Dear Users

Please note that there will be two YNiC seminars this week; one at the usual time on Thursday and an additional seminar on Wednesday afternoon.

On Wednesday Dr. Susanne Weis and Dr. Markus Hausmann, from the University of Durham, will give project proposal presentations from 4-5 pm: Dr. Susanne Weis: "Object location memory: Differences between verbal and non-verbal strategies during memory encoding and retrieval" Dr. Markus Hausmann: ""Sex hormonal effects on the functional connectivity within and across hemispheres in postmenopausal women"

On Thursday there will be 3 project proposal presentations by Prof. David Lurie, Prof. Thomas Redpath and Dr. Hugh Seton from the University of Aberdeen: Prof. David Lurie: ""Field-Cycling Magnetic Resonance Imaging" Prof. Thomas Redpath: "Dynamic contrast-enhanced MRI in breast cancer" Dr. Hugh Seton: "Ultra-low field MRI with cooled receiver coils and SQUID preamplifiers"

Please see below for further information about each talk.

Everyone is welcome to attend and refreshments will be available afterwards.

Best wishes Rebecca

*1) Wednesday 10th November *

i) Susanne Weis "Object location memory: Differences between verbal and non-verbal strategies during memory encoding and retrieval"

It has repeatedly been shown that the medial temporal lobe (MTL), and especially the hippocampus, play an important role during memory encoding and retrieval. Specifically,activation of the hippocampus has been related to associative and contextual memory and binding of an item with its context. It is therefore assumed, that the hippocampus interacts with cortical regions during object location memory (OLM) tasks, where an object has to be bound to its spatial location. A variety of studies have shown that men on average perform better than women in specific aspects of spatial cognition. On the other hand, women have been shown to be superior in OLM tasks. One explanation which has been proposed for this findings suggests that women use verbal strategies during OLM encoding and retrieval, while man rely more on spatial strategies. It can be assumed that different strategies during OLM task are linked to different patterns of brain activation. It is the aim of our study to examine functional connectivity between the hippocampus and cortical areas during encoding and retrieval of an OLM task. Further, we intend to find out if inter-individual differences in strategies result in changes of patterns of brain activation and the functional connectivity within these networks.

ii) Markus Hausmann

"Sex hormonal effects on the functional connectivity within and across hemispheres in postmenopausal women"

Previous research in postmenopausal women has shown that hormone therapy (HT), and estrogen therapy (ET) in particular, affects the functional brain organization such as interhemispheric integration and functional cerebral asymmetries (FCAs) (Bayer & Erdmann, 2008; Bayer & Hausmann, 2009a,b; Bayer & Hausmann, 2010). The results suggest that these effects are mediated by the neuromodulatory properties of estradiol on intrahemispheric functional networks. Specifically, it seems that estradiol enhances verbal processing at the expense of visuo-spatial processing within the right hemisphere. This idea might explain why several studies found divergent effects of HT on verbal and visuo-spatial cognition (including verbal and non-verbal memory). Moreover, estradiol-related effects on FCAs have also been demonstrated in normally cycling women during hormonal distinct cycle-phases (Weis et al., 2008). Specifically, this fMRI study found estradiol-related changes in the interhemispheric inhibition between homotopic areas in the inferior frontal gyrus of the left and right hemispheres. The present study is set out to elucidate whether HT-related changes in FCAs as measured by a verbal and visuo-spatial visual half-field tasks in postmenopausal women might be subserved by changes in the functional connectivity between cortical networks within and across hemispheres.

*2) Thursday 11th November * i) Prof. David Lurie "Field-Cycling Magnetic Resonance Imaging"

Contrast between normal and diseased tissue in MRI arises mainly from differences in relaxation times. It is also well known from in vitro studies that the variation of T1 with field strength (T1 dispersion) changes from tissue to tissue, and may also be altered in disease. Thus, it is potentially useful to be able to measure T1 dispersion in vivo; however, this information cannot be obtained by conventional MRI scanners, which operate at fixed magnetic field. We are developing field-cycling MRI systems, in which the magnetic field is switched rapidly between levels during the pulse sequence, always returning to the same field for signal measurement. FC-MRI offers the possibility of new image contrast mechanisms based on T1 dispersion. In particular, immobilised proteins give rise to "quadrupole dips" in the dispersion curve, and this mechanism may give insight into the behaviour (and misbehaviour) of proteins in disease. This talk will discuss the methodology, technology and applications of FC-MRI.

ii) Prof. Thomas Redpath

"Dynamic contrast-enhanced MRI in breast cancer".

My talk will cover the basic physiology underlying dynamic contrast-enhanced MRI, the scanning methods used, and will describe the pharmaco-kinetic models used in analysing the signal versus time curves which are seen in breast cancers. The need for arterial input functions in the newer models will be discussed and a novel approach which we have proposed will be outlined. The particular problem of scanning at 3 tesla, namely RF pulse angle variation across the body, and methods of overcoming it will also be covered.

iii) Dr. Hugh Seton

"Ultra-low field MRI with cooled receiver coils and SQUID preamplifiers"

"The presentation will describe MRI developments at 10-20mT. Imaging at such low fields has the potential to deliver improved contrast compared to high field, partly because T1 differences between tissues can increase at low field but also because there is greater flexibility to employ contrast-enhancing pulse sequences which would exceed RF power deposition limits at high field. Normally the SNR is poor at low field, but we have developed cooled receiver coils and ultra-low noise SQUID preamplifiers that yield 3-6 fold SNR gains compared to conventional room temperature coils."