Abstract
Attention is a major cognitive function and attention deficits occur in various neurodevelopmental (e.g. Attention-deficit hyperactivity disorder) and neuropsychiatric disorders (e.g. schizophrenia). Uncovering some of the mechanisms of non-pathological attention processes may help to find targets for the treatment of attention deficits. Attention has several facets including selective attention, sustained attention and divided attention. Notably, sustained attention can be defined as the ability to detect intermittent and unpredictable stimuli overprolonged periods of time and has been proposed to be one of the elementary attentional components that can influence not only the other attention processes but also other cognitive performances.Over the last decades, much progress has been made in understanding the neural mechanisms of attention, especially in humans and monkeys. Critically, in sustained visual attention tasks, it has been shown that performance fluctuates rhythmically over time, with a periodicity in the theta frequency range (4-8Hz). This cycling is linked to theta oscillations in the frontoparietal network. However, it remains unclear whether these rhythmical attention processes, expressed both at the behavioral (performance fluctuations) and neural levels in the theta range, are a general principle of attention processing. Are there common neural network dynamics, across all sensory modalities, governing performance fluctuations during sustained attention? To address these questions, it is necessary to investigate other sensory modalities outside vision and to develop new approaches, especially in rodents, a model offering a wide range of possibilities to record and manipulate neuronal activity and in which studies on the temporal aspect of attention are very sparse. In this SniffAttention project, I propose to use the olfactory modality, a dominant sense for rodents, thus an appropriate and ecological modality to study attention in rats. Another important asset of the olfactory modality is that it may have an inherent support for rhythmical attention processes. Indeed, olfactory sampling is inextricably linked to a vital rhythm: respiration, with odorants entering the nasal cavity at each inspiration. In addition, respiratory rhythm frequency encompasses the frequency of the observed performance fluctuations during visual attention (in the theta frequency range).The SniffAttention project aims 1) to test whether performance during a sustained olfactory attention task fluctuates,like in the visual system, and whether it is related to the inherently rhythmical olfactory sampling mode: respiration and 2) to decipher the neural dynamics of some of the structures involved during a sustained olfactory attention task in rodents. The SniffAttention project will address these two aims by using a combination of complementary approaches involving a sophisticated behavioral assay with simultaneous recording of respiration and brain network oscillatory activities in freely moving rats as well as optogenetic tools to dissect the underpinnings of attentional performance fluctuations.