Consciousness beyond the human case.

There is growing interest in the relationship been AI and consciousness. Joseph LeDoux and Jonathan Birch thought it would be a good moment to put some of the big questions in this area to some leading experts. The challenge of addressing the questions they raised was taken up by Kristin Andrews, Nicky Clayton, Nathaniel Daw, Chris Frith, Hakwan Lau, Megan Peters, Susan Schneider, Anil Seth, Thomas Suddendorf, and Marie Vanderkerckhoeve.

Role of the amygdala in decisions under ambiguity and decisions under risk: evidence from patients with Urbach-Wiethe disease.

Various neuropsychological studies have shown that decision-making deficits can occur in a wide range of patients with brain damage or dysfunctions. Decisions under ambiguity, as measured with the Iowa Gambling Task, primarily depend on the integrity of the ventromedial prefrontal cortex and the amygdala, as well as on further brain regions such as the somatosensory cortex. However, little is known about the specific role of these structures in decisions under risk measured with tasks that offer explicit rules for gains and losses and winning probabilities, for example, the Game of Dice Task. We aimed to investigate the potential role of the amygdala for decisions under risk. For this purpose, we examined three patients with Urbach-Wiethe disease--a rare syndrome associated with selective bilateral mineralisation of the amygdalae. Neuropsychological performance was assessed with the Iowa Gambling Task (decisions under ambiguity), the Game of Dice Task (decisions under risk), and an extensive neuropsychological test battery focussing on executive functions. Furthermore, previous studies found relationships between generating skin conductance responses and deciding advantageously in the Iowa Gambling Task. Accordingly, we recorded skin conductance responses during both decision tasks as a measure of emotional reactivity. Results indicate that patients with selective amygdala damage have lower scores in both decisions under ambiguity and decisions under risk. Decisions under risk are especially compromised in patients who also demonstrate deficits in executive functioning. In both gambling tasks, patients showed reduced skin conductance responses compared to healthy comparison subjects. The results suggest that deciding advantageously under risk conditions involves both the use of feedback from previous trials, as required by decisions under ambiguity, and in addition, executive functions.

Lack of decay of HIV-1 in gut-associated lymphoid tissue reservoirs in maximally suppressed individuals.

Although peripheral blood mononuclear cells (PBMCs) and lymph nodes represent a principal reservoir, the contribution of gut-associated lymphoid tissue (GALT) has not been evaluated. In 15 HIV-1-infected subjects with maximal suppression of HIV replication by highly active antiretroviral therapy, we quantified HIV-1 DNA and RNA in mucosal biopsy specimens, PBMCs, and plasma with ultrasensitive assays. We also calculated compartmental burdens of HIV-1 DNA-positive cells and characterized the temporal decay of these reservoirs in a period of 1 year (with projections to >50 years). HIV-1 RNA was detected in 20% of the subjects' mucosal biopsy specimens and in 80% of the PBMC samples. Mucosal HIV-1 DNA was detected in 80% of the subjects and in 100% of the PBMC samples. Calculated numbers of lymphoid cells containing "potentially replication-competent" HIV-1 DNA showed that the PBMC compartment contained approximately 70,000 such cells, and GALT contained approximately 160,000 cells. Rates of decay slopes for all 15 subjects in both compartments were not statistically significantly different when compared with each other or with zero slope. Our data indicate that GALT is a quantitatively important reservoir of potentially replicative cells containing HIV-1 DNA, harboring at least as many or more of such cells as the PBMC compartment. In well-suppressed patients on highly active antiretroviral therapy, the GALT compartment showed no clear pattern of HIV-1 decay, similar to that in the PBMCs.

Bi-hemispheric engagement in the retrieval of autobiographical episodes.

Functional magnetic resonance imaging (fMRI) was used to study the neural correlates of neutral, stressful, negative and positive autobiographical memories. The brain activity produced by these different kinds of episodic memory did not differ significantly, but a common pattern of activation for different kinds of autobiographical memory was revealed that included (1) largely bilateral portions of the medial and superior temporal lobes, hippocampus and parahippocampus, (2) portions of the ventral, medial, superior and dorsolateral prefrontal cortex, (3) the anterior and posterior cingulate, including the retrosplenial, cortex, (4) the parietal cortex, and (5) portions of the cerebellum. The brain regions that were mainly activated constituted an interactive network of temporal and prefrontal areas associated with structures of the extended limbic system. The main bilateral activations with left-sided preponderance probably reflected reactivation of complex semantic and episodic self-related information representations that included previously experienced contexts. In conclusion, the earlier view of a strict left versus right prefrontal laterality in the retrieval of semantic as opposed to episodic autobiographical memory, may have to be modified by considering contextual variables such as task demands and subject variables. Consequently, autobiographical memory integration should be viewed as based on distributed bi-hemispheric neural networks supporting multi-modal, emotionally coloured components of personal episodes.

Engagement of lateral and medial prefrontal areas in the ecphory of sad and happy autobiographical memories.

Autobiographic memory is usually affect-laden, either positively or negatively. A central question is whether the retrieval of both emotive forms of memory engages the same or a different neural net. To test this we studied 13 normal subjects with functional magnetic resonance imaging while they retrieved a number of distinct episodes, all of which were either rated as strongly positive (happy) or strongly negative (sad) in affect. Comparing the retrieval of sad with that of happy episodes revealed activation in both lateral orbital cortices symmetrically (extending into the ventrolateral prefrontal cortex as well), together with a small region in the right lateral temporal cortex and the left cerebellum. Vice versa, comparing the retrieval of happy with that of sad episodes revealed a major activation in the left hippocampal region, bilateral (though more right-sided) activation in the medial orbitofrontal/subgenual cingulate and a left sided activation in the dorsolateral prefrontal activation. These findings point to the importance of the orbitofrontal cortex for affect-laden information processing and to the existence of distinct neural nets for the re-activation of positively and negatively viewed autobiographic episodes.

[Clinical and surgical aspects of cervicofacial lymphangiomas and hemolymphangiomas]. / Aspects cliniques et chirurgicaux des lymphangiomes et hémolymphangiomes cervico-faciaux.

After an embryological review, the author describes the macroscopic and surgical aspects of cervicofacial lymphangiomas and hemolymphangiomas. Therapeutic difficulties are variable and are discussed with regard to different clinical forms. There are all degrees between benign forms which are easy to treat and major forms which raise difficult therapeutic problems because of their extent. These severe forms may threaten the vital prognosis by virtue of their own complications but also because of their excision. Lymphangiomas, or rather hemolymphangiomas, are a complex vascular malformation diagnosed most often shortly after birth, the treatment and surgical excision of which are often delicate, possibly influencing not only the functional prognosis but also the vital prognosis.

[Relative concentration of phosphorus and calcium in the ameloblastic layer and in the enamel. Preliminary study (author's transl)]. / Concentration relative du phosphore et du calcium dans la couche améloblastique et dans l'émail. Etude préliminaire.

It may be inferred from this observation, that all of the phosphorus necessary to the formation of the enamel, reaches it, during its formation process, by way of compounds, formed in the ameloblastic layer, and containing only part of the calcium necessary to the crystallisation of the hydroxyapatite. The remainder of the calcium may attain, by another route, the enamel under formation where the hydroxyapatite crystallises.

[A case of epidermal cyst of the maxilla (author's transl)]. / Un cas de kyste épidermique du maxillaire supérieur.

In the light of one case of epidermal cyst of the maxilla, the authors emphasize the operative difficulties and the need, in the presence of a severe abnormality of the pedicles of the upper wisdom teeth, to perform a careful tomographic examination of the head.

[A new case of basal cell naevomatosis (author's transl)]. / Un nouveau cas de naevomatose baso-cellulaire. (Syndrome de Gorlin-Goltz).

The authors, in the light of a new case of naevomatosis, review the description of the disease, emphasising its symptoms and signs, and inheritance, drawing attention to the need for surveillance of such patients in view of the risk of malignant change in the naevi. The other signs of the disease must be sought following the discovery of multiple epidermal cysts of the maxilla and mandible.

[Acid application on dental tartar as preliminary treatment before mechanical scaling]. / Contribution à l'étude de l'attaque acide du tartre dentaire, en tant que traitement préliminaire au détartrage mécanique.

The action of the preparation studied, containing 20% hydrochloric acid in an alcohol-chloroform medium: 1) affected both white tartar as well as the submucosal tartar, progressively replacing the phosphorus radicles of tricalcium phosphate by CL ions, transforming the insoluble tricalcium phosphate into soluble calcium chloride; 2) was practically complete in 2 minutes; 3) was more rapid on tartar than on enamel or even cement; 4) did not appear to alter the superficial structure of the tooth in 4 minutes whilst, for the same period of time, the superficial structure of the cement was deeply attacked with 50% preparations of citric acid or phosphoric acid; 5) in our trials, carried out after 4 minutes treatment, caused the tartar to undergo a relatively superficial but adequate chemical action to facilitate its removel, whilst leaving the underlying hard tissue, enamel or cement, unharmed. It would thus appear that such a substance may be used for the preparation and speeding of mechanical descaling.

[Superficial structure of dental cement as shown by acid etching and scanning electron microscope]. / Contribution á l'étude de la structure superficielle du cément dentaire par attaque acide et observation au microscope électronique á balayage (M.E.B.).

The superficial layer of the cement is made up of a mineralised structure in which are included organic fibres which would seem to serve as the intracemental anchorage of Sharpey's fibre. The appearance seen on sweep electron microscopy after acid demineralisation confirm those seen using the electron microscope by Selvig. These fibres included in the cement have a variable diameter ranging from a few microns and 45 microns on our pictures (10 microns according to Selvig). They consist of a numerous fibrils with a diameter of the order of 0.3 microns. In the cement these fibers are parallel to the surface of the tooth, this confirming Selvig's finding. Finally, our observations show that, in the superficial part of the cement, these fibres form a markedly flattened three-dimensional network.