4 YEAR PhD IN NEUROSCIENCE
Our research seeks to link the patterns of neural activity in auditory cortex to our perception of the world around us. While sounds within an environment, such as a person talking, may be clearly intelligible at their source, noisy and reverberant listening conditions often combine to degrade the intelligibility of the sound wave arriving at the ear. The challenge faced by the auditory brain is to recover and identify the original sound source. This requires appropriately grouping sound elements into auditory ‘objects’ and developing neural representations that are robust to background noise. Our research methods combine human and animal psychophysics, computational modelling and neurophysiological recording. Since attentional state, behavioural context and even the presence of visual stimuli can modulate or drive activity in auditory cortex, we believe that visualising neural and behavioural sensitivity simultaneously is key to understanding how neurons in auditory cortex support sound perception.
Possible research projects include:
(1) How neural activity represents vowel identity in the presence of background noise? While we have a good understanding of how noise influences the neural representation at the auditory nerve, little is known about how auditory cortical neurons maintain their sensitivity to sound identity in noisy listening conditions. We will address this question by recording neural activity with multi-electrode recordings during behavioural testing.
(2) Where do visual responses in auditory cortex come from? Recent studies have revealed that even at the earliest stages of sensory cortex there is considerable cross-talk between sensory modalities. Anatomical tract-tracing studies have revealed candidate visual cortical regions that might provide visual innervation to auditory cortex. In this project we will inactivate (via cooling or using optogenetics) a particular visual cortical area (field SSY) while recording neural responses to sound and light in auditory cortex.
(3) What do multiple cortical fields contribute to auditory perception? Sensitivity to sound features, such as the identity of a vowel, are distributed across multiple auditory cortical fields. Understanding which fields are essential for vowel discrimination is a necessary first step in developing our understanding of how neural activity in multiple areas is decoded for perception. In this project we will reversibly silence discrete regions of auditory cortex during vowel discrimination.
Bizley JK , Walker KM, Nodal FR, King AJ, Schnupp JW. Auditory cortex represents both pitch judgments and the corresponding acoustic cues. Current Biology. 2013, 23:620-25.
Bizley JK, Walker KM, King AJ, Schnupp JW. Spectral timbre perception in ferrets: discrimination of artificial vowels under different listening conditions. Journal of the Acoustical Society of America. 2013, 133:365-76.
Bizley JK, Shinn-Cunningham BG, Lee AK Nothing is irrelevant in a noisy world: sensory illusions reveal obligatory within-and across-modality integration. Journal of Neuroscience 2012 32:13402-10.