The basal ganglia-thalamocortical (BGT) circuit controls the acquisition and production of motor skills in vertebrates, particularly human speech. Motor skills are hypothetically learned through reinforcement learning (RL). In songbirds, male juvenile zebra finches mimic the vocalizations of adults. Even in adulthood, their song may undergo slight modifications. The circuits underlying song learning and plasticity are called the song system.The song system, including the BGT loop and motor pathway, assesses vocal performance and controls song execution. The lateral magnocellular nucleus of the anterior neostriatum (LMAN) is the cortical output nucleus from the BGT loop, which is responsible for acoustic variability. Indeed, studies show that lesioning LMAN in zebra finches eliminates song fluctuations. According to the RL framework, LMAN would send an efference copy of this modulation of the song to Area X, homologous to the human motor BG. LMAN also projects to the motor pathway, which coordinates syrinx and respiration muscles, indirectly controlling song production and acoustic features. However, the exact mechanism by which LMAN and Area X activity influence features remains unknown.Using in vivo electrophysiology and song recordings in adult zebra finches, we investigated the relationship between LMAN/Area X activity and song acoustic features. Currently, we found no linear correlation between neural unit activity in these BGT structures and birdsong features. However, including population analysis and non-linear models might help us uncover more complex relationships. Understanding how BGT structures encode feature variation could help us comprehend the intricacies of song learning and sensory-motor learning, particularly in speech acquisition.