How our brains determine where to look is a long-standing problem that embodies sensory processing and motor behavior. The optic tectum (homologue of the mammalian superior colliculus) is central for multisensory integration and motor control of gaze movements. To elicit orientation/gaze towards an object or evasivse movements to avoid for instance a collision is dependent on tectal output channels to the brainstem, it relies on multisensory input to tectum as well as input from pallium/cortex and the basal ganglia.

I will talk about the range of intact and isolated preparations that we have developed in the lamprey - which we use as our reductionist experimental model - to dissect tectal function during unisensory (visual) and multisensory (visual and electrosensory) stimulation. Excitatory multisensory inputs drive tectal output neurons but also feedforward inhibitory interneurons forming a disynaptic circuit that is able to generate spatiotemporal rivalry across the tectal map of space. I will also describe how the state of the tectal circuit can be manipulated by forebrain and dopaminergic modulation and how this in turn can control oculomotor, reticulospinal and ventral root activity.

Our overarching aim is to understand/control/model the dynamic interaction between sensory, cortical and basal ganglia inputs with the collicular microcircuit and how it leads to gaze action selection – a neural architecture that is phylogenetically conserved across the vertebrate phylum.