Realistic (3D) looming of emotional visual stimuli: Attentional effects at neural and behavioral levels.

Previous research shows that endogenous attention (the controlled selection of certain aspects of our environment) is enhanced toward emotional stimuli due to its biological relevance. Although looming affective stimuli such as threat seem even more critical for survival, little is known about their effect on endogenous attention. Here, we recorded neural (event-related potentials, ERPs) and behavioral responses (errors and reaction times) to explore the combined effect of emotion and looming motion. 3D-recreated static and moving animals assessed as emotionally positive, negative, and neutral, were presented to participants (n = 71), who performed an indirect categorization task (vertebrate vs. invertebrate). Behavioral results showed better task performance, as reflected by lower number of errors and reaction times, in response to threatening stimuli. Neural indices revealed significant early (P1p, 150 milliseconds), intermediate (P2p, 240), and late (LPP, 450) effects, the latter being more intensely associated with behavior, as revealed by regression analyses. In general, neural indexes of attention to both static and dynamic stimuli showed a positivity offset in early stages and a negativity bias in subsequent phases. However, and importantly, the progressive inclusion of negative stimuli in the attentional focus is produced earlier in the case of dynamic (at P2p latency) than in static versions (at LPP). These results point to an enhancement of attention, particularly in temporal terms, toward stimuli combining motion and biological significance.

Retinotopy of emotion: Perception of negatively valenced stimuli presented at different spatial locations as revealed by event-related potentials.

Scarce previous data on how the location where an emotional stimulus appears in the visual scene modulates its perception suggest that, for functional reasons, a perceptual advantage may exist, vertically, for stimuli presented at the lower visual field (LoVF) and, horizontally, for stimuli presented at the left visual field (LeVF). However, this issue has been explored through a limited number of spatial locations, usually in a single spatial dimension (e.g., horizontal) and invariant eccentricities. Event-related potentials (ERPs) were recorded from 39 participants perceiving brief neutral (wheels) and emotional stimuli (spiders) presented at 17 different locations, one foveal and 16 at different peripheral coordinates. As a secondary scope, we explored the role of the magnocellular (M) and the parvocellular (P) visual pathways by presenting an isoluminant/heterochromatic (P-biased) and a heteroluminant/isochromatic version (M-biased) of each stimulus. Emo > Neu effects were observed in PN1 (120 ms) for stimuli located at fovea, and in PN2 (215 ms) for stimuli located both at fovea and diverse peripheral regions. A factorial approach to these effects further revealed that: (a) emotional stimuli presented in the periphery are efficiently perceived, without evident decrease from para- to perifovea; (b) peripheral Emo > Neu effects are reflected 95 ms later than foveal Emo > Neu effects in ERPs; (c) LoVF is more involved than UVF in these effects; (d) our data fail to support the LeVF advantage previously reported, and (e) Emo > Neu effects were significant for both M and P stimuli.

Sleep-wakefulness effects after microinjections of hypocretin 1 (orexin A) in cholinoceptive areas of the cat oral pontine tegmentum.

Hypocretinergic/orexinergic neurons, which are known to be implicated in narcolepsy, project to the pontine tegmentum areas involved in the control of rapid eye movement (REM) sleep. Here, we report the effects on sleep-wakefulness produced by low-volume microinjections of hypocretin (Hcrt)1 (20-30 nL, 100, 500 and 1000 microm) and carbachol (20-30 nL, 0.1 m) delivered in two areas of the oral pontine tegmentum of free-moving cats with electrodes for chronic sleep recordings: in the dorsal oral pontine tegmentum (DOPT) and in the ventral part of the oral pontine reticular nucleus (vRPO). Carbachol in the DOPT produced dissociate polygraphic states, with some but not all REM sleep signs. In contrast, carbachol in the vRPO produced a shift with short latency from wakefulness (W) to REM sleep with all of its polygraphic and behavioral signs. Hcrt-1 in the DOPT increased W and decreased both slow-wave sleep (SWS) and REM sleep during the first 3 h post-drug. The same doses of Hcr-1 in the vRPO produced a significant suppression of REM sleep without a definitive trend for changes in the other states. Both groups showed significant decreases in the number of transitions from SWS to REM sleep. Thus, Hcrt-1 produced distinct effects in cholinoceptive areas of the oral pontine tegmentum; in the DOPT it promoted W, suppressed SWS and probably defacilitated REM sleep, and in the vRPO it directly inhibited REM sleep. Hypocretinergic/orexinergic signaling is lost in narcoleptics and this absence would mean that pontine defacilitation/inhibition of REM sleep would also be absent, explaining why these patients can fall directly into REM sleep from W.