Modulation of tremor amplitude during deep brain stimulation at different frequencies

Rest tremor was quantified in the index finger tip of 16 patients with Parkinson's disease (PD) receiving deep brain stimulation (DBS) of the ventro-intermediate nucleus (Vim) of the thalamus, the subthalamic nucleus (STN), or the internal part of the globus pallidus (GPi) while being off L-dopa for 12h. Clinically, without DBS, tremor amplitude varied from absent to high. Tremor was recorded continuously for about 5 min under three conditions of DBS repeated twice, namely, effective frequency (E), ineffective frequency (I), and no DBS (O). No changes in tremor were observed across conditions in subjects with little or no tremor. However, in subjects with moderate to large amplitude tremor, DBS decreased tremor amplitude to near normal values within a few seconds. Generally, transitions were progressive and occurred with a varying time delay. Occasionally, tremor escaped from control regardless of the stimulation condition considered. In some cases tremor amplitude in one condition appeared to depend on the preceding condition. Finally, the results were reproducible on two consecutive days. We conclude that tremor control with DBS follows specific dynamical rules, which must be compatible with the hypotheses proposed regarding the underlying mechanisms of DBS.     

Cross-modal and non-sensory influences on auditory streaming

Carlyon et al (2001 Journal of Experimental Psychology: Human Perception and Performance 27 115-127) have reported that the buildup of auditory streaming is reduced when attention is diverted to a competing auditory stimulus. Here, we demonstrate that a reduction in streaming can also be obtained by attention to a visual task or by the requirement to count backwards in threes. In all conditions participants heard a 13 s sequence of tones, and, during the first 10 s saw a sequence of visual stimuli containing three, four, or five targets. The tone sequence consisted of twenty repeating triplets in an ABA - ABA ... order, where A and B represent tones of two different frequencies. In each sequence, three, four, or five tones were amplitude modulated. During the first 10 s of the sequence, participants either counted the number of visual targets, counted the number of (modulated) auditory targets, or counted backwards in threes from a specified number. They then made an auditory-streaming judgment about the last 3 s of the tone sequence: whether one or two streams were heard. The results showed more streaming when participants counted the auditory targets (and hence were attending to the tones throughout) than in either the 'visual' or 'counting-backwards' conditions.     

Stimulus control of predatory behavior by the Iberian wall lizard (Podarcis hispanica, Sauria, Lacertidae): effects of familiarity with prey

The authors examine the relative roles of vision and chemoreception and the influence of previous experience with prey on the predatory behavior of Iberian wall lizards (Podarcis hispanica). Experiment 1 compared the responses to visual, chemical, and a combination of visual and chemical cues of a familiar prey by 2 groups of lizards that had been kept in captivity for either 3 months or 21 days. Experiment 2 assessed the responses of lizards kept in the laboratory for more than 3 months to a novel prey species. The results reveal that feeding on a prey species affects the lizards' responses to chemical stimuli from that prey. The response to chemical cues of a novel prey requires a 1st-feeding experience with that prey. Lizards that have been fed the same prey species for several months cease responding to the chemical stimuli of that particular prey.     

The Prospective and Retrospective Memory Questionnaire (PRMQ): Normative data and latent structure in a large non-clinical sample

The Prospective and Retrospective Memory Questionnaire (PRMQ; Smith, Della Sala, Logie, & Maylor, 2000) was developed to provide a self-report measure of prospective and retrospective memory slips in everyday life. It consists of sixteen items, eight asking about prospective memory failures, and eight concerning retrospective failures. The PRMQ was administered to a sample of the general adult population (N = 551) ranging in age between 17 and 94. Ten competing models of the latent structure of the PRMQ were derived from theoretical and empirical sources and were tested using confirmatory factor analysis. The model with the best fit had a tripartite structure and consisted of a general memory factor (all items loaded on this factor) plus orthogonal specific factors of prospective and retrospective memory. The reliabilities (internal consistency) of the Total scale and the Prospective and Retrospective scales were acceptable: Cronbach's alpha was 0.89, 0.84, and 0.80, respectively. Age and gender did not influence PRMQ scores, thereby simplifying the presentation and interpretation of normative data. To ease interpretation of scores on the PRMQ, tables are presented for conversion of raw scores on the Total scale and Prospective and Retrospective scales to T scores (confidence limits on scores are also provided). In addition, tables are provided to allow users to assess the reliability and abnormality of differences between an individual's scores on the Prospective and Retrospective scales.     

Phenomenal characteristics of cryptomnesia

Qualitative characteristics of cryptomnesia, or unintentional plagiarism were investigated. In Experiment 1 we compared accurate and inaccurate source attributions in terms of their level of confidence using instructions that did not require a fixed number of responses. Confidence was lower for plagiarised responses than for correct responses. Nevertheless, participants provided high ratings of certainty for a large proportion of their plagiarised responses. In Experiment 2 the phenomenological differences between plagiarised recall and veridical recall were compared by using an adaptation of the memory characteristics questionnaire (Johnson, Foley, Suengas, & Raye, 1988). Correct responses were associated with more experiential detail than plagiarised responses. However, a considerable number of plagiarised responses were accompanied by a confident memory of at least one qualitative characteristic. Results are discussed in terms of the source monitoring framework developed by Johnson, Hashtroudi, and Lindsay (1993).     

Divergent ethical perspectives on the duty-to-warn principle with HIV patients

This article presents the case of an HIV-positive client who reported having sexual relations with an unknowing partner. The issue raised is whether the therapist was required to warn the unknowing partner, similar to the Tarasoff mandate that is imposed on therapists. The case is analyzed from an ethical framework similar to that presented by Beauchamp and Childress (1994). Two opinions are presented, each leading to different conclusions about whether the therapist should inform the unknowing partner. It is concluded that although such analysis is valuable in aiding the therapist in his or her decision-making process, no clear professional standard for the management of the problem is evident.     

Why liberals should accept financial incentives for organ procurement

Free market libertarians have long supported incentives to increase organ procurement, but those oriented to justice traditionally have opposed them. This paper presents the reasons why those worried about justice should reconsider financial incentives and tolerate them as a lesser moral evil. After considering concerns about discrimination and coercion and setting them aside, it is suggested that the real moral concern should be manipulation of the neediest. The one offering the incentive (the government) has the resources to eliminate the basic needs that pressure the poor into a willingness to sell. It is unethically manipulative to withhold those resources and then offer payment for organs. Nevertheless, the poor have been left without basic necessities for 20 years since the passage of the prohibition on incentives. As long as the government continues to withhold a decent minimum of welfare, liberals should, with shame, cease opposing financial incentives for organ procurement.     

The Dissociative Factor in Symptom Reports of Rheumatic Patients with and Without Fibromyalgia

The main objective of this study was to investigate the prevalence of dissociation and its relationships to symptom reporting in fibromyalgia (FM) and other rheumatic disorders (non-FM). The participants were 73 women with FM and 85 relatively matched women with other rheumatic disorders. The participants were administered the Dissociative Experiences Scale (DES), the Profile Of Mood States (POMS), and a 50-item medical checklist. The prevalence of dissociation (DES q 25) was significantly higher in FM patients(30.1%) compared to other rheumatic disorders (7.0%). Symptom reporting correlated with measures of dissociation in both patient groups (FM:R = 0.42, p < .001; non-FM:R = 0.44, p < .001), when controlled for age, depression, and anxiety. A regression analysis confirmed the strong linkage between somatic variation and dissociation. The results suggest that dissociation is a problem for a substantial segment of patients with fibromyalgia and that dissociation is related to certain physical symptoms of fibromyalgia. Dissociation offers a different perspective on medically unexplained symptoms and may need to be addressed in future research.     

The time-based word length effect and stimulus set specificity

The word length effect is the finding that short items are remembered better than long items on immediate serial recall tests. The time-based word length effect refers to this finding when the lists comprise items that vary only in pronunciation time. Three experiments compared recall of three different sets of disyllabic words that differed systematically only in spoken duration. One set showed a word length effect, one set showed no effect of word length, and the third showed a reverse word length effect, with long words recalled better than short. A new fourth set of words was created, and it also failed to yield a time-based word length effect. Because all four experiments used the same methodology and varied only the stimulus sets, it is argued that the time-based word length effect is not robust and as such poses problems for models based on the phonological loop.