Michael Dorris
Laboratory of Decision-Making, Institute of Neuroscience, Shanghai Institutes for Biological Sciences, Chinese Academy of Sciences

The vertebrate tectum is critical for orienting the eyes, head, body and specialized organs towards targets of value. In fish, frogs and birds the tectum is often the largest brain structure. In primates, tectal size is greatly reduced but it remains a critical orienting structure largely by integrating a wide variety of sensory and cognitive inputs from the evolutionarily recent neo-cortex. Does the evolutionarily old tectum still decide where to orient or does it simply enact decisions already completed by the neo-cortex? We are currently examining three conditions in which the tectum may be heavily involved in the decision-making process.

1) Urgency – Under time pressure, the tectum may choose fast (albeit inaccurate!) responses before deliberation is finished in the cortex.
2) Nash Equilibrium – The cortex biases competition within the tectum towards higher valued options, however, during mixed-strategy interactions, noise within the tectum may result in stochastic choices.
3) Individual Item from a Particular Good – Once the most valued good is identified by cortex, the particular item from that good may be selected by tectal mechanisms.
Together, cortical structures may provide primates with increased flexibility in decision-making while primitive tectal circuitry provides speed and automaticity.