Sequence Processing in the Cortex: An Investigation of the Function of the Canonical Cortical Circuit

Abstract

The cortex is a very important brain structure which coordinates sensory perception, cognition, and motion in mammals. Crucial to the structure of the cortex is the fact that all areas are made up of the same repeating motif, known as the canonical cortical circuit. One theory about the function of the circuit is that its fundamental job is that of sequence recognition and prediction. This thesis takes a multi-pronged approach to advancing the understanding of cortical sequence processing. It describes two experiments done in V1 in mouse, both of which investigate how layer 2/3 cells respond to violations in an expected order of images. These experiments found that V1 is able to learn the statistics of the experiment over time and adjust the strength of its predictions accordingly. In addition to these experiments, the thesis describes the results two projects of data analysis on experiments which had previously been conducted by someone else. The first data analysis investigates how the duration for which each image is presented to a mouse affects a variety of neural responses. The second data analysis attempts to discover how the hippocampus responds to violations in an expected image order, and concludes that no response could be found. Finally, the thesis contains a literature review which describes the relationship between stimulus specific adaptation and the mismatch negativity in the auditory cortex, two phenomena related to sequence processing. Overall, by taking a multi-pronged approach, this thesis seeks to advance our understanding of how the canonical cortical circuit processes sequences, as well as shed light on the areas which need to be investigated further.