Biology subjects

Phillips, I.

Publications and source records attributed to Phillips, I..

3 recordsLinked to original sources

bioRxiv2024

Sensitivity to visual features in inattentional blindness

The relation between attention, perception and awareness is among the most fundamental problems in the science of the mind. One of the most striking and well-known phenomena bearing on this question is inattentional blindness (IB; Neisser & Becklen, 1975; Mack & Rock, 1998; Most et al., 2001, 2005). In IB, naive observers fail to report clearly visible stimuli when their attention is otherwise engaged--famously even missing a gorilla parading before their eyes (Simons & Chabris, 1999). This phenomenon and the research programs it has motivated carry tremendous theoretical significance, both as crucial evidence that awareness requires attention (Cohen et al., 2012; Prinz, 2012; Noah & Mangun, 2020) and as a key tool in seeking the neural correlates of consciousness (Rees et al., 1999; Pitts et al., 2014; Hutchinson, 2019). However, these and other implications critically rest on a notoriously biased measure: asking participants whether they noticed anything unusual (and interpreting negative answers as reflecting a complete lack of perception). Here, in the largest ever set of IB studies, we show that, as a group, inattentionally blind participants can successfully report the location, color and shape of the stimuli they deny noticing. This residual visual sensitivity shows that perceptual information remains accessible in IB. We further show that subjective reports in IB are conservative, by introducing absent trials where no IB stimulus is presented; this approach allows us to show for the first time that observers collectively show a systematic bias to report not noticing in IB--essentially playing it safe in reporting their sensitivity. This pair of results is consistent with an alternative hypothesis about IB, namely that inattentionally blind subjects retain some degree of awareness of the stimuli they fail to report. Overall, these data provide the strongest evidence to date of significant residual visual sensitivity in IB. They also challenge the use of inattentional blindness to argue that awareness requires attention.

neuroscience↗

bioRxiv2024

300 Hz transcutaneous auricular vagus nerve stimulation (taVNS) impacts pupil size nonlinearly as a function of intensity

Transcutaneous auricular vagus nerve stimulation (taVNS) is a neuromodulatory technique that may have numerous potential health and human performance benefits. However, optimal stimulation parameters for maximizing taVNS efficacy are unknown. Progress is impeded by disagreement on the identification of a biomarker that reliably indexes activation of neuromodulatory systems targeted by taVNS, including the locus coeruleus-norepinephrine (LC-NE) system. Pupil size varies with LC-NE activity and is one potential taVNS biomarker that has shown inconsistent sensitivity to taVNS in prior studies. The present study examined the relationship between pupil size and taVNS using stimulation parameters that have shown promising behavioral effects in prior studies but have received comparatively little attention. Participants received 30-second trains of 50 s taVNS pulses delivered below perceptual threshold at 300 Hz to the left external acoustic meatus (EAM) while pupil size was recorded during a pupillary light reflex task. Analysis of pupil size using generalized additive mixed modelling (GAMM) revealed a nonlinear relationship between taVNS intensity and pupil diameter. Active taVNS increased pupil size during stimulation for participants who received taVNS between 2 and approximately 4.8 mA, but not for participants who received higher intensity taVNS (up to 8.1 mA). In addition, taVNS effects persisted in subsequent blocks, mitigating decreases in pupil size over the course of the task. These findings suggest 300 Hz taVNS activates the LC-NE system when applied to the EAM, but its effects may be counteracted at higher intensities.

neuroscience↗

bioRxiv2023

Metabolomic and transcriptomic analyses of Fmo5-/- mice reveal roles for flavin-containing monooxygenase 5 (FMO5) in NRF2-mediated oxidative stress, the unfolded protein response, lipid homeostasis, and carbohydrate and one-carbon metabolism

Flavin-containing monooxygenase 5 (FMO5) is a member of the FMO family of proteins best known for their roles in the detoxification of foreign chemicals and more recently in endogenous metabolism. We have previously shown that Fmo5-/- mice display an age-related lean phenotype, with much reduced weight gain from 20 weeks of age. The phenotype is characterized by decreased fat deposition, lower plasma concentrations of glucose and cholesterol, higher glucose tolerance and insulin sensitivity, and resistance to diet-induced obesity. In the present study we report the use of metabolomic and transcriptomic analyses of livers of Fmo5-/- and wild-type mice to identify factors underlying the lean phenotype of Fmo5-/- mice and gain insights into the function of FMO5. Disruption of the Fmo5 gene has wide-ranging effects on the abundance of metabolites and expression of genes in the liver. The results reveal that FMO5 is involved in upregulating the NRF2-mediated oxidative stress response, the unfolded protein response and response to hypoxia and cellular stress, indicating a role for the enzyme in adaptation to oxidative and metabolic stress. FMO5 also plays a role in stimulating a wide range of metabolic pathways and processes, particularly ones involved in the regulation of lipid homeostasis, the uptake and metabolism of glucose, the generation of cytosolic NADPH, and in one-carbon metabolism. The results predict that FMO5 acts by stimulating the NRF2, XBP1, PPARA and PPARG regulatory pathways, while inhibiting STAT1 and IRF7 pathways.

biochemistry↗