Shifts in attention drive context-dependent subspace encoding in anterior cingulate cortex in mice during decision making.

Attention supports decision making by selecting the features that are relevant for decisions. Selective enhancement of the relevant features and inhibition of distractors has been proposed as potential neural mechanisms driving this selection process. Yet, how attention operates when relevance cannot be directly determined, and the attention signal needs to be internally constructed is less understood. Here we recorded from populations of neurons in the anterior cingulate cortex (ACC) of mice in an attention-shifting task where relevance of stimulus modalities changed across blocks of trials. In contrast with V1 recordings, decoding of the irrelevant modality gradually declined in ACC after an initial transient. Our analytical proof and a recurrent neural network model of the task revealed mutually inhibiting connections that produced context-gated suppression as observed in mice. Using this RNN model we predicted a correlation between contextual modulation of individual neurons and their stimulus drive, which we confirmed in ACC but not in V1.

Shifts in attention drive context-dependent subspace encoding in anterior cingulate cortex during decision making.

Attention is a cognitive faculty that selects part of a larger set of percepts, driven by cues such as stimulus saliency, internal goals or priors. The enhancement of the attended representation and inhibition of distractors have been proposed as potential neural mechanisms driving this selection process. Yet, how attention operates when the cue has to be internally constructed from conflicting stimuli, decision rules, and reward contingencies, is less understood. Here we recorded from populations of neurons in the anterior cingulate cortex (ACC), an area implicated in ongoing error monitoring and correction during decision conflicts, in a challenging attention-shifting task. In this task, mice had to attend to the rewarded modality when presented identical auditory and visual stimuli in two contexts without direct external cues. In the ACC, the irrelevant stimulus continuously became less decodable than the relevant stimulus as the trial progressed to the decision point. This contrasted strongly with our previous findings in V1 where both relevant and irrelevant stimuli were equally decodable throughout the trial. Using analytical tools and a recurrent neural network (RNN) model, we found that the linearly independent representation of stimulus modalities in ACC was well suited to context-gated suppression of a stimulus modality. We demonstrated that the feedback structure of lateral connections in the RNN consisted of excitatory interactions between cell ensembles representing the same modality and mutual inhibition between cell ensembles representing distinct stimulus modalities. Using this RNN model showing signatures of context-gated suppression, we predicted that the level of contextual modulation of individual neurons should be correlated with their relative responsiveness to the two stimulus modalities used in the task. We verified this prediction in recordings from ACC neurons but not from recordings from V1 neurons. Therefore, ACC effectively operates on low-dimensional neuronal subspaces to combine stimulus related information with internal cues to drive actions under conflict.

Emission modulation of fluorescent turn-on mode dibenzothienyl sulfonyl ethene photoswitches embedded in a polymer film.

For decades photochromic molecules have attracted attention for their potential in using light as an external stimulus to change their photophysical properties. Here we report the spectroscopic characterization of two emissive photochromic molecules that are intrinsically fluorescent and that undergo a photocyclization/cycloreversion reaction upon illumination with light in the UV and VIS spectral ranges. For appropriately adjusted illumination intensities the emission can be modulated between the high- and the low-level with a contrast ratio exceeding 80%. The data are in reasonable agreement with the predictions from a simple kinetic model.

Utilidad de la ecografía torácica en infección neonatal por SARS-CoV-2 / Usefulness of chest ultrasound in a neonatal infection due to SARS-CoV-2

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Utilidad de la ecografía torácica en infección neonatal por SARS-CoV-2 / Usefulness of chest ultrasound in a neonatal infection due to SARS-CoV-2

No disponible

The course of inattention and hyperactivity/impulsivity symptoms after foster placement.

BACKGROUND: It is largely unknown whether symptoms of inattention and hyperactivity/impulsivity of foster children decline over time after placement and what the role of the quality and stability of the foster placement is on the course of attention-deficit hyperactivity disorder (ADHD) symptom trajectories. Longitudinal studies of normative trajectories of symptom types in nonreferred children may assist in appropriately diagnosing ADHD and designing the clinical treatment for foster children. OBJECTIVE: We described average level and slope of inattention and hyperactivity/impulsivity symptoms over time and examined parental (biological and foster) warmth and hostility and placement stability (number of foster-home moves and discharge from care) as reported by 3 informants (biological parent, foster parent, and classroom teacher) after considering maltreatment risks (child age, gender, sibling ADHD, and comorbidity) and use of ADHD medication. METHODS: We studied 252 maltreated children in 95 families during 4 yearly waves, beginning shortly after placement; children were assessed whether they remained in or were discharged from foster care. RESULTS: Average level of inattention declined according to the biological parent, whereas hyperactivity/impulsivity symptoms declined according to both biological and foster parents. Higher inattention was associated with lower parental warmth (foster parent), higher parental hostility (biological, foster, and teacher), and discharge from care (biological parent). Higher hyperactivity was also associated with lower parental warmth (foster parent) and higher parental hostility (biological and foster parent), higher (average) number of foster-home moves, and discharge from care (biological report). Higher teacher-derived hyperactivity symptoms were associated with a history of child abuse (versus neglect); however, abused children showed a steeper decline of hyperactivity over time than those with neglect histories. Unexpected interactions were found for the impact over time of parental (foster) warmth and number of foster-home moves. CONCLUSION: Findings point to the clinical usefulness of attending to the parenting quality and placement stability as malleable factors affecting symptom reduction subsequent to placement.

Practical synthesis and highly diastereoselective Diels-Alder reactions of 1-alkylthio-3-silyloxybutadienes.

An efficient acid-catalyzed method for the synthesis of vinylogous thioesters was developed. 1-Alkylthio-3-silyloxybutadienes were then produced in high yields from the corresponding vinylogous thioesters. These dienes were highly reactive in Diels-Alder reactions, affording the cycloadducts in high endo selectivity under mild conditions.