Oscillations support co-firing of neurons in the service of human memory formation

Brain oscillations have been demonstrated to support information transfer between neurons in animal models of memory. However, direct evidence for a similar role of oscillations in humans has so far remained unclear. Here we show that theta and gamma oscillations in the medial-temporal-lobe synchronize neural firing during a memory task. We observe that faster oscillations at theta- and gamma frequencies correlate with co-firing of neurons at short latencies (~20-30 ms) and occur during successful memory formation. Slower oscillations in these same frequency bands, by contrast, correlate with longer co-firing latencies and occur during memory failure. A computational model supports the present effects and links these findings to synaptic plasticity. Together, the results support the long-standing assumption that correlated neural firing supports human episodic memory formation.