Temporal theta slow-wave activity (TTA-SW) in premature infants is a specific signature of the early development of temporal networks, as it is observed at the turning point between nonsensory driven spontaneous local processing and cortical network functioning. Previous studies have demonstrated that preterms from 28 weeks of gestational age (wGA) are able to discriminate phonemes and voice, supporting the idea of a prior genetic structural or activity-dependent fingerprint that would prepare the auditory network to compute auditory information at the onset of thalamocortical connectivity.

To specify the role in development and the specific location of TTA-SW.

We recorded TTA-SW in 26–32 wGA preterms. The rate of TTA-SW in response to click stimuli was evaluated using low-density EEG in 30 preterms. The sources of TTA-SW were localized by high-density EEG using different tissues conductivities, head models and mathematical models.

We observed that TTA-SW is not sensory driven. Regardless of age, conductivities, head models and mathematical models, sources of TTA-SW were located adjacent to auditory and temporal junction areas. These sources become situated closer to the surface during development.

TTA-SW corresponds to spontaneous transient endogenous activities independent of sensory information at this period, which might participate in the implementation of auditory, language, memory, attention and or social cognition and represents a general interaction between the subplate and the cortical plate.