Sixteenth Annual Meeting of ISBN
20-24 June 2008

 

Manly Pacific Hotel

Sydney, Australia

Symposia

Functional and effective connectivity: Application to patient populations

The past decade has seen great advances in the use of functional neuroimaging to map the neural bases of cognition. However, much of the focus has been on task or group differences in specific regions. However, neural regions do not act in isolation; they function in a neural context, specifically, complex neural networks. Many groups are now examining patterns of interregional interactions to identify the regions comprising networks (functional connectivity) and the patterns of influence between regions within networks (effective connectivity). These connectivity techniques have distinct advantages over univariate analyses, and have proved particularly useful in approaching certain research questions, for instance, how networks change in patient populations. The objective of this symposium is to highlight the analytic advantages afforded by some of the various connectivity techniques available and the valuable insights provided by these analytic techniques in patient populations.

(1) Regional vs. interregional analyses: Advantages of connectivity approaches
Donna Rose Addis; Dept. of Psychology, Harvard University
A variety of methods have been advanced for assessing functional (partial least squares, independent components analysis, correlational approaches) and effective (structural equation modeling, dynamic causal modeling) connectivity. A brief overview of some of these methods will be provided, and a comparison of SPM univariate analyses and partial least squares (PLS) functional connectivity analyses will be presented using data from fMRI studies on (1) autobiographical memory and (2) imagining past and future events.

(2) Memory-relevant connectivity in cases of abnormal mesial temporal structure and function
Mary Pat McAndrews & Andrea Protzner; Toronto Western Research Institute
We will present data on autobiographical memory retrieval in patients with temporal lobe epilepsy, both prior and subsequent to surgical excision of the hippocampus, on scene encoding and retrieval in a single patient during and after an episode of transient global amnesia, and on item encoding and recognition in patients with amnestic mild cognitive impairment. Different strategies and challenges in modeling networks will be emphasized.

(3) New insights into individual differences and disease from formal analyses of connectivity in brain imaging data
James Rowe; MRC Cognition and Brain Sciences Unit, University of Cambridge
The world of neuroimaging is evolving rapidly, across PET, MRI, TMS and MEG technologies. It is soften integrated with other specialties like neurogenetics, psychopharmacology, neuropsychology and neurological disciplines related to development and degeneration. Different methods of network analysis of human neuroimaging data are increasingly available - PPI, SEM, DCM, PLS, ICA etc - and I will illustrate how they can be applied to understand the effects of focal trauma and diffuse neurodegeneration in a way that could not have been done with traditional analyses.

(4) Prefrontal hypoactivation partly restored after non medicated sleep therapy: functional imaging of connectivity patterns in insomnia
Ellemarije Altena & Ysbrand D. Van der Werf; Dept. of Sleep & Cognition, Netherlands Institute for Neuroscience and VU University Medical Center
Experimental sleep deprivation results in prefrontal malfunctioning the following day. No such effects are conclusively found in insomnia, despite the characteristic chronic sleep deprivation. Here, we investigated whether task-related brain activity patterns differ between insomniacs and healthy controls during verbal fluency and visual memory encoding tasks. In addition, we assessed the effects of non medicated sleep therapy on brain activity in the insomnia patients. We show that although performance levels are preserved until high levels of task complexity, prefrontal hypoactivation is found in insomnia patients regardless of difficulty level relative to controls. These effects partly reverse after sleep therapy. Functional connectivity of the networks supporting these cognitive tasks was assessed using Independent Component Analysis (ICA), revealing networks of synchronously active areas. We selected components from the ICA showing prefrontal and medial temporal networks active during the tasks; within these components, patients showed consistently decreased activity in the prefrontal areas but relative increased activity in the medial temporal cortex. To our knowledge, this is the first connectivity study performed in insomnia.


New Directions in TMS Research

On the 10th anniversary of the ISBN symposium sponsored by Tomas Paus, at which he introduced transcranial magnetic stimulation as a research tool, this symposium will serve as an update that will showcase current, innovative approaches to human neuroscience with TMS and repetitive (r)TMS.

Jason Mattingley; Queensland Brain Institute & School of Psychology, University of Queensland

Tomas Paus; U. of Nottingham: Simultaneous TMS and neuroimaging (PET and fMRI)

Brad Postle; U. of Wisconsin-Madison: Simultaneous rTMS and EEG reveals interactions with endogenous brain oscillations and provides insight into the neural codes underlying working memory task performance

Christian Ruff*: Institute for Cognitive Neuroscience & Wellcome Trust Centre for Neuroimaging, University College of London: Causal functional interactions in the human visual system studied by concurrent TMS-fMRI

*prospective new member