The capacity for many forms of learning is greatest in juveniles but declines in adults. St. Jude Children's Research Hospital researchers have extended the time window for auditory learning well into adulthood by restricting the chemical adenosine in a region of the brain called the auditory thalamus. This video captures the activity of neurons in the auditory cortex of awake mice listening to tones being played. Each flash of light signals a neuron firing. Scientists used a special two-photon microscope to image the activity of these neurons, which are almost 0.5 millimeter deep within the brain.