Professor Kamal Sen
Natural Sounds and Neural Coding Laboratory

Professor Kamal Sen
Hearing Research Center, Rm 414B
Department of Biomedical Engineering
Boston University
44 Cummington Street
Boston, MA 02215
617-353-5919 (phone)
617-353-6766 (fax)
kamalsen@bu.edu (email)
Natural Sounds and Neural Coding Laboratory
Departmental Site

Research Interests:

1) Neural Coding of Natural Sounds

How do neurons in the brain respond to complex natural sounds such as speech? Although understanding the processing of natural sounds is an important goal in auditory neuroscience, relatively little is known about the neural coding of these sounds. My laboratory studies the neural coding of natural sounds using a combination of experimental, theoretical and computational methods in the model system of songbirds. Songbirds offer several advantages for studying the processing of natural sounds. Songbirds display a remarkable ability to process auditory information. Auditory information plays a critical role in song learning in young songbirds and in song maintenance in adult birds, and is an important component of many social behaviors in songbirds. For this highly sophisticated behavioral repertoire to be possible, a wide variety of natural sounds, especially songs, must be detected and discriminated by the auditory system of songbirds. Currently, the neural basis of these behaviors is poorly understood.

We use electrophysiological techniques to record the responses of auditory neurons in the songbird brain to complex natural sounds such as birdsong. We will then apply theoretical and computational techniques from areas such as Statistical Signal Processing, Systems Theory, Probability Theory and Pattern recognition to understand how neurons in the brain encode natural sounds.

2) Hierarchical Processing of Natural Sounds

How are natural sounds processed in successive auditory areas of the brain? One hypothesis is that neurons in successive auditory areas in the brain become increasingly more selective, with neurons in earlier areas responding to relatively simple features of sounds and neurons in higher level areas responding to increasingly more complex features of sounds. Such "feature detectors" may contribute to the behavioral ability of songbirds to detect and discriminate a variety of behaviorally relevant natural sounds such as the songs of their own species.

We use a combination of experimental, theoretical and computational techniques to characterize the features of complex natural sounds to which neurons respond in successive auditory areas in the songbird brain, and construct computational models of hierarchical auditory networks to understand how natural sounds are processed in successive stages of the auditory system.

3) Learning

How do auditory neurons change during learning ? Songbirds provide an excellent opportunity to investigate this question as young male songbirds learn how to sing from an adult songbird tutor (usually the father) during development by a process that is strikingly similar to the acquisition of speech in human infants.

We obtain electrophysiological recordings of neural responses in songbirds at different stages of the song learning process. We then analyze these neural responses using theoretical and computational techniques to assess how auditory neurons change during song learning. Because of the similarities between speech and song learning, such experiments may ultimately help in understanding changes in auditory processing in the brain during speech and language acquisition in humans.

Students in the laboratory may be involved in the experimental or the theoretical/computational components of these projects. We are particularly interested in students who are interested in combining these two components.