sentence: The coupling variable s ( t ) , will have dynamics given by ( 59 ) s ′ ( t ) = u ( t ) = − s τ s +1 τ s ∑ i = 1N ϕ iei ( s ( t ) + τ su ( t ) ) − aiwhere e = 1 if neuron i is an ON neuron and − 1 for OFF neurons .