming pairs (e.g., boom-pijn).ResultsBehaviorally, both groups had difficulty judging overlapping but not rhyming and unrelated pairs. The neural data of second graders showed overlapping pairs were processed in a similar fashion as unrelated pairs; both showed a more negative deflection of the N450 component than rhyming items. Kindergartners did not show a typical N450 rhyme effect. However, some other interesting ERP differences were observed, indicating preliterates are sensitive to rhyme at a certain level.SignificanceRhyme judgments of globally similar items rely on the same process as rhyme judgments of rhyming and unrelated items. Therefore, incorporating a globally similar condition in rhyme assessments may lead to a more in-depth measure of early phonological awareness skills.     

Visual half-field presentations of incongruent color words: effects of gender and handedness

Right-handed (dextral) and left-handed (sinistral) males and females (N = 15) were compared for language lateralization in a visual half-field (VHF) incongruent color-words paradigm. The paradigm consists of repeated brief (less than 200 msec) presentations of color-words written in an incongruent color. Presentations are either to the right or to the left of center fixation. The task of the subject is to report the color the word is written in on each trial, ignoring the color-word. Color-bars and congruent color-words were used as control stimuli. Vocal reaction time (VRT) and error frequency were used as dependent measures. The logic behind the paradigm is that incongruent color-words should lead to a greater cognitive conflict when presented in the half-field contralateral to the dominant hemisphere. The results showed significantly longer VRTs in the right half-field for the dextral subjects. Furthermore, significantly more errors were observed in the male dextral group when the incongruent stimuli were presented in the right half-field. There was a similar trend in the data for the sinistral males. No differences between half-fields were observed for the female groups. It is concluded that the present results strengthen previous findings from our laboratory (Hugdahl and Franzon, 1985) that the incongruent color-words paradigm is a useful non-invasive technique for the study of lateralization in the intact brain.     

Visual half-field presentations of incongruent color-words reveal mirror-reversal of language lateralization in dextral and sinistral subjects

Two experiments are reported concerning identification of left and right hemisphere dominance for language in dextral and sinistral subjects. A visual half-field (VHF) incongruent color-words paradigm was used. Color-words written in incongruent colors were presented either to the right or left half-field. Subjects were instructed to report the color, ignoring the color-word. Vocal reaction time (VRT) and frequency of errors were measured. Twenty dextral adult males were tested in Experiment 1. Results showed significantly more errors and a trend towards longer VRT:s when the words were presented in the right half-field, i.e. initially to the left hemisphere. No differences between half-fields were observed to color-stripes serving as control-stimuli. The results were followed up in Experiment 2 with a preselected sinistral group. All subjects in the sinistral group had revealed a left-ear-advantage (LEA) in a previous dichotic listening test, i.e. right hemisphere language dominance. The results from the VHF inconguent color-words test showed a reverse pattern of responding compared to the dextral group, i.e. more errors and longer VRTs when the color-words were initially presented to the right hemisphere.     

Symmetry detection in typically and atypically speech lateralized individuals: A visual half-field study

Visuospatial functions are typically lateralized to the right cerebral hemisphere, giving rise to a left visual field advantage in visual half-field tasks. In a first study we investigated whether this is also true for symmetry detection off fixation. Twenty right-handed participants with left hemisphere speech dominance took part in a visual half-field experiment requiring them to judge the symmetry of 2-dimensional figures made by joining rectangles in symmetrical or asymmetrical ways. As expected, a significant left visual field advantage was observed for the symmetrical figures. In a second study, we replicated the study with 37 left-handed participants and left hemisphere speech dominance. We again found a left visual field advantage. Finally, in a third study, we included 17 participants with known right hemisphere dominance for speech (speech dominance had been identified with fMRI in an earlier study; Van der Haegen, Cai, Seurinck, & Brysbaert, 2011). Around half of these individuals showed a reversed pattern, i.e. a right visual half-field advantage for symmetric figures while the other half replicated the left visual-field advantage. These findings suggest that symmetry detection is indeed a cognitive function lateralized to the right hemisphere for the majority of the population. The data of the participants with atypical speech dominance are more in line with the idea that language and visuospatial functions are lateralized in opposite brain hemispheres than with the idea that different functions lateralize independently, although there seems to be more variability in this group.     

Visual half-field superiority for righthanders with familial sinistrality: sex differences and cognitive/motor interference in a lexical decision task

By means of a lexical decision task in which words and nonwords were controlled for familiarity, the question whether sex and familial handedness influence right-field superiority for righthanded subjects was investigated. Analyses of unimanual reaction times and response accuracy revealed sex differences and a cognitive-motor interference for the male group. For hit rates the men, reacting with their right hands, showed a right-field superiority for words and a left-field superiority for meaningless syllables, and the men reacting with their left hands showed the reversed asymmetry. Theoretical problems associated with reaction time and hit rate asymmetry as indicators of language lateralisation are discussed.     

Visual half-field word recognition as a function of syntactic class and imageability

Twenty-four normal right-handed subjects were shown vertically oriented strings of letters in the left and right visual half-fields (VHF) and asked to discriminate words from non-words. Analysis of manual reaction time responses showed a significant right VHF (left hemisphere) advantage for low imagery nouns, adjectives and verbs as well as high imagery verbs. There was no VHF difference in speed of response for high imagery nouns and adjectives. It was concluded that right hemisphere word recognition is related to both imageability and syntactic class.     

The effects of word orientation and imageability on visual half-field presentations with a lexical decision task

Two studies examined the effects of word orientation and word imageability in a visual half-field procedure. The studies involved a lexical decision task in which items were presented in either a horizontal or vertical orientation randomly intermixed in Experiment 1 and blocked in Experiment 2. Overall, a RVF advantage resulted with horizontal items, yet no visual-field asymmetries were found with the vertical items. These results indicate that altering the orientation can affect visual-field superiority. It is proposed that the novelty of vertical displays leads to greater involvement of the right hemisphere. Imageability was related to performance only for horizontal displays; but there were no significant differences in imageability effects between the two visual fields. It is concluded that word imageability has little effect on visual-field differences, at least not for lexical decisions.     

Performance of illiterate and literate nondemented elderly subjects in two tests of long-term memory.

Cognitive evaluation in developing countries is a difficult undertaking due to low levels of schooling and particularly the illiteracy still frequent in the elderly. This study was part of the epidemiologic evaluation of dementia in Catanduva, Brazil, and had the objective of comparing the performance of illiterate and literate nondemented elderly individuals in 2 tests of long-term memory-the delayed recall of a word list from the CERAD and the delayed recall of common objects presented as simple drawings from the Brief Cognitive Screening Battery (BCSB). Fifty-one elderly subjects (23 illiterates) were evaluated, and the performance of the illiterates and literates differed in the CERAD memory test, but not in the BCSB memory test. This test may be more suitable for the assessment of long-term memory in populations with a high frequency of illiterates, and therefore might prove to be a useful screening tool for the diagnosis of dementia.     

Left and right lateralization for letter matching: strategy and sex differences

Studies showing different processing styles or biases for the two cerebral hemispheres often confound stimulus qualities with task requirements. A letter matching task avoids this problem [5–7] by using the same stimuli for two task strategies that differentiate hemisphere advantage. We have confirmed these findings in a similar paradigm, but also find that the sexes do not contribute equally to the effect.     

Visual half-field experiments are a good measure of cerebral language dominance if used properly: evidence from fMRI

Traditional neuropsychology employs visual half-field (VHF) experiments to assess cerebral language dominance. This approach is based on the assumption that left cerebral dominance for language leads to faster and more accurate recognition of words in the right visual half-field (RVF) than in the left visual half-field (LVF) during tachistoscopic presentation. Information in the RVF is directly projected to the left hemisphere, whereas information presented in the LVF needs interhemispheric transfer to reach the left half of the brain. This interpretation of the RVF superiority for word recognition lacks direct evidence however, and a multitude of studies have lead to contradictory findings. To investigate this matter further we try to establish the ideal parameters for VHF experiments to measure language dominance, and subsequently compare laterality indices (LIs) obtained from RT patterns in bilateral VHF tasks to those LIs acquired in the same individuals during a mental word generation task in the fMRI scanner. Our results reveal a direct link between VHF advantages and individual language lateralization. Differences in behavioral performance between left-hemisphere dominant and right-hemisphere dominant individuals suggest that carefully designed VHF tests can be used as a reliable predictor of cerebral language dominance.     

Language differences between institutionalized and noninstitutionalized retarded children.

The linguistic performances of 15 noninstitutionalized and 15 institutionalized retarded children were compared on usage of grammatical categories and structure of spoken language (Length--Complexity Index) and for underlying subskills (Illinois Test of Psycholinguistic Abilities). Differences were not found between the groups for usage of grammatical categories or structures but were found for subskills of Auditory Reception. Auditory Sequential Memory, Verbal Expression, and Auditory Closure. Further analysis by multiple stepwise regression indicated that noninstitutionalized and institutionalized retarded children may be differentiated by examining a number of linguistic variables. The grammatical structure of language appeared less affected by environment than were the semantic and auditory elements.     

Visual evoked potentials to lateralized visual stimuli and the measurement of interhemispheric transmission time

Visual evoked potentials (VEPs) to lateralized light flashes were recorded from the parietal midline, and from homologous occipital and central sites, in a GO/NOGO reaction time task. The N160 component of the VEP was found to be larger over the hemisphere contralateral to the visual field of stimulus exposure at all pairs of lateral electrodes. At the occipital sites only, N160 latency was also shorter from the contralateral hemisphere, by an average of approximately 14msec. This was not so centrally, where a non-significant value of approximately 4 msec was obtained. These data are considered to be consistent with Milner and Lines' hypothesis that callosal transmission occurs at different rates in different functional regions of the corpus callosum.     

The polarity inversion of scalp potentials evoked by upper and lower half-field stimulus patterns: latency or surface distribution differences?

Evoked potentials to patterned stimulation of the upper and lower half of the visual field are generally inverted in polarity. Two conflicting proposals have been made to explain this effect, both based on surface distribution studies of pattern-reversal and/or pattern-onset VEPs. The first suggests that this polarity inversion is due to differences in surface distribution of corresponding components of constant latency; the second that it is due to differences in the latencies of peaks of similar surface distributions in the upper and lower half-field responses. Experimental evidence is here presented which supports the first explanation for the case of the pattern-onset VEPs. These results, which illustrate how different components in the same response can be identified from the selective adaptation effects of pre-exposure to outline patterns, show that there is no difference in latency of components of corresponding properties in the upper and lower half-field VEPs.     

Clinical differences between suicidal and nonsuicidal depressed children and adolescents

OBJECTIVE: To examine the clinical symptoms and comorbid psychiatric disorders of depressed children and adolescents with and without clinically significant suicidal ideation. METHOD: Children and adolescents aged 7 to 17 years with current DSM-III-R major depressive disorder (MDD) (N = 135) were recruited between January 1987 and April 2002. Current MDD symptoms and lifetime comorbid psychiatric disorders were assessed using either a combination of the Schedule for Affective Disorders and Schizophrenia for School Age Children-Epidemiologic and -Present Episode versions or the -Present Lifetime version. Thirty-two percent (N = 43) of the depressed subjects were classified as suicidal (at least suicidal ideation with a plan). RESULTS: Depressed suicidal youth presented with a more severe episode (p = .001) and a poorer functional status (p = .019), were more hopeless (p = .001), and presented more frequently with insomnia (p = .011). There was an interaction between suicide x sex x pubertal status for severity of MDD (p = .013), the presence of hopelessness (p < .001), poor functional status (p = .023), and comorbidity with a lifetime history of any disruptive behavior (p = .019). Among pre-pubertal depressed males, suicidal boys had significantly increased severity of MDD (p = .025) and poorer functional status (p = .044) than non-suicidal boys. Among postpubertal depressed females, suicidal girls were more frequently hopeless (p = .008) and presented an increased severity of MDD (p = .022) and more frequent lifetime history of any disruptive behavior (p = .03) when compared with nonsuicidal girls. CONCLUSION: There appears to be a sex difference for some clinical features, particularly hopelessness, among depressed suicidal children and adolescents. Whether hopelessness is a sex-specific characteristic of depressed suicidal children and adolescents requires further study.     

EEG differences in children between eyes-closed and eyes-open resting conditions

ObjectiveRecent work on arousal vs. activation in adults showed that skin conductance levels (SCLs) increased, and global alpha levels decreased, from eyes-closed to eyes-open resting baseline conditions. This study explored whether similar effects occur in children.MethodsEEG activity was recorded from 30 children aged 8–12 years during counterbalanced eyes-closed and eyes-open resting conditions; SCL was measured as an index of arousal.ResultsSCLs were negatively correlated with mean alpha levels in the eyes-closed condition, and increased significantly from eyes-closed to eyes-open. Reductions were found in across-scalp mean absolute delta, theta, alpha, and beta from eyes-closed to eyes-open. Topographic changes were evident in all bands except alpha.ConclusionsResults confirm the use of mean alpha level as a measure of resting-state arousal under eyes-closed and eyes-open conditions. Focal changes in the other bands suggest that these reflect differences in activation, rather than the simple increase in arousal shown in alpha.SignificanceThis child study confirms the generality of eyes-closed vs. eyes-open non-alpha EEG measures differing in mean power levels and topography, the latter indicating brain activity related to visual processing. Such differences should be considered when evaluating EEG research, and in choosing baseline conditions for different paradigms.     

fMRI auditory language differences between dyslexic and able reading children

During fMRI, dyslexic and control boys completed auditory language tasks (judging whether pairs of real and/or pseudo words rhymed or were real words) in 30 s 'on' conditions alternating with a 30 s 'off' condition (judging whether tone pairs were same). During phonological judgment, dyslexics had more activity than controls in right than left inferior temporal gyrus and in left precentral gyrus. During lexical judgment, dyslexics were less active than controls in bilateral middle frontal gyrus and more active than controls in left orbital frontal cortex. Individual dyslexics were reliably less active than controls in left insula and left inferior temporal gyrus. Dyslexic and control children differ in brain activation during auditory language processing skills that do not require reading.     

Use of collision tests to identify physiological differences between the median and ulnar nerves

Introduction: Median and ulnar nerves are used in comparative electrophysiological studies. We analyzed the conduction values in these hand nerves in healthy volunteers to find any physiological differences between them. Methods: We performed standard conduction studies and conduction velocity distribution (CVD) tests with estimation of 3 quartiles in 31 healthy right-handed volunteers (17 women, 14 men) with a mean age of 44.8 ± 15.5 years. Results: The conduction velocities in all quartiles of CVD tests were statistically faster in the ulnar nerve (P < 0.00001), with no differences in the spread of conduction values and no differences between sides. In the ulnar nerve, CVD velocities in all quartiles were faster in the female group (P < 0.05). Discussion: The ulnar nerve has more fibers conducting with high velocities than does the median nerve. Electrophysiological comparisons between hand nerves must be performed carefully. Muscle Nerve 59:470–474, 2019     

Hemispheric asymmetry for classifying upright and inverted letter pairs: Handedness and sex differences

Eighty subjects, 20 in each sex/handedness combination, performed a lateralized physical and name matching task with upright and inverted letter pairs. “Same” reaction times only displayed Orientation × Hemisphere × Subject Group interactions which, it was suggested, might be rather too readily interpreted in terms of the usual sex and handedness differences in hemispheric asymmetry.