Monthly Archives: February 2009
In this paper, we combine neurological and developmental evidences in order to differentiate between two levels of sharing: dyadic sharing, virtually present from birth and depending on the activation of shared representation, and triadic sharing, requiring that agents not only share a common representation, but also represent complementary perspectives. Mirror neurons are proposed as a fundamental mechanism to account for dyadic sharing, explaining why infants are able to interact symmetrically and contingently with others from very early on in infancy. In the second part of this paper, we reinterpret the 9-month revolution as a revolution in sharedness: the transition from dyadic sharing to triadic sharing. The neural event which renders this transition possible might be the emergence of a basic mechanism that allows the attribution of actions and intentions to their owner. We suggest two neuronal networks possibly responsible for the shift to triadic sharing.
Developmental Species Differences in Brain Cell Cycle Rates between Northern Bobwhite Quail (Colinus virginianus) and Parakeets (Melopsittacus undulatus): Implications for Mosaic Brain Evolution
Adult brains differ among species in the proportional sizes of their major subdivisions. For example, the telencephalon occupies 71% of the entire brain in parakeets (Melopsittacus undulatus) but only 54% in quail (Colinus virginianus). In contrast, the tectum is smaller in parakeets than in quail. To determine whether these differences in brain region size arise because of species differences in cell cycle rates, parakeet and quail embryos were collected at various stages of development (HH24-HH37) and stained with antibodies against proliferating cell nuclear antigen (PCNA), which labels all dividing cells, and phosphorylated histone-3 (pH3), which labels M-phase cells. Analysis of pH3+ cell densities and pH3+/PCNA+ cell ratios were used to compare cell cycle rates across stages and species. Cumulative labeling with bromodeoxyuridine (BrdU) was also used to compare cell cycle rates at stages 24 and 28 in quail. We found that telencephalic cell cycle rates lengthen with age in both species, but that they lengthen significantly later in parakeets than in quail. This species difference in cell cycle rates explains, at least partly, why adult parakeets have a proportionately larger telencephalon. Tectal cell cycle rates also remain elevated for a prolonged period of time in parakeets compared to quail. This seems paradoxical at first, given that the parakeet’s adult tectum is relatively small. However, the tectum is initially much smaller but then grows more extensively in parakeets than in quail. Thus, species differences in adult brain proportions can be traced back to species differences in cell cycle kinetics.
Abstract This study examined whether specific emotion-related constructs may be uniquely related to anxious or depressive symptoms in youth. Although anxiety and depression are comorbid in both youth and adult populations, delineation of these disorders is a worthwhile endeavor given that such differentiation may lead to a clearer conceptualization of the disorders that in turn may facilitate more efficient diagnosis and effective treatment. Children in the 4th and 5th grades (N = 187; M age = 10 years, 3 months) completed measures to assess symptoms of anxiety and depression and emotion-related functioning. Using structural equation modeling, emotion-related variables were identified that were common to both anxiety and depression (poor emotion awareness, emotion dysregulation, poor emotion regulation coping, high frequency of negative affect), most strongly related to depression (low frequency of positive affect), and most distinctly associated with anxiety (frequency of emotion experience, somatic response to emotion activation). The findings suggest that comprehensive theoretical formulations of anxiety and depression in youth should consider emotion-related variables. The results also suggest potential avenues that may facilitate more efficient assessment and treatment of such youth.
Abstract The aim of this study was to determine whether depression can explain the negative relationship between academic performance and the belief that intelligence is a fixed trait, i.e., entity belief. A sample of 353 French volunteer adolescents (age 11–16) completed questionnaires assessing entity theory and depressive symptoms (Children Depression Inventory: CDI). Academic performance was assessed by math performance while controlling for baseline level of math ability. Results of this study revealed that entity theory is a significant negative predictor of academic performance and a significant positive predictor of depression. Importantly, our findings also show that depression plays a significant mediating role between entity theory and academic performance. Our findings indicate that individuals who consider their abilities to be non-malleable are more likely to develop depressive symptoms which, in turn, decrease academic performance. These findings contribute to tailoring specific prevention and treatment programs for childhood and adolescent depression
Several authors have reported that participants have a leftward bias when holding a newborn or young infant. Our study of mothers met before and after their infant’s birth sought to ascertain whether particular combinations of affective symptoms (depression, anxiety) and holding positions (horizontal versus vertical) were related to holding-side biases. Our results showed that (a) mothers displayed a significant leftward (71%) holding bias, (b) mothers with affective symptoms held their newborn on the right side and more frequently in the vertical position, and (c) hemispheric specialization for perceiving visual emotions had no significant effect on the holding-side biases of new mothers. These results suggest that maternal affective symptoms have a dominant effect on the determination of holding-side preferences, when associated with a particular holding position. Copyright © 2008 John Wiley & Sons, Ltd.
Interspecific variation in relative brain size (encephalization), the relative size of the five major brain areas (the telencephalon, diencephalon, mesencephalon, cerebellum, and medulla) and the level of cerebellar foliation was assessed in over 20 representative species of batoid (skates and rays), from eight families. Using species as independent data points and phylogenetically independent contrasts, relationships among each of the neuroanatomical variables and two ecological variables, habitat and lifestyle, were assessed. Variation in relative brain size and brain organization appears to be strongly correlated with phylogeny. Members of the basal orders Rajiformes and Torpediniformes tend to have relatively small brains, with relatively small telencephalons, large medullas, and smooth, unfoliated cerebellums. More advanced Myliobatiformes possess relatively large brains, with relatively large telencephalons, small medullas, and complex, heavily foliated cerebellums. Increased brain size, telencephalon size, and cerebellar foliation also correlate with living in a complex habitat (such as in association with coral reefs) and an active, benthopelagic lifestyle, but as primary habitat and lifestyle also closely match phylogenetic relationships in batoids, it is difficult to separate the influence of phylogeny and ecological factors on brain organization in these animals. However, the results of two forms of multivariate analysis (principal component analysis and cluster analysis) reveal that certain species are clustered with others that share ecological traits, rather than with more closely related species from the same order. This suggests that ecological factors do play a role in defining patterns of brain organization and there is some evidence for ‘cerebrotypes’ in batoids.
Decapod crustacean escape responses are adaptive behaviors whose neural bases are well understood. The escape circuit is composed of giant neurons. Lateral giant interneurons (LGs) respond to posterior stimuli by generating a somersaulting tailflip; medial giant interneurons (MGs) respond to anterior stimuli with a backwards tailflip. Both sets of interneurons connect to giant fast flexor motor neurons (MoGs). Most features of the escape circuit are thought to result from strong selective pressure to respond to stimuli in the shortest possible time. Despite the apparent advantages of the escape circuit, it has been lost in multiple taxa independently. Some losses of the escape circuit may be rare cases of disaptation, where organisms are less well adapted than related species (i.e., those with the escape circuit). The losses of the escape circuit might be key deletions that promoted the radiation of decapod crustaceans by increasing selection pressure for species to evolve new anti-predator strategies and removing constraints against change.
In anurans, much is known about the role of the auditory midbrain in processing conspecific calls, but comparatively little is known about the role of the pallium. To address this deficiency, we investigated the induction of the immediate early gene egr-1 by natural mate chorus in the medial, dorsal, lateral, and ventral pallium of female túngara frogs. We found strong acoustically evoked egr-1 expression in the dorsal medial pallium (p < 0.01) and ventral pallium (p = 0.02), with a weaker effect in the lateral pallium (p = 0.05). In the ventral pallium, acoustically induced egr-1 expression was stronger in the anterior portion. Measures of movement and olfactory activity could not explain a significant portion of acoustically evoked pallial egr-1 expression. In contrast, egr-1 expression in the auditory midbrain covaried with egr-1 expression in the dorsal medial pallium and ventral pallium, suggesting that their activity was coupled with auditory activity. Taken together, these results suggest that the acoustically evoked egr-1 expression in the dorsal medial pallium and ventral pallium were a direct result of auditory stimulation. Furthermore, although both anatomical and electrophysiological evidence demonstrate that multiple modalities overlap in the frog pallium, our results show that a multimodal stimulus is not required to activate pallial neurons. Although the functional role of the frog pallium is not known, our results demonstrate that species-specific sounds activate spatially segregated and anatomically distinct areas of the frog pallium, inviting further investigation into the role of the frog pallium in acoustic communication.
Cross-Sectional Study of Women with Trichotillomania: A Preliminary Examination of Pulling Styles, Severity, Phenomenology, and Functional Impact
Abstract The current study utilized a cross-sectional design to examine pulling severity, phenomenology, functional impact, and “focused” and “automatic” pulling styles in women with TTM across a wide age spectrum. “Automatic” pulling refers to pulling occurring primarily out of one’s awareness, while “focused” pulling refers to pulling with a compulsive quality that may include pulling in response to a negative emotional state (e.g., anxiety, stress, anger, etc.), an intense thought or urge, or in an attempt to establish symmetry. In the present study, data were collected from 1,471 female participants (age 10–69) meeting modified diagnostic criteria for TTM via two separate online surveys (one for children/adolescents, one for adults). Pulling severity remained stable across the different developmental cohorts. However, fluctuations in functional impact (e.g., social and interpersonal impairment) were noted. “Automatic” pulling showed relatively little fluctuation from adolescence to adulthood, while “focused” pulling demonstrated considerable fluctuation coinciding with psychological distress and typical ages of important biological changes (e.g., pubertal onset) in children/adolescents and adults (e.g., perimenopause). Conclusions, treatment implications, limitations, and future areas of research are discussed.
The Relationship Between Theory of Mind and Executive Function in a Sample of Children from Mainland China
Abstract To explore the relationship between theory of mind (ToM) and executive function (EF) in a sample of individuals from mainland China, 20 children with autism spectrum disorders (ASD), 26 children with Attention Deficit Hyperactivity Disorder (ADHD), and 30 normal control subjects were compared on two batteries of ToM tasks and EF tasks. Children with ASD had a significant theory of mind impairment relative to the other controls, while non-verbal IQ removed group differences in executive function. ToM was significantly correlated with inhibitory control. Performance on inhibitory control tasks, however, did not affect performance on ToM tasks.
Five Systems of Psychiatric Classification for Preschool Children: Do Differences in Validity, Usefulness and Reliability Make for Competitive or Complimentary Constellations?
Abstract DSM-IV and ICD-10 have limitations in the diagnostic classification of psychiatric disorders at preschool age (0–5 years). The publication of the Diagnostic Classification 0-3 (DC:0-3) in 1994, its basically revised second edition (DC:0-3R) in 2005 and the Research Diagnostic Criteria––Preschool Age (RDC-PA) in 2004 have provided several modifications of these manuals. Taking into account the growing empirical evidence highlighting the need for a diagnostic classification system for psychiatric disorders in preschool children, the main categorical classification systems in preschool psychiatry will be presented and discussed. The paper will focus on issues of validity, usefulness and reliability in DSM-IV, ICD-10, RDC-PA, DC:0-3, and DC:0-3R. The reasons for including or excluding postulated psychiatric disorder categories for preschool children with variable degrees of empirical evidence into the different diagnostic systems will be discussed
Non-invasive measurements of intralabyrinthine pressure changes by electrocochleography and otoacoustic emissions
By varying the mechanical load on the stapes footplate, intralabyrinthine pressure (ILP) influences the stiffness of the middle ear and modifies its transfer function. This results in a characteristic phase shift of the otoacoustic emissions (OAEs) around 1 kHz [Buki, B., Avan, P., Lemaire, J.J., Dordain, M., Chazal, J., Ribari, O., 1996. Otoacoustic emissions: a new tool for monitoring intracranial pressure changes through stapes displacements. Hear. Res. 94, 125–139]. This finding provides non-invasive means of monitoring changes of ILP and indirectly of intracranial pressure. Yet the vulnerability of OAEs to sensorineural hearing loss excludes many patients from being monitored in this manner. Being dependent on the middle-ear transfer function, the phase of the cochlear microphonic potential (CM) around 1 kHz should also respond to ILP changes while being less affected by impaired hearing than OAEs. Here, normal volunteers were subjected to body tilt resulting in stepwise changes in their intracranial pressure and ILP. Their CM around 1 kHz was recorded by extratympanic electrocochleography and its dependence on body position was compared to that of distortion-product OAEs. The posture-induced CM changes were also monitored in ears with sensorineural deafness and impaired OAEs to assess the usefulness of CM in the presence of hearing impairment. Last, OAEs and CM were simultaneously monitored in gerbils during intracranial pressure changes brought about via an intracranial catheter. The phase and level shifts induced by body tilt in man and intracranial pressure changes in gerbils showed up both in distortion-product OAEs and CM with similar time courses. In normally-hearing subjects, the mean phase shifts reached 16.3° for CM and 41.6° for OAEs, and CM remained large enough in hearing-impaired subjects for ILP to be monitored. The ratio of about two of OAEs to CM phase shifts matched the prediction of middle-ear models allowing for the fact that CM does not travel back through the middle ear while OAEs do. It follows that CM phase around 1 kHz provides non-invasive access to ILP changes even if OAEs cannot be measured due to sensorineural hearing loss.
from Hearing Research
Abstract Dyslexia is a complex reading and writing disorder with a strong genetic component. In a German case-control cohort, we studied the influence of the suspected dyslexia-associated gene DCDC2. For the first time in a German cohort, we describe association of a 2445 basepair deletion, first identified in an American study. Evidence of association for three DCDC2 single nucleotide polymorphisms (rs807724, rs793862, rs807701), previously identified in German or American cohorts, was replicated. A haplotype of these polymorphisms showed evidence for association as well. Thus, our data further corroborate association of DCDC2 with dyslexia. Analysis of functional subgroups suggests association of investigated DCDC2 variants mainly with nondysphonetic, nonsevere, but probably dyseidetic (surface) dyslexia. Based on the presumed function of DCDC2, our findings point to a role of impaired neuronal migration in the etiology of the disease.
from Annals of Dyslexia
All distinguished forms of treatment were effective. However, only for a proportion of the children this meant a clinical relevant improvement. For the improvement of language comprehension targeted language therapy seems essential, as children without this (children receiving surgical hearing impairment) did not improve their LCQ.