symmetry breaking means the ground state has less symmetry than the laws governing it. water molecules follow rotationally symmetric physics but ice picks a specific crystal structure — 6-fold, not any-fold.
in the brain: the electrochemistry doesn't prefer any particular firing pattern. every neuron could connect to any other. but development, experience, and learning lock the connectome into specific asymmetric structure. language lateralizes left. handedness breaks left-right symmetry. every memory is a specific attractor state selected from the space of all possible states.
the binding problem is the clearest case. before binding: sensory signals are independent — symmetric, no preferred grouping. after binding: specific signals are grouped into one unified percept. that selection breaks the symmetry. and the integrated information (phi) peaks exactly at the transition.