Material-specific hemispheric activation

Attention is defined as consisting of three components—arousal, attentiveness and activation (preparation for action). The purpose of this study was to determine: (1) whether verbal and nonverbal stimuli differentially prepare the hemispheres for action; (2) how long this asymmetric activation persists; and (3) whether a response-linked decisional process is necessary for inducing these asymmetries.The findings indicated that: (1) although verbal warning stimuli (WS) reduced reaction times (RTs) of the right hand more than those of the left hand, visuospatial WS reduced RTs of both hands equally; (2) the asymmetries induced by the verbal WS were less robust at 15–20 sec after the WS and were not present during post-session testing; and (3) a response-linked decisional process was necessary for inducing activation asymmetries.     

Tachistoscopic recognition of Kana and Hangul words,handedness and shift of laterality difference

Nonsense Kana words as verbal stimuli and Hangul words (Korean orthographic characters) as non-verbal were presented tachistoscopically in the left or right visual field to normal right-handed, non-familial left-handed and familial left-handed Japanese subjects, who have not seen Hangul characters. Right-handers showed a significant right (or left) field superiority for the recognition of verbal (or non-verbal) stimuli. This pattern of differences found in right-handers is, though to a slightly lesser degree, also present in non-familial left-handers, while it is absent in familial left-handers. Initial left field superiority for Hangul word recognition shifted to no laterality difference in left-handers as well as in right-handers during the learning period for Hangul words.     

Recognition of tachistoscopically presented verbal and non-verbal material after unilateral cerebral damage

Three groups of S's were examined in order to study the effects of unilateral brain-damage on recognition rates for verbal and non-verbal stimuli in the lateral visual fields. Patients with damage in the region of the middle cerebral artery of the left or right hemisphere and neurologically intact individuals were asked to identify verbal and non-verbal stimuli presented tachistoscopically in each field. The results indicate superior recognition for both types of stimuli in the visual field contralateral to the intact hemisphere. The effect is greater for non-verbal material with right hemisphere injury and greater for verbal material with left hemisphere injury. A significant superiority of recognition in the nasal field of each eye is found to interact with the effect of the side of lesion and type of material.     

Discrepancy between musical ability and language skills in children with Williams syndrome

BackgroundChildren with Williams syndrome (WS) show a marked interest in music, a characteristic often explored in clinical settings. However, the actual musical abilities of patients with WS remain debatable due to some of the relevant data being derived from experimental tasks that require a verbal response, despite the known language impairments in WS. The present study aimed to examine musical ability in children with WS using a newly invented pitch discrimination task with minimal involvement of language and clarify its relationship with language skill.MethodsEleven children with WS participated in the study. We used a novel pitch discrimination task that required minimal language use. Two piano tones were presented sequentially, and children were asked to give a non-verbal response as to whether the second tone was higher than, lower than, or the same as the first tone.ResultsPitch discrimination performance in children with WS was lower than the level predicted for their chronological age (CA), even in the non-verbal task. Pitch discrimination ability and verbal mental age (VMA) were shown to be dissociated, such that children with WS with a lower skill level for language showed an unexpectedly higher level of pitch discrimination ability and vice versa.ConclusionsOur results indicated reduced musical ability with respect to CA in children with WS. The dissociation between musical ability and language skills may indicate unique developmental relationships that differ from those in normal children. These findings provide new evidence to support the importance of assessing actual musical ability in WS prior to implementing interventional music therapy.     

Brain regions involved in verbal or non-verbal aspects of facial emotion recognition

To depict the neural substrates for facial emotion recognition and to determine whether their activation is confounded by a verbal factor, we studied eight normal volunteers with functional magnetic resonance imaging (fMRI). Verbal and non-verbal sample stimuli were used in a facial emotion matching task and a gender matching task (control condition). Compared with the gender tasks, the emotion tasks significantly activated the right ventral prefrontal cortex, the right lingual cortex, and the left lateral fusiform cortex, irrespective of sample stimuli. The visual association cortices showed a significant interaction between the task and the material presented, as the activation for verbal materials was higher than for non-verbal materials during the emotion matching tasks. By contrast, no significant interaction was found in the right ventral prefrontal cortex. These results suggest that the verbal factor has a different effect on the neural networks for facial emotion, processing.     

Auditory event-related potentials among dyslexic and normal-reading children: 3CLT and midline comparisons.

Event-related potentials (ERP's) to verbal and non-verbal auditory stimuli were recorded from normal-reading and from dyslexic children while performing a target-detection task ("oddball" paradigm). Two methods of analysis were used: (1) Peak latency and amplitude measures of P3 recorded from 3 midline electrodes; (2) P3 apex latency, amplitude and orientation in the three-channel Lissajous' trajectory (3CLT) derived from 3 orthogonal pairs of electrodes. P3 peak amplitude was significantly attenuated in dyslexic children compared to normal-reading children and in response to verbal stimuli compared to non-verbal stimuli. P3 apex latencies were longer and apex amplitudes larger in response to non-verbal compared to verbal stimuli. The most striking finding involved P3 apex orientation, which pointed in an upward-posterior direction with a slight tilt to the left among normal readers, but with a tilt to the right in dyslexics.     

Developmental aphasia: rate of auditory processing and selective impairment of consonant perception

We have previously demonstrated that, compared with control children, non-verbal auditory processing by developmental dysphasics is subject to a speed constraint [4]. In the present experiments the same subjects were tested for their ability to (a) discriminate between and (b) perceive binary sequences of, synthesized stop consonants, and steady-state vowels. With vowel stimuli, dysphasics were inferior to controls only on stimulus patterns of five elements, which also provoked inferior performance by dysphasics with non-verbal stimuli of the same duration (250 msec). However, dysphasics' discrimination of consonant stimuli was significantly inferior to controls and to their own discrimination of vowel stimuli and non-verbal auditory stimuli of the same duration. It is hypothesized that it is the brief duration of formant transitions which results in dysphasics' inability to discriminate consonant stimuli, and this deficit may be sufficient to explain the speech disorder of these children.     

Functional asymmetry of the human brain in the recognition of faces

Lateralized cerebral function in the recognition of facial stimuli was tested directly by examining patients before and after they were administered a single, unilateral electroconvulsive treatment. Functional demands imposed by the task (i.e. verbal or non-verbal) were the chief factors influencing the relative importance of the right or the left cerebral hemisphere to task performance.     

Self-ordered pointing in children with autism: failure to use verbal mediation in the service of working memory?

This study tested the hypothesis that children with autism are impaired in using verbal encoding and rehearsal strategies in the service of working memory. Participants were 24 high-ability, school-age children with autism and a comparison group matched on verbal and non-verbal IQ, receptive and expressive vocabulary, and visual memory. Working memory was assessed using verbal and non-verbal variants of a non-spatial, self-ordered pointing test [Petrides, M., & Milner, B. (1982). Deficits on subject-ordered tasks after frontal- and temporal-lobe lesions in man. Neuropsychologia, 20, 249-262] in which children had to point to a new stimulus in a set upon each presentation without repeating a previous choice. In the verbal condition, the stimuli were pictures of concrete, nameable objects, whereas in the non-verbal condition, the stimuli were not easily named or verbally encoded. Participants were also administered a verbal span task to assess non-executive verbal rehearsal skills. Although the two groups were equivalent in verbal rehearsal skills, the autism group performed significantly less well in the verbal, but not the non-verbal, self-ordered pointing test. These findings suggested that children with autism are deficient in the use of verbal mediation strategies to maintain and monitor goal-related information in working memory. The findings are discussed in terms of possible autistic impairments in episodic memory as well as working memory.     

Linguistic heterogeneity in Williams syndrome

Williams syndrome (WS) is a rare genetic disorder resulting from a deletion on chromosome 7. A number of studies have shown that individuals with WS have a superior linguistic profile compared to their non-verbal abilities, however the evidence has been inconclusive, as many studies have disputed such a profile. The vast majority of studies on WS have assumed a single, homogeneous WS linguistic profile in order to support various theoretical viewpoints. The present study investigated the linguistic profiles of 5 individuals with WS on a number of standardized verbal measures and in conversational settings. The results indicated substantially variable performance in all aspects of the verbal domain, which supports the view that WS, linguistically, is a rather heterogeneous condition and this should be taken into consideration when referring to it in theoretical accounts of language acquisition and debates on modularity.     

Perceptual grouping ability in Williams syndrome: evidence for deviant patterns of performance

Williams syndrome (WS) is a rare genetic disorder. At a cognitive level, this population display poor visuo-spatial cognition when compared to verbal ability. Within the visuo-spatial domain, it is now accepted that individuals with WS are able to perceive both local and global aspects of an image, albeit at a low level. The present study examines the manner in which local elements are grouped into a global whole in WS. Fifteen individuals with WS and 15 typically developing controls, matched for non-verbal ability, were presented with a matrix of local elements and asked whether these elements were perceptually grouped horizontally or vertically. The WS group was at the same level as the control group when grouping by luminance, closure, and alignment. However, their ability to group by shape, orientation and proximity was significantly poorer than controls. This unusual profile of grouping abilities in WS suggests that these individuals do not form a global percept in a typical manner.     

The visual attention span deficit in dyslexia is visual and not verbal

The visual attention (VA) span deficit hypothesis of dyslexia posits that letter string deficits are a consequence of impaired visual processing. Alternatively, some have interpreted this deficit as resulting from a visual-to-phonology code mapping impairment. This study aims to disambiguate between the two interpretations by investigating performance in a non-verbal character string visual categorization task with verbal and non-verbal stimuli. Results show that VA span ability predicts performance for the non-verbal visual processing task in normal reading children. Furthermore, VA span impaired dyslexic children are also impaired for the categorization task independently of stimuli type. This supports the hypothesis that the underlying impairment responsible for the VA span deficit is visual, not verbal.     

Verbal Peaks and Visual Valleys in Theory of Mind Ability in Williams Syndrome

Research on theory of mind (TOM) has provided a major contribution to the understanding of developmental disorders characterized by atypical social behaviour. Yet, there is still little consensus relative to TOM abilities in Williams syndrome (WS). This study used visual and verbal tasks to investigate attribution of intentions in individuals with WS relative to mental age-matched typically developing individuals. Results showed that individuals with WS perform as accurately as controls on the verbal but not on the visual task. Such modality differences did not affect WS group’s performance on a control condition not requiring TOM neither were found for the control group. These results suggest the existence of a verbal peak and a visual valley in TOM ability in WS.     

Motor cortex involvement during verbal versus non-verbal lip and tongue movements

We evaluated left and right motor cortex involvement during verbal and non-verbal lip and tongue movements in seven healthy subjects using whole-head magnetoencephalography. The movements were paced by tone pips. The non-verbal tasks included a kissing movement and touching the teeth with the tongue. The verbal tasks comprised silent articulation of the Finnish vowel /o/, which requires mouth movement similar to that in the kissing task, pronouncing the same self-selected word repeatedly, and producing a new word for every tone pip. Motor cortex involvement was quantified by task-related suppression and subsequent rebound of the 20-Hz activity. The modulation concentrated to two sites along the central sulcus, identified as the motor face and hand representations. The 20-Hz suppression in the face area was relatively similar during all tasks. The post-movement rebound, however, was significantly left-lateralized during word production. In the non-verbal tasks, hand areas showed pronounced suppression of 20-Hz activity that was significantly diminished for the verbal tasks. The latencies of the 20-Hz suppression in the left and right face representations were correlated across subjects during verbal mouth movements. Increasing linguistic content of lip and tongue movements was thus manifested in spatially more focal motor cortex involvement, left-hemisphere lateralization of face area activation, and correlated timing across hemispheres.     

Visuo-spatial and linguistic abilities in a twin with Williams syndrome

The present study reports a case of dizygotic twins, one boy with Williams syndrome (WS) and one typically developing girl, and compares their neuropsychological profiles. The goal of the present authors was to verify whether the child with WS displayed a cognitive profile which is unique to the syndrome. Several tests designed to assess visuo-perceptual, visuo-motor, linguistic and memory abilities were administered to both children when they were 10.9 years old. Compared to his sister, the boy with WS displayed a homogeneous developmental delay in both non-verbal and verbal abilities. He achieved a level of performance similar to his sister only in facial recognition, phonological word fluency and memory for phonologically similar words. Furthermore, despite the overall delayed performance of the boy, both the twins displayed a cognitive profile characterized by strength in lexical comprehension and relative weakness in visuo-motor abilities.     

Regional modulation of high resolution evoked potentials during verbal and non-verbal matching tasks

Nine subjects performed a cued S1-S2 matching task in which two sequentially presented visual stimuli (either letter strings or non-verbal graphical patterns) were compared according to verbal (phonemic, semantic, syntactic) or non-verbal (graphic identity) criteria. The Laplacian derivation was used to spatially enhance the topography of averaged evoked potentials (EPs) recorded from 59 scalp electrodes. Several effects distinguished the non-verbal from the verbal conditions. For example, following S1 a P250 EP that reached maximum amplitude over the occipital area was larger for the non-verbal patterns, whereas word and word-like letter strings (but not unfamiliar characters) elicited an N470 in the left temporal region. In anticipation of S2, a CNV-like slow potential was enhanced over posterior regions for the non-verbal stimuli. During the matching interval following S2, a P475 peak was observed to be larger for non-verbal patterns than for letter strings over right frontal and temporal regions. Other effects distinguished the verbal conditions from one another. In particular, following S1 a left frontal P445 potential was enhanced to closed class versus open class words, and following S2 a P620 potential in the left temporal region was enhanced for phonological matching relative to semantic matching. These results suggest that processing of verbal and non-verbal stimuli depends on a network of subprocessors that are regionalized to functionally specialized cortical areas and that operate both sequentially and in parallel in order to extract and synthesize multiple forms of attribute-specific information. In contrast to neuropsychological approaches to the study of pattern recognition and reading, the fine-grain temporal resolution of EP measurements, in combination with the improved spatial resolution obtained through computation of Laplacian derivation wave forms from a large number of electrodes, permits characterization of both the regionalization of subprocesses and the subsecond dynamics of their engagement.     

The relationship between right-handed children's assessed and familial handedness and lateral specialization

Eighty right-handed males (6–12 yr of age) stratified into age x degree of handedness x family history of handedness groups were administered three dichotic (digit, syllable, environmental sound) tests. Older subjects accurately identified more stimuli than the younger subjects across tasks. There were significant laterality differences for both verbal and nonverbal stimuli between family history of handedness groups regardless of the subjects' age and degree of handedness. Those subjects with familial sinistrality had attenuated right-side advantage for verbal and non-verbal stimuli and decreased nonverbal accuracy scores compared to the familial dextral subjects who evidenced a right-ear (left hemisphere) advantage for verbal stimuli and a left-ear (right hemisphere) advantage for nonverbal.     

A comparison of interhemispheric transmission times as measured by verbal and manual reaction time.

Interhemispheric transmission times (IHTTs) were calculated for 33 right-handed subjects. Verbal and manual response times (RTs) were recorded to visual stimuli exposed in either the left or right visual fields (LF, RF) for 50 msec. Each subject received 15 stimuli (dots) in the LF (1.5 degrees to the left of fixation), 15 stimuli in the RF, and 15 blank trials in both the verbal and manual response condition. IHTTs were calculated for each subject by subtracting the mean RF RT (I.E., uncrossed path) from the means LF RT (i.e., crossed path). Results indicated a nonsignificant IHTT obtained under the manual response condition of 5 msec and a highly significant IHTT obtained under the verbal response condition of 20 msec. While no significant correlation was found between IHTTs obtained under both response conditions, high correlations were found between component RT measures (i.e., manual RF RT, manual LF RT, verbal RF RT, and verbal LF RT). Thus, IHTT is independent of simple RT.     

Intra- and interhemispheric processing of visual information in callosal agenesis

Two siblings with total callosal agenesis were compared with two control groups on a number of tachistoscopic tasks involving unilateral and bilateral presentation of verbal and non-verbal stimuli. Acallosals were able to effect intra- and interhemispheric comparisons and to correctly identify all kinds of stimuli in either visual field. However, they responded more slowly, especially in the bilateral condition where they also made more errors than the controls. The results are interpreted in terms of increased use of extra-callosal commissures.