Implicit learning: What does it all mean - Response

In the original target article (Shanks & St. John 1994), one of our principal conclusions was that there is almost no evidence that learning can occur outside awareness. The continuing commentaries raise some interesting questions, especially about the definition of learning, but do not lead us to abandon our conclusion

Exploring long-term determinants of chronological lifespan using system-wide approaches

Ageing is a great research challenge. Age is the primary risk factor for many complex diseases, including cardiovascular disease, neurodegeneration and cancer. Anti-ageing interventions aim to delay the onset of these diseases and extend health span. Ageing remains enigmatic, however, and its proximal cause and mechanisms are not understood. This partly reflects the laborious nature of ageing experiments, typically requiring large timeframes and numerous individuals, which creates a bottleneck for systematic ageing studies. Yeast can be grown under highly parallelised experimental platforms and are well suited to systematic studies. However, ageing research is a notable exception, with the traditional colony-forming unit (CFU) assay for chronological lifespan being notoriously time- and resource-consuming. I present two alternative assays which circumnavigate this bottleneck. One is a high throughput CFU assay that is automated by robotics and supported by an R package to estimate culture viability by constructing a statistical model based on colony patterns. The second assay employs barcode sequencing to monitor strain viability in competitively ageing pools of deletion libraries, providing genome-scale functional insights into the genetics of lifespan. I employ this assay to dissect the genetic basis of rapamycin-mediated longevity, providing insights into the condition-specific nature of lifespan-extending mutations and the anti-ageing action of rapamycin. Experimental reproducibility is essential for research. Ageing studies, including those in yeast, are notably sensitive to batch effects: genetically identical cells grown under identical conditions can exhibit substantial phenotypic differences. I systematically test typically neglected factors, and demonstrate that chronological lifespan is strongly affected by pre-culture protocol such as the amount of colony picked for the pre-culture – suggesting a ‘memory’ which is passed across cell divisions from pre-culture to non-dividing, ageing cells. Hence, this work addresses key issues in yeast ageing research, both technological and biological, establishing a platform to robustly perform future studies at large scales

Porphyromonas gingivalis periodontal infection and its putative links with Alzheimer’s disease

Periodontal disease (PD) and Alzheimer’s disease (AD) are inflammatory conditions affecting the global adult population. In the pathogenesis of PD, subgingival complex bacterial biofilm induces inflammation that leads to connective tissue degradation and alveolar bone resorption around the teeth. In health, junctional epithelium seals the gingiva to the tooth enamel, thus preventing bacteria from entering the gingivae. Chronic PD involves major pathogens (Porphyromonas gingivalis, Treponema denticola and Tannerella forsythia) which have an immune armoury that can circumvent host’s immune surveillance to create, and maintain an inflammatory mediator rich, and toxic environment to grow and survive. The neurodegenerative condition, AD is characterised by poor memory and specific hallmark proteins; periodontal pathogens are increasingly being linked with this dementing condition. It is therefore becoming important to understand associations of periodontitis with relevance to late-onset AD. The aim of this review is to discuss the relevance of finding the keystone periodontal pathogen P. gingivalis in AD brains and its plausible contribution to the aetiological hypothesis of this dementing condition

CHARACTERISTICS OF DISSOCIABLE HUMAN LEARNING-SYSTEMS

A number of ways of taxonomizing human learning have ben proposed. We examine the evidence for one such proposal, namely, that there exist independent explicit and implicit learning systems. This combines two further distinctions, (1) between learning that takes place with versus without concurrent awareness, and (2) between learning that involves the encoding of instances (or fragments) versus the induction of abstract rules or hypotheses. Implicit learning is assumed to involve unconscious rule learning. We examine the evidence for implicit learning derived from subliminal learning, conditioning, artificial grammar learning, instrumental learning, and reaction times in sequence learning. We conclude that unconscious learning has not been satisfactorily established in any of these areas. The assumption that learning in some of theses tasks (e.g., artificial grammar learning) is predominantly based on rule abstraction is questionable. When subjects cannot report the ''implicitly learned'' rules that govern stimulus selection, this is often because their knowledge consists of instances or fragments of the training stimuli rather than rules. In contrast to the distinction between conscious and unconscious learning, the distinction between instance and rule learning is a sound and meaningful way of taxonomizing human learning. We discuss various computational models of these two forms of learning

Prospective, longitudinal assessment of quality of life inpatients with cancer of the head and neck and their primary carers

Cancer of the head and neck has profound psychosocial and physical effects on patients, so quality of life (QoL) is an essential consideration—not only is it of importance to the patient but it also provides a subjective measure of the success of treatment. However, we know of little work about its influence on carers. The aim of this study was to assess the impact of the diagnosis and treatment on the QoLof patients and their carers from baseline (preoperatively) to three months postoperatively. Thirty-six patients and 21 primary carers were enrolled, and patients completed one head-and-neck-specific measure, the University of Washington Head and Neck, Version Four (UW-V4),and three other questionnaires, both at the time of diagnosis and at one and three months postoperatively. The carers completed similar questionnaires except for the UW-V4. Analysis of the patients’ data showed a serious deterioration in psychosocial and physical domains atone month postoperatively. However, the analysis of carers’ data showed a highly significant deterioration in anxiety and depression domains(p < 0.01), which remained low after three months. These findings highlight the need for psychological support not only for patients but also for their primary carers during the management of carcinoma of the head and neck

Challenging the Clostridium botulinum toxin type A (BoNT/A) with a selection of microorganisms by culture methods and extended storage of used vials to assess the loss of sterility

In 2002, botulinum toxin type A (BoNT/A) was approved by the US Food and Drug Administration (FDA) for cosmetic use. However, there may be procedural differences between the ways in which a clinician handles, applies and stores the product compared to the suggested guidelines of the manufacturer for handling and storage. To this end vials (N = 12) of BoNT/A were tested for the incidence of microbial contamination followed by challenging the product with a selection of microorganisms by culture methods and by using a calcein release assay to contaminate multi-dose vials at the single concentration used for facial aesthetics. A culture, droplet method was used to count microorganisms challenged with the therapeutic product and to compare viability levels in appropriate controls as well as measuring their lytic properties via an existing cell-free system involving calcein release. Counts of test organisms within the droplets, with the product and the controls without the product were undertaken using Image J software. The result from the incidence of in-vial contamination was inconclusive. Bacterial levels between controls and product challenged groups demonstrated no differences in the growth of viable microorganisms following immediate contact (p = ≥ 0.05). The cell-free calcein release assay demonstrated differences at all time points for low levels of lysis in each case with bacterial lipid extract and were statistically significant (p = 0.011). Although these data appear to correlate with the minimum inhibitory concentration, the additives and vial integrity are also likely to contribute to the maintenance of BoNT/A sterility

Oral Inflammation, Tooth Loss, Risk Factors, and Association with Progression of Alzheimer’s Disease

Periodontitis is a polymicrobial chronic inflammatory disease of tooth-supporting tissues with bacterial etiology affecting all age groups, becoming chronic in a subgroup of older individuals. Periodontal pathogens Porphyromonas gingivalis, Tannerella forsythia, and Treponema denticola are implicated in the development of a number of inflammatory pathologies at remote organ sites, including Alzheimer’s disease (AD). The initial inflammatory hypothesis proposed that AD hallmark proteins were the main contributors of central nervous system (CNS) inflammation. This hypothesis is expanding to include the role of infections, lifestyle, and genetic and environmental factors in the pathogenesis of AD. Periodontal disease (PD) typifies a condition that encompasses all of the above factors including pathogenic bacteria. These bacteria not only are the source of low-grade, chronic infection and inflammation that follow daily episodes of bacteremia arising from everyday tasks such as brushing, flossing teeth, chewing food, and during dental procedures, but they also disseminate into the brain from closely related anatomical pathways. The long-term effect of inflammatory mediators, pathogens, and/or their virulence factors, reaching the brain systemically or otherwise would, over time, prime the brain’s own microglia in individuals who have inherent susceptibility traits. Such susceptibilities contribute to inadequate neutralization of invading agents, upon reaching the brain. This has the capacity to create a vicious cycle of sustained local inflammatory milieu resulting in the loss of cytoarchitectural integrity and vital neurons with subsequent loss of function (deterioration in memory). The possible pathways between PD and AD development are considered here, as well as environmental factors that may modulate/exacerbate AD symptoms

Active invasion of Porphyromonas gingivalis and infection-induced complement activation in ApoE-/- mice brains

Periodontal disease is a polymicrobial inflammatory disease that leads to chronic systemic inflammation and direct infiltration of bacteria/bacterial components, which may contribute to the development of Alzheimer’s disease. ApoE-/- mice were orally infected (N = 12) with Porphyromonas gingivalis, Treponema denticola, Tannerella forsythia and Fusobacterium nucleatum as mono- and polymicrobial infections. ApoE-/- mice were sacrificed following 12 and 24 weeks of chronic infection. Bacterial genomic DNA was isolated from all brain tissues except for the F. nucleatum mono-infected group. Polymerase chain reaction was performed using universal 16s rDNA primers and species- specific primer sets for each organism to determine whether the infecting pathogens accessed the brain. Sequencing amplification products confirmed the invasion of bacteria into the brain during infection. The innate immune responses were detected using antibodies against complement activation products of C3 convertase stage and the membrane attack complex. Molecular methods demonstrated that 6 out of 12 ApoE-/- mice brains contained P. gingivalis genomic DNA at 12 weeks (P = 0.006), and 9 out of 12 at 24 weeks of infection (P = 0.0001). Microglia in both infected and control groups demonstrated strong intracellular labeling with C3 and C9, due to on-going biosynthesis. Tthe pyramidal neurons of the hippocampus in 4 out of 12 infected mice brains demonstrated characteristic opsonization with C3 activation fragments (P = 0.032). These results show that the oral pathogen P. gingivalis was able to access the ApoE-/- mice brain and thereby contributed to complement activation with bystander neuronal injury

'Heal thy Self - thy Planet': ConFest, Eco-Spirituality and the Self/Earth Nexus

Australia's popular calendar event of alternatives, ConFest (Conference/Festival), is a principal location for the (re)affirmation of alternative lifestyle sacra. Attending to Victor Turner's "cultural drama", this article draws on fieldwork and archival research to circumscribe the complications of Self and Earth within this public event. After charting the manifestations of personal growth and environmental consciousness at ConFest, I demonstrate that, for the alternative lifestyler, the Self and the Earth are embroiled in a complex 'web of significance'. What I call the Self-Earth nexus - signalled by the ConFest theme "Heal thy Self - thy Planet" - is characterised by interconnection (a sense of profound interdependence) and responsibility (an ethical self-commitment). I give detail to on-site expressions of Neo-Pagan eco-spirituality which 'dramatise' this nexus