Hippocampal long-term potentiation, memory, and longevity in mice that overexpress mitochondrial superoxide dismutase

Superoxide has been shown to be critically involved in several pathological manifestations of aging animals. In contrast, superoxide also can act as a signaling molecule to modulate signal transduction cascades required for hippocampal synaptic plasticity. Mitochondrial superoxide dismutase (SOD-2 or Mn-SOD) is a key antioxidant enzyme that scavenges superoxide. Thus, SOD-2 may not only prevent aging-related oxidative stress, but may also regulate redox signaling in young animals. We used transgenic mice overexpressing SOD-2 to study the role of mitochondrial superoxide in aging, synaptic plasticity, and memory-associated behavior. We found that overexpression of SOD-2 had no obvious effect on synaptic plasticity and memory formation in young mice, and could not rescue the age-related impairments in either synaptic plasticity or memory in old mice. However, SOD-2 overexpression did decrease mitochondrial superoxide in hippocampal neurons, and extended the lifespan of the mice. These findings increase our knowledge of the role of mitochondrial superoxide in physiological and pathological processes in the brain.     

Cross-task individual differences in error processing: Neural,electrophysiological, and genetic components

The error-related negativity (ERN) and error positivity (Pe) are electrophysiological markers of error processing thought to originate in the medial frontal cortex. Previous studies using probabilistic reinforcement showed that individuals who learn more from negative than from positive feedback (negative learners) had larger ERNs than did positive learners. These findings support the dopamine (DA) reinforcement-learning hypothesis of the ERN and associated computational models. However, it remains unclear (1) to what extent these effects generalize to tasks outside the restricted probabilistic reinforcement-learning domain and (2) whether there is a dopaminergic source of these effects. To address these issues, we tested subjects’ reinforcement-learning biases behaviorally and recorded EEG during an unrelated recognition memory experiment. Initial recognition responses were speeded, but the subjects were subsequently allowed to self-correct their responses. We found that negative learners, as assessed via probabilistic learning, had larger ERNs in the recognition memory task, suggestive of a common underlying enhanced error-processing mechanism. Negative learners also had enhanced Pes when selfcorrecting errors than did positive learners. Moreover, the ERN and Pe components contributed independently to negative learning. We also tested for a dopaminergic genetic basis of these ERP components. We analyzed the COMT val/met polymorphism, which has been linked to frontal DA levels. The COMT genotype affected Pe (but not ERN) magnitude; met/met homozygotes showed enhanced Pes to self-corrected errors, as compared with val carriers. These results are consistent with a role for the Pe and frontal monoamines in error awareness.     

Intentional Objects

The idea of an intentional object, or an object of thought, gives rise to a dilemma for theories of intentionality. Either intentional objects are existing objects, in which case it is impossible, contrary to appearances, to think about something which does not exist. Or some intentional objects are non-existent real objects. But this requires an obscure and implausible metaphysics. I argue that the way out of this dilemma is to deny that being an intentional object is being an entity of any kind. 'Object' here does not mean thing or entity. Rather, to say that something is an intentional object is just to say that it is an object of thought (or other intentional state or act) for a subject. It is further argued that theories of intentionality should not dispense with the idea of an intentional object.     

What's Really Wrong with the Limited Quantity View?

In Part Four of Reasons and Persons, Derek Parfit seeks Theory X – the Utilitarian account of the morality of choices where the number of people who will ever exist depends upon our actions. Parfit argues that X has yet to be found. The two simplest versions of Theory X are Total Utilitarianism and Average Utilitarianism. Unfortunately, Parfit argues, each of these leads to unacceptable results. Parfit explores various alternatives and finds them all unsatisfactory. This paper deals with one of those alternatives: the Limited Quantity View. I argue that ParfitÕs argument against this view fails. However, I then present a new and more general objection which defeats a broad range of utilitarian views, including the Limited Quantity View.     

Exclusion Problems and the Cardinality of Logical Space

Wittgenstein’s atomist picture, as embodied in his Tractatus, is initially very appealing. However, it faces the famous colour-exclusion problem. In this paper, I shall explain when the atomist picture can be defended (in principle) in the face of that problem; and, in the light of this, why the atomist picture should be rejected. I outline the atomist picture in Section 1. In Section 2, I present a very simple necessary and sufficient condition for the tenability (in principle) of the atomist picture. The condition is: logical space is a power of two. In Sections 3 and 4, I outline the colour-exclusion problem, and then show how the cardinality-condition supplies a response to exclusion problems. In Section 5, I explain how this amounts to a distillation of a proposal due to Moss (2012), which goes back to Carruthers (1990: 144–7). And in Section 6, I show how all this vindicates Wittgenstein’s ultimate rejection of the atomist picture. The brief reason is that we have no guarantee that there are any solutions to a given exclusion problem but, if there are any, then there are far too many.     

The Rise of the Machines: Deleuze's Flight from Structuralism

In this paper, I offer an account of the conceptual shift that occurs between the work completed by Gilles Deleuze prior to 1969 and his later work with Félix Guattari, beginning in 1972 with Anti‐Oedipus. Against previous interpretations, which have concentrated on the developments initiated by Deleuze, I argue for the primary importance of Guattari's influence, especially his insistence on a theory of “machinic processes.” The importance of these processes is made manifest in Deleuze and Guattari's move away from theories of structuralism. In order to carry out this task, I offer a close reading of Guattari's essay “Machine and Structure.” This essay was first written as a review of Deleuze's acclaimed work in Difference and Repetition and Logic of Sense and formed the basis for Deleuze and Guattari's first meeting. In the concluding sections of the paper, I show how the integration of the concept of the machine allows Deleuze and Guattari to develop a theory of the unconscious that operates outside of the boundaries traditionally set by structuralist analysis.     

Nostalgia in response to group‐based exclusion: The role of attachment‐related avoidance

We proposed that nostalgia, by virtue of its sociality, can be an indirect strategy to counteract relational deficiencies stemming from group‐based exclusion. We instructed Greek participants to recall an event in which they experienced exclusion on the basis of their nationality versus a control event. We anticipated that participants would react to group‐based exclusion with increased nostalgia. Specifically, because low attachment‐related avoidance facilitates proximity‐seeking in response to distress, we hypothesized that group‐based exclusion would increase nostalgia (a form of proximity‐seeking) more strongly when avoidance is low. Results supported this moderation hypothesis. In turn, increased nostalgia in response to group‐based exclusion predicted stronger ingroup identification. For low‐avoidants, then, group‐based exclusion fortified ingroup identification via increased nostalgia (moderated mediation).     

Economic Hardship and Well-Being: Examining the Relative Role of Individual Resources and Welfare State Effort in Resilience Against Economic Hardship

With the aftermath of the economic crisis starting to fold out, the extent and the conditions under which the experience of economic hardship thwarts subjective well-being spark academic interest. In this paper, we examine the cushioning impact of three immaterial buffers embedded within civil society—namely social networks, religiosity, and confidence in politics—in combination with the cushioning role of the welfare state. Analyzing the 2010 wave of the European Social Survey, the results confirm that the experience of economic hardship is inversely related to happiness. All three proposed protective measures cushion the negative impact of economic strain on happiness, whereby the positive effect of social networks and confidence in politics is stronger in countries with lower levels of social expenditure. The latter finding provides some evidence for the crowding out-thesis but mainly suggests that a strong welfare state can take over the role of protective buffers in civil society, which is helpful as such buffers are less present among the most vulnerable social groups. The results of the analysis are discussed in relation to social science research and public policy.     

A meditation on boredom: re-appraising its value through introspective phenomenology

Boredom is almost universally regarded as a dysphoric mental state, characterised by features such as disengagement and low arousal. However, in certain quarters (e.g., Zen Buddhism), boredom is seen as potentially having great value and even importance. The current study sought to explore boredom through a case study involving introspective phenomenology. The author created conditions in which he would experience boredom for an hour and recorded his experience in real-time using a variant of the Experiencing Sampling Method. The data were analysed using an adaptation of Interpretative Phenomenological Analysis. The results indicated that the state of boredom contained three main sources of value: altered perception of time, awakened curiosity about the environment, and exploration of self. Consequently, the article offers a re-appraisal of boredom, suggesting that rather than necessarily being a negative state, if engaged with, boredom has the potential to be a positive and rewarding experience.