• Option + “[“ or “]” (Mac) | Alt + “[“ or “]” (Win) targets the layer above or below the currently targeted layer.
• Option + Shift + “] “or + “[“ (Mac) | Alt + Shift + “] “or + “[“ (Win) adds the next layer up or down to the targeted layer(s) (note when you get to the top or bottom of the layer stack, Photoshop will “wrap around” to continue adding/subtracting layers).
• Option + “,“ or “.” (Mac) | Alt + “,“ or “.” (Win) targets the bottom/top -most layer.
• Option + Shift + “,“ or “.” (Mac) | Alt + Shift + “,“ or “.” (Win) targets all layers that fall between the currently targeted layer to the top or bottom of the layer stack.
Note: these shortcuts are essential when recording actions as they help to select layers, but do not record the specific “name” of the layer in the action.
Source: http://blogs.adobe.com/jkost/2015/11/more-shortcuts-for-targeting-layers-via-the-keyboard-in-photoshop.html