A neuron can receive thousands of inputs that, together, tell it when to fire. New techniques can image the activity of many inputs, and shed light on how single neurons perform computations in response

Many sensory neurons in the mammalian cortex are tuned to specific stimulus features — for example, some fire only when horizontal bars move from top to bottom in the visual field. But it has been unclear whether such tuning is encoded in a neuron's inputs, or whether the neuron itself computes its response. Here, a new technique for visualizing and mapping sensory inputs to the dendrites of neurons in the mouse visual cortex has shown that each neuron makes its own 'decision' as to the orientation preference of its output