Level 1, 16 University Avenue
Macquarie University NSW 2109
Studying how the brain and ear influence perception
The Efferent Systems Lab aims to uncover how the feedback loops in the brain shape what we hear through both internal and external mechanisms of modulation.
Learn more about the projects we are undertaking in this area, and the research teams involved in them.
Uncovering central gain mechanisms in the subcortex
Central gain is a delicate balance of inhibitory and excitatory neurons in the brain. When disturbed, it can lead to run-away gain, like the screech of loudspeakers in a public address system when a microphone is brought closer. Except, in the auditory brain it can lead to tinnitus – phantom ringing – and hyperacusis – reduced tolerance to loud sounds.
We are studying mechanisms in the human auditory brainstem using non-invasive techniques that has the potential to detect subtle changes in central gain early, ie before individuals develop hearing loss, tinnitus, and hyperacusis. Such early detection can help in earlier administration of therapeutics or changing lifestyle.
- Dr Sriram Boothalingam (lead)
- Viji Easwar – National Acoustic Laboratories
Our research partners:
- National Acoustic Laboratories
Contact: sriram.boothalingam@mq.edu.au
Developing a rapid, cheap, and informative hearing screening test
Funded by: Macquarie University Cochlear Research Joint Fund, National Acoustic Laboratories, Royal National Institute for the Deaf (UK)
Newborn hearing screening (NBHS) is a critical program that, by detecting hearing loss at birth, provides the best opportunity for the child’s speech and language development through the provision of hearing aids or cochlear implants.
Australia is the world leader in NBHS. However, we use one of the costliest, and less informative, technologies in our NBHS.
We are working on a new-age tool that cleverly repurposes existing cheaper technology to provide us more information about hearing deficit. We envision our new test could cut costs owing to lesser running costs (consumables, training), and faster triage of newborns to the correct audiological management.
- Dr Sriram Boothalingam (lead)
- Professor Benoit Liquet-Weiland
- Associate Professor Georgy Sofronov
- Dr Thomas Fung
- Dr François Deloche
- Viji Easwar– National Acoustic Laboratories
- Zachary Smith – Cochlear
Patent: Boothalingam, S., & Dhar, S. (2023). U.S. Patent No. 11,839,467. Washington, DC: U.S. Patent and Trademark Office.
Our research partners:
- Cochlear
- National Acoustic Laboratories
Contact: sriram.boothalingam@mq.edu.au
Unraveling the functional relevance of feedback circuits in the brain
A rich neural network travels in reverse from the brain back to the ear making multiple loops along the way. While we know broadly that these neural systems influence our hearing, how exactly the multiple systems work collaboratively, and their contributions to our listening experience is unclear.
Through series of experiments that test various hypotheses, we aim to unravel the functional relevance of these feedback networks in the brain for human hearing.
- Dr Sriram Boothalingam (lead)
- Professor Shawn Goodman – University of Iowa
- Dr Aravind Parthasarathy – University of Pittsburgh
- Professor David McAlpine
- Jason Mikiel-Hunter
Our research partners:
- University of Iowa
- University of Pittsburgh
Contact: sriram.boothalingam@mq.edu.au
Developing protocols for robust auditory transcranial magnetic stimulation
Transcranial magnetic stimulation (TMS) is a neuromodulation technique where a magnetic field is applied to the scalp over a brain region of interest to modulate short-term neural activity. TMS is an FDA approved technique that is used both in research and clinic, eg for treating depression.
We use TMS to temporarily modulate auditory cortical activity while we study its effects throughout the auditory system. Almost all protocols for performing TMS come from applying TMS to the motor cortex without any tailor-made recommendations for the auditory cortex.
In a first-of-a-kind program we aim to develop TMS protocols that accurately, efficiently, safely, and robustly stimulates the auditory cortex.
- Dr Sriram Boothalingam (lead)
- Sarah Steele
- Professor Jennifer Rodger – University of Western Australia
- Associate Professor Ann-Maree Vallence – Murdoch University
- Professor David McAlpine
- Professor Andrej Kral – Macquarie University and Hannover Medical School
Our research partners:
- University of Western Australia
- Murdoch University
Contact: sriram.boothalingam@mq.edu.au
The overworked listening brain: Investigations at the nexus of sleep, cognition, and hearing impairment
Funded by: Macquarie University Cochlear Research Joint Fund
During sleep, specifically during the slow wave or deep sleep, biological processes remove metabolic waste products, such as beta-amyloids and tau proteins, that accumulate in the brain during wakefulness. These proteins are linked to neurodegenerative diseases like dementia, making their removal critical for overall well-being.
Hearing impairment has emerged as one of the most significant modifiable risk factors for dementia, although the evidence for this relationship is still emerging. Critically, the exact mechanisms linking hearing loss, cognitive decline, and neurodegeneration remain elusive.
Given the convergence of listening-related fatigue and sleep's role in recovery from fatigue, we posit that sleep is a critical mediator between increased listening effort in hearing impairment and the risk of developing dementia. However, the extent to which hearing loss impacts objective sleep patterns remains unknown.
In collaboration with Woolcock Institute of Medical Research, world leaders in sleep and respiratory research, and Cochlear Limited, we ask, to what extent does increase listening effort affect sleep?
- Dr Sriram Boothalingam (lead)
- Professor Nathaniel Marshall
- Associate Professor Angela D’Rozario
- Gabriel Katzeff – Cochlear Limited
Our research partners:
- Woolcock Institute of Medical Research, Macquarie University
- Cochlear Limited
Contact: sriram.boothalingam@mq.edu.au