Cognitive and structural aspects of addiction: Relation between iris patterns, time perception, eyeblink rate, impulsivity and cigarette addiction

Objectif : Le but de ce travail est d'étudier les corrélations existantes entre les patterns de l'iris, la perception du temps et la fréquence de clignement des paupières (eye blink rate) et ceci en relation avec l'addiction à la cigarette. Méthodologie: Revue de la littérature existante. Expériences sur une cohorte d'au moins trente sujets fumeurs/non-fumeurs. Analyses statistiques. Résultats: Nos résultats confirment qu'il existe des relations entre l'impulsivité, les patterns d'iris, l'eye blink rate spontané et la perception du temps. Nous observons également que l'addiction à la cigarette et son niveau de dépendance ont une influence sur ces différentes mesures. En effet, les sujets fumeurs tendent à avoir une personnalité plus impulsive par rapport aux sujets contrôles. On remarque également une nette diminution de l'eye blink rate dans le groupe des fumeurs et une tendance à la sur-estimation du temps qui passe. Conclusion : Ce travail nous permet de mieux comprendre les différentes corrélations qui existent entre les différentes variables que nous avons mesurées (patterns d'iris, score d'impulsivité et eye blink rate) ainsi que leur relation à l'addiction à la cigarette. Dès lors qu'il est avéré que les fumeurs peuvent avoir une perception du temps altérée par rapport au groupe contrôle, il serait intéressant d'en étudier l'évolution sur le long terme (aggravation avec la durée du tabagisme actif) ainsi que les conséquences qui en découlent écologiquement au moyen d'études longitudinales et de terrain.

Increased Levels of Diadenosine Polyphosphates in Dry Eye

Purpose. To analyze the levels of the diadenosine polyphosphates Ap4A and Ap5A in tears, in a set of control subjects and in groups of symptomatic and nonsymptomatic persons with dry eye. Methods. Ninety-seven subjects participated in the study. The subjects were divided into five experimental groups: control subjects; symptomatic patients with normal tear secretion; symptomatic patients with low tear secretion; forced blink; and corneal mechanical stimulation provided by a gas esthesiometer. The Schirmer I test was used to measure and collect tear secretions from each subject. All samples were processed by high pressure liquid chromatography (HPLC) and their Ap4A and Ap5A levels determined. Results. The levels of Ap4A and Ap5A in tears were greater in all symptomatic patients than in control subjects, especially in symptomatic subjects with low tear secretion. Within the symptomatic subjects with normal tear secretion, significant differences in concentrations of Ap4A and Ap5A were found between men and women. In the forced blink experiments, concentrations of the Ap4A and Ap5A rose with increasing blink frequency. When the cornea was mechanically stimulated, the levels of Ap4A and Ap5A rose significantly during both moderate and high-flow rate tests. Conclusions. The increased levels of Ap4A and Ap5A in tears of patients with dry eye allow these dinucleotides to be used as objective biomarkers in dry eye conditions.

Unmasking of the trigemino-accessory reflex in accessory facial anastomosis

To evaluate the possible blink reflex responses in facial muscles reinnervated by the accessory nerve. Method: Eleven patients with a complete facial palsy were submitted to a surgical repair by an accessory facial nerve anastomosis (AFA). In this pathological group, blink reflex was studied by means of percutaneous electrical stimulation of the supraorbital nerve and recording from the orbicularis oculi muscle. A control group comprised seven normal people and seven patients with a complete Bell's facial palsy; in this group, responses on the sternocleidomastoideus (SCM) muscles were studied after supraorbital nerve stimulation. Results: All the patients with AFA showed a consistent degree of facial reinnervation. Ten out of the 11 patients with AFA showed reflex responses; in six, responses were configured by a double component pattern, resembling the R1 and R2 components of the blink reflex; three patients had an R1-like response and one patient showed a unique R2 component. Mean values of latencies were 15.2 (SD 4.6) ms for the R1 and 85.3 (SD 9.6) ms for the R2. In the control group, eight out of 14 people had evidence of reflex responses in the SCM muscles; these were almost exclusively configured by a bilateral late component (mean latency 63.5 (SD 15.9) ms) and only one of the subjects showed an early response at 11 ms. Conclusion: The trigemino-accessory reflex response in the pathological group was more complex and of a significantly higher incidence than in the control group. These differences could be tentatively explained by a mechanism of synaptic plasticity induced by the impairment of the efferent portion of the reflex. This could unmask the central linking between the trigeminal and the accessory limbs of the reflex. The findings described could be a demonstration of neurobionomic function in the repairing process of the nervous system.