How does the bird brain encode head direction?

Elhanan Ben-Yishay, Ksenia Krivoruchko, Shaked Ron, Nachum Ulanovsky, Dori Derdikman, Yoram Gutfreund. Head-Direction Coding in the Hippocampal Formation of Birds. bioRxiv 2020.08.31.274928; doi: https://doi.org/10.1101/2020.08.31.274928

Abstract
Birds strongly rely on spatial memory and navigation. However, it is unknown how space is represented in the avian brain. Here we used tetrodes to record neurons from the hippocampal formation (HPF) of Japanese quails – a migratory ground-dwelling species – while the quails roamed a 1×1-meter arena (~2,100 neurons from 21 birds). Whereas spatially-modulated cells (place-cells, border-cells, etc.) were generally not encountered, the firing-rate of 12% of the neurons was unimodally and significantly modulated by the head-azimuth – i.e. these were head-direction cells (HD cells, n=260). Typically, HD cells were maximally active at one preferred-direction and minimally at the opposite null-direction, with preferred-directions spanning all 360°. The HD tuning was relatively broad (mean ~130°), independent of the animal’s position and speed, and was stable during the recording-session. These findings support the existence of an allocentric head-direction representation in the quail HPF, and provide the first demonstration of head-direction cells in birds.

Elhanan Ben-Yishay, Ksenia Krivoruchko, Shaked Ron, Nachum Ulanovsky, Dori Derdikman, Yoram Gutfreund. Head-Direction Coding in the Hippocampal Formation of Birds. bioRxiv 2020.08.31.274928; doi: https://doi.org/10.1101/2020.08.31.274928