It is Not (Always) the Mismatch That Beats You—On the Relationship Between Interaction of Early and Recent Life Stress and Emotion Regulation,an fMRI Study

Brain Topography - Stress may impact the ability to effectively regulate emotions. To study the impact of stressful experiences in early and recent life on emotion regulation, we examined the...     

Spatial and temporal visual properties of the neurons in the intermediate layers of the superior colliculus

Although the visual perception depends on the integration of spatial and temporal information, no knowledge is available concerning the responsiveness of neurons in the intermediate layers of the superior colliculus (SCi) to extended visual grating stimuli. Accordingly, we set out to investigate the responsiveness of these neurons in halothane-anesthetized cats to drifting sinewave gratings at various spatial and temporal frequencies. The SCi units responded optimally to gratings of low spatial frequencies (none of the analyzed SCi units exhibited maximal activity to spatial frequencies higher than 0.3 c/deg) and exhibited low spatial resolution and narrow spatial frequency tuning. On the other hand, the SCi neurons preferred high temporal frequencies and exhibited high temporal resolution. Thus, the SCi neurons seem to be good spatio–temporal filters of visual information in the low spatial and high temporal frequency domain. Based upon the above summarized results we suggest that the SCi units can detect large contours moving at high velocities well, but are unable to distinguish small details. This is in line with the generally held view that the SCi could possess visuomotor function, such as organizing the complex, sensory-guided oculomotor and skeletomotor responses during the self-motion of the animal.     

Comparison of vespid venoms collected by electrostimulation and by venom sac extraction

Venoms of three vespid species, yellow jacket, bald-faced hornet, and yellow hornet, obtained by either electrostimulation or venom sac extraction were compared with regard to their enzymatic activity, antigenicity, and allergenicity. Phospholipase A, phospholipase B, and hyaluronidase enzymatic activities were present in all six preparations. The activity of venom sac extracts lay in the range found in different batches of venoms obtained by electrostimulation for each species. Analysis of sera from vespid-sensitive patients in the radioallergosorbent test (RAST) with discs coupled with either venom sac extracts or venoms obtained by electrostimulation showed a good correlation of the results within all three species (r = 0.95). In RAST inhibition the potency of venom sac extracts and venom obtained by electrostimulation was similar for each species. Analysis of rabbit antisera to the six preparations revealed similar patterns in immunoelectrophoresis and identity reactions between the major antigens within each species. Tissue protein contamination was detected in all venom sac extracts but not in venoms obtained by electrostimulation.     

Kidney antigens active in isoimmunization: I. The antigenic diversity

Isoimmunization of rabbits with kidney extracts and Freund's adjuvant leads to the development of responses to a multiplicity of autoantigens. If a large number of kidneys is pooled, there is increased probability that responses directed toward isoantigens can also be detected. Such immunization thus results largely in antisera that possess multiple specificities, but the amount of antibody directed toward each specific antigen varies from one antiserum to another.

Advantage can be taken of these uneven responses by different animals, to enumerate the variety of responses to uniquely separable sets of determinants, by carefully selecting the antisera. In immunodiffusion studies, lines for such separable antigens can be sorted in an unambiguous manner. A total of five such antigens has now been found in kidney, three of which are kidney-specific and two of which are shared with liver. A sixth antigen, separable from liver, may be only a minor constituent of kidney, and was not directly detected in kidney extracts. It is important that fresh concentrated extracts of kidney homogenates be used. The detection of isoantigens requires concentrated extracts prepared from individual kidneys.

     

Spatial and temporal visual properties of single neurons in the suprageniculate nucleus of the thalamus

The spatial and temporal visual sensitivity to drifting sinusoidal gratings was studied in 105 neurons of the suprageniculate nucleus of the feline thalamus. Extracellular single-unit recordings were performed in halothane-anesthetized, immobilized, artificially ventilated cats. Most suprageniculate nucleus cells were strongly sensitive to the direction of drifting gratings. The suprageniculate nucleus units had a clear preference for very low spatial frequencies with a mean of 0.05 cycle/deg. The spatial resolution was also very low with a mean of 0.16 cycle/deg. Most of the cells displayed low-pass spatial tuning characteristics, while the remainder of the units were band-pass tuned. The suprageniculate nucleus units were extremely narrowly tuned, to spatial frequencies with a mean spatial bandwidth of 1.07 octaves. A majority of the units responded optimally to high temporal frequencies, with a mean of 8.53 Hz. The temporal frequency tuning functions predominantly revealed a band-pass character, with a mean temporal bandwidth of 1.66 octaves. These results demonstrate that the neurons in the suprageniculate nucleus display particular spatial and temporal characteristics. The spatial and temporal tuning properties of the suprageniculate nucleus neurons are very similar to those of the superior colliculus and the anterior ectosylvian cortex, structures that provide the main visual afferentation toward the suprageniculate nucleus. This suggests their common function in motion perception, and especially in the recording of movements of the visual environment relative to the body, and the related behavioral action.     

Studies of the antigenicity and allergenicity of phospholipase A2 of bee venom.

The antigenic and allergenic properties of phospholipase A2 (PLA2) and whole bee venom were compared by measuring the IgG and IgE antibody responses in animals and man. Precipitating antibodies raised in rabbits and reaginic and other antibodies raised in mice reacted about equally with both bee venom and PLA. The majority of human sera containing bee venom-specific IgE also contained PLA-specific IgE, although in somewhat lower titers. Similarly, most human sera with significant amounts of total antibodies reacting with bee venom also had antibodies reacting with PLA. Histamine and SRS-a release from leukocytes of sensitive patients followed challenge with whole bee venom and PLA in the majority of instances. However, mediator release from several patients' cells was obtained with bee venom only. These studies suggest that although PLA is a major allergen and antigen in bee venom, significant exceptions in patients' reactivity may limit its potential diagnostic and therapeutic usefulness.     

Comparison of the allergenicity and antigenicity of Polistes venom and other vespid venoms

The crossantigenicity of Polistes venom with other vespid venoms was examined with rabbit and human antisera. Venom preparations from various Polistes species were obtained by electrical stimulation of individual insects and venom sac dissection. Rabbit antibodies were raised to the venom (P. apachus) and venom sac extract (P. exclamans). Human antisera were obtained from patients allergic to Polistes and other vespid venoms. The venom appeared to be more potent than the venom sac preparations in reactions with rabbit IgG and human IgE antibodies. Among the Polistes species, P. exclamans, P. instablis, and P. apachus venoms showed several lines of precipitation with rabbit antisera, and P. annularis and P. fuscatus venoms only one line, suggesting quantitative or qualitative antigenic differences. In RAST analysis, most sera reacted equally to all Polistes species but occasional exceptions were noted, again suggesting differences in venom allergens. P. exclamans-coupled discs gave the most consistent results. In gel diffusion experiments, there was no crossreactivity between Polistes and yellow jacket venoms and only limited crossreactivity between Polistes and hornet venoms. Patients sensitive to Polistes venom showed varying degrees of reactivity to yellow jacket and hornet venoms in RAST analysis. Patients sensitive to other vespid venoms also showed varying degrees os sensitivity to Polistes venom. Polistes venom appears to contain a genus-unique antigen (allergen). In addition, there appear to be some crossreacting antigens in Polistes and other vespid venoms but to a much lesser degree than found previously in the analysis of the relationship of yellow jacket and hornet venoms.     

Comparison of the biochemical, immunologic and allergenic properties of vespid venoms collected in early and late summer

The biochemical, immunologic and allergenic properties of yellow hornet (Vespula arenaria) and bald-faced hornet (Vespula maculata) venoms collected in early and late summer were compared. The phospholipase A content of both hornet venoms decreased in late summer while protease, hyaluronidase and acid phosphatase contents were unchanged. The antigenic and allergenic properties of the two venoms, as measured by their reaction with rabbit antisera and sera from insect-allergic patients, respectively, were unchanged. These results suggest no changes in venom properties during the summer which influence the allergic response to insect stings.