Monthly Archives: May 2010
Cerebral Localization of Functions and the Neurology of Language: Fact versus Fiction or Is It Something Else?
Over the last 15 years there has been a burgeoning number of publications using functional brain imaging (>40,000 articles based on an ISI/Web of Science search) to localize behavioral and cognitive processes to specific areas in the human brain that are often not confirmed by traditional, lesion-based studies. Thus, there is a need to reassess what cerebral localization of functions is and is not. Otherwise, there is no rational way to interpret the escalating claims of localization in the functional imaging literature that is taking on the appearance of neurophysiologic “phrenology”. This article will present arguments to suggest that functional localization in the brain is a robust but very dynamic, four-dimensional process. It is a learned phenomenon driven over time by large-scale, spatially distributed, neural networks seeking to efficiently maximize the processing, storage, and manipulation of information for cognitive and behavioral operations. Because of historical considerations and space limitations, the main focus will be on localization of language-related functions whose theoretical neurological basis can be generalized for any complex cognitive-behavioral function.
from The Neuroscientist
Asymmetric TDP-43 distribution in primary progressive aphasia with progranulin mutation
Conclusion: These results demonstrate a phenotypically concordant distribution of abnormal TDP-43 inclusions in primary progressive aphasia (PPA). This contrasts with PPA cases with Alzheimer pathology where no consistent leftward asymmetry of neurofibrillary degeneration or amyloid deposition has been demonstrated despite the leftward asymmetry of the atrophy, and where neurofibrillary tangles show a greater density in memory than language areas despite the predominantly aphasic phenotype. This case suggests that the TDP-43 inclusions in PPA–frontotemporal lobar degeneration are more tightly linked to neuronal death and dysfunction than neurofibrillary and amyloid deposits in PPA–Alzheimer disease.
from Neurology
The Sensitivity and Specificity of Cognitive Screening Instruments to Detect Cognitive Impairment in Older Adults With Severe Psychiatric Illness
Conclusions: Overall, the MMSE was found to be the more clinically useful cognitive screening tool for use in CMHC. Yet, because of the poor sensitivity of the MMSE for detecting CI in this patient population, alternative screening methods should be explored.
Clinical staging and disease progression in frontotemporal dementia
Conclusions: Disease progression differs across frontotemporal dementia (FTD) variants. Patients with behavioral variant FTD progress rapidly whereas those with semantic dementia progress more slowly. The Frontotemporal Dementia Rating Scale can aid in staging and determining disease progression. Length of symptoms and global cognitive assessments alone do not reflect disease severity and progression in FTD.
from Neurology
Phosphodiesterase Type 5 Inhibitor Use and Hearing Impairment
Conclusions Current warnings regarding the risk of hearing loss related to PDE-5i use seems to be justified. However, the cross-sectional nature of the current study provides only limited insight regarding this relationship, and thus additional research is warranted.
Case-Control Analysis of Cochlear Implant Performance in Elderly Patients
Conclusions Elderly patients benefit significantly from cochlear implantation. Compared with a younger cohort matched for preimplantation performance, however, their postimplantation scores are significantly lower on some measures. These results may provide guidelines for candidacy and counseling regarding elderly patients with cochlear implants.
Outcomes of Fat Injection Laryngoplasty in Unilateral Vocal Cord Paralysis
Conclusions Fat injection laryngoplasty seems to be effective in enhancing acoustic and quality of life outcomes in patients with unilateral vocal cord paralysis. The effect is sustainable over 12 months.
Sing that tune: Infants’ perception of melody and lyrics and the facilitation of phonetic recognition in songs
To better understand how infants process complex auditory input, this study investigated whether 11-month-old infants perceive the pitch (melodic) or the phonetic (lyric) components within songs as more salient, and whether melody facilitates phonetic recognition. Using a preferential looking paradigm, uni-dimensional and multi-dimensional songs were tested; either the pitch or syllable order of the stimuli varied. As a group, infants detected a change in pitch order in a 4-note sequence when the syllables were redundant (experiment 1), but did not detect the identical pitch change with variegated syllables (experiment 2). Infants were better able to detect a change in syllable order in a sung sequence (experiment 2) than the identical syllable change in a spoken sequence (experiment 1). These results suggest that by 11 months, infants cannot “ignore” phonetic information in the context of perceptually salient pitch variation. Moreover, the increased phonetic recognition in song contexts mirrors findings that demonstrate advantages of infant-directed speech. Findings are discussed in terms of how stimulus complexity interacts with the perception of sung speech in infancy.
Tonal synchrony in mother–infant interaction based on harmonic and pentatonic series
This study reports the occurrence of ‘tonal synchrony’ as a new dimension of early mother–infant interaction synchrony. The findings are based on a tonal and temporal analysis of vocal interactions between 15 mothers and their 3-month-old infants during 5 min of free-play in a laboratory setting. In total, 558 vocal exchanges were identified and analysed, of which 84% reflected harmonic or pentatonic series. Another 10% of the exchanges contained absolute and/or relative pitch and/or interval imitations. The total durations of dyads being in tonal synchrony were normally distributed (M = 3.71, SD = 2.44). Vocalisations based on harmonic series appeared organised around the major triad, containing significantly more simple frequency ratios (octave, fifth and third) than complex ones (non-major triad tones). Tonal synchrony and its characteristics are discussed in relation to infant-directed speech, communicative musicality, pre-reflective communication and its impact on the quality of early mother–infant interaction and child’s development.
Semantic and acoustic analysis of speech by functional networks with distinct time scales
Speech perception requires the successful interpretation of both phonetic and syllabic information in the auditory signal. It has been suggested by Poeppel (2003) that phonetic processing requires an optimal time scale of 25 ms while the time scale of syllabic processing is much slower (150250 ms). To better understand the operation of brain networks at these characteristic time scales during speech perception, we studied the spatial and dynamic properties of EEG responses to five different stimuli: (1) amplitude modulated (AM) speech, (2) AM speech with added broadband noise, (3) AM reversed speech, (4) AM broadband noise, and (5) AM pure tone. Amplitude modulation at gamma band frequencies (40 Hz) elicited steady-state auditory evoked responses (SSAERs) bilaterally over primary auditory cortices. Reduced SSAERs were observed over the left auditory cortex only for stimuli containing speech. In addition, we found over the left hemisphere, anterior to primary auditory cortex, a network whose instantaneous frequencies in the theta to alpha band (4-16 Hz) are correlated with the amplitude envelope of the speech signal. This correlation was not observed for reversed speech. The presence of speech in the sound input activates a 416 Hz envelope tracking network and suppresses the 40-Hz gamma band network which generates the steady-state responses over the left auditory cortex. We believe these findings to be consistent with the idea that processing of the speech signals involves preferentially processing at syllabic time scales rather than phonetic time scales.
from Brain Research
Intonation and Emotion: Influence of Pitch Levels and Contour Type on Creating Emotions
Intonation is a vehicle for communication, which sometimes contributes greater meaning than the semantic content of speech itself. This prosodic element lends the message linguistic and paralinguistic meaning, which carries a highly significant communicative value when conveying emotional states. For this reason, this article analyses the use of intonation as an instrument for arousing various sensations in the listener. The aim was to verify which elements of intonation are more decisive to generate a specific sensation. Experimental research is conducted, in which certain pitch patterns (pitch levels and contour type) are assigned different emotions (joy, anxiety, sadness, and calmness) and are then listened to and assessed using a questionnaire with a bipolar scale of opposed pairs, by a sample audience comprising 100 individuals. The main conclusion drawn is that, although both the variables analyzed—pitch level and contour type—are representative of expressing emotions, contour type is more decisive. In all the models analyzed, contour type has been highly significant and constitutes the variable that has been determined as the final component for recognizing various emotions.
from the Journal of Voice
Perturbation and Nonlinear Dynamic Analysis of Adult Male Smokers
Discussion
This study indicated that D2 is highly sensitive to changes associated with smoking and has the potential to be implemented clinically as an indicator of abnormal voice. Further research could focus on using nonlinear dynamic analysis to create a normative database, producing standards for monitoring voice changes caused by cigarette smoking.
from the Journal of Voice
Speech production intelligibility of early implanted pediatric cochlear implant users
Conclusions
Profoundly deaf children who receive cochlear implants in the first 2 years of life produce highly intelligible speech before the age of 6. This is also true for most, but not all children implanted in their third year.
from the International Journal of Pediatric Otorhinolaryngology
The influence of the auditory prosthesis type on deaf children’s voice quality
Conclusions
In the study of voice quality in children with profound hearing loss, it is very important to have information both about the degree of hearing loss and the kind of prosthesis used. Implant users show more altered voice quality than digital hearing aid users. However, the hearing loss they compensate is much more important than the hearing loss compensated by the hearing aids. Therefore, we consider that both prostheses help children with hearing loss to have a more normalized voice quality than what scientific literature has traditionally stated.
Finally, we question the validity of using some acoustic parameters as indicators of voice quality in deaf children having no laryngeal problems.
from the International Journal of Pediatric Otorhinolaryngology
Altered Spatial Distribution of Visual Attention in Near and Far Space after Early Deafness
Early deafness results in a redistribution of more attentional resources to the visual periphery in near space, specifically under conditions of selective attention, probably to compensate for the loss of auditory alertness to potentially dangerous stimuli from outside the current attentional focus. It remains poorly understood, however, whether spatial distribution of attention in far space is altered by early deafness as well. In the present study, we investigated whether and how early deafness alters the distribution of visuospatial attention in far space, compared to hearing controls. We asked deaf individuals and hearing controls to perform a flanker task with either peripheral or central distractors, either in near or far space. Sizes of compatibility effect were used to assess the amount of attentional resources received by the peripheral and central distractors. In near space, peripheral distractors induced significantly larger compatibility effect in deaf individuals than in hearing controls while central distractors induced significantly larger compatibility effect in hearing controls than in deaf individuals. On the other hand in far space, although peripheral distractors induced equivalent sizes of compatibility effect in the deaf and hearing groups, central distractors caused significant compatibility effect only in deaf individuals, but not in hearing controls. Our results suggest that early deafness results in a redistribution of visuospatial attention not only in near space but also in far space, with enhanced peripheral attention in near space and enhanced central attention in far space.
from Neuropsychologia
