Research


Overview


Broadly speaking, our lab seeks to explore quantitative modelling approaches to the analysis of sensory electrophysiology in humans. Such a framework has two important advantages over more traditional approaches to this type of research:

1. It enables the examination of the neural processing of natural stimuli such as speech, music and video, thereby facilitating the flexible design of highly naturalistic cognitive neuroscience experiments.

2. It allows for improved spatiotemporal resolution and (accordingly) improved interpretability of non-invasively recorded neuro-electric responses to such naturalistic stimuli.


We seek not only to develop these modelling approaches, but also to exploit them in tackling a number of specific cognitive and clinical neuroscience questions. In terms of cognition much of this work has focused on how we direct our attention to behaviourally relevant stimuli in our environment. This includes studies on visual spatial attention and more recent work on the cocktail party problem. In addition, we are interested in how we integrate visual and auditory information when processing natural speech.



Selective Auditory Attention
and the Cocktail Party Problem


In human electrophysiological experiments, stimuli typically take the form of simple, isolated, discrete events, such as flashes and beeps. Such stimulation is not always ideal for examining cognitive processes. We are interested in developing novel methods of continuous stimulation to allow us to address several important and outstanding questions involving selective attention in humans using electrophysiology. In particular we are interested in attention to natural speech - the so called 'cocktail party problem'; that is, our ability to easily attend to one speaker in a multi-speaker environment.



Neurophysiology of Music


How the brain creates coherent perceptions of music from complex combinations of sounds is poorly understood. For example, when listening to an orchestra, one can choose to listen to the ensemble, to a particular instrument (e.g. the trumpet), or to a group of instruments (e.g., the strings). How we do this so easily is simply not known. The project aims to build on the success of methods developed for investigating neuro-electric activity in response to other types of natural stimuli (e.g., speech). Unlike standard methods, which usually require researchers to present simple, discrete stimuli in isolation (e.g., beeps and clicks), these new methods allow the acquisition of spatiotemporally detailed responses (i.e., where and when in the brain) to complex, continuous stimuli. This line of research could have important implications for both cognitive and clinical research, for understanding the biological psychology of music, for the development of therapeutic techniques based on music, and could, perhaps, lead to a greater understanding of the creative process underlying musical composition.


Visual Spatial Attention


How flexible is the human ability to pay attention to regions of their visual field? Can we divide our attention to non-contiguous locations? Can we modulate how much attention we pay to where we are actually fixating? These are questions we aim to address using some novel stimulus paradigms and human EEG.



Increasing the Specificity of
Electrophysiological Measures of the Visual System


Non-invasive investigation of human sensory processing with high temporal resolution typically involves repeatedly presenting discrete stimuli and extracting an average event-related response from scalp recorded neuro-electric or neuro-magnetic signals. While this approach is and has been extremely useful, it suffers from two drawbacks: a lack of 'naturalness' in terms of the stimulus and a lack of 'naturalness' in terms of the stimulus and of precision in terms of the cortical response generators.We are developing a linear modelling approach that aims to exploit functional specialization in sensory systems to rapidly obtain spatiotemporally precise responses to complex sensory stimuli using electroencephalography (EEG).



The Integration of Audio and Visual Speech


Sensory events often do not occur in isolation and the complex integration of inputs from multiple senses is still poorly understood. We aim to use novel methods to tackle questions in this research field that have been difficult or impossible to address thus far with discrete stimulus methods. These questions include those involving the integration of visual and audio speech.



Measures of Sensory Dysfunction
in Psychiatric and Developmental Disorders


Patients with schizophrenia and their clinically unaffected first degree relatives have been shown to have deficits in electrophysiological markers of early sensory processing. We are interested in examining the specificity of the dysfunction underpinning these deficits. We also aim to develop new approaches for exploiting this specificity with a view to increasing the clinical sensitivity of visual processing measures. It is hoped that this work, in combination with genetic information, could produce endophenotypic markers of this devastating disorder. Sensory processing in autism spectrum disorders has also been receiving increased attention. Recent work with our US-based collaborators has shown unusual responses to peripheral visual stimuli in children with autism spectrum disorder. We aim to build on this finding towards identifying biomarkers that have some predictive power with respect to clinical outcomes.


Edmund Lalor

Adjunct Assistant Professor,
School of Engineering,
Trinity Centre for Bioengineering and
Trinity College Institute of Neuroscience
Printing House,
Trinity College Dublin,
College Green,
Dublin 2

Phone: +353-1-8961743
Email: edlalor@tcd.ie
Web: http://www.lalorlab.net/ed
Twitter: http://www.twitter.com/edmundlalor

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