Primarily, one should note that these cells were identified in mice where they found a subset of cells that potentially respond to multiple taste stimuli includ

Primarily, one should note that these cells were identified in mice where they found a subset of cells that potentially respond to multiple taste stimuli including bitter, sweet, sour, and umami. There are already existing classes of cells that respond to bitter, sweet, and umami taste and those that respond to sour and salty stimuli. The cells identified here (BR- Broadly Responsive cells) respond to bitter, sweet, sour, and umami. But if you look at Fig. 3D, even within these BR cells, there is separation between cells that uniquely respond to specific tastes so it is not clear to me how they are all classified into "Broadly Responsive".