Sounds and hearing play a pivotal role in human communication. People who suffer from central auditory processing abnormalities are affected in their daily lives and might not be able to appreciate even the most basic verbal communication. Tinnitus, in which phantom sounds are experienced in the absence of acoustic stimulation, is an example of pathology of the central auditory system. More than 10% of the population suffers from it.
Despite the importance of hearing in human communication, we still understand very little of how sounds are perceived and how they are processed in the central auditory system, and particularly in the auditory cortex, to allow us to make sense out of them. The periphery of the auditory system is better understood; the powerful cochlear implants or hearing aids used nowadays are model results of the translational research stemming from basic findings in the peripheral auditory system. However, the central auditory system, and the auditory cortex in particular, is still only poorly understood.
The aim of our lab is to understand the role of specific neuron circuits in making sense of sounds. We combine optogenetics, in vivo physiology, voltage-sensitive imaging, behavioural assays, cochlear implants and computer modeling to explore the functions of neuronal circuits in the mouse auditory cortex.
Ongoing work in our group is directed towards three main questions:
- How do auditory cortical responses develop and how can they be modified?
- What neuronal circuits are involved in specific sound features, and how do they influence behaviour?
- What influences does the environment have on regulating these auditory neuronal circuits?
The lab’s results will provide a new understanding of how sounds are processed and perceived. Learning how distinct neural circuits code for auditory inputs of increasing complexity will shed light on the function of the auditory cortex, on the role of different circuits in characterizing the behavioural response to a sensory input, and eventually on the cause of abnormal signal processing in brain disorders. The results will contribute towards a richer comprehension of normal function and will hold the key for remediating abnormal auditory signal processing following a history of compromised hearing or deafness
Ongoing projects in the lab are aimed at:
- Characterizing the development of auditory responses to sounds of increasing complexity. We will also determine critical periods for these complex sounds, as well as factors controlling this developmental plasticity.
The results will shed a new light on how the brain processes different sound features during development, and will identify what cortical circuits are engaged by specific sound features. By characterizing the plasticity of the auditory cortex, our research will eventually be crucial for remediating abnormal signal processing following compromised hearing in adults.
- Probing whether these circuits depend on the maturation or function of each other. We will also assess the behavioural consequences of modifying a specific cortical circuit in auditory relevant tasks and describe the relationship of auditory cortical activity to perception and behaviour. Together, these results will tell us to what extend a circuit associated to a sound feature has to be functional in order for a circuit associated to another sound feature to function properly.
- Defining the neuronal subpopulations involved in specific sound features and describing the corresponding behavioural phenotypes. Using optogenetics, auditory responses will be characterized following light-driven control of the excitability of subsets of neurons. We will then assess the behavioural consequences of controlling targeted neuronal subpopulations in auditory relevant tasks.
The results will elucidate the role of neuronal subpopulations in the central auditory system. Our aim is to set the ground for a theory of auditory forebrain function.
- Probing the influence of the environment on the rules regulating the development and plasticity of auditory circuits. The same experiments and measurements described previously will be applied to mice exposed to an abnormal auditory environment or to a non-auditory related stressful environment.
The results will add to our understanding of the role of the external environment on shaping – or misshaping – neuronal circuits and behavioural phenotypes. This research will have an impact on the way we look at the constant occupational noise and emotional stress that we and our children are exposed to on a daily basis, ranging from background music, phone conversations, construction work or psycho-social distress.