Semantic representations of word meanings by the cerebral hemispheres

Two priming experiments investigated kind and strength of semantic knowledge underlying known, frontier, and unknown low frequency words. Results from Experiment 1 suggest that known words reflect categorical knowledge, but frontier and unknown words reflect thematic knowledge. Thematic knowledge for frontier words appears to be stronger than that for unknown words. Experiment 2 entailed visual half-field presentation of targets. All facilitory effects were restricted to the lvf/RH, and inhibitory effects to the rvf/LH. Experiment 1 findings were mirrored by the RH. Thematic knowledge appears to precede categorical knowledge for the RH, but the opposite may be true of the LH. Results are also discussed in terms of the RH role in meaning acquisition and metacontrol.     

The Effects of Estrogen Replacement Therapy on Neuropsychological Functioning in Postmenopausal Women With and Without Dementia: A Critical and Theoretical Review

We review 42 studies examining the effects of estrogen replacement therapy (ERT) on memory and cognition in nondemented postmenopausal women. Although there are an appreciable number of nonsignificant findings, the number of significant findings favoring ERT users considerably outnumbers the rare findings of better performance in controls. Experimental studies demonstrate a consistent beneficial effect on verbal memory, but these are short-term studies of the more acute effects of ERT. The observational studies suggest that there may be a long-lasting effect of continued ERT on cognitive functioning, but these studies need to be interpreted with caution because of the lack of random assignment and a possible healthy user bias. We also summarize findings from studies on the effects of ERT on Alzheimer's disease (AD). ERT is associated with a decreased risk for dementia, but there is little evidence for a positive effect on cognition in women with AD. Definitive answers to questions about the long-term effects of ERT on cognitive aging and risk of developing AD should be provided by 3 ongoing clinical trials.     

Early Versus Late Onset of Spinal Cord Injury Among the Elderly

The objective of this study is to compare elderly individuals with late (60 years old) versus early (<60 years old) onset spinal cord injury (SCI) across quality of life (QOL) domains for which cross-sectional design was used. The outcome measures selected were secondary medical complications (e.g., pneumonia, autonomic dysreflexia, number of days hospitalized), Functional Independence Measure (FIM), Satisfaction With Life Scale (SWLS), and the Craig Handicap Assessment and Reporting Technique (CHART). Analyses between groups showed that individuals with SCI onset 60 years of age or older were significantly older, had a greater proportion of incomplete lesions, were more likely to have SCI resulting from medical complication, and were less likely to be working. After controlling for differences in demographic and lesion characteristics, the majority of QOL domains were similar between groups. However, overall self-reported handicap (CHART-total score) was significantly greater among elderly with late onset SCI, particularly in the areas of physical independence and social integration. Differences in QOL between elderly with late versus early onset SCI were most prominent in the area of physical independence and social integration. The importance of appropriate statistical control, theoretical implications, and future directions are discussed.     

Different Ways to Hurt: An Elderly Woman's Narrative of Suffering

This article presents and interprets the case study of an elderly woman's story of suffering. It results from interviews conducted with African-American and Caucasian men and women, aged 70 and above, concerning their personal definitions, attributions, and theories about suffering. Elders' experiences of suffering were examined under the rubrics of gerontology, narrative, and religious studies. Key themes offered in this case study are: (a) How the life course unfolds because of or despite suffering, (b) what moral status an elder confers on past or present suffering, (c) how a personal sense of the sacred accommodates suffering, (d) how this particular respondent alters her identity based on assimilating the new information of suffering, and (e) how the story of suffering stands out against or blends in with the backdrop of the life story. The uniqueness of this case study also mirrors commonalities of elders' narratives of suffering, particularly those of women. This elder's story demonstrates that smaller individual suffering is rooted in the frame of the larger public world. It also illustrates that the language women use to attribute, define, and theorize suffering is embedded in relationships.     

The vulnerable C-domain

The purpose of this article is to document the existence of a group of natural language speakers who display non-target-like production of the syntax at the highest structural level, the C-domain, but produce the syntax of lower structural levels in a target-like way. This group consists of very early L1 learners, children with Specific Language Impairment, adult L2 learners, and patients with Broca's aphasia. The group is established on the basis of data from Swedish and German, but can presumably be discerned for any language. The assumption that the non-target-like production of C-domain syntax is related to Broca's area is discussed, as are some consequences for modern syntactic theory.     

Dopamine and cognitive functioning: brain imaging findings in Huntington's disease and normal aging

Recent brain imaging studies in Huntington's disease (HD) and normal aging suggest a relationship between central dopaminergic neurotransmission and cognitive performance. Results demonstrate substantial losses in dopamine (DA) function in both HD and aging. Moreover, HD patients and older adults show deficits across multiple cognitive domains, including episodic memory, speed of processing, and executive functioning. Although few studies are available at present, there is converging evidence that multiple measures of pre- and postsynaptic DA biochemistry are (a) highly interrelated, and (b) strongly associated with the cognitive deficits that accompany HD and aging. There is also emerging evidence that DA neurotransmission influences cognitive performance independent of HD or age. In general, the research reviewed in this article indicates that the nigrostriatal DA system is an important component of a frontostriatal circuitry that is critically involved in cognitive functioning.     

Does dyslexia develop from learning the alphabet in the wrong hemisphere? A cognitive neuroscience analysis

A new perspective is described which views developmental dyslexia as the outcome of learning to write the alphabet in the nondominant (right) hemisphere. The letter-level and whole-word subtypes of dyslexia are seen as differing responses adopted to cope with this predicament. Striking similarities between dyslexics and callosotomy patients in the allocation of covert attention to lateralized stimuli provide direction for integrating a diversity of dyslexic research within this framework. This synthesis, together with information from pure alexia, brain activation, and reading research, lends insight into the neural circuitry of the compensatory strategies adopted by the two dyslexic subtypes.     

Linking sight and sound: fMRI evidence of primary auditory cortex activation during visual word recognition

We describe two studies that used repetition priming paradigms to investigate brain activity during the reading of single words. Functional magnetic resonance images were collected during a visual lexical decision task in which nonword stimuli were manipulated with regard to phonological properties and compared to genuine English words. We observed a region in left-hemisphere primary auditory cortex linked to a repetition priming effect. The priming effect activity was observed only for stimuli that sound like known words; moreover, this region was sensitive to strategic task differences. Thus, a brain region involved in the most basic aspects of auditory processing appears to be engaged in reading even when there is no environmental oral or auditory component.     

Toward an understanding of aging in plutonium from direct measurements of stored energy

ABSTRACT

We present here the first direct measurement of the radiation-damage-induced energy stored in δ-phase plutonium. The primary mode of radioactive decay of ²³⁹Pu occurs with a time constant of τ=1.1?×?10¹²?s. Each decay imparts about 85?keV of recoil energy to the uranium byproduct, 5.2?Mev to the alpha particle, and a spectrum of mostly low energy gamma rays with the most probable at 51?keV [1]. Most of the decay energy is converted immediately to heat, releasing about 1.9?mW/g. However, some thermally-recoverable energy remains trapped. Reported here are measurements of that stored energy using differential scanning calorimetry (DSC) applied to ²³⁹Pu-2.0 at.%Ga δ-phase alloy. Retained energy of ～2 J/g saturates at about 5 months and is unchanged after 30 years. The magnitude of the stored energy agrees with a short-bond defect model that that we present here. This model treats radiation damage as a Pu impurity with shortened bond lengths. It explains the change in known properties with age and predicts that density increases with age, contrary to current thinking. The short-bond impurities proposed are expected to act like other impurities, affecting strength, phase transitions, grain boundaries and other metallurgical properties.     

Euthanasia,Senicide, and the Aging Society

ABSTRACT

The elderly, particularly the severely demented, are at the cutting edge of the debate over active euthanasia. Such debilitated persons fall below the standards of “personhood” as these have been defined by various moral philosophers. With the pressures of economic hard times, one might predict that the most impaired aged would be candidates for “direct termination.” However, this essay defends the thesis that the prohibition against mercy killing must be upheld despite such pressures. It draws on the wisdom of both Hippocrates and Abraham.