Dr Leo Lui
ARC (DECRA) Research Fellow
Sensory and Cognitive Neuroscience Group, Department of Physiology.
ARC Centre of Excellence for Integrative Brain Function (Associate Investigator)
Monash Vision Group
Location: Room F123A, Department of Physiology (Building 13F)
Phone: +61 3 9905 8398
Email: leo.lui@monash.edu
Background
I completed a Bachelor of Science degree with honours in Physiology here at Monash University in 2002. This was followed by a PhD under the supervision of Professor Marcello Rosa and Associate Professor James Bourne in the Department of Physiology, Monash University, which I completed in 2007. Upon completing my PhD, I undertook a post-doctoral appointment at the University of Rochester (NY, USA) to study vision and behaviour with Professor Tatiana Pasternak; the latter part of this appointment was funded by a NHMRC overseas-based early career (CJ Martin) fellowship. I retuned to Australia to complete the second component of this Fellowship when I joined the Monash Vision Group in 2010, to develop and build a visual prosthesis for the blind; work in this project is still continuing. I was awarded a Discovery Early Career Research Award from the ARC in 2013, therefore beginning an independent research program within the Sensory and Cognitive Neuroscience Group.
Research Interests
I’m interested in how the activity of neurons leads to human behaviour. I use a combination of psychophysical and physiological techniques to address this aim. My early work has been in the visual system, investigating the way in which the activity of neurons allows for the perception of motion. More recently, I’ve used visual motion to study higher cognitive function such as working memory and decision-making.
I study sensory systems; this is because sensory systems have historically given the most robust insights into brain function, partly due to the way in which these experiments can be tightly controlled within laboratory settings. Therefore, sensory systems act as a “tool” to study higher-order function such as decision-making, memory, sensory integration and consciousness. I believe, as has been proven in the past, the results of these experiments will extend knowledge not only to sensory processing but also general brain function.
I have the capacity to supervise graduate (PhD or masters) as well as undergraduate (honours and 3rd year project) students, the resources within the group will also be extended to these candidates. Therefore, if you’re interested in any of the projects below, please do not hesitate to contact me.
Laboratory Personnel
Maureen Hagan, Post-Doctoral Researcher
Ben Allitt, Post-Doctoral Researcher (co-supervision with Ramash Rajan).
Tristan Chaplin, Graduate (PhD) Student (co-supervision with Marcello Rosa).
Jonathan Chan, Research Assistant (co-supervision with Marcello Rosa).
Funding
Australian Research Council: Discovery Early Career Research Award (2013-2016)
National Health and Medical Research: Project Grant (Lui, Price and Rajan; 2014-2016)
Projects
1. Audiovisual Integration
Major Collaborators: A/Prof Ramesh Rajan and Dr Nic Price.
We are able to integrate information from multiple sensory modalities with little loss of information. Of all the combinations of senses, audiovisual integration is considered to be the most important: It’s most important for providing information regarding extrapersonal space (i.e. locating dangerous predators/prey for animals, moving cars for humans), and its role in communication (the combination of voice together with body language) cannot be underestimated. While we are able to do this remarkably well, the neural mechanisms underlying this ability is not well understood… this is a question which my laboratory is addressing using behavioural, anatomical and physiological techniques. As well as understanding audiovisual integration specifically, this experimental approach serves as a model for more complex decision-making, as it involves combining multiple sources of evidence represented by distinct parts of the brain.
2. Neural Mechanisms underlying Blindsight
Major Collaborators: Prof Marcello Rosa and Dr Hsin-Hao Yu.
This is a remarkable phenomenon that was discovered many years ago in human patients: After damage to the primary visual cortex (a very important part of the brain for visual function), people loose conscious visual experience in the corresponding parts of visual field. However, when these patients are asked to choose between multiple alternatives regarding an attribute of an object presented within this “blindfield”, they get it right most of the time without having any idea that the object was even there (i.e. they have to be made to guess). Much of the neural physiology underlying this sub-conscious “blindsight” vision was mapped out by pioneering work of Marcello Rosa earlier this century, this work is still continuing today by Marcello and others in the group. My laboratory turns our attention to behaviour: using this experimental model, we are able to investigate the neural pathways underlying conscious and sub-conscious vision and decision-making. It was found recently that behavioural training can improve vision within the “blindfield” almost to the extent to that of normal subjects. My laboratory also investigates the neural mechanisms underlying this recovery.
3. Neural Mechanisms of Sound localisation
Major Contributors: A/Prof Ramesh Rajan, Prof Marcello Rosa
This project is led by Ramesh Rajan. We are investigating the neural signals that allow us to localize sounds. There are two cues that allow individual to locate a sound source along the azimuth (horizontal plane), interaural time differences, and interaural level differences. The latter is the dominant cue, which has to be calculated by comparing the loudness between sounds presented to the two ears. While humans can do this remarkably well, there is little known about the brain activity that supports this performance. Our results suggest the primary auditory cortex participate in these neural “calculations”, however, we also found that these signals require further processing by higher-order auditory brain areas before it can sufficiently account for behavioural performance.
4. Monash Vision Group: building a bionic eye
Major Contributors: Prof Marcello Rosa, Dr Nic Price and Dr Konstantinos Chatzidimitrakis.
I’m a member of the Monash Vision Group, our goal is to develop a cortically-based visual prosthesis for the blind. We are made up of more than 60 staff from the departments of Physiology, Engineering at Monash University, neurosurgeons at the Alfred Hospital and a number of biomedical companies. I’m apart of the pre-clinical team lead by Marcello Rosa.
Publications
1. Lui LL, Mokri Y, Reser DH, Rosa MGP, Rajan R (submitted) Neurons in the primary auditory cortex of anaesthetized marmosets are selective for interaural level differences of natural vocalizations.
2. Lui LL, Rosa MPG (2014), Structure and function of the middle temporal visual area (MT) in the marmoset: comparisons with the macaque monkey. Neurosci Res pii: S0168-0102(14)00223-5. doi: 10.1016/j.neures.2014.09.012 [Epub ahead of print].
3. Lui LL, Bourne JA, Rosa MGP (2013) Relationship between size summation properties, contrast sensitivity and response latency in the dorsomedial and middle temporal areas of the primate extrastriate cortex. PLoS One, 8:e68276
4. Lui LL, Dobiecki A, Bourne JA, Rosa MGP (2012) Breaking camouflage: responses of neurons in the middle temporal area to stimuli defined by coherent motion. European Journal of Neuroscience, 36:2063-76
5. Lui LL, Pasternak T (2011) Representation of comparison signals in cortical area MT during a delayed direction discrimination task. J Neurophysiol 106: 1260-1273.
6. Yu HH, Verma R, Yang Y, Tibballs HA, Lui LL, Reser DH, Rosa MGP (2010) Spatial and temporal frequency tuning in striate cortex: functional uniformity and specializations related to receptive field eccentricity, Eur J Neurosci 31: 1043-62.
7. Lui LL, Bourne JA, Rosa MGP (2007) Spatial and temporal frequency selectivity of neurones in the middle temporal visual area of New World monkeys (Callithrix jacchus) Eur J Neurosci 25: 1780-1792.
8. Burman KJ, Lui LL, Rosa MGP, Bourne JA (2007) Development of non-phosphorylated neurofilament expression in neurones of the new the new world monkey dorsolateral frontal cortex. Eur J Neurosci 25: 1767-1779.
9. Lui LL, Bourne JA, Rosa MGP (2007) Spatial summation, end- and side-inhibition in the middle temporal visual area (MT). J Neurophysiol 97:1135-1148.
10. Lui LL, Bourne JA, Rosa MGP (2006), Functional properties of neurons in the dorsomedial area of New World monkeys. Cerebral Cortex. 16(2):162-177.
11. Lui LL, Bourne JA, Rosa MGP (2005), Single-unit responses to kinetic stimuli in New World monkey area V2: Physiological characteristics of cue-invariant neurones. Exp Brain Res. 162(1): 100-108.
12. Bourne JA, Lui L, Tweedale R, Rosa MGP (2004) First- and second-order stimulus length selectivity in New World monkey striate cortex. Eur J Neurosci 19:169-180.
