The influence of serotonergic signaling on visual and somatosensory cortical processing and its relevance for motor behavior

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Visual perception and its coupling to somatosensory processing are important for precise motor behavior. Perception and motor action is in particular influenced during certain emotional states, such as motivation, anger, fear, or attention. Serotonin has been identified as a main transmitter involved in emotional behavior, which acts in particular on G protein coupled receptors (GPCRs). Serotonergicprojections are known to modulate processing as early as in primary sensory and motor cortical areas. Furthermore, sensory areas closely interact with cortical motor output activities but these widespread interareal interactions are currently poorly understood. In this grant we will investigate the influence of serotonergic transmitter release and intracellular signaling for visual and somatosensory cortical processing and will determine which serotonergic signaling pathway is involved. We will then investigate how information processing during serotonergic input can modulate predictive properties, adaptation, and learning of motor behavior. Specifically we will test in how far serotonergic input modulates local intraareal processing vs. modulation of interareal interactions. We will therefore develop optogenetic tools for the control of serotonin release and the down-stream signals in anaesthetized as well as awake and behavingmice. To capture the network activity patterns within and across multiple brain areas we will exploit the unique capacities of voltage-sensitive dye (VSD) imaging, which allows recording of synaptic population activity at both high spatial and temporal resolutions. We will use our tools to monitor the cortical activity during visual tasks in the context of precise control of serotonergic signals. We quantify intra- and interareal interactions by autoregressive models and information theoretic methods. The behavioral consequences of the modulation of sensory processing will be tested in a behavioral motor learning task, where the animal has to associate a visual cue with an error step signal. We will test if serotonergic modulation will enhance motor learning and error prediction and how such processes are encoded in cortical network activity patterns. The experiments will lead to create a computational model for the modulation of visual task detection by serotonin and its importance for movement adjustment. In order to perform these experiments we have assembled a team of three experts on the development of optogenetic tools (Herlitze), analysis of visual processing in vivo on a systems level (Jancke) and complex computational modeling of neuronal signals (Koenig).