Dr Vincent Nguyen graduated with Honours as an orthoptist in 1993 and with a Master of Applied Science in 1996. Vincent was awarded a PhD (University of Sydney) in 2003 for his work in visual psycho-physics on image perception between the two eyes, known as binocular rivalry. He then completed a two year postdoctoral at the Centre for Vision Research, York University, Toronto, Canada, working with Professor Ian Howard on human depth perception. On returning to University of Sydney, Vincent worked collaboratively on the organisation of receptive fields of retinal ganglion cells using patch-clamp techniques.
In clinical practice, Vincent was appointed by NSW Health as a Clinical Electrophysiologist in 2007 and later at the School of Optometry and Vision Sciences, UNSW. In 2012 Vincent joined Vision Australia to work as an orthoptist assisting people with low vision. Vincent joins the Orthoptic discipline in the Graduate School of Health at UTS to fulfil his lifelong journey to study and teach the biological underpinnings of vision.
Australian Orthoptic Board
Can supervise: YES
Therapy, management and rehabilitation – 96037
Clinical management of refractive error – 96031
Protti, DA, Di Marco, S, Huang, JY, Vonhoff, CR, Nguyen, V & Solomon, SG 2014, 'Inner retinal inhibition shapes the receptive field of retinal ganglion cells in primate.', The Journal of Physiology, vol. 592, no. 1, pp. 49-65.View/Download from: Publisher's site
The centre-surround organisation of receptive fields is a feature of most retinal ganglion cells (RGCs) and is critical for spatial discrimination and contrast detection. Although lateral inhibitory processes are known to be important in generating the receptive field surround, the contribution of each of the two synaptic layers in the primate retina remains unclear. Here we studied the spatial organisation of excitatory and inhibitory synaptic inputs onto ON and OFF ganglion cells in the primate retina. All RGCs showed an increase in excitation in response to stimulus of preferred polarity. Inhibition onto RGCs comprised two types of responses to preferred polarity: some RGCs showed an increase in inhibition whilst others showed removal of tonic inhibition. Excitatory inputs were strongly spatially tuned but inhibitory inputs showed more variable organisation: in some neurons they were as strongly tuned as excitation, and in others inhibitory inputs showed no spatial tuning. We targeted one source of inner retinal inhibition by functionally ablating spiking amacrine cells with bath application of tetrodotoxin (TTX). TTX significantly reduced the spatial tuning of excitatory inputs. In addition, TTX reduced inhibition onto those RGCs where a stimulus of preferred polarity increased inhibition. Reconstruction of the spatial tuning properties by somatic injection of excitatory and inhibitory synaptic conductances verified that TTX-mediated inhibition onto bipolar cells increases the strength of the surround in RGC spiking output. These results indicate that in the primate retina inhibitory mechanisms in the inner plexiform layer sharpen the spatial tuning of ganglion cells.
Whatham, AR, Nguyen, V, Zhu, Y, Hennessy, M & Kalloniatis, M 2014, 'The value of clinical electrophysiology in the assessment of the eye and visual system in the era of advanced imaging', CLINICAL AND EXPERIMENTAL OPTOMETRY, vol. 97, no. 2, pp. 99-115.View/Download from: Publisher's site
Di Marco, S, Nguyen, VA, Bisti, S & Protti, DA 2009, 'Permanent Functional Reorganization of Retinal Circuits Induced by Early Long-Term Visual Deprivation', JOURNAL OF NEUROSCIENCE, vol. 29, no. 43, pp. 13691-13701.View/Download from: Publisher's site
Nguyen, VA, Freeman, AW & Alais, D 2003, 'Increasing depth of binocular rivalry suppression along two visual pathways', VISION RESEARCH, vol. 43, no. 19, pp. 2003-2008.View/Download from: Publisher's site
Stuart, M, Turman, AB, Shaw, J, Walsh, N & Nguyen, V 2003, 'Effects of aging on vibration detection thresholds at various body regions', BMC Geriatrics, vol. 3, pp. 1-10.View/Download from: Publisher's site
Background: The ability to detect sinusoidal vibrations on the skin surface is dependent on the activation of two classes of receptors. The density of such receptors varies across the skin surface and is a factor in determining the sensory acuity of each skin area. However, the acuity of many sensory systems is known to deteriorate with advancing age. The aim of this study was to determine if vibrotactile sensibility of several skin surfaces deteriorated equally with advancing age. Methods: Vibration detection thresholds for two frequencies of vibration (30 Hz and 200 Hz) were determined using a method of limits protocol, in two groups of healthy adults, one group aged 17 to 27 years and the other aged 55 to 90 years. Sinusoidal vibrations were generated by a computer and delivered to the skin surface via the probe (diameter = 2 mm) of a mechanical vibrator. Four skin sites (palmar surface of the tip of the middle finger, volar surface of the forearm, lateral aspect of the shoulder, cheek just caudal to the zygoma) were tested. Results: The fingertip was the most sensitive site for vibrotactile detection at both frequencies in a substantial majority of subjects. The older group of subjects showed significantly higher detection thresholds for both frequencies at all sites, except the fingertip, when compared to young subjects. Conclusion: The study confirms the deterioration of vibrotactile acuity at several skin sites previously reported in the literature. However, there appears to be no significant reduction in vibrotactile detection at the fingertips in older subjects. This may reflect the high receptor density of this area, or the functional importance of vibrotactile sensibility of the fingertips or some combination of both of these factors.
Nguyen, VA, Freeman, AW & Wenderoth, P 2001, 'The depth and selectivity of suppression in binocular rivalry', PERCEPTION & PSYCHOPHYSICS, vol. 63, no. 2, pp. 348-360.View/Download from: Publisher's site
Freeman, AW, Nguyen, VA & Alais, D 2005, 'The nature and depth of binocular rivalry suppression' in Blake, R & Alais, D (eds), Binocular Rivalry and Perceptual Ambiguity.
Nguyen, V, Freeman, A, Wenderoth, P & Heard, R 1997, 'Interocular suppression: large perceptual loss, small sensitivity loss' in Kasabov, N, Kozma, R, Ko, K, O'Shea, R & Gedeon, T (eds), Progress in Connectionist-Based Information Systems.