Dyslexia Impairs Speech Recognition but Can Spare Phonological Competence

Dyslexia is associated with numerous deficits to speech processing. Accordingly, a large literature asserts that dyslexics manifest a phonological deficit. Few studies, however, have assessed the phonological grammar of dyslexics, and none has distinguished a phonological deficit from a phonetic impairment. Here, we show that these two sources can be dissociated. Three experiments demonstrate that a group of adult dyslexics studied here is impaired in phonetic discrimination (e.g., ba vs. pa), and their deficit compromises even the basic ability to identify acoustic stimuli as human speech. Remarkably, the ability of these individuals to generalize grammatical phonological rules is intact. Like typical readers, these Hebrew-speaking dyslexics identified ill-formed AAB stems (e.g., titug) as less wordlike than well-formed ABB controls (e.g., gitut), and both groups automatically extended this rule to nonspeech stimuli, irrespective of reading ability. The contrast between the phonetic and phonological capacities of these individuals demonstrates that the algebraic engine that generates phonological patterns is distinct from the phonetic interface that implements them. While dyslexia compromises the phonetic system, certain core aspects of the phonological grammar can be spared.     

Reading “Sun” and Looking Up: The Influence of Language on Saccadic Eye Movements in the Vertical Dimension

Traditionally, language processing has been attributed to a separate system in the brain, which supposedly works in an abstract propositional manner. However, there is increasing evidence suggesting that language processing is strongly interrelated with sensorimotor processing. Evidence for such an interrelation is typically drawn from interactions between language and perception or action. In the current study, the effect of words that refer to entities in the world with a typical location (e.g., sun, worm) on the planning of saccadic eye movements was investigated. Participants had to perform a lexical decision task on visually presented words and non-words. They responded by moving their eyes to a target in an upper (lower) screen position for a word (non-word) or vice versa. Eye movements were faster to locations compatible with the word''s referent in the real world. These results provide evidence for the importance of linguistic stimuli in directing eye movements, even if the words do not directly transfer directional information.     

Intersensory Interactions in Hermissenda

Hair cells of the Hermissenda statocyst respond to photic stimulation. This response requires the presence of at least one of the two eyes. Two principal hair cell responses to light were observed. The activity of photoreceptors in response to a light step is interrupted during firing of contralateral hair cells. The intersensory interactions between the statocyst and visual pathway underlying these responses were examined with simultaneous intracellular recordings. Evidence is presented that the statocyst of Hermissenda is an important channel for visual information.     

Rapid Extraction of Lexical Tone Phonology in Chinese Characters: A Visual Mismatch Negativity Study

Background

In alphabetic languages, emerging evidence from behavioral and neuroimaging studies shows the rapid and automatic activation of phonological information in visual word recognition. In the mapping from orthography to phonology, unlike most alphabetic languages in which there is a natural correspondence between the visual and phonological forms, in logographic Chinese, the mapping between visual and phonological forms is rather arbitrary and depends on learning and experience. The issue of whether the phonological information is rapidly and automatically extracted in Chinese characters by the brain has not yet been thoroughly addressed.

Methodology/Principal Findings

We continuously presented Chinese characters differing in orthography and meaning to adult native Mandarin Chinese speakers to construct a constant varying visual stream. In the stream, most stimuli were homophones of Chinese characters: The phonological features embedded in these visual characters were the same, including consonants, vowels and the lexical tone. Occasionally, the rule of phonology was randomly violated by characters whose phonological features differed in the lexical tone.

Conclusions/Significance

We showed that the violation of the lexical tone phonology evoked an early, robust visual response, as revealed by whole-head electrical recordings of the visual mismatch negativity (vMMN), indicating the rapid extraction of phonological information embedded in Chinese characters. Source analysis revealed that the vMMN was involved in neural activations of the visual cortex, suggesting that the visual sensory memory is sensitive to phonological information embedded in visual words at an early processing stage.     

STUDIES ON PRIMARY CULTURES OF DIFFERENTIATED FETAL LIVER CELLS

A method for culturing non- or slowly growing, differentiated fetal rat liver cells is described. It involves the use of collagenase as a digesting agent and of a selective medium deficient in arginine which suppresses the growth of nonparenchymal liver cells. Evidence is presented that surviving cells (a) retain liver-specific urea cycle functions measured by their capacity to transform ornithine into arginine, (b) synthesize DNA in glucose-deficient medium, and (c) synthesize and secrete albumin. This primary cell culture responds to partially hepatectomized rat serum and may be an appropriate assay system for the study of mechanisms which regulate liver regeneration.     

A proposed phylogenetic relationship between sea cucumber polian vesicles and the vertebrate lymphoreticular system

Evidence is presented that Polian vesicles of the sea cucumber, Holothuria cinerascens, a member of an echinoderm class considered close to the vertebrate evolutionary line, are organs of inflammatory (including immunologic) responsiveness. As such, they might represent a rudimentary beginning of what later evolved into the vertebrate lymphoreticular system.     

Genetic studies with heteroduplex DNA of bacteriophage f1. Asymmetric segregation,base correction and implications for the mechanism of genetic recombination

Heteroduplex DNA of bacteriophage f1 constructed in vitro was used to transfect Escherichia coli. The progeny phage produced were analyzed by genetic means. A strongly asymmetric transfer of information was observed. This result shows that one strand—usually the minus strand—determines in large part the genotypes of progeny phage. These results are discussed in the light of the available information on DNA duplication. Evidence for an activity that corrects mismatched bases will be presented and discussed. Heteroduplex molecules which were heterozygous at the sites that govern sensitivity to B restriction and modification were constructed and analyzed in restricting and non-restricting hosts. Results of these studies give support to a model for f1 genetic recombination that envisages asymmetric heteroduplex formation as an intermediate. These results are discussed in relation to earlier data.     

Alteration of the binding constants of malathion and carbaryl to cytochrome P-450 due to hydrolysis by rat hepatic microsomal esterases

During studies to determine spectral binding properties of malathion and carbaryl to rat liver microsomal cytochrome P-450, it was observed that final concentrations of 5 μM malathion and 10 μM carbaryl produced unstable binding spectra. Evidence is presented which demonstrates that a major reason for the unstable binding spectra of these insecticides is rapid degradation by hepatic microsomal esterases. In this respect, carbaryl and malathion, and possibly other compounds that contain ester linkages, appear to be unique, since most compounds are not metabolized under the conditions in which binding spectra are determined, i.e. in the absence of an NADPH generating system.     

An S-adenosyl-l-methionine; coniine methyltransferase from Conium maculatum

Evidence is presented for a cell free system from Conium maculatum which catalyses the transfer of a methyl group from S-adenoysl-l-methionine to coniine with the formation of N-methyl coniine. Maximum enzyme activity which occurred in the unripe fruits was enhanced by dithiothreitol, and evidence for the role of sulphydryl groups of the enzyme was obtained from inhibition with p-CMB, iodoacetamide and N-methyl maleimide. A divalent metal cation dependency was not detected.     

Individual Differences in the Effect of Orthographic/Phonological Conflict on Rhyme and Spelling Decisions

In typical readers, orthographic knowledge has been shown to influence phonological decisions. In the present study, we used visual rhyme and spelling tasks to investigate the interaction of orthographic and phonological information in adults with varying reading skill. Word pairs that shared both orthography and phonology (e.g., throat/boat), differed in both orthography and phonology (e.g., snow/arm), shared only orthography (e.g., farm/warm), and shared only phonology (e.g., vote/boat) were visually presented to university students who varied in reading ability. For rhyme judgment, participants were slower and less accurate to accept rhyming pairs when words were spelled differently and to reject non-rhyming pairs when words were spelled similarly. Similarly, for spelling judgments, participants were slower and less accurate when indicating that word endings were spelled differently when words rhymed, and slower and less accurate when indicating that words were spelled similarly when words did not rhyme. Crucially, while these effects were clear at the group level, there were large individual differences in the extent to which participants were impacted by conflict. In two separate samples, reading skill was associated with the extent to which orthographic conflict impacted rhyme decisions such that individuals with better nonword reading performance were less impacted by orthographic conflict. Thus, university students with poorer reading skills may differ from their peers either in the reading strategies they use or in the degree to which they automatically access word form information. Understanding these relationships is important for understanding the roles that reading processes play in readers of different skill.     

Photoreduction of Pyridine Nucleotide by Subcellular Preparations from Rhodopseudomonas spheroides

We have investigated the photoreduction of pyridine nucleotides by crude extracts and chromatophores of Rhodopseudomonas spheroides.

Our findings are as follows:

NADP is preferentially photoreduced by crude extracts (37,000 × g supernatant fraction) and there is no requirement for the addition of exogenous substrates. Crude extracts also catalyze a nonphotosensitive reduction of NAD.

NADP photoreduction is completely inhibited if an NADH trapping system is present and indicates that NADH is required for NADP photoreduction.

Washed chromatophores (150,000 × g pellet) do not catalyze NADP photoreduction unless the supernatant fraction is added. The restoring effect of supernatant fraction is lost upon boiling and dialysis. However, supernatant materials can be replaced by an NADH generating system. There is no requirement for anaerobic conditions.

Evidence has been presented which suggests that Rhodopseudomonas spheroides contains an energy-linked transhydrogenase that can be driven by a high energy intermediate generated by light or ATP. This intermediate may also be functional in ATP synthesis. The synthesis of ATP and the ATP-supported transhydrogenase is inhibited by oligomycin. This inhibitor does not affect the light-mediated reaction.

     

FOOD VACUOLE MEMBRANE GROWTH WITH MICROTUBULE-ASSOCIATED MEMBRANE TRANSPORT IN PARAMECIUM

Evidence from a morphological study of the oral apparatus of Paramecium caudatum using electron microscope techniques have shown the existence of an elaborate structural system which is apparently designed to recycle digestive-vacuole membrane. Disk-shaped vesicles are filtered out of the cytoplasm by a group of microtubular ribbons. The vesicles, after being transported to the cytostome-cytopharynx region in association with these ribbons, accumulate next to the cytopharynx before they become fused with the cytopharyngeal membrane. This fusion allows the nascent food vacuole to grow and increase its membrane surface area. The morphology of this cytostome-cytopharynx region is described in detail and illustrated with a three-dimensional drawing of a portion of this region and a clay sculpture of the oral apparatus of Paramecium. Evidence from the literature for the transformation of food vacuole membrane into disk-shaped vesicles both from condensing food vacuoles in the endoplasm and from egested food vacuoles at the cytoproct is presented. This transformation would complete a system of digestive vacuole membrane recycling.     

Breakdown of exogenous insulin by langerhans islets of the pancreas in vitro

Pancreatic islets were isolated from Wistar rats, albino mice, spiny mice and sand rats (Psammomys obesus). Evidence is presented that pancreatic islets contain an enzyme system degrading insulin in the presence of glutathione or other sulfhydryl-containing compounds. Apparent K_m values for insulin and glutathione (in the presence of EDTA) are 14.0 μM (mol. wt 5700) and 1.28 mM, respectively. Maximum breakdown of ¹²⁵I-labeled insulin was found at about pH 7.2. After ultracentrifugation of islet homogenates the microsomal fraction contained the greatest relative specific insulin-degrading activity. The specific insulin-degrading actvitity was found to be higher in Wistar rats and albino mice than in spiny mice and sand rats. Starvation of Wistar rats for 72 h caused a decrease inthe enzymatic activity.     

Acoustic-Emergent Phonology in the Amplitude Envelope of Child-Directed Speech

When acquiring language, young children may use acoustic spectro-temporal patterns in speech to derive phonological units in spoken language (e.g., prosodic stress patterns, syllables, phonemes). Children appear to learn acoustic-phonological mappings rapidly, without direct instruction, yet the underlying developmental mechanisms remain unclear. Across different languages, a relationship between amplitude envelope sensitivity and phonological development has been found, suggesting that children may make use of amplitude modulation (AM) patterns within the envelope to develop a phonological system. Here we present the Spectral Amplitude Modulation Phase Hierarchy (S-AMPH) model, a set of algorithms for deriving the dominant AM patterns in child-directed speech (CDS). Using Principal Components Analysis, we show that rhythmic CDS contains an AM hierarchy comprising 3 core modulation timescales. These timescales correspond to key phonological units: prosodic stress (Stress AM, ~2 Hz), syllables (Syllable AM, ~5 Hz) and onset-rime units (Phoneme AM, ~20 Hz). We argue that these AM patterns could in principle be used by naïve listeners to compute acoustic-phonological mappings without lexical knowledge. We then demonstrate that the modulation statistics within this AM hierarchy indeed parse the speech signal into a primitive hierarchically-organised phonological system comprising stress feet (proto-words), syllables and onset-rime units. We apply the S-AMPH model to two other CDS corpora, one spontaneous and one deliberately-timed. The model accurately identified 72–82% (freely-read CDS) and 90–98% (rhythmically-regular CDS) stress patterns, syllables and onset-rime units. This in-principle demonstration that primitive phonology can be extracted from speech AMs is termed Acoustic-Emergent Phonology (AEP) theory. AEP theory provides a set of methods for examining how early phonological development is shaped by the temporal modulation structure of speech across languages. The S-AMPH model reveals a crucial developmental role for stress feet (AMs ~2 Hz). Stress feet underpin different linguistic rhythm typologies, and speech rhythm underpins language acquisition by infants in all languages.     

Spin-trapping studies of hydroxyl radical production involved in lipid peroxidation.

Evidence presented in this report suggests that the hydroxyl radical (OH.), which is generated from liver microsomes is an initiator of NADPH-dependent lipid peroxidation. The conclusions are based on the following observations: 1) hydroxyl radical production in liver microsomes as measured by esr spin-trapping correlates with the extent of NADPH induced microsomal lipid peroxidation as measured by malondialdehyde formation; 2) peroxidative degradation of arachidonic acid in a model OH · generating system, namely, the Fenton reaction takes place readily and is inhibited by thiourea, a potent OH · scavenger, indicating that the hydroxyl radical is capable of initiating lipid peroxidation; 3) trapping of the hydroxyl radical by the spin trap, 5,5-dimethyl-1-pyrroline-1-oxide prevents lipid peroxidation in liver microsomes during NADPH oxidation, and in the model system in the presence of linolenic acid. The possibility that cytochrome P-450 reductase is involved in NADPH-dependent lipid peroxidation is discussed. The optimal pH for the production of the hydroxyl radical in liver microsomes is 7.2. The generation of the hydroxyl radical is correlated with the amount of microsomal protein, possibly NADPH cytochrome P-450 reductase. A critical concentration of EDTA (5 × 10^?5m) is required for maximal production of the hydroxyl radical in microsomal lipid peroxidation during NADPH oxidation. High concentrations of Fe²⁺-EDTA complex equimolar in iron and chelator do not inhibit the production of the hydroxyl radical. The production of the hydroxyl radical in liver microsomes is also promoted by high salt concentrations. Evidence is also presented that OH radical production in microsomes during induced lipid peroxidation occurs primarily via the classic Fenton reaction.     

Phorbic Acid biosynthesis in the latex vessel system of euphorbia

Evidence is presented that phorbic acid is formed in the latex producing cell system, rather than in photosynthetic or chlorophyll-free tissues of Euphorbia resinifera Berg. When a branch of the plant was kept first in a ¹⁴CO₂ atmosphere with 12 hr light-dark periods for 2 days and then left under natural conditions in the air outside for at least 2 to 3 days, radioactive phorbic acid was found in the latex. Phorbic acid synthesis appeared to be independent of the photosynthetic and respiratory activities of the plant.     

Event-related potentials at different stages of the operation of visual working memory

Trace fixation and comparison with incoming information was studied using event-related potentials (ERPs) recorded from various cortical areas during passive viewing and matching of two consecutive pictures. Visual stimuli differing in the spatial location of elements (4 × 4 square patterns with random positions of 4 black and 12 white squares) and phonological stimuli (differently written letters) were used. Trace fixation was studied by comparing the ERPs generated in response to the first (reference) stimulus in the pair with those generated during passive viewing. Sensory analysis of the reference stimuli was observed in the time interval 128–196 ms. For the patterns presented, it was reflected by an increased amplitude of the N1 component in the caudal areas as compared with passive viewing. The phonological stimuli produced a higher amplitude of a positive wave in the frontotemporal area in the same time interval. Processing of subsequent information to be stored in memory was observed in the interval 232–452 ms. Processing of patterns was reflected by a decreased positivity, most pronounced in the left temporo-parieto-occipital area. Comparison of a trace with incoming information was studied by comparing the ERPs generated in response to the first (reference) and second (test) stimuli. The number of cortical areas involved in the sensory analysis of the test stimuli was larger than the number involved in the analysis of the reference stimuli. Comparison of the new information with the trace was reflected by an increased amplitude of the late positive wave (components P3, Pc, and Pc-Nc) in the frontocentral and caudal cortical areas. The topographic changes in the late positive components depended on the type of stimulus.     

Interference of 5-hydroxytryptamine in the assay of glucose by glucose oxidase:peroxidase:chromogen based methods

The interference of 5-hydroxytryptamine with the assay of glucose by glucose oxidase:peroxidase:chromogen methods is demonstrated. Evidence is presented that this interference results from competition by 5HT and other indoles, which can act as hydrogen donors to the peroxidase: H₂O₂ system, with the chromogenic hydrogen donors guaiacol, o-dianisidine and ABTS 2,2′-azino-di[3-ethylbenzthiazoline-6-sulphonic acid] ammonium salt commonly used in glucose assay systems.     

The basis of graft rejection in the earthworms Lumbricus terrestris and Eisenia foetida

Body wall grafts have been exchanged between Lumbricus terrestris and Eisenia foetida unicolor, and the survival times of second-set grafts and a limited number of third-set grafts have been compared with those of first-set grafts. Survival of grafts has also been studied following implantation. The results do not support the hypothesis that second-set rejection is accelerated due to an immune response as in higher vertebrates. Evidence is presented that Eisenia are individually different and that the differential graft survival may be due to tissue incompatibility, survival times depending on the degree of difference in the environment presented by the recipient.     

Glycoprotein biosynthesis in the developing rat brain IV. Effects of guanosine nucleotides on soluble glycoprotein galactosyl- and N-acetylgalactosaminyltransferases

The effects of GTP on soluble cerebral glycoprotein galactosyl- and N-acetylgalactosaminyltransferases were studied. The transfer of galactose from UDP-galactose to both endogenous and exogenous acceptors was stimulated by GTP while the transfer of N-acetylgalactosamine to endogenous and defined exogenous acceptors was inhibited by the nucleotide. Similar results were obtained with β,γ-methylene GTP, a structural analog of GTP. Evidence is presented which suggests that GTP is as an allosteric modulator of these two glycosyltransferases.