Features of Criticality Are Present in the Zebrafish Habenula

The habenula is a dynamic region of the brain involved in various processes such as reward processing and stress response. When at rest it is known to be spontaneously active, while upon stimulation it has also been observed to be able to access a number of different states according to the type of stimulation itself. This ability to flexibly access different states can potentially be understood through the context of criticality, which describes a system at the boundary between different phases or dynamical states. Here we analyze fluorescence recordings of the left (LdHb) and right dorsal habenula (RdHb) of the zebrafish for known statistical features of criticality, namely power law distributions (for avalanche size and duration), avalanche size given duration, as well as shape collapse. We see from there that LdHb and RdHb, which are already known to be asymmetric in both connectivity and function, also display asymmetric features of criticality, suggesting that the LdHb is at or near a critical state, while the RdHb is not. This research is supported by the Singapore Ministry of Education under its Academic Research Fund Tier 1 (Project No. 2016-T1-001-152).