Judith G. Foy

Does Strength of Phonological Representations Predict Phonological Awareness in Preschool Children

Previous research has shown a clear relationship between phonological awareness and early reading ability. This article concerns some aspects of spoken language skill that may contribute to the development of phonological awareness, as manifested in rhyme awareness and phoneme awareness. It addresses the hypothesis that phonological awareness abilities are associated with measures that purportedly tap into the strength of phonological representations. We examined rhyme awareness, phoneme awareness, articulatory skill, speech perception, vocabulary, and letter and word knowledge in 40 children, aged 4 to 6, who were just beginning to be exposed to formal reading experiences in private preschools. The children also received cognitive tests and tests of reading ability. The results did not validate strength of phonological representation as a unitary construct underlying phonological awareness more generally, but instead revealed a selective pattern of associations between spoken language tasks and aspects of phonological awareness. Speech perception was closely associated with rhyme awareness measures when age, vocabulary, and letter knowledge were controlled. Children with a less developed sense of rhyme had a less mature pattern of articulation, independent of age, vocabulary, and letter knowledge. Phoneme awareness was associated with phonological perception and production. Children with low phoneme awareness skills showed a different pattern of speech perception and articulation errors than children with strong abilities. However, these differences appeared to be largely a function of age, letter knowledge, and especially vocabulary knowledge. It is now well established that early reading problems are associated with difficulties in phonological awareness – difficulties in phoneme awareness being the clearest case in point (for reviews, see Lyon, 1994; Mann, 1998; Stanovich, 1993; Wagner & Torgesen, 1987). Despite the strong relationship between phonological skills and reading, the nature of the phonological deficits that underlie poor reading remains to be elucidated. Differences in performance on various measures of phonological awareness have been attributed to educational experi

17β-estradiol suppresses expression of long-term depression in aged rats

It has been recently reported that the female steroid hormone 17beta-estradiol enhances synaptic transmission and the magnitude of long-term potentiation (LTP) in adult rodent hippocampus. Moreover, 17beta-estradiol ameliorates cognitive and memory function in postmenopausal women. Since aging is associated with an alteration of synaptic plasticity (e.g., higher susceptibility to long-term depression [LTD]), we examined whether 17beta-estradiol alters the expression of LTD in aged rats. We now report that the induction of LTD recorded from CA1 hippocampal neurons of aged rats is suppressed by 17beta-estradiol treatment, which produced only a minimal effect in suppressing LTD in adult rats. These results suggest that estrogen may act to improve memory by suppressing forgetfulness via a synaptic mechanism, such as LTD.

17β-estradiol modifies stress-induced and age-related changes in hippocampal synaptic plasticity.

The female steroid hormone 17beta-estradiol enhances synaptic transmission and the magnitude of longterm potentiation (LTP) in adult rodent hippocampal slices. Long-term depression (LTD), another form of synaptic plasticity, occurs more prominently in hippocampal slices from aged rodents. A decrease in LTP has been recorded in hippocampal slices from adult rodents behaviorally stressed just before tissue preparation and electrophysiological recording. Here, the authors test the hypothesis that estrogen modifies synaptic plasticity in both adult and aged rodents, whether behaviorally stressed or not. Our results indicate that estrogen enhances LTP and attenuates LTD, thus producing a protective effect against both aging and stress. These results also provide new approaches that can be used to reverse age and stress-related learning and memory dysfunction.

Bilingual children show advantages in nonverbal auditory executive function task

Previous studies have shown that bilinguals have greater control over attentional resources than monolinguals in nonverbal tasks, perhaps reflecting domain-general enhancements of executive functioning (EF). Most studies of this bilingual advantage have used tasks with visual stimuli whereas fewer studies have examined attentional control in bilinguals in auditory tasks. We studied components of EF in two Go/No-Go auditory tasks with (1) nonverbal auditory stimuli and (2) verbal auditory stimuli in 5-year-old Spanish–English bilingual (n = 30) and English-speaking monolingual (n = 30) children matched on age, gender, short-term memory (digits forward subtest), and early reading skills (phoneme awareness and letter naming). The Go/No-Go tasks were modeled after a continuous performance task (CPT) (Mahone, Pillion, & Hiemenz, 2001) and included additional blocks of trials to measure the effects of switching targets. The bilingual children made fewer errors and had shorter reaction times (RTs) in the second block of the nonverbal auditory tasks than the monolinguals, but there were no differences on the verbal auditory task. Our results suggest that early bilingualism may confer advantages in young children for responding to nonverbal auditory stimuli under conditions that require cognitive flexibility.

Manipulation of Pituitary-Adrenal Activity Affects Neural Plasticity in Rodent Hippocampus

Hormones secreted from the pituitary-adrenal system during stress affect learning and memory processes. The phenomenon of long-term potentiation (LTP) is a robust example of neuronal plasticity and has become widely regarded as a possible physiological substrate for learning and memory in the mammalian brain. The current study supports our previous finding that stress impairs LTP in the in vitro hippocampal slice. In addition, manipulation of the pituitary-adrenal axis by dexamethasone (DEX), a synthetic glucocorticoid that blocks the pituitary-adrenal response to stress, appears to influence the temporal patterns of the development of the neuronal plastic changes which occur immediately after tetanus (post-tetanic potentiation period, or PTP). Since the stress-induced impairment of LTP occurs, regardless of DEX treatment, we suggest the action of DEX is to modulate the temporal pattern of the PTP/LTP interaction in response to stress.

Reversal of long-delay conditioned taste aversion learning in rats by sex hormone manipulation.

Conditioned taste aversion (CTA) learning is an adaptive, robust, well-established learning and memory paradigm. Strong taste, aversions develop to the conditioned stimulus (CS=saccharin) despite long delays between exposure to the CS and unconditioned stimulus (US=LiCl). Rats display a sexually dimorphic pattern of long-delay CTA learning (Foy et al., 1996). The present study examines whether this sex difference is a result of activational or organizational hormone action, because here we implanted gonadectomized rats with their normal hormone replacements, or with opposing hormones prior to testing in a 4-hr delayed CTA learning task. We found that gonadally intact male rats displayed a more robust CTA response than intact female rats. Gonadectomy essentially eliminated this sex difference; gonadectomized males and gonadectomized females displayed similar CTA responses. In gonadectomized rats, when their normal sex hormones were replaced with implanted hormone pellets, the sex difference in CTA learning was reinstated. In contrast, when gonadectomized rats were implanted with opposing hormones, the sex difference was reversed. Gonadectomized female rats implanted with 5α-DHT pellets (metabolite of testosterone) displayed a stronger CTA response compared to gonadectomized males implanted with 17β-estradiol pellets. Regardless of the original developmental hormonal environment, our study suggests that an activational manipulation of circulating hormones serves to significantly influence long-delay CTA learning in rats.

Effects of onset density in preschool children: Implications for development of phonological awareness and phonological representation

Neighborhood density influences adult performance on several word processing tasks. Some studies show age-related effects of density on childrens performance, reflecting a developmental restructuring of the mental lexicon from holistic into segmental representations that may play a role in phonological awareness. To further investigate density effects and their implications for development of phonological awareness, we compared performance on dense and sparse onset words. We adapted these materials to three phonological awareness tests that were pretested on adults then administered to preschool children who were expected to vary in phonological awareness skills. For both the adults and the children who passed a phonological awareness screening task, dense onset neighborhoods were associated with slower reaction times and increased errors. A separate comparison of word repetition by the children who passed and who did not pass the phoneme awareness screening failed to provide evidence that lexical restructuring was a sufficient condition for the attainment of phonological awareness. Both groups of children more accurately repeated words from high onset density neighborhoods, regardless of the level of their phonological awareness. Thus, we find no evidence of either age- or ability-driven effects in childrens performance, contradictory to a view that the attainment of phoneme awareness relates to developmental changes in the segmental representation of words in dense neighborhoods.

Conditioned Taste Aversion

Conditioned taste aversion (CTA) is an evolutionarily adaptive, robust learning paradigm that is considered a special form of classical conditioning. CTA occurs when a conditioned stimulus (e.g., novel taste of saccharin) is paired with an unconditioned stimulus (e.g., lithium chloride injection that results in nausea). Recipients of the stimuli will then avoid the new taste when it is subsequently presented to them. In CTA, the processes of learning acquisition, retention, and extinction can be systematically examined. Under conditions that weaken CTA in younger stimulus recipients, aging is associated with stronger CTA acquisition and a greater resistance to extinction.

Speech perception and production as evidence for the role of phonological representation in the development of phonological awareness

Previous research has shown a clear relationship between phonological awareness and early reading ability. The factors underlying the development of phonological awareness are not well understood; both exposure to literacy and the adequacy of underlying phonological representations are cited as antecedents. To test the hypothesis that phonological awareness associates with strength of phonological representations, this study examined speech perception, production, and phonological awareness in 40 four‐ to six‐year‐old children attending private preschools. An extensive questionnaire was administered as a probe to home literacy environment; vocabulary letter knowledge and reading ability were also determined. The data indicate that both literacy environment and the adequacy of phonological representation are factors in phonological awareness. They further suggest that strength of phonological representations may be more closely associated with the awareness of onset‐rime than with true phoneme awareness. C...