“Study of sequence encoding in the prefrontal cortex of non-human primates“, supervised by Béchir Jarraya and Timo van Kerkoerle

Across species, being able to process sequences is crucial for communication, from bird song and non-human primate vocalization to language in humans. While language is unique to humans, non-human primates are capable to recognize certain higher order sequence structures, so-called algebraic patterns. The prefrontal cortex (PFC) has been shown to be involved in processing such sequence patterns. The question, however, remains what mechanism the PFC uses to encode sequence regularities. My thesis explores the neural encoding of sequences in the PFC of non-human primates. The focus lies on the local-global paradigm, which allows us to examine the representation of higher-order structures, which are only perceived under conscious awareness. Using chronic electrophysiological recordings in macaques, I investigated the spiking activity of neural populations in the PFC during a passive sequence processing tasks. My findings demonstrate that the neural ensembles in the PFC encode various aspects of sequences in distinct subspaces, ranging from stimulus- specific to more abstract, generalized representations. The global sequence structure, whose processing is reflective of conscious perception, is encoded by PFC neural populations. These results provide insights into the mechanisms of sequence representation in non-human primates and prompt further inquiry into the broader mechanisms underlying the encoding of abstract information in the brain.