Response speed measurements on the psychomotor vigilance test: how precise is precise enough?

Study ObjectivesThe psychomotor vigilance test (PVT) is frequently used to measure behavioral alertness in sleep research on various software and hardware platforms. In contrast to many other cognitive tests, PVT response time (RT) shifts of a few milliseconds can be meaningful. It is, therefore, important to use calibrated systems, but calibration standards are currently missing. This study investigated the influence of system latency bias and its variability on two frequently used PVT performance metrics, attentional lapses (RTs ≥500 ms) and response speed, in sleep-deprived and alert participants.MethodsPVT data from one acute total (N = 31 participants) and one chronic partial (N = 43 participants) sleep deprivation protocol were the basis for simulations in which response bias (±15 ms) and its variability (0–50 ms) were systematically varied and transgressions of predefined thresholds (i.e. ±1 for lapses, ±0.1/s for response speed) recorded.ResultsBoth increasing bias and its variability caused deviations from true scores that were higher for the number of lapses in sleep-deprived participants and for response speed in alert participants. Threshold transgressions were typically rare (i.e. <5%) if system latency bias was less than ±5 ms and its standard deviation was ≤10 ms.ConclusionsA bias of ±5 ms with a standard deviation of ≤10 ms could be considered maximally allowable margins for calibrating PVT systems for timing accuracy. Future studies should report the average system latency and its standard deviation in addition to adhering to published standards for administering and analyzing the PVT.     

The concept and measurement of fathers’ stimulating play: a review

Reviews of attachment research point to fathers’ capacity to provide for a secure child-parent attachment relationship; a suggested mechanism for the development of this relationship may be sensitive and challenging play interactions. This review synthesises research on fathers’ challenging and stimulating play by mapping the variation in construct definitions and reporting on the association of fathers’ stimulating play with child outcomes. Using search terms such as “father”, “stimulating”and “challenging”, 26 studies were identified, including 16 longitudinal studies, which assessed the association between father-child stimulating or challenging play, and child outcomes. Five categories of stimulating play were derived from the analysis,ranging on a continuum of activation and complexity. Most studies reported positive associations with children’s cognitive, psycho social and physical development. The discussion highlights the variation in the operationalisation of challenging and stimulating play, and suggestions for future research on the function of fathers’ play interactions are made.     

The androgen receptor gene: A major modifier of speed of neuronal transmission and intelligence?

Humans show considerable additive genetic variance in cognitive ability or general intelligence (g) but the genes that influence this variation are largely unknown. It is suggested here that the X-linked androgen receptor gene (AR) has a major modifying effect on speed of neuronal transmission and thus on g. The AR is polymorphic in its N-terminal transactivation domain which encodes a polyglutamine tract (CAGn) with a parametric mean of n=21 CAG repeats and normal variation between n=11 and n=30 repeats . Very low repeat numbers are associated with mental retardation, repeat numbers above 30 with reduced cognitive function, and CAGn greater than 40 with spinal and bulbar muscular atrophy. Within the range of 11-30 repeats short CAG chains are associated with high androgen sensitivity and high sperm counts. Despite this, all human populations contain many individuals with n>21 repeats. I suggest that within the range of 11-30 repeats there is a positive association with speed of neuronal transmission and values of g. The advantage of high g and the consequent spread of alleles for high CAGn will be countered by the negative effects on sperm production. Below CAGn=11 and above CAGn=30 neuronal speed may reduce, thus leading to reductions in g and loss of function of neurons. In support of the model I discuss the link between the X-chromosome and g, the comparative structure of the AR gene in the primates, and the variation in CAGn and g in human ethnic groups.     

The olfactory fascia: an evo–devo concept of the fibrocartilaginous nose

Purpose

Evo–devo is the science that studies the link between evolution of species and embryological development. This concept helps to understand the complex anatomy of the human nose. The evo–devo theory suggests the persistence in the adult of an anatomical entity, the olfactory fascia, that unites the cartilages of the nose to the olfactory mucosa.

Methods

We dissected two fresh specimens. After resecting the superficial tissues of the nose, dissection was focused on the disarticulation of the fibrocartilaginous noses from the facial and skull base skeleton.

Results

Dissection shows two fibrocartilaginous sacs that were invaginated side-by-side in the midface and attached to the anterior skull base. These membranous sacs were separated in the midline by the perpendicular plate of the ethmoid. Their walls contained the alar cartilages and the lateral expansions of the septolateral cartilage, which we had to separate from the septal cartilage. The olfactory mucosa was located inside their cranial ends.

Conclusion

The olfactory fascia is a continuous membrane uniting the nasal cartilages to the olfactory mucosa. Its origin can be found in the invagination and differentiation processes of the olfactory placodes. The fibrous portions of the olfactory fascia may be described as ligaments that unit the different components of the olfactory fascia one to the other and the fibrocartilaginous nose to the facial and skull base skeleton. The basicranial ligaments, fixing the fibrocartilaginous nose to the skull base, represent key elements in the concept of septorhinoplasty by disarticulation.

     

The Orientating Reflex: The “Targeting Reaction” and “Searchlight of Attention”

A concept of the orientating reflex is presented, based on the principle of vector coding of cognitive and executive processes. The orientating reflex is a complex of orientating reactions of motor, autonomic, and subjective types, accentuating new and significant stimuli. Two main systems form the orientating reflex: the targeting reaction and the searchlight of attention. In the visual system, the targeting reaction ensures that the image of the object falls onto the fovea; this is mediated by involvement of premotor neurons which are excited by saccade command neurons in the superior colliculi. The searchlight of attention is activated as a result of resonance within the gamma frequency range, selectively enhancing cortical detectors and involving the reticular nucleus of the thalamus. Novelty signals arise in novelty neurons of the hippocampus. The synaptic weightings of neocortical detectors for hippocampal novelty neurons is initially characterized by high efficiency, which assigns a significant level of excitation of these neurons to the new stimulus. During repeated stimulation, the synaptic weightings of all the detectors representing a given stimulus decrease, with the result that the novelty signal becomes weaker. When the stimulus changes, it acts on other detectors, whose weightings for novelty neurons remain high, which strengthens the novelty signal. Decreases in the synaptic weightings on repetition of a standard stimulus form a trace of this stimulus in the novelty neurons – this is the neural model of the stimulus. The novelty signal is determined by the non-concordance of the new stimulus with this neural model, which is formed under the influence of the standard stimulus. The greater the difference between the new stimulus and the previously formed neural model, the stronger the novelty signal.     

The “Heart” of depression during early adolescence

This study examined the concurrent associations linking youths’ parasympathetic nervous system activity, specifically baseline respiratory sinus arrhythmia (RSA) and respiratory sinus arrhythmia reactivity (RSAR; vagal withdrawal), with youth depression risk in a community sample of young adolescents. Youth gender was examined as a moderator of associations. Participants included 100 youth (53% boys; M age = 11.05 years, SD = 0.33; 43% ethnic minorities), along with their mothers and teachers. Youth and mothers participated in a laboratory protocol involving a peer problem-solving conversation, during which youths’ physiological activity was measured. Youth reported on their depressive symptoms. Teachers reported on youth depression risk via internalizing symptoms and emotion regulation (e.g., emotion lability/negativity). Results from regression analyses revealed that youths’ vagal withdrawal during the mother-youth peer problem conversation was associated with lower youth-reported depressive symptoms. Further, gender moderated the associations linking youth baseline RSA and RSAR with youth depression risk. Specifically, among girls but not boys, higher baseline RSA was associated with lower depressive symptoms and emotion lability/negativity, and higher RSAR (i.e., vagal withdrawal) was linked with lower internalizing symptoms. Findings contribute to the relatively small literature linking youth parasympathetic functioning with depression risk, and point to specific implications for girls.     

Re-evaluating the concept of “dominant/index tumor nodule” in multifocal prostate cancer

Prostate cancer (PCa) often presents as a multifocal disease with heterogeneity in Gleason score (GS) and genetic alterations. Dominant/index tumor nodule (DN), the largest nodule in a multifocal disease, is presumed to harbor the most aggressive biological behavior and therefore dictate the overall clinical behavior of PCa. In this study, we examined the pathological features of DN and re-evaluated the validity of the “DN” concept in multifocal PCa. A total of 201 consecutive radical prostatectomy specimens were totally submitted and examined. All independent cancer foci were recorded with prognostically important pathological parameters. Unifocal and multifocal disease was present in 25 (12.4 %) and 176 (87.6 %) cases, respectively. In 20 (11.3 %) multifocal cases, the highest GS, the largest tumor volume (TV), and extraprostatic extension (EPE) did not concur in the same tumor nodules. Non-DNs had a higher GS and EPE in 13 cases each and had both the highest GS and EPE in 5 cases. In the majority of multifocal prostate cancer (88.7 %), DNs have the highest GS and EPE. In these cases, DN is still a valid concept and can be used for assigning overall GS and procuring tissue for research. However, in a significant number of cases (11.3 %), the largest TV, the highest GS, and EPE did not concur in the same tumor nodules. In these cases, pathologists should de-emphasize the concept of DN. Instead, they should place the emphasis on the multifocal nature of the disease and document the pathological features of all independent tumor foci that have the largest TV, the highest GS, and EPE.     

Clinical “case series”: a concept analysis

Objectives

To analyze the concept of “case series” in the medical literature compared with case reports.

Methods

A PubMed search for articles published during 2009 which had “case series” in their title was performed. A total number of 621 articles were retrieved. 586 papers were included in the analysis and 35 were excluded (18 were commentary letters, 5 were not in English, and twelve could not be retrieved by our Library). The number of patients and category of these articles were analyzed.

Results

The median (range) of the number of cases of articles having “case series” in their title was 7 (1–6432) cases. 186/ 586 articles had less than 5 cases (31.7%, 95% CI (28.3–35.1%)). The median (range) of the number of cases of articles having “case report” as their publication type was 4 (1–178) cases. Out of the 219 articles categorized as case reports 114 (52.1%, 95% CI (45.6–58.6%)) had less than five cases.

Conclusions

The concept of “case series” is not well defined in the literature and does not reflect a specific research design. We suggest that a case series should have more than four patients while four paitents or less should be reported individually as case reports.     

An in depth analysis of the concept of “polyspecificity” assumed to characterize TCR/BCR recognition

A workshop group developed the concept of a “polyspecific” TCR/BCR in the framework of today’s consensus model. They argue that the individual TCR/BCR combining site is composed of a packet of specificities randomly plucked from the repertoire, hence it is “polyspecific.” This essay analyzes the conclusions of the workshop and suggests an alternative. “Polyspecificity” must be dissected into its two component parts, specificity and degeneracy. The TCR and the BCR must be treated differently because the TCR recognizes allele-specifically the MHC-encoded restricting element (R) that serves as the platform presenting peptide (P). Only the anti-P paratope of the TCR behaves analogously to the BCR paratope. The two paratopes are selected to recognize a shape-determinant referred to as an epitope or ligand. The paratope is functionally unispecific in recognition, not polyspecific, with respect to shape; it is degenerate in recognition with respect to chemistry. The recognized shape-determinant can be the product of many chemically different substances, peptide, carbohydrate, lipid, steroid, nucleic acid, etc. Such a degenerate set is functionally treated by the paratope as one shape/epitope/ligand and, in no sense, can a paratope recognizing such a degenerate set be described as “polyspecific.” Degeneracy and specificity are concepts that must be distinguished. The two positions are analyzed in this essay, the experiments used to support the view that the paratope of the TCR/BCR is polyspecific, are reinterpreted, and an alternative framework with its accompanying nomenclature, is presented.     

CD8 T-cell-based immunotherapy of cytomegalovirus infection: “proof of concept” provided by the murine model

Adoptive transfer of antiviral effector or memory CD8 T cells is a therapeutic option for preventing acute cytomegalovirus (CMV) disease after primary or recurrent infection in immunocompromised recipients of hematopoietic stem cell transplantation (HSCT) aimed at curing hematopoietic malignancies. Preclinical research in murine models has demonstrated the power of CD8 T-cell-based preemptive immunotherapy and has encouraged clinical trials that gave promising results. The clinical evidence, however, is based primarily on statistical analyses indicating a reduced incidence of CMV-associated complications. Here, we will briefly review the data obtained from the murine model showing that CD8 T cells derived from CMV-immune donors and administered either as peptide-selected cytolytic T lymphocyte lines or after ex vivo purification by T-cell-receptor-specific cell sorting can indeed prevent CMV-mediated histopathology and multiple organ failure.     

Duodeno-jejunal junction: a histoanatomical study with the concept of the existence of an “anatomical” sphincter

Background Duodenojejunal junction (DJJ) pressure decreased on duodenal contraction and increased on jejunal contraction. These findings postulated potential existence of anatomical sphincter at DJJ. Methods DJJ was studied by direct dissection in 34 cadavers and histologically in 24. Transverse and longitudinal sections across DJJ were cut and stained. Results DJJ was narrower than duodenum or jejunum and had one or two grooves occupied by arterial branch derived from superior mesenteric artery and we call it “duodenojejunal junction artery”. DJJ was thicker on palpation than duodenum or jejunum. Its mucous membrane was crowded into “DJJ rosette”. DJJ length varied in adults from 0.75 to 0.9 cm. Microscopically, circular muscle layer was thickened at DJJ. Conclusion The thickened circular muscle, mucosal rosette and narrowing at DJJ point to possible existence of anatomical sphincter at DJJ. Together with presence of high-pressure zone at DJJ, these findings would support such postulation.     

“The Reality of Repressed Memories” Revisited and Principles of Science

Abstract

An article in the 1993 issue of the American Psychologist entitled “The reality of repressed memories” (Loftus, 1993) forms the foundation for how many contemporary professionals understand the recovered memory/false memory controversy. The message conveyed to the readership was that recovered memories are by-products of therapy. Paradoxically, the message enjoys wide-ranging influence on the basis of “facts” that lack the rigor of science. Status was established on the basis of speculative theory, artifacts of interpretation, and the power of selectively filtered information. The message illustrates the dilemma posed for readers without personal familiarity with the subject matter, when messages are advanced on the basis of imperfect disclosure of prevailing knowledge. This article revisits the “evidence” and acquaints readers with the many errors of omission and fact that plague the false memory message (Loftus, 1993), and that cloud the science concerning memory and learning.     

The “critical zones” of entrapment of the nerves of the lower limb

Summary The author has studied, in a group of 40 dissections on cadavers of individuals of different ages, the main critical zones of entrapment of some terminal branches of the lumbo-sacral plexus, which include canals (fibrous, osteo-fibrous, fibro-muscular), intervals (intermuscular, fibro-muscular, musculo-ligamentous), rings (fibrous or fibro-muscular) and foramina. They provide the topographical anatomical basis for possible compressive phenomena of the nerves of the lower limb.

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Les zones critiques d'étranglement des nerfs du membre inférieur

Résumé L'auteur a étudié sur 40 dissections cadavériques d'individus d'âges différents, les principales zones critiques d'étranglement de certaines branches terminales du plexus lombo-sacré, constituées de canaux (fibreux, ostéo-fibreux, fibro-musculaires) d'interstices (musculaires, fibro-musculaires, ligamento-musculaires), d'anneaux (fibreux, fibro-musculaires) et de trous. Elles représentent les bases anatomotopographiques d'èventuels phénomènes de compression des nerfs du membre inférieur.

     

The organization of the conceptual system: The case of the “object versus action” dimension

There are very numerous reports in the neuropsychological literature of patients showing, in naming and/or comprehension tasks, a disproportionate deficit for nouns in comparison with verbs or a disproportionate deficit for verbs in comparison with nouns. A number of authors advanced that, in at least some or even in every of these reported cases, the noun/verb dissociation in fact reflected an underlying conceptual deficit disproportionately affecting either object or action concepts. These patterns thus would put an additional constraint on theories of conceptual knowledge organization, which should be able to explain how brain damage could selectively disrupt the concepts of objects or the concepts of actions. We have reviewed 69 papers (published from 1984 to 2009) that reported a pattern of a noun or a verb disproportionate deficit in a single-case, multiple-case, or group study of brain-damaged patients with various aetiologies. From this review, we concluded that none of these studies provided compelling evidence in favour of the interpretation that the observed noun or verb disproportionate deficit arose at the conceptual processing level and, accordingly, that this level may be organized according to the “object/action” dimension. Furthermore, we argue that investigating conceptual impairments in brain-damaged patients according to the “object/action” dichotomy is not empirically fruitful if the purpose is to inform theories of conceptual knowledge organization. In order to provide evidence relevant to these theories, one needs to consider finer grained distinctions within both the object and the action category when investigating the scope of the patients' conceptual impairment.