Synaptic Reliability Correlates with Reduced Susceptibility to Synaptic Potentiation by Brain-Derived Neurotrophic Factor

Recent studies have implicated brain-derived neurotrophic factor (BDNF) in use-dependent modification of hippocampal synapses. BDNF can rapidly potentiate synaptic transmission at glutamatergic synapses by enhancing transmitter release. Using simultaneous perforated patch recording from pairs and triplets of glutamatergic hippocampal neurons, we have examined how the initial state of the glutamatergic synapse determines its susceptibility to synaptic modification by BDNF. We found that the degree of synaptic potentiation by BDNF depends on the initial reliability and strength of the synapse: Relatively weak connections were strongly potentiated, whereas the effect was markedly reduced at stronger synapses. The degree of BDNF-induced potentiation strongly correlated with the initial coefficient of variation (CV) of the amplitude of excitatory postsynaptic currents (EPSCs) and inversely correlated with the initial paired–pulse facilitation, suggesting that synapses with lower release probability (P_r) are more susceptible to the action of BDNF. To determine whether saturation of P_r could have masked the potentiation effect of BDNF in the stronger synapses, we lowered the initial P_r either by reducing the extracellular Ca²⁺ concentration ([Ca²⁺]_o) or by bath application of adenosine. Synapses that were initially strong remained unaffected by BDNF under these conditions of reduced P_r. Thus, the lack of BDNF effect on synaptic efficacy cannot simply be accounted for by saturation of P_r, but rather may be due to intrinsic changes associated with synaptic maturation that might covary with P_r. Finally, the dependence on initial synaptic strength was also found for divergent outputs of the same presynaptic neuron, suggesting that synaptic terminals with different degrees of responsiveness to BDNF can coexist within in the same neuron.     

Emotion and perception of one's own actions--a comment on Wilke, Synofzik and Lindner

Wilke et al. (2012) make significant headway in gaining a better understanding of the influence affect cues may have on action perception and judgement. In our view their account also brings up a row of important questions demanding further research. This concerns (a) the role of conceptual and non-conceptual content and (b) the different effects emotions of the same valence may play in the perception and judgement of action.     

Thinking sadly: In favor of an adverbial theory of emotions

Introspective as well as empirical evidence indicates that emotions shape our thinking in numerous ways. Yet, this modificatory aspect of emotions has received relatively little interest in the philosophy of emotion. I give a detailed account of this aspect. Drawing both on the work of William James and adverbialist conceptions of perception, I sketch a theory of emotions that takes these aspects into consideration and suggest that we should understand emotions as manners of thinking.     

Cognitive representation of personal stereotypes

A production task analogue of the traditional multiple choice trait checklist method was used to investigate stereotypes. Subjects were asked to supply rather than to select the most characteristic attributes of specified social groups. In a departure from tradition, stability of the content of stereotypes was analysed for personal stereotypes held by individuals rather than for social stereotypes shared by a cultural group. In contrast to the widely held belief that social stereotypes are fixed and unchanging, personal stereotypes were found to be only moderately stable over time. Only about two-fifths of the most characteristic attributes were duplicated in sessions separated by one week, and only about one-fifth of the most Characteristic attributes were duplicated in sessions separated by one-month or two-month intervals. Findings also supported the notion that general attributes, most characteristic attributes, and least characteristic attributes of a social category are not totally redundant and are represented quasi-independently in memory. Only about half of the most characteristic responses had also occurred on free response protocols and over half of the least characteristic responses tended not to be polar opposites of the most characteristic responses. It was the case, however, that with a production analogue of the multiple-choice trait checklist, trait-adjectives were the most frequent class of person information and accounted for between 50 and 60 per cent of the responses. However, eleven other classes of person information also occurred. Empirical results were applied toward a reexamination of the concepts of stereotype (data structure for the most characteristic attributes of a social group) and stereotyping (rigid procedures for processing data structures) and to a conceptual analysis of how stereotypes and social categories are structurally related.     

Writing problems in developmental dyslexia: under-recognized and under-treated

The International Dyslexia Association defines dyslexia as unexpected problems of neurobiological origin in accuracy and rate of oral reading of single real words, single pseudowords, or text or of written spelling. However, prior research has focused more on the reading than the spelling problems of students with dyslexia. A test battery was administered to 122 children who met the inclusion criteria for dyslexia and qualified their families for participation in a family genetics study that has been ongoing for over a decade. Their parents completed the same test battery. Although a past structural equation modeling study of typically developing children identified a significant path from handwriting to composition quality, the current structural equation modeling study identified a significant path from spelling to composition for children and their parents with dyslexia. Grapho-motor planning did not contribute uniquely to their composition, showing that writing is not just a motor skill. Students with dyslexia do have a problem in automatic letter writing and naming, which was related to impaired inhibition and verbal fluency and may explain their spelling problems. Results are discussed in reference to the importance of providing explicit instruction in the phonological, orthographic, and morphological processes of spelling and in composition to students with dyslexia and not only offering accommodation for their writing problems.     

Growth in Phonological,Orthographic, and Morphological Awareness in Grades 1 to 6

Growth curve analyses showed that (a) word-level phonological and orthographic awareness show greatest growth during the primary grades but some additional growth thereafter, and (b) three kinds of morphological awareness show greatest growth in the first three or four grades but one—derivation—continues to show substantial growth after fourth grade. Implications of the findings for the role of three kinds of linguistic awareness—phonological, orthographic, and morphological—in learning to read and spell words are discussed. A case is made that phonological awareness, while necessary, is not sufficient for learning to read English—all three kinds of linguistic awareness that are growing during the primary grades need to be coordinated and applied to literacy learning. This finding and a review of the research on linguistic awareness support the conclusion that the recommendations of the National Reading Panel need to be amended so that the research evidence supporting the importance of both orthographic and morphological awareness, and not only phonological awareness, is acknowledged. Moreover, evidence-based strategies for teaching each of these kinds of linguistic awareness and their interrelationships need to be disseminated to educational practitioners.     

Gender differences in orthographic, verbal, and compositional fluency: Implications for assessing writing disabilities in primary grade children

Measures of oral verbal fluency (word finding), written orthographic fluency (alphabet task), and written composition (narrative and oral expository) were administered to 300 children (50 girls and 50 boys each in the first, second, and third grades). Both oral verbal fluency and written orthographic fluency correlated significantly with the number of words (fluency) and the number of clauses (microorganization) in the compositions, but boys performed significantly better than girls on oral verbal fluency and girls performed significantly better than boys on written orthographic fluency. Girls consistently outperformed boys on the number of words and the number of clauses produced in narrative and expository composition. Thus, in beginning writing, orthographic fluency may be relatively more important than verbal fluency and boys may be at greater risk for writing disabilities. However, more boys were identified as having a disability in composition when absolute criteria (lowest 5% of normal distribution) were used, but about the same number of boys and girls were identified as having a disability in composition when relative criteria (significant discrepancy between Verbal IQ and compositional skill, based on the Mahalanobis statistic) were used. School psychologists are encouraged to use standardized measures of othographic, verbal, and compositional fluency to identify primary grade children needing early intervention to prevent more severe writing disabilities.     

Gender differences in severity of writing and reading disabilities

Gender differences in mean level of reading and writing skills were examined in 122 children (80 boys and 42 girls) and 200 adults (115 fathers and 85 mothers) who showed behavioral markers of dyslexia in a family genetics study. Gender differences were found in writing and replicated prior results for typically developing children: Boys and men were more impaired in handwriting and composing than were girls and women, but men, who were more impaired in those writing skills, were also more impaired in spelling than women. Men were more impaired than women in accuracy and rate of reading passages orally, but boys were not more impaired than girls on any of the reading measures. Males were consistently more impaired than females in orthographic skills, which may be the source of gender differences in writing, but not motor skills. Population-based studies that report gender differences in reading in children with dyslexia may be confounding reading and writing disorders—the latter being the true source of gender differences in both children and adults with dyslexia.     

Questions and the allocation,construction, and timing of turns in child discourse

The role of questions (i.e., interrogative forms with illocutionary force of questioning) in turn-taking was investigated. Turn-taking has three components: speaker selection, turn construction, and timing of turn transfer. Questions explicitly, via the verbal code, provide a clearance signal and a requested topic for the response, whereas assertions do not. Consequently, questions, in general, but not all linguistically defined sub-types of questions, contrast with assertions on the first two turn-taking components. It was shown that the probability of a turn transfer, of a relevant response, and of a turn transfer and relevant response is higher following questions, in general, than assertions. Questions also transmit an earlier speaker-selection signal (initial or terminal clausal position) whereas in the case of assertions speaker selection must be managed following clause completion. Questions do not seem to contrast with assertions on the third component as a result of this earlier clearance signal. Keeping the relevance of an utterance to prior text and the content of the response constant, switching pauses were about the same following both questions and assertions.This research was supported from funds of the Biomedical Research Support Grant, 5SO7RR07041-12 to The Johns Hopkins University and a grant from the Spencer Foundation to the second author.     

Relevant replies to questions: Answers versus evasions

A taxonomy was developed that accounts for all relevant partner responses to questions in the natural discourse of nursery school dyads. Evasive replies as well as answers must be included in such a scheme. Evasive replies are discoursally linked to questions, whereas answers are grammatically linked to questions. Nursery school children in this sample tended to inspect the nature of the relevance of a reply to a question and, at least on some occasions, to acknowledge replies to questions (explicitly or implicitly) and to respond differently to evasive replies than replies in general.This work was supported by a grant from the Spencer Foundation to the second author.