Figure 1
The experimental setup. (a) Schematic overview of the experimental setup: a fish swims freely in a water tank with electrodes, and a wireless data logger mounted on its head. The fish's movements are recorded by a video camera positioned above the tank. The tank's walls were coated with yellow foam sheets depicting different visual landmarks. (b) Example of a raw recording from a tetrode (black traces) and a reference electrode (gray) in the fish's lateral pallium. Neural activity can be seen in the tetrode alone. (c) Projection on the first three principal components of the data from the tetrode of all spike candidates that crossed the threshold. (d) Waveforms of two neurons after spike sorting. Other clusters were not distinguishable from other multiunit activity and neural noise. The blue cluster forms a velocity-vector cell, and the red cluster forms a head direction cell (additional examples can be found in Supplementary Figure S1a–h). (e) Inter spike interval histogram of the detected clusters. Insets show there were no violations of the refractory period.
