Tyrosine ameliorates heat induced delay in event related potential P300 and contingent negative variation

The efficacy of tyrosine, a catecholamine precursor, as a countermeasure in the reduction of cognitive decline during heat exposure (HE) using event-related potential P300, and contingent negative variation (CNV) was evaluated. Ten healthy males, age 20–30 years participated in the study. Volunteers received placebo or tyrosine (6.5 g) 90 min prior to HE (1.5 h in 45 °C + 30% RH). P300 latency was significantly increased (p < 0.01) during exposure with placebo, which was reduced significantly (p < 0.01) after tyrosine supplementation. There was an increase in CNV M100 latency (p < 0.05) and reaction time (p < 0.01) and decrease in M100 amplitude (p < 0.01) during HE with placebo, which returns to near normal level with the tyrosine administration. A significantly higher plasma norepinephrine (p < 0.05), dopamine and epinephrine levels were detected in tyrosine supplemented group post heat exposure. HE increases the brain catecholamine activity thereby reduces the plasma norepinephrine and dopamine level leading to a reduction in cognitive performances. Tyrosine supplementation increases the catecholamine level and reduces the impairment of cognitive performance during HE.     

A temporal sampling framework for developmental dyslexia

Neural coding by brain oscillations is a major focus in neuroscience, with important implications for dyslexia research. Here, I argue that an oscillatory 'temporal sampling' framework enables diverse data from developmental dyslexia to be drawn into an integrated theoretical framework. The core deficit in dyslexia is phonological. Temporal sampling of speech by neuroelectric oscillations that encode incoming information at different frequencies could explain the perceptual and phonological difficulties with syllables, rhymes and phonemes found in individuals with dyslexia. A conceptual framework based on oscillations that entrain to sensory input also has implications for other sensory theories of dyslexia, offering opportunities for integrating a diverse and confusing experimental literature.     

Reading acquisition, developmental dyslexia, and skilled reading across languages: a psycholinguistic grain size theory

The development of reading depends on phonological awareness across all languages so far studied. Languages vary in the consistency with which phonology is represented in orthography. This results in developmental differences in the grain size of lexical representations and accompanying differences in developmental reading strategies and the manifestation of dyslexia across orthographies. Differences in lexical representations and reading across languages leave developmental "footprints" in the adult lexicon. The lexical organization and processing strategies that are characteristic of skilled reading in different orthographies are affected by different developmental constraints in different writing systems. The authors develop a novel theoretical framework to explain these cross-language data, which they label a psycholinguistic grain size theory of reading and its development.     

Becoming literate in different languages: similar problems, different solutions

The teaching of reading in different languages should be informed by an effective evidence base. Although most children will eventually become competent, indeed skilled, readers of their languages, the pre-reading (e.g. phonological awareness) and language skills that they bring to school may differ in systematic ways for different language environments. A thorough understanding of potential differences is required if literacy teaching is to be optimized in different languages. Here we propose a theoretical framework based on a psycholinguistic grain size approach to guide the collection of evidence in different countries. We argue that the development of reading depends on children's phonological awareness in all languages studied to date. However, we propose that because languages vary in the consistency with which phonology is represented in orthography, there are developmental differences in the grain size of lexical representations, and accompanying differences in developmental reading strategies across orthographies.     

Melting chocolate and melting snowmen: analogical reasoning and causal relations

Children's performance in the classical a:b::c:d analogy task is traditionally very poor prior to the Piagetian stage of formal operations. The interpretation has been that the ability to reason about higher-order relations (the relations between the a:b and c:d parts of the analogy) is late-developing. However, an alternative possibility is that the relations used to date in the analogies are too difficult for younger children. Two experiments presented children aged 3, 4 and 6 years with a:b::c:d analogies which were based on relations of physical causality such as melting and cutting, for example chocolate bar:melted chocolate::snowman:melted snowman. Understanding of these particular causal relations is known to develop between the ages of 3 and 4 years. It was found that even 3-year-olds could solve the classical analogies if they understood the causal relations on which they were based.     

Phonological priming and orthographic analogies in reading

Recent work has demonstrated that children can use orthographic analogies between the spelling patterns in words to help in decoding new words (e.g., using beak to read peak; Goswami, 1986, 1988). However, one objection has been that these analogy effects may be due to phonological priming. Two experiments examined the phonological priming alternative. In Experiment 1, a single word reading task compared the use of analogies to read words that shared both orthography and phonology (e.g., most-post), that shared orthography only (e.g., most-cost), or that shared phonology only (e.g. most-toast--the phonological priming condition). Limited effects of phonological priming were found. Experiment 2 then presented the same words embedded in prose passages--"real reading." While the orthographic analogy effect remained robust, the small phonological priming effect disappeared. It is argued that phonological priming is an insufficient explanation of the analogy effect at the single word level, and plays no role in the use of analogies in story reading.     

Playgroup attractiveness studied with information integration theory

Playgroup attractiveness was studied in two critical tests of information integration theory. In Experiment 1, the ratio of good to bad members in the group, and the number of toys available to the group, were varied in a 4 × 4 factorial design. The results obeyed the parallelism prediction of the theory, thereby indicating that group attractiveness was a sum or an average of the two given pieces of information. Experiment 2 provided a critical qualitative test between the adding and averaging hypotheses. The results eliminated the adding rule, supported the averaging rule. These results illustrate the potential power that integration theory provides to the experimental study of group attractiveness in children.     

Measuring Executive Function Deficits Following Head Injury: An Application of SMS Simulation Technology

The Psychological Record - Neuropsychological tests have limited sensitivity in identifying subtle residual cognitive impairments in patients with good medical recovery from head injury and...