The neural basis of event-time introspection

We explored the neural mechanisms allowing humans to report the subjective onset times of conscious events. Magnetoencephalographic recordings of neural oscillations were obtained while human subjects introspected the timing of sensory, intentional, and motor events during a forced choice task. Brain activity was reconstructed with high spatio-temporal resolution. Event-time introspection was associated with specific neural activity at the time of subjective event onset which was spatially distinct from activity induced by the event itself. Different brain regions were selectively recruited for introspection of different event types, e.g., the bilateral angular gyrus for introspection of intention. Our results suggest that event-time introspection engages specific neural networks to assess the contents of consciousness. Subjective event times should therefore be interpreted as the result of complex interactions between introspection and experience networks, rather than as direct reproduction of the individual’s conscious state or as a mere post hoc interpretation.     

Illusory own body perceptions: Case reports and relevance for bodily self-consciousness

Neurological disorders of body representation have for a long time suggested the importance of multisensory processing of bodily signals for self-consciousness. One such group of disorders – illusory own body perceptions affecting the entire body – has been proposed to be especially relevant in this respect, based on neurological data as well as philosophical considerations. This has recently been tested experimentally in healthy subjects showing that integration of multisensory bodily signals from the entire body with respect to the three aspects: self-location, first-person perspective, and self-location, is crucial for bodily self-consciousness. Here we present clinical and neuroanatomical data of two neurological patients with paroxysmal disorders of full body representation in whom only one of these aspects, self-identification, was abnormal. We distinguish such disorders of global body representation from related but distinct disorders and discuss their relevance for the neurobiology of bodily self-consciousness.     

Gamma oscillations distinguish true from false memories

ABSTRACT— To test whether distinct patterns of electrophysiological activity prior to a response can distinguish true from false memories, we analyzed intracranial electroencephalographic recordings while 52 patients undergoing treatment for epilepsy performed a verbal free-recall task. These analyses revealed that the same pattern of gamma-band (28–100 Hz) oscillatory activity that predicts successful memory formation at item encoding—increased gamma power in the hippocampus, prefrontal cortex, and left temporal lobe—reemerges at retrieval to distinguish correct from incorrect responses. The timing of these oscillatory effects suggests that self-cued memory retrieval begins in the hippocampus and then spreads to the cortex. Thus, retrieval of true, as compared with false, memories induces a distinct pattern of gamma oscillations, possibly reflecting recollection of contextual information associated with past experience.     

Condorcet and communitarianism: Boghossian’s fallacious inference

This paper defends the communitarian account of meaning against Boghossian’s (Wittgensteinian) arguments. Boghossian argues that whilst such an account might be able to accommodate the infinitary characteristic of meaning, it cannot account for its normativity: he claims that, since the dispositions of a group must mirror those of its members, the former cannot be used to evaluate the latter. However, as this paper aims to make clear, this reasoning is fallacious. Modelling the issue with four (justifiable) assumptions, it shows that Condorcet’s ‘Jury Theorem’ can be used to prove that the dispositions of the majority of the members of a group can differ from those of any individual member in a way that makes it possible to use communal dispositions as a standard with which individual dispositions can be assessed. Moreover, the argument of the paper is also shown to have general implications for the use of formal methods in the explanation of the nature of certain fallacious inferences.     

Neural substrates of word generation during stroke recovery: the influence of cortical hypoperfusion

Several studies have demonstrated reorganization of cognitive and motor function caused by stroke. This study examined the influence of hypoperfused brain regions, in addition to the area of the infarct itself, on reorganization of the cognitive processes underlying word generation in stroke patients. In addition, we also sought to determine the influence of hypoperfusion on the blood oxygen level dependent/(BOLD) effect. Subjects with left and right subacute or chronic subcortical strokes, along with normal controls, were imaged while performing a verbal fluency task (word generation). The study population included six normal subject and six stroke patients with subcortical infarcts and cortical hypoperfusion in the middle cerebral artery territory who had recovered or improved markedly in word fluency. While normal subjects displayed a left-lateralized fronto-temporo-parietal and bilateral cingulo-striatal-thalamic-cerebellar network, the activation pattern of stroke patients was determined both by the hypoperfused regions and infarcted areas of the brain. Specifically, patients showed diminished BOLD effect in the cortical regions that were hypoperfused, even though their infarcts were subcortical, and showed increased BOLD effect in the homologous regions of the normal hemisphere. This finding raises the possibility that cortical hypoperfusion in the absence of infarct can cause shift of language functions to the opposite, intact hemisphere. However, reduced BOLD effect in the task relative to rest was found in hypoperfused regions in two patients, raising the possibility that regional function persisted, even though vascular reactivity was impaired. Results illustrate the complexities of functional imaging studies of recovery in patients with vascular lesions.     

Visions and Ethics in Current Discourse on Human Enhancement

Since it is now broadly acknowledged that ethics should receive early consideration in discourse on emerging technologies, ethical debates tend to flourish even while new fields of technology are still in their infancy. Such debates often liberally mix existing applications with technologies in the pipeline and far-reaching visions. This paper analyses the problems associated with this use of ethics as “preparatory” research, taking discourse on human enhancement in general and on pharmaceutical cognitive enhancement in particular as an example. The paper will outline and discuss the gap between the scientific and technological state of the art and the ethical debates, pointing out epistemic problems in this context. Furthermore, it will discuss the future role of genuine ethical reflection in discourse on human enhancement, arguing also that such discourse needs to include a technology assessment—in the broad sense of the term—which encompasses, inter alia, anthropological perspectives and aspects of social theory.     

Pain and Sacrifice: Experience and Modulation of Pain in a Religious Piercing Ritual

Fascinating pain-related rituals have been observed throughout the world, but so far no systematic evidence exists to support previous ethnographic reports of analgesic states and dissociative symptoms during these events. To address this issue, we combined quantitative and qualitative measures with the aim of investigating pain experience and modulation of pain during the Thaipusam Kavadi ritual in Mauritius. In Study 1, results indicated low levels of pain intensity during the ritual, and regression analyses showed that expectations of pain were significantly predictive of actual pain intensity ratings. In Study 2, the meanings surrounding the ritual were found to generate expectations of low pain and a positive outcome, and intense prayer was reported as the main coping strategy. In addition, most participants expressed symptoms of dissociation (including amnesia, absorption, and depersonalisation) during Thaipusam, and a high prevalence of these symptoms was associated with low levels of pain.     

Archaic ontology and white shamanism

John D. Loftin, Religion and Hopi Life in the Twentieth Century, (Religion in North America), Bloomington & Indianapolis, Indiana University Press, 1991. xxi, 168 pp., $19.95. ISBN 0 253 33517 5.

Felicitas D. Goodman, Where the Spirits Ride the Wind. Trance Journeys and Other Ecstatic Experiences, Bloomington & Indianapolis, Indiana University Press, 1990. xii, 242 pp., ISBN 0 253 20566 2.     

Attention during adaptation weakens negative afterimages of perceptually colour-spread surfaces

The visual system can complete coloured surfaces from stimulus fragments, inducing the subjective perception of a colour-spread figure. Negative afterimages of these induced colours were first reported by S. Shimojo, Y. Kamitani, and S. Nishida (2001). Two experiments were conducted to examine the effect of attention on the duration of these afterimages. The results showed that shifting attention to the colour-spread figure during the adaptation phase weakened the subsequent afterimage. On the basis of previous findings that the duration of these afterimages is correlated with the strength of perceptual filling-in (grouping) among local inducers during the adaptation phase, it is proposed that attention weakens perceptual filling-in during the adaptation phase and thereby prevents the stimulus from being segmented into an illusory figure.