Infants deploy selective attention to the mouth of a talking face when learning speech

The mechanisms underlying the acquisition of speech-production ability in human infancy are not well understood. We tracked 4-12-mo-old English-learning infants' and adults' eye gaze while they watched and listened to a female reciting a monologue either in their native (English) or nonnative (Spanish) language. We found that infants shifted their attention from the eyes to the mouth between 4 and 8 mo of age regardless of language and then began a shift back to the eyes at 12 mo in response to native but not nonnative speech. We posit that the first shift enables infants to gain access to redundant audiovisual speech cues that enable them to learn their native speech forms and that the second shift reflects growing native-language expertise that frees them to shift attention to the eyes to gain access to social cues. On this account, 12-mo-old infants do not shift attention to the eyes when exposed to nonnative speech because increasing native-language expertise and perceptual narrowing make it more difficult to process nonnative speech and require them to continue to access redundant audiovisual cues. Overall, the current findings demonstrate that the development of speech production capacity relies on changes in selective audiovisual attention and that this depends critically on early experience.     

Dichotomy and perceptual distortions in absolute pitch ability

Absolute pitch (AP) is the rare ability to identify the pitch of a tone without the aid of a reference tone. Understanding both the nature and genesis of AP can provide insights into neuroplasticity in the auditory system. We explored factors that may influence the accuracy of pitch perception in AP subjects both during the development of the trait and in later age. We used a Web-based survey and a pitch-labeling test to collect perceptual data from 2,213 individuals, 981 (44%) of whom proved to have extraordinary pitch-naming ability. The bimodal distribution in pitch-naming ability signifies AP as a distinct perceptual trait, with possible implications for its genetic basis. The wealth of these data has allowed us to uncover unsuspected note-naming irregularities suggestive of a "perceptual magnet" centered at the note "A." In addition, we document a gradual decline in pitch-naming accuracy with age, characterized by a perceptual shift in the "sharp" direction. These findings speak both to the process of acquisition of AP and to its stability.     

Improving vision in adult amblyopia by perceptual learning

Practicing certain visual tasks leads, as a result of a process termed "perceptual learning," to a significant improvement in performance. Learning is specific for basic stimulus features such as local orientation, retinal location, and eye of presentation, suggesting modification of neuronal processes at the primary visual cortex in adults. It is not known, however, whether such low-level learning affects higher-level visual tasks such as recognition. By systematic low-level training of an adult visual system malfunctioning as a result of abnormal development (leading to amblyopia) of the primary visual cortex during the "critical period," we show here that induction of low-level changes might yield significant perceptual benefits that transfer to higher visual tasks. The training procedure resulted in a 2-fold improvement in contrast sensitivity and in letter-recognition tasks. These findings demonstrate that perceptual learning can improve basic representations within an adult visual system that did not develop during the critical period.     

Age-related differences in dual-task visual search: are performance gains retained?

Older and young adults practiced a verbal/spatial dual task and were tested for retention performance 1 month later. Participants first practiced each component task separately to individually determine component processing time. Thus, age-related differences in single-task detection sensitivity were minimized prior to performing the dual task. Participants practiced the dual task for two 1.5-hour sessions. Following the retention interval, they were retested on the single-task components and on the dual task. Correct detection as well as signal detection parameters were examined. Older adults demonstrated decreased sensitivity as well as a more conservative response bias during acquisition. Retention performance for the single tasks replicated previous retention studies, demonstrating age-related performance declines when stimulus-specific learning is assessed. Dual-task retention capability declined for both older and young adults equally when detection accuracy, but not perceptual sensitivity, was measured. Response bias changed differentially for older and young adults across the retention interval.     

The decline of cross-species intersensory perception in human infants

Between 6 and 10 months of age, infants become better at discriminating among native voices and human faces and worse at discriminating among nonnative voices and other species' faces. We tested whether these unisensory perceptual narrowing effects reflect a general ontogenetic feature of perceptual systems by testing across sensory modalities. We showed pairs of monkey faces producing two different vocalizations to 4-, 6-, 8-, and 10-month-old infants and asked whether they would prefer to look at the corresponding face when they heard one of the two vocalizations. Only the two youngest groups exhibited intersensory matching, indicating that perceptual narrowing is pan-sensory and a fundamental feature of perceptual development.     

Does activity engagement protect against cognitive decline in old age? Methodological and analytical considerations

The literature about relationships between activity engagement and cognitive performance is abundant yet inconclusive. Some studies report that higher activity engagement leads to lower cognitive decline; others report no functional links, or that higher cognitive performance leads to less decline in activity engagement. We first discuss some methodological and analytical features that may contribute to the divergent findings. We then apply a longitudinal dynamic structural equation model to five repeated measurements of the Swiss Interdisciplinary Longitudinal Study on the Oldest Old. Performance on perceptual speed and verbal fluency tasks was analyzed in relation to six different activity composite scores. Results suggest that increased media and leisure activity engagement may lessen decline in perceptual speed, but not in verbal fluency or performance, whereas cognitive performance does not effect change in activity engagement.     

Increased narrowing of bronchial segments from immature pigs.

Bronchial narrowing was investigated to determine whether changes in smooth muscle force, described previously in different aged pigs, are associated with differences in airway narrowing. The sensitivity of bronchial segments from suckling and young pigs was compared by perfusion through the lumen with a Krebs solution at a pressure of 5 cmH2O, measuring the reduction in flow in response to carbachol and histamine. Segments of the same internal diameter (i.d. approx. 2.5 mm) from each age were used by selecting proximal segments from suckling and distal segments from young pigs. The sensitivity to carbachol or histamine was the same in smooth muscle strips from proximal and distal bronchi in each age. Furthermore, segments from either age had a similar pressure-volume relationship between -10 and 30 cmH2O. However, concentration-flow curves showed that the airways from sucklings were five times more sensitive than airways from young animals to carbachol (p less than 0.01) and, less consistently, to histamine (p greater than 0.05), when flow was reduced by 50% of maximum. Flow was abolished by maximum concentrations of carbachol at both ages whereas histamine stopped flow in the young segments and reduced it by 80% in the suckling age group. Data indicate a greater sensitivity of bronchial narrowing to carbachol in the intact airway--this is consistent with a greater force production in suckling pig airway smooth muscle. These findings support a postnatal development of airway function, as suggested from clinical observations and provocation studies in humans.     

Decreased in vitro sensitivity to dexamethasone in corticotropes from middle-age rats

A disregulation of the hypothalamic-pituitary-adrenal (HPA) axis due to a decline of negative feedback regulation is a consistent feature of the aging process. Hippocampus has been proposed to be a primary site responsible for this alteration in the HPA axis in aging in rat. In this study an alternative hypothesis that the decreased sensitivity of the HPA axis to glucocorticoids in aging occurs directly in pituitary corticotropes has been tested. The sensitivity of corticotropes isolated from 2- and 13-month old male Sprague-Dawley rats to dexamethasone (DEX) in vitro was examined using a modification of the combined DEX/CRH challenge test that was originally designed for investigation of relative glucocorticoid resistance in vivo. No significant difference in basal ACTH production by corticotropes from the two age groups was detected. Corticotropes from middle-aged rats showed a diminished response of ACTH to CRH stimulation. DEX treatment did not cause a significant inhibition of either basal or CRH-stimulated ACTH release in corticotropes from middle-aged rats. These findings demonstrate an age-related decrease in the sensitivity of corticotropes to glucocorticoids in vitro suggesting that there is a direct, pituitary-mediated dysregulation of the HPA axis in rat starting as early as middle age.     

Broad bandwidth of perceptual learning in the visual system of adults with anisometropic amblyopia

Recent studies have demonstrated that training adult amblyopes in simple visual tasks leads to significant improvements of their spatial vision. One critical question is: How much can training with one particular stimulus and task generalize to other stimuli and tasks? In this study, we estimated the bandwidth of perceptual learning in teenage and adult observers with anisometropic amblyopia and compared it to that of normal observers. We measured and compared contrast sensitivity functions—i.e., sensitivity to sine-wave gratings of various spatial frequencies—before and after training at a single spatial frequency in teenagers and adults with and without amblyopia. We found that the bandwidth of perceptual learning in the amblyopic visual system is much broader than that of the normal visual system. The broader bandwidth, suggesting more plasticity and wider generalization in the amblyopic visual system, provides a strong empirical and theoretical basis for perceptual learning as a potential treatment for amblyopia.     

Chronic cough and the cough reflex in common lung diseases

Following the experience of asthma, characterised by the presence of bronchial hyper-responsiveness, the notion has been accepted that the chronic cough of disease occurs as a result of altered sensitivity of the afferent limb of the cough reflex. Methods for testing for the 'threshold' for eliciting the cough reflex have also been borrowed from asthma care. In the main aerosols are inhaled that contain the relevant stimulus.A number of factors influence the cough response to inhaled aerosols. The distribution of the inhaled aerosol is important as certain chemically sensitive receptors are distributed in different regions of the lungs. The larynx and central airways are important but so too are the peripheral airways. The degree of bronchodilatation is also important as airway narrowing can, itself, induce coughing in man.Asthma, oesophageal reflux and rhinitis patients experience increased coughing, that is associated with increased sensitivity to inhaled capsaicin. In syndromes of chronic obstructive pulmonary disease (COPD) and interstitial lung disease (ILD) increased sensitivity to coughing with capsaicin is common. This appears a specific effect of the pathogenic process of the disease. Modification of the disease process can lessen coughing and the sensitivity to capsaicin.     

Between- and within-individual effects of visual contrast sensitivity on perceptual matching, processing speed, and associative memory in older adults

BACKGROUND: Although cross-sectional studies have demonstrated associations between visual contrast sensitivity and cognitive test performance, it remains unclear whether peripheral visual or perceptual factors explain the association. OBJECTIVE: We aimed at determining whether reducing static contrast of the study stimuli would simulate the performance deficits on measures of processing speed and associative memory that are associated with aging. METHODS: We investigated the mechanism by which vision and memory are associated in a sample of 91 volunteers aged 60-87 years. In tests of perceptual matching, digit-symbol matching, and associative memory, the level of static contrast of the stimuli was manipulated, with three contrast levels. The duration of stimuli presentation was also manipulated in the associative memory task in a full-factorial experimental design. Accuracy and response latencies (for correct trials) were measured. RESULTS: Experimental results showed that within subjects, lower contrast was associated with longer latencies, indicating an effect on information processing speed. Regression analyses replicated previous findings of a moderate to strong association between visual contrast sensitivity and cognitive performance in cross-sectional studies. CONCLUSION: These results provide support for a theory in which visual aging is associated with slower encoding of information as well as being involved at a more central level.     

Color categorization: a possible concordance between genes and culture.

A marked correspondence is found to relate the categories of infant wavelength discrimination and the ethnographic distribution of adult color terms. The structure of the infant category system accounts for at least 75% of the variance in the world ethnographic categories (P less than 0.001). Such a correspondence is predicted to be favored by natural selection when perceptual mechanisms interact with their associated cultural traits.     

Infant and toddler polysomnography

The acquisition process for infant and toddler polysomnography requires pediatric-specific equipment and specially trained personnel. Pediatric laboratories must keep in mind the importance of including the parent through-out the process. The demand for infant and pediatric polysomnography continues to grow as new research increasingly demonstrates the value of studying physiologic variables collected during the study.     

Plasticity of face processing in infancy

Experience plays a crucial role for the normal development of many perceptual and cognitive functions, such as speech perception. For example, between 6 and 10 months of age, the infant's ability to discriminate among native speech sounds improves, whereas the ability to discriminate among foreign speech sounds declines. However, a recent investigation suggests that some experience with non-native languages from 9 months of age facilitates the maintenance of this ability at 12 months. Nelson has suggested that the systems underlying face processing may be similarly sculpted by experience with different kinds of faces. In the current investigation, we demonstrate that, in human infants between 6 and 9 months of age, exposure to non-native faces, in this case, faces of Barbary macaques (Macaca sylvanus), facilitates the discrimination of monkey faces, an ability that is otherwise lost around 9 months of age. These data support, and further elucidate, the role of early experience in the development of face processing.     

Compression of auditory space during rapid head turns

Studies of spatial perception during visual saccades have demonstrated compressions of visual space around the saccade target. Here we psychophysically investigated perception of auditory space during rapid head turns, focusing on the "perisaccadic" interval. Using separate perceptual and behavioral response measures we show that spatial compression also occurs for rapid head movements, with the auditory spatial representation compressing by up to 50%. Similar to observations in the visual system, this occurred only when spatial locations were measured by using a perceptual response; it was absent for the behavioral measure involving a nose-pointing task. These findings parallel those observed in vision during saccades and suggest that a common neural mechanism may subserve these distortions of space in each modality.     

Somatic pain sensitivity in children with recurrent abdominal pain

OBJECTIVE: Evidence is accumulating that recurrent abdominal pain (RAP) in children is associated with visceral hyperalgesia. However, it is not known whether somatic sensitivity is altered as well. Therefore, the aim of our study was to assess somatic pain sensitivity in children with RAP and healthy controls at the abdomen and a distal site (thenar).
METHODS: We examined 20 children with RAP (age 8–14) and 23 healthy control children (age 9–14). Heat and mechanical pain thresholds as well as measures of perceptual sensitization in response to repetitive mechanical or tonic thermal noxious stimulation were assessed.
RESULTS: At the abdominal site, pain sensitivity in children with RAP did not differ significantly when compared to controls. At the thenar, pain thresholds of children in the RAP group were not significantly different from control children. However, children with RAP showed less perceptual sensitization in response to tonic heat and repetitive mechanical stimuli (ps ≤ 0.05) than controls.
CONCLUSIONS: We found no evidence for somatic hyperalgesia in RAP arguing against generalized hyperalgesia in these children. Somatic hypoalgesia at the thenar might either be related to a dysregulation of sensory processing and/or attentional avoidance of pain-related stimuli.     

Amplitude envelope onsets and developmental dyslexia: A new hypothesis

A core difficulty in developmental dyslexia is the accurate specification and neural representation of speech. We argue that a likely perceptual cause of this difficulty is a deficit in the perceptual experience of rhythmic timing. Speech rhythm is one of the earliest cues used by infants to discriminate syllables and is determined principally by the acoustic structure of amplitude modulation at relatively low rates in the signal. We show significant differences between dyslexic and normally reading children, and between young early readers and normal developers, in amplitude envelope onset detection. We further show that individual differences in sensitivity to the shape of amplitude modulation account for 25% of the variance in reading and spelling acquisition even after controlling for individual differences in age, nonverbal IQ, and vocabulary. A possible causal explanation dependent on perceptual-center detection and the onset-rime representation of syllables is discussed.     

The effect of codeine on the Urge-to-Cough response to inhaled capsaicin

We have shown previously in normal subjects that a sensory measure, the Urge-to-Cough rating, increases at concentrations of inhaled capsaicin that are lower than those necessary to elicit reflex cough. This finding suggests that the Urge-to-Cough may represent an index of the cough response. Research on cough in the human has most often employed challenge with inhaled capsaicin to induce reflex cough. Current measures of cough sensitivity in the human provide no information regarding the intensity of cough. The influence of codeine on cough perceptual sensitivity and the relationship to cough intensity with capsaicin-induced cough in normal subjects has not been evaluated. This study determined the effect of codeine on capsaicin-induced cough perceptual sensitivity and motor response in normal subjects in a double-blind, placebo-controlled, crossover study. This approach investigated the relevance of cough sensitivity, intensity, and sensory modalities in the assessment of cough suppression in humans. This study consisted of three experimental trials: administration of placebo, 30 mg codeine and 60 mg codeine. The study was double-blinded. The order of the three trials was randomized. Respiratory motor pattern was recorded with EMGs from the rectus abdominis, lateral abdominal muscles and eighth intercostal space. The subjects leaned into a fume hood to inspire deeply for 2 s once through a mouthpiece connected to the nebulizer. A modified Borg scale was used to estimate their Urge-to-Cough. The experimental trial consisted of eight test solutions of 0-200 microM capsaicin. Each solution was presented three times in a randomized block order for a total of 24 presentations. The lowest capsaicin concentration to elicit a cough was determined. The lowest capsaicin concentration to elicit an Urge-to-Cough greater than zero was identified. The Urge-to-Cough sensitivity was determined from the log-log slope. For placebo, the Urge-to-Cough was zero with inhalation of the vehicle and no coughs were observed. The threshold capsaicin concentration for subjects to report an Urge-to-Cough was 15.6 microM (+/-2.6 SEM). The capsaicin concentration threshold for eliciting a cough was significantly greater, 39.3 microM (+/-5.6 SEM). As the capsaicin concentration increased, the magnitude estimation of the Urge to-Cough increased. The slope of the log-log relationship for the Urge-to-Cough was 0.94 (+/-0.07 SEM). As the capsaicin concentration increased, the number and intensity of the coughs increased. The administration of 30 and 60 mg codeine had no significant effect on the threshold capsaicin concentration for the Urge-to-Cough. There was also no significant codeine effect on the slope of the log-log Urge-to-Cough relationship. Thirty and sixty milligram codeine had no significant effect on the relationship between the capsaicin concentration and the number and intensity of the coughs. The results of this study demonstrate that the threshold for a subject to perceive an Urge-to-Cough was less than the capsaicin concentration that elicits the cough motor response. There was a direct relationship between the sensory intensity (magnitude estimation of the Urge-to-Cough) and the cough number and intensity. Thus, as the sense of an Urge-to-Cough increased the cough motor response increased. Neither the 30 nor 60 mg codeine affected the perceptual or motor sensitivity to capsaicin-induced cough. These results showed that the initial threshold for responding to capsaicin-induced cough is the perception of an Urge-to-Cough, followed by a motor cough response if the capsaicin is increased above the perceptual threshold. As the capsaicin concentration increases, both the perceptual need to cough and the cough motor response increase. The response of subjects to inhalation of capsaicin consisted of both a sensory component leading to perception of an Urge-to-Cough and motor cough behavior.     

Negative washout rate of myocardial thallium-201--a specific marker for high grade coronary artery narrowing.

A decline is usually observed in the myocardial uptake of thallium-201 in delayed imaging compared with initial imaging. In patients with severe coronary artery disease (CAD), the uptake is sometimes higher in the delayed than in the initial imaging, which is expressed as negative washout rate. To evaluate the diagnostic implications of this negative washout rate the findings of dipyridamole thallium scintigraphy in 582 patients with coronary artery disease were evaluated. The negative washout rate was present in 201 of 582 patients (35%). It had a significant association with high grade coronary artery narrowing of > or = 90%. Sensitivity in detecting patients with this high grade narrowing by negative washout rate was 48%, its specificity was 93%, and its positive predictive value was 94%. Sensitivity to detect individual coronary artery narrowing of > or = 90% did not decrease according to the extent of CAD, with the highest detection in the left anterior descending coronary artery and the lowest in the left circumflex coronary artery. Since patients with high grade coronary narrowing often require coronary intervention, the results of this study suggest the diagnostic importance of negative washout rate in the identification of the particular subset of patients with CAD.     

The mechanism of deep inspiration-induced bronchoprotection: evidence from a mouse model

In healthy individuals, deep inspirations (DIs) taken prior to a bronchial challenge reduce the bronchoconstrictor response, which is termed "bronchoprotection". The mechanism(s) of DI-induced bronchoprotection is unclear. The forced oscillation technique was used to assess the effect of prior DI on subsequent bronchoconstriction to methacholine (MCh) in BALB/c mice. We assessed likely mechanisms for the bronchoprotective effects of DI including reduced airway narrowing (from changes in airway resistance) and/or closure (changes in tissue elastance) and enhanced bronchodilation to a subsequent DI (% reversal in airway narrowing). DI prior to MCh challenge: 1) did not reduce but instead enhanced airway narrowing (p<0.05); 2) increased ventilation heterogeneity (p<0.05); 3) enhanced the subsequent bronchodilatory response to DI (p<0.05); and 4) reduced tissue elastance (p<0.05), suggesting opening of closed airways or alveoli units. Our findings suggest that DI prior to MCh challenge may elicit a series of changes, some of which are beneficial to respiratory function (enhanced bronchodilation), while others place greater load on the system (enhanced bronchoconstriction and ventilation heterogeneity). It is proposed that the relative magnitudes of these opposing physiological and mechanical effects will determine the net effect on respiratory function in health and disease.