Impact of cortical plasticity

29 The performance of neural codes to represent attributes of sensory signals has been 30 evaluated in the vertebrate peripheral and central nervous system. Here we determine 31 how information signaled by populations of neurons is modified by plasticity. 32 Suprathreshold neuronal responses from a large number of neurons were recorded in the 33 juvenile mouse barrel cortex using dithered random-access scanning. Pairing of one input 34 signal with another input signal resulted in a long-lasting, input-signal specific modification 35 of the cortical responses. Mutual information analysis indicated that cortical plasticity 36 efficiently changed information signaled by populations of neurons. The contribution of 37 neural correlations to the change in mutual information was negative. The largest factor 38 limiting fidelity of mutual information after pairing was a low reliability of the modified 39 cortical responses. 40 41