A PET meta‐analysis of object and spatial mental imagery

Neuroimaging studies have described the functional neuroanatomy of mental imagery. Taken separately, specific studies vary in the nature of the task used and are limited by statistical power and sensitivity. We took advantage of a multistudy PET database of 54 subjects acquired in our laboratory to reveal the neural bases of spatial versus object mental imagery tasks. Our first goal was to evaluate to what extent the activated foci elicited by both object and spatial studies overlap. A second aim was to compare activations elicited by spatial imagery tasks to those elicited by object imagery tasks. We also explored applying regression analyses to the relationships between the scores on the Mental Rotations Test (MRT) and changes in regional cerebral blood flow (rCBF) during spatial and object imagery tasks. This meta‐analysis yielded the following observations: (1) both spatial and object imagery tasks shared a common neural network composed of occipitotemporal (ventral pathway) and occipitoparietal (dorsal pathway) regions and also by a set of frontal regions (related to memory); (2) the superior parietal cortex was more strongly implicated during spatial imagery; (3) object imagery specifically engaged the anterior part of the ventral pathway, including the fusiform, parahippocampal, and hippocampal gyrus; (4) object imagery activated the early visual cortex, whereas spatial imagery induced a deactivation of the early visual cortex; (5) blood flow values in some of the regions noted above were positively correlated with scores on the MRT: the higher the subjects performed on the MRT, the more pronounced the rCBF was in these regions. These results may reconcile some of the apparent discrepancies among previous studies concerning the activation of early visual cortex in mental imagery. They also contribute to a better knowledge of the neural bases of object and spatial mental imagery.     

Grounding,Essence, and Identity

Recent metaphysics has turned its focus to two notions that are—as well as having a common Aristotelian pedigree—widely thought to be intimately related: grounding and essence. Yet how, exactly, the two are related remains opaque. We develop a unified and uniform account of grounding and essence, one which understands them both in terms of a generalized notion of identity examined in recent work by Fabrice Correia, Cian Dorr, Agustín Rayo, and others. We argue that the account comports with antecedently plausible principles governing grounding, essence, and identity taken individually, and illuminates how the three interact. We also argue that the account compares favorably to an alternative unification of grounding and essence recently proposed by Kit Fine.     

An Impure Logic of Representational Grounding

I give a semantic characterisation of a system for the logic of grounding similar to the system introduced by Kit Fine in his “Guide to Ground”, as well as a semantic characterisation of a variant of that system which excludes the possibility of what Fine calls ‘zero-grounding’.     

Impaired ability to give a meaning to personally significant events in patients with schizophrenia

Schizophrenia is a severe mental illness affecting sense of identity. Autobiographical memory deficits observed in schizophrenia could contribute to this altered sense of identity. The ability to give a meaning to personally significant events (meaning making) is also critical for identity construction and self-coherence. Twenty-four patients with schizophrenia and 24 control participants were asked to recall five self-defining memories. We assessed meaning making in participants’ narratives (spontaneous meaning making) and afterwards asked them explicitly to give a meaning to their memories (cued meaning making). We found that both spontaneous and cued meaning making were impaired in patients with schizophrenia. This impairment was correlated with executive dysfunctions and level of negative symptoms. Our results suggest that patients’ difficulties in drawing lessons about past experiences could contribute to explain the lack of coherence observed in their life trajectories and their impaired social adjustment abilities. Implications for psychotherapy are also discussed.     

Motivations underlying attitudes: regulatory focus and majority versus minority support

Drawing on regulatory focus theory, the present work examined the motivations underlying intergroup attitudes expressed under conditions of majority versus minority support. In two studies, participants expressed their attitudes towards equality and non‐discrimination of foreigners and were informed that the equality and non‐discrimination principle was supported by either a majority or a minority. Regulatory focus was assessed as the extent to which participants felt promotion‐related and prevention‐related emotions when acting either inconsistently or consistently with the egalitarian principle. Results provided evidence supporting the hypothesis that attitudes are related to prevention emotions when supported by a majority, but to promotion emotions when supported by a minority. Copyright © 2007 John Wiley & Sons, Ltd.     

Beyond Therapy and Enhancement: The Alteration of Human Nature

With the rapid progress and considerable promise of nanobiotechnology/neurosciences there is the potential of transforming the very nature of human beings and of how humans can conceive of themselves as rational animals through technological innovations. The interface between humans and machines (neuro-digital interface), can potentially alter what it means to be human, i.e., the very idea of human nature and of normal functioning will be changed. In this paper, I argue that we are potentially on the verge of a paradigm shift in terms of the ends and goals of techno-science and its applications in the biomedical sciences. In particular, the development of brain-computer interfaces could reconceptualize the very notion of what it means to be human. Hence, we should not limit our reflections of applications in terms of therapy and enhancement but also include an examination of applications aiming at the alteration of human nature. To this end I will first delineate the potential paradigm shift and then map out four distinct clusters of concerns in relation to the brain-computer interface. Finally, I argue that our moral and philosophical reflections should follow a procedural model based on managed consensus due to our pluralistic context.

A General Theory of Location Based on the Notion of Entire Location

It would be a good thing to have at our disposal a general theory of location that is neutral with respect to (i.e. that does not rule out or entail) (i) the view that some objects have more than one exact location, (ii) the view that some objects are located without having an exact location, and (iii) the view that some objects are “spanners”—where a spanner is an object exactly located at a region that has proper parts but which has no proper part exactly located at a proper part of the region. As far as I know, no theory of location that can be found in the literature has this feature. I put forward a new theory that does—or so I argue. The theory takes as its sole locational primitive the notion of being entirely located at.

     

Modality,Quantification, and Many Vlach-Operators

Consider two standard quantified modal languages \(\textbf{\textsf{A}}\) and \(\textbf{\textsf{P}}\) whose vocabularies comprise the identity predicate and the existence predicate, each endowed with a standard S5 Kripke semantics where the models have a distinguished actual world, which differ only in that the quantifiers of \(\textbf{\textsf{A}}\) are actualist while those of \(\textbf{\textsf{P}}\) are possibilist. Is it possible to enrich these languages in the same manner, in a non-trivial way, so that the two resulting languages are equally expressive—i.e., so that for each sentence of one language there is a sentence of the other language such that given any model, the former sentence is true at the actual world of the model iff the latter is? Forbes (1989) shows that this can be done by adding to both languages a pair of sentential operators called Vlach-operators, and imposing a syntactic restriction on their occurrences in formulas. As Forbes himself recognizes, this restriction is somewhat artificial. The first result I establish in this paper is that one gets sameness of expressivity by introducing infinitely many distinct pairs of indexed Vlach-operators. I then study the effect of adding to our enriched modal languages a rigid actuality operator. Finally, I discuss another means of enriching both languages which makes them expressively equivalent, one that exploits devices introduced in Peacocke (1978). Forbes himself mentions that option but does not prove that the resulting languages are equally expressive. I do, and I also compare the Peacockian and the Vlachian methods. In due course, I introduce an alternative notion of expressivity and I compare the Peacockian and the Vlachian languages in terms of that other notion.