Pupil size

Perceivers benefit from integrating their prior beliefs with sensory signals based on their relative reliability to mitigate the effects of stochastic noise. However, in volatile environments, one should avoid integrating these signals when changes in the signal source render their prior beliefs irrelevant. Bayesian causal inference could offer the brain an optimal strategy for adaptively adjusting its reliance on priors. Mechanistically, it has been suggested that the arousal system modulates the weights between prior beliefs and sensory signals accordingly. We tested these hypotheses using a

Listeners benefit from integrating prior beliefs with auditory sensory signals according to their relative reliability to reduce effects of stochastic noise. In volatile environments, however, listeners should not integrate when a change of signal source renders their prior beliefs irrelevant. Bayesian causal inference could provide the brain with an optimal strategy for adaptively adjusting its reliance on priors. Mechanistically, it has been suggested that the arousal system modulates the weights between prior and likelihoodaccordingly. We tested these hypotheses in an auditory localization

…We hypothesized that arousal, which impacts a variety of internal states and behaviours, could be one of these signals that orexin neurons transmit. To test this, we investigated the causal and correlative links between orexin neurons and pupil size, which is often taken as a readout of arousal. Optogenetic stimulation, 2-photon imaging, photometry, ablation, and pharmac

How do humans make decisions? Some theories propose that a prospective brain allows us to predict future events, enabling us to simulate the consequences of our actions and progress toward our goals. Despite increased emphasis on gaze-driven evidence accumulation models, existing decision models underestimate or neglect the significance of mental imagery in decision-making. We aim to explore how gaze behavior and visual imagery interact, simulating mental states associated with potential outcomes during deliberation. Previous research has suggested the 'looking-at-nothing' phenomenon, a behavi

Moment-to-moment fluctuations in neuromodulatory brainstem arousal systems (e.g., dopamine and noradrenaline systems) can show large effects on learning and memory. Dopaminergic projections to the hippocampus play an important role in the formation of long-term memories. For example, previous studies have employed a reward anticipation manipulation during memory formation, eliciting dopaminergic responses in the midbrain and subsequently enhancing the encoding of memories. Until now, the origin of these dopaminergic projections has been attributed to the ventral tegmental area/substantia nigra

Perceptual filling-in occurs when a blank patch in the periphery of a texture field perceptually disappears after sustained fixation. This process may be mediated by horizontal spreading of activity in the early visual cortex. To test this proposal, we assessed if the oblique effect and the surround suppression effect, known to modulate activity in early visual cortex, modulates filling-in. In a psychophysics and eye-tracking experiment, 63 participants reported filling-in while attending peripherally to a grey rectangle on a dynamic texture field. We varied the orientation of elements in the

The aim of this fMRI study was to assess the role of affect sharing (AS), an important aspect of empathy, in observational fear learning. N=37 students completed an observational Pavlovian fear conditioning paradigm, in which they learned to fear a cue (assessed in a subsequent test stage) by watching videos of a demonstrator receiving shocks with that cue (learning stage). Participants watched the videos in a state of high or low AS, respectively, induced by hypnotic suggestions, using a within-subjects design. Unconditioned responses (UR) to the demonstrator’s pain during learning and condit

…in neuromodulation, as measured by pupil size, in line with theories proposing that neuromodulatory systems may regulate the balance between bottom-up and top-down processes. Although intriguing, there is scarce causal evidence tying neuromodulator activity to decision biases. Here, we manipulated decision bias through non-monetary punishments to specific errors (false alarms or misses) while up

…cortices; 2) correlated with pupil size; and 3) associated with performance on cognitive tasks. These results demonstrate that changes in brain state are represented in the coordinated activity of cortical neurons. However, it is unknown if these fluctuations are also

Fluctuations in arousal, controlled by subcortical neuromodulatory systems, continuously shape cortical state, with profound consequences for information processing. Yet, how arousal signals influence cortical population activity in detail has so far only been characterized for a few selected brain regions. Traditional accounts conceptualize arousal as a homogeneous modulator of neural population activity across the cerebral cortex. Recent insights, however, point to a higher specificity of arousal effects on different components of neural activity and across cortical regions. Here, we provide

…remain unknown, one possibility is pupil-linked neuromodulatory systems. However, it is not clear whether pupil size predicts the neural signatures of exploration, much less the sudden

The dorsolateral geniculate nucleus (dLGN) of the thalamus is an essential processing stage for retinal signals to reach the primary visual cortex (V1). How these feedforward signals are modulated by corticothalamic (CT) feedback and behavior remains an open question. To quantify how feedforward, feedback and behavior combine in shaping dLGN responses, direct and selective control of CT feedback in behaving animals is needed, as well as a computational model that takes the various contributing factors into account. We here recorded extracellular responses in dLGN of awake mice to a rich, dynam

The pupil provides a rich, non-invasive measure of the neural bases of perception and cognition, and has been of particular value in uncovering the role of arousal-linked neuromodulation, which alters cortical processing as well as pupil size. But pupil size is subject to a multitude of influences, which complicates unique interpretation. We measured pupils of observers experiencing perceptual multistability -- an ever-changing subjective percept in the face of unchanging but inconclusive sensory input. In separate conditions the endogenously generated perceptual changes were either task-relev

Neural responses in the visual system are usually not purely visual but depend on behavioural and internal states such as arousal. This dependence is seen both in primary visual cortex (V1) and in subcortical brain structures receiving direct retinal input. In this talk, I will show that modulation by behavioural state arises as early as in the output of the retina.To measure retinal activity in the awake, intact brain, we imaged the synaptic boutons of retinal axons in the superficial superior colliculus (sSC) of mice. The activity of about half of the boutons depended not only on vision but