To what extent are sensory responses in the brain compatible with first-order principles. The efficient coding hypothesis projects that neurons use as few spikes as possible to faithfully represent natural stimuli. However. many sparsely firing neurons in higher brain areas seem to violate this hypothesis in that they respond more to familiar stimuli than to nonfamiliar stimuli. https://www.chiggate.com/3m-speedglas-9002nc-welding-helmet-fashion/