Pyridostigmine-induced inhibition of blood acetylcholinesterase (AChE) and resulting effects on manual ocular tracking performance in the trained baboon

A method was developed to determine the effects of pyridostigmine on sensory-motor control in baboons trained to perform visuo-oculo-manual tracking tasks. The performance was evaluated in terms of accuracy, maximum smooth pursuit velocity, and gain. Administration of pyridostigmine (0.4-0.7 mg/kg intramuscularly) induced a dose-related decrease in smooth pursuit performance which appeared 10 to 30 min after injection and lasted about 1 h. If the animal was allowed to track the target with its hand or to move the target itself, the smooth pursuit performance increased significantly, returning to near normal values. The movement of the hand was not altered. The effect of intramuscular injections of pyridostigmine (0.5 mg/kg) was studied on blood acetylcholinesterase activity in alert baboons. Maximum inhibition of about 60% of baseline activity was observed 10 min after pyridostigmine injection. Subsequently the activity slowly tended to return to control level. Three hours after drug administration, acetylcholinesterase activity inhibition was still 34.1% of control value. In the baboon, the time-course of acetylcholinesterase activity recovery after injection is similar to that recorded in human. The similarity of the time-course of blood acetylcholinesterase activity and changes in smooth pursuit performance suggests a causal relationship between the two factors. A further experiment showed that pyridostigmine administered per os at a dose normally used as a prophylactic against organophosphates does not significantly alter sensorimotor performance as evaluated at the oculomanual tracking system level. When compared to the literature, our results suggest that the baboon can be used as a human experimental analog for pharmacological studies such as the action of acetylcholinesterase inhibitors.     

Grip Control in Children before,during, and after Impulsive Loading

The manipulation of small objects requires continuous contributions from both predictive and reactive mechanisms. The authors aimed to study the development of predictive and reactive mechanisms used by children from 6 to 14 years of age to manage impulsive loading. The load of a handheld object was increased rapidly by the drop of a weight hung on the object. The drop was triggered either by the child (predictive condition) or by the examiner (reactive condition). Regardless of the condition, the control strategy was refined with age. Younger children were unable to adapt their grip force (GF) to the friction of their fingers, whereas the older children provided GF that was well adapted to their variable coefficient of friction, thereby producing a secure grip. This reflected either an inadequate amount of force or an inability to integrate cutaneous information from the fingers in younger children. Additionally, a modulation with age for both predictive and reactive mechanisms was observed. All together, the better predictive abilities and the more secure grip exhibited by older children allow decreased slipping and improved performance in an impulsive loading task.     

Enhancement of spatial learning by predator odor in mice: Involvement of amygdala and hippocampus

Olfaction has particular links with learning and memory compared with other sensory cues, due to the interrelations between their neural circuitry. The present study deals with the effects of a putative stressor (i.e. a predator odor) on visuo-spatial learning in mice. Firstly, the results show that a predator odor spread during the Morris water maze task led to learning enhancement. In addition, a stereotaxic approach was used to investigate the involvement of the amygdala in this hippocampus-dependent type of learning. Thus, the performance of mice in visuo-spatial learning under predator odor conditions was dramatically reduced by an ibotenate bilateral amygdala lesion. The involvement of the amygdala was confirmed by a reduced expression of c-fos in the CA1 hippocampus of amygdala-lesioned mice at the end of the learning procedure.Mild exposure to a predator odor during hippocampus-dependent learning therefore leads to an enhancement of performance through the co-activation of the amygdala, probably by a stress mediated mechanism.     

Motives for secondary social sharing of emotions

This study provides new evidence of motives of secondary social sharing of emotions. In a retrospective study, 140 female (Mage = 29.4 yr., SD=12.8) and 116 male (M = 29.5 yr., SD = 13.1) participants were asked to recall a recent situation in which they had talked to a third person about a positive or negative, low or high intensity emotional narrative they had heard. 70% of the respondents reported having secondarily shared the reported event rapidly after the narration with several persons and at several times. Moreover, they not only described the event, the speaker's reaction and their own reactions, but also revealed the identity of their first confidant. Participants reported having spread the emotional narrative more widely in the high negative condition in order to seek emotional support and social comparison.     

Neuropsychology in France

The main steps in the development of neuropsychology in France are briefly reviewed, from the early contribution of Paul Broca (1861) up until the early 1990s. The current epistemological and institutional crises is analyzed with respect to some general factors inherent to the domain (e.g., disputes between the proponents of the psychological and biological dimensions) and to particular factors related to the French situation (e.g., retirement of prominent neuropsychologists). As regards clinical practice and research activities, the future will probably show some fractionation of goals and techniques prior to new synthesis.Died suddenly in March 1991.     

Logique et Realite

Sans résumé     

A modular,computer-controlled system for olfactory stimulation in the MRI environment

Although the cerebral networks involved in sensory perception are of general interest in neuroscience, registration of the effects of olfactory stimulation, especially in a magnetic resonance imaging (MRI) environment, presents particular problems and constraints. This article presents details of a reliable and portable system for olfactory stimulation that is modular in design and based on microcontroller technology. It has the following characteristics: (1)?It is under software control; (2)?the presentation of olfactory stimulation can be synchronized with respiration; (3)?it can be manually controlled; and (4)?it is fully compatible with an MRI environment. The principle underlying this system is to direct an odor to the subject’s nostrils by switching airflow to different odor diffusers. The characteristics of this system were established using (1)?ultraviolet (UV) spectroscopy, to measure its response time, and (2)?gas chromatography, to measure the repeatability of odor presentation in terms of gas concentration. A response time of 200?± 25 ms was obtained for the system, and the standard deviations of the gas concentration delivered during stimulation ranged from 1.5% to 22%, depending on the odor, the airflow, and the dilution of the odor used. Since it is portable, controlled by software, and reliable, on the basis of the results we obtained, this system will lend itself to a wide range of applications in olfactory neuroscience.