Role of the Posterior Parietal Cortex in short- but not long-term Memory-dependent Behaviour

Memory encompasses much more than simply remembering the past. It is the toolbox that allows us to evolve on the timescale of a lifetime. Similar to centuries of evolution for a species, the ability to form and retrieve memories endows individuals with the means to be better fit for the future based on the past.
Breaking down memory to its essential purpose, increasing the chance for survival, it becomes clear that the more effectively an individual is able to shape its future behaviour based on extracting relevant information from past experiences, the better it is equipped for success.
Thus, the crucial aspect of memory must not lie in its mere existence, but in the way individuals are able to direct their focus on what is most relevant, and to integrate the latter effectively with other memories to adapt their behaviour to changing circumstances. In many situations, deviations from existent behaviour are driven by the prospect of increasing the chances for benefit while keeping the cost as low as possible.
In this thesis, I am discussing work I have carried out in order to understand how short-term as well as long-term memories shape decision-making and associated behaviour and which role the posterior parietal cortex (PPC) plays for the latter. I have chosen the PPC as a candidate because it is traditionally viewed as an associative multisensory region whose roles are diverse, including spatial navigation, decision-making, attention direction, route planning, and multisensory integration. By connecting to visual, auditory, somatosensory and motor regions to name only a few, I was curious to find out whether PPC was particularly relevant for integrating multisensory input to respond adaptively to environmental circumstances on a short-term memory scale.
By employing chemogenetic tools in combination with viral tracing techniques in diverse behavioural paradigms, I will show that PPC plays a crucial role in enabling short-term memory to affect behaviour adaptively. Additionally, I will show which roles the downstream projections of PPC to the dorsal as well as to the tail of the striatum play regarding the implementation of PPC function.