Topic: pupil size

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

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

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

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