A role for visceral feedback and interoception in feelings-of-knowing.

Guided by the framework that autonomic feedback shapes emotional experience and other feeling states, we asked whether feeling-of-knowing (FOK) judgments may be influenced by visceral information through interoception. Participants performed a FOK task for previously studied face-name pairs while changes in cardiovascular and facial muscle activity were recorded. Previously studied face cues for which the corresponding name could not be recalled elicited an increased cardiac rate relative to novel face cues. Critically, the relationship between this pattern of cardiovascular activity and FOK ratings was moderated by interoception, such that for individuals with high interoceptive sensitivity, relative increases in cardiac rate for old items were associated with larger corresponding differences in FOK. Consistent with a link between familiarity and positive affect, we also found that old items elicited less frowning, as reflected in muscle activity recorded from the corrugator muscle. These results provide psychophysiological evidence that visceral signals contribute to experiential metamemory processes.

Specification and spatial arrangement of cells in the germline stem cell niche of the Drosophila ovary depend on the Maf transcription factor Traffic jam.

Germline stem cells in the Drosophila ovary are maintained by a somatic niche. The niche is structurally and functionally complex and contains four cell types, the escort, cap, and terminal filament cells and the newly identified transition cell. We find that the large Maf transcription factor Traffic jam (Tj) is essential for determining niche cell fates and architecture, enabling each niche in the ovary to support a normal complement of 2-3 germline stem cells. In particular, we focused on the question of how cap cells form. Cap cells express Tj and are considered the key component of a mature germline stem cell niche. We conclude that Tj controls the specification of cap cells, as the complete loss of Tj function caused the development of additional terminal filament cells at the expense of cap cells, and terminal filament cells developed cap cell characteristics when induced to express Tj. Further, we propose that Tj controls the morphogenetic behavior of cap cells as they adopted the shape and spatial organization of terminal filament cells but otherwise appeared to retain their fate when Tj expression was only partially reduced. Our data indicate that Tj contributes to the establishment of germline stem cells by promoting the cap cell fate, and controls the stem cell-carrying capacity of the niche by regulating niche architecture. Analysis of the interactions between Tj and the Notch (N) pathway indicates that Tj and N have distinct functions in the cap cell specification program. We propose that formation of cap cells depends on the combined activities of Tj and the N pathway, with Tj promoting the cap cell fate by blocking the terminal filament cell fate, and N supporting cap cells by preventing the escort cell fate and/or controlling the number of cap cell precursors.

Stimulus exposure duration alters implicit processing of neutral and emotional faces.

Stimulus exposure duration in emotion perception research is often chosen pragmatically; however, little work exists on the consequences of stimulus duration for the processing of emotional faces. We utilized the spatiotemporal resolution capabilities of magnetoencephalography (MEG) to characterize early implicit processing of emotional and neutral faces in response to stimuli presented for 80 and 150ms. We found that the insula was recruited to a greater degree within the short (80ms) condition for all face categories, and this effect was more pronounced for emotional compared to neutral faces. The orbitofrontal cortex was more active in the 80-ms condition for neutral faces only, suggesting a modulation of task difficulty by both the duration and the emotional category of the stimuli. No effects on reaction time or accuracy were observed. Our findings caution that differences in stimulus duration may result in differential neural processing of emotional faces and challenge the idea that neutral faces constitute a neutral baseline.