Inconsistent effects of photoperiod manipulations in tests for affective-like changes in mice: implications for the selection of appropriate model animals

Deficiencies in appropriate animal models are a significant factor hindering the research of affective disorders. Significant data suggest that systems related to circadian rhythms are strongly linked to affective changes, but study with animal models in this context had unclear and inconsistent results. Circadian physiology is significantly different in diurnal and nocturnal animals and a recent project showed that in diurnal rodents, short photoperiods induce depression and anxiety-like phenotypes. This study was designed to evaluate the possibility that using a similar methodology would also result in behavioral changes in nocturnal mice. Mice from two strains were maintained in either short photoperiod, neutral photoperiod or long photoperiod for 3 weeks and tested for depression or anxiety-related behaviors, as done earlier with the diurnal rodents. Tests included activity levels, sweet solution preference, elevated plus-maze, resident-intruder aggression, and forced swim test. Tests were conducted either during the light phase or during the dark phase of the mice. In contrast to the clear phenotype in diurnal rodents, the effects of photoperiod manipulations in nocturnal mice were inconsistent. These results suggest that diurnal rodents may be advantageous compared with nocturnal species for studies exploring the relationship between circadian rhythms and affective disorders.     

Lupus erythematosus tumidus induced by sex reassignment surgery

OBJECTIVE: We describe a case of sex reassignment surgery and the subsequent development of lupus erythematosus tumidus (LET). LET is characterized clinically by erythematous, succulent, edematous, nonscarring plaques in sun-exposed areas. Results of histological examination show perivascular and periadnexal lymphocytic infiltration and interstitial mucin deposition. This report emphasizes that environmental triggers, including prolonged exposure to significant doses of estrogens as part of sex reassignment surgery, may lead to the development of lupus in a nonpredisposed individual.     

The Broadband-Transient Induced Gamma-Band Response in Scalp EEG Reflects the Execution of Saccades

The contraction of the extra-ocular muscles, during the execution of saccades, produces a strong electric potential in the EEG called the saccadic spike potential (SP). At the frequency spectrum, this SP manifests as a broadband response with most of its power at the gamma-band frequencies. Saccadic activity is known to follow a time-pattern of repression (at around 50–150 ms post stimulus) which is followed by a large increase in saccadic rate at around 200–300 ms post stimulus. Due to this temporal pattern relative to the stimulus, and to the appearance of a SP at each saccade, this increase in saccadic rate shows up after averaging as an increase in gamma-band activity at the time-range of 200–300 ms. Thus, the broadband-transient “induced gamma-band response” frequently reported in the EEG literature, is in fact a “gamma-imposter”, due to ocular myographic activity, and not to neural activity. Previous findings regarding the scalp EEG broadband-transient induced gamma-band response, relating it to neural synchronization and to various cognitive functions should be reevaluated considering the systematic contamination by ocular activity. This article is one of five on the “Special Topic: Discussing Gamma” in issue 22(1) of Brain Topography.     

The dog’s meow: asymmetrical interaction in cross-modal object recognition

Little is known on cross-modal interaction in complex object recognition. The factors influencing this interaction were investigated using simultaneous presentation of pictures and vocalizations of animals. In separate blocks, the task was to identify either the visual or the auditory stimulus, ignoring the other modality. The pictures and the sounds were congruent (same animal), incongruent (different animals) or neutral (animal with meaningless stimulus). Performance in congruent trials was better than in incongruent trials, regardless of whether subjects attended the visual or the auditory stimuli, but the effect was larger in the latter case. This asymmetry persisted with addition of a long delay after the stimulus and before the response. Thus, the asymmetry cannot be explained by a lack of processing time for the auditory stimulus. However, the asymmetry was eliminated when low-contrast visual stimuli were used. These findings suggest that when visual stimulation is highly informative, it affects auditory recognition more than auditory stimulation affects visual recognition. Nevertheless, this modality dominance is not rigid; it is highly influenced by the quality of the presented information. Electronic supplementary material  The online version of this article (doi:) contains supplementary material, which is available to authorized users.

The contribution of stressful life events throughout the life cycle to combat-induced psychopathology

This study examines the contribution of prewar life events, war exposure, and postwar life events to combat-induced psychopathology among 425 Israeli War veterans from the Lebanon War. Data was collected at two time points (1983 and 2002). The sample included veterans with and without combat stress reaction (CSR). Battle intensity and subjective experience of risk in war were associated with CSR. Negative childhood life events, CSR, PTSD in 1983 and postwar negative life events were associated with PTSD in 2002. Furthermore, a path analysis revealed that CSR mediated the relation between battle intensity and PTSD in 2002. Our findings suggest that stressful life events throughout the life cycle contribute significantly to veterans' posttraumatic symptomatology, above and beyond combat exposure.     

Placental transfer of maternal rubella antibodies to full-term and preterm infants

Summary Premature infants are vulnerable to infections, partly because of the low transplacental transfer of maternal antibodies. The present study investigated the placental transfer of maternal rubella-specific antibodies to full-term and preterm infants. The study group consisted of 133 healthy, native Israeli mothers and their 159 newborns. Of these, 69 were full-term infants (gestational age >37 weeks) of 69 mothers, and 90 were preterm infants (gestational age <35 weeks) of 64 mothers. Antibody titers against rubella were measured in maternal and umbilical cord blood samples by hemagglutination inhibition and microneutralization techniques. There was no significant difference in the level of protection and in geometrical mean titers by hemagglutination between the full-term and preterm groups. Conversely, significant differences in geometric mean titers of neutralizing antibodies were found between full-term and preterm infants, e.g., 65.9 and 39.8, respectively (P<0.001). Very low birth weight preterm infants are at greater risk of rubella infection during the first year of life, due to the diminished transfer of neutralizing maternal antibodies. Therefore, earlier vaccination of this group may be beneficial.