Principles of belief acquisition. How we read other minds

Reading other minds is a pervasive feature of human social life. A decade of research indicates that people can automatically track an agent's beliefs regardless of whether this is required. But little is known about the principles t guide automatic belief tracking. In six experiments adapting a false belief task introduced by Kovács et al. (2010), we tested whether belief tracking is interrupted by either an agent's lack of perceptual access or else by an agent's constrained action possibilities. We also tested whether such manipulations create interruptions when participants were instructed to track beliefs. Our main finding: the agent's lack of perceptual access did not interrupt belief tracking when participants were not instructed to track beliefs. Overall, our findings raise a challenge: some of the phenomena that have been labelled mindreading are perhaps not mindreading at all, or-more likely-they are mindreading but not as we know it.

Distinguishing intentional from nonintentional actions through eeg and kinematic markers

How can an intentional movement be distinguished from the same movement done nonintentionally? How can this distinction be drawn without asking the subject, or in patients who are unable to communicate? Here we address these questions, by focusing on blinking. This is one of the most frequent spontaneous actions in our daily life, but it can also be done intentionally. Furthermore, blinking is often spared in patients with severe brain injuries, and for some, it is the only way to report complex meanings. Using kinematic and EEG-based measures, we found that intentional and spontaneous blinking are preceded by different brain activities, even when they are indistinguishable. Unlike spontaneous ones, intentional blinks are characterized by a slow negative EEG drift, resembling the classic readiness potential. We investigated the theoretical implication of this finding in stochastic decision models as well as the practical significance of using brain-based signals to improve the discrimination between intentional and nonintentional actions. As proof of principle, we considered three brain-injured patients with rare neurological syndromes characterized by motor and communicative impairments. Although further research is needed, our results indicate that brain-based signals can offer a feasible way to infer intentionality even in absence of overt communication.

Preventing action slows down performance in perceptual judgment

Action and vision are known to be tightly coupled with each other. In a previous study, we found that repeatedly grasping an object without any visual feedback might result in a perceptual aftereffect when the object was visually presented in the context of a perceptual judgement task. In this study, we explored whether and how such an effect could be modulated by presenting the object behind a transparent barrier. Our conjecture was that if perceptual judgment relies, in part at least, on the same processes and representations as those involved in action, then one should expect to find a slowdown in judgment performance when the target object looks to be out of reach. And this was what we actually found. This indicates that not only acting upon an object but also being prevented from acting upon it can affect how the object is perceptually judged.

Vitality form expression in autism

The notion of "vitality form" has been coined by Daniel Stern to describe the basic features of action, which may reflect the mood or affective state of an agent. There is general consensus that vitality forms substantiate social interactions in children as well in adults. Previous studies have explored children with Autism Spectrum Disorder (ASD)'s ability in copying and recognizing the vitality forms of actions performed by others. In this paper we investigated, for the first time, how children with ASD express different vitality forms when acting themselves. We recorded the kinematics of ASD and typically developing (TD) children while performing three different types of action with two different vitality forms. There were two conditions. In the what condition we contrasted the three different types of action performed with a same vitality form, while in the how condition we contrasted the same type of action performed with two different vitality forms. The results showed a clear difference between ASD children and TD children in the how, but not in the what, condition. Indeed, while TD children distinguished the vitality forms to be expressed by mostly varying a specific spatiotemporal parameter (i.e. movement time), no significant variation in this parameter was found in ASD children. As they are not prone to express vitality forms as neurotypical individuals do, individuals with ASD's interactions with neurotypical peers could therefore be difficult to achieve successfully, with cascading effects on their propensity to be tuned to their surrounding social world, or so we conjecture. If this conjecture would turn out to be correct, our findings could have promising implication for theoretical and clinical research in the context of ASD.

Looking ahead: anticipatory gaze and motor ability in infancy

The present study asks when infants are able to selectively anticipate the goals of observed actions, and how this ability relates to infants' own abilities to produce those specific actions. Using eye-tracking technology to measure on-line anticipation, 6-, 8- and 10-month-old infants and a control group of adults were tested while observing an adult reach with a whole hand grasp, a precision grasp or a closed fist towards one of two different sized objects. The same infants were also given a comparable action production task. All infants showed proactive gaze to the whole hand grasps, with increased degrees of proactivity in the older groups. Gaze proactivity to the precision grasps, however, was present from 8 months of age. Moreover, the infants' ability in performing precision grasping strongly predicted their ability in using the actor's hand shape cues to differentially anticipate the goal of the observed action, even when age was partialled out. The results are discussed in terms of the specificity of action anticipation, and the fine-grained relationship between action production and action perception.

Effects of glucose on chemically induced acute hepatic failure in rats

TOPIC

Acute hepatic failure (AHF) is a physiopathological entity difficult to reproduce experimentally but necessary to evaluate new therapies such as bioartificial liver (BAL) or hepatocyte transplantation (HcTX). Two main animal models are available: surgical or chemical induction of an AHF. Many authors have assessed BAL or HcTX with such models and observed increased survival rate in the treated groups. However, during AHF, severe hypoglycemia takes place. Some authors have shown that adjunction of glucose in beverage after surgically induced AHF may induce by itself an improvement of survival rate.

METHOD

The purpose of the present study is to test if the adjunction of glucose leads to the same effect in an AHF chemically induced by D-Galactosamine (D-Gal). A group of animals (rats) receiving glucose 20% as beverage immediately after intoxication (Group 1), is compared with a control group receiving tap water (Group 2).

RESULTS

The required dose to achieve AHF is 2.75 g/kg body weight (Gr. 0). Survival rates are as follows: Gr. 1: Day 3:20%; day 5: 10%; day 8: 0%. Gr. 2: Day 3: 0%. The difference in survival rate is not statistically significant between the two groups. Liver enzymes peak at 24 hours, then return to normal values; blood sugar levels show no difference between groups. Histological examination of Gr. 0 animals surviving and sacrificed on day 28 shows restitutio ad integrum of hepatic structure.

CONCLUSION

Glucose adjunction does not alter survival rate. We can conclude that this particular model of AHF is reliable.

Does hepatocyte transplantation in a chemically induced acute hepatic failure make sense?

PURPOSE

Acute hepatic insufficiency (AHF) is one of the major challenges of intensive care medicine. Liver transplantation is the current solution to unsuccessful medical management. Owing to the lack of organ donors, other methods such as hepatocyte transplantation (HcTX) and bioartificial livers need to be explored. The aim of our experimental study is to evaluate the effect of hepatocyte transplantation on the survival in AHF animals intoxicated with D-Galactosamine (D-Gal).

METHODS

The first step consists of the determination of the dose of D-Gal needed to induce at least 80% mortality between 48 and 72 hours. Two groups of a single strain of male Wistar rats are then compared, one being intoxicated with D-Gal (control group), the other receiving and HcTX in the splenic parenchyma 48 hours after intoxication.

RESULTS

The required dose to achieve AHF is 3 gr/kg body weight (Gr. 0). Survival rates are as follow: Gr. 1: D0: 93%; from D1 to D28: 13%. Gr. 2: D0: 80%; D1 and D2: 33%; D3: 20%; D4: 13%, from D5 to D28: 6%. (D0 = Day of transplantation). Liver enzymes show a peak of deterioration at 24 hours, then return to normal values in both groups. Histological examination of those animals still alive and sacrificed on day 28 demonstrates a restitutio ad integrum of hepatic structure. In Group 2, it is possible to observe remaining living hepatocytes in the splenic parenchyma.

CONCLUSIONS

When HcTX is performed 48 hours after D-Gal intoxication, i.e., when the animals begin to develop AHF symptoms, animal survival only significantly improves between days 0 and 3. Unlike other trials, we cannot demonstrate an improvement in long-term survival. Thus, according to this particular experimental model, HcTX is not an alternative for the treatment of AHF.

[Long-term follow-up of 9 islets of Langerhans autografts after resection of the pancreas]

INTRODUCTION

Preservation of physiological endocrine pancreatic function represents a major problem in pancreatectomised patients. In 40 to 100%, pancreatic resection can result in diabetes, which is often difficult to manage. Islet autotransplantation has been proposed to prevent this severe metabolic consequence.

PATIENTS AND METHODS

Between March 1992 and January 1997 we performed 9 human islet autotransplantations in Geneva. The patients comprised 6 males and 3 females aged 40 to 81 years (median: 51 years). The pancreatectomy was total in 3 cases, subtotal (95%) in 2 cases and partial (40-80%) in the others. Indications for resection were alcohol-induced chronic pancreatitis (6 cases) and focal benign pancreatic pathologies (3 cases). After collagenase digestion, unpurified islets were injected intraportally and embolised into the liver. Patient metabolic status was regularly tested by 24-hour serum glucose profile, measurement of glycosylated haemoglobin, oral and intravenous glucose tolerance tests and glucagon stimulation test.

RESULTS

Immediately after autotransplantation, one patient had persistent insulin-dependent diabetes. Among the 8 patients who were insulin-independent soon after the graft, 4 presented a progressive deterioration of endocrine pancreatic function and required insulin therapy 5, 8, 24 and 36 months after the graft. Currently, 4 patients are insulin-independent: three of them have normal glucose tolerance tests (24, and 48 months after the graft) and the last presented with glucose intolerance 22 months after the graft but still does not require exogenous insulin.

CONCLUSION

Islet autotransplantation can be considered a useful therapeutic option serving to prevent or delay the occurrence of surgically-induced diabetes. In our opinion, islet autotransplantation should be offered to any non diabetic patient needing to undergo major pancreatic resection.

[Isolation of the pig islets of Langerhans: evaluation of in vitro and in vivo function]

Pig islets are considered the best alternative to human islets in the treatment of insulin-dependent diabetes. Pigs could represent a potential islet donor for xenotransplantation in humans because of the close similarity between human and porcine insulin and the theoretically unlimited availability of porcine pancreas. From November 1991 to January 1997 we performed 221 pig islet isolations from 3 pig sources: group 1: minipigs (age 9-18 months) and white pigs (3-8 months), group 2: large white pigs (5-8 months), group 3: large white pigs (12-24 months). Islets were isolated according to a semi-automated method using enzymatic digestion and purification through discontinuous Euro-Ficoll gradients. The pancreases were surgically removed in our laboratory for group 1, while pancreases from groups 2 and 3 were removed at the slaughterhouse with an average warm ischemia time of 15 minutes. In vitro islet function was assessed by static incubations and perifusions, and in vivo islet function by transplantation under the kidney capsule of nude diabetic mice. The results were as follows: [table: see text] Insulin secretion increased twofold after in vitro glucose stimulation. We obtained restoration of euglycemia in diabetic mice which survived > 3 months after the graft and returned to diabetes after nephrectomy. This study shows that our isolated pig islets are viable and functional in vitro and in vivo after transplantation.

[Islands of Langerhans autotransplantation after pancreatic resection for benign pathology]

One way to prevent the occurrence of insulin-dependent diabetes after major pancreatic resection is to perform islet of Langerhans autotransplantation. Thus far, we have performed nine autotransplantations. The last three autotransplantations were performed in patients with benign tumoral pathology (one corporeal mucinous cyst, one isthmic insulinoma and one corporeal cystadenoma). In these three cases, we performed a distal 40%, 75% and 80% pancreatectomy respectively, since enucleation was not indicated or not feasible. After resection and removal of the tumoral lesion, pancreatic segments were injected intraductally with collagenase and digested according to a modified semi-automated Ricordi's technique. We obtained 105,000, 415,000 and 144,300 non-purified islets which were then embolized into the liver by intraportal injection during the same operative procedure. After surgery, all patients were insulin-independent. There was no morbidity or mortality. In a patient who presented acute pancreatitis of the residual pancreas five months after transplantation, insulin therapy was introduced. More than one year after the graft, the two other patients remain insulin-independent. In conclusion, we propose islet autotransplantation after pancreatic resection for benign focal pathology, to prevent or delay the occurrence of insulin-dependent diabetes.