The Primacy Effect and Functional Connectivity

Background: The “primacy effect,” i.e., increased memory recall for the first items of a series compared to the following items, is reduced in amnestic mild cognitive impairment (aMCI). Memory task-fMRI studies demonstrated that primacy recall is associated with higher activation of the hippocampus and temporo-parietal and frontal cortical regions in healthy subjects. Functional magnetic resonance imaging (fMRI) at resting state revealed that hippocampus functional connectivity (FC) with neocortical brain areas, including regions of the default mode network (DMN), is altered in aMCI. The present study aimed to investigate whether resting state fMRI FC between the hippocampus and cortical brain regions, especially the DMN, is associated with primacy recall performance in aMCI.

Methods: A number of 87 aMCI patients underwent resting state fMRI and verbal episodic memory assessment. FC between the left or right hippocampus, respectively, and all other voxels in gray matter was mapped voxel-wise and used in whole-brain regression analyses, testing whether FC values predicted delayed primacy recall score. The delayed primacy score was defined as the number of the first four words recalled on the California Verbal Learning Test. Additionally, a partial least squares (PLS) analysis was performed, using DMN regions as seeds to identify the association of their functional interactions with delayed primacy recall.

Results: Voxel-based analyses indicated that delayed primacy recall was mainly (positively) associated with higher FC between the left and right hippocampus. Additionally, significant associations were found for higher FC between the left hippocampus and bilateral temporal cortex, frontal cortical regions, and for higher FC between the right hippocampus and right temporal cortex, right frontal cortical regions, left medial frontal cortex and right amygdala (p < 0.01, uncorr.). PLS analysis revealed positive associations of delayed primacy recall with FC between regions of the DMN, including the left and right hippocampus, as well as middle cingulate cortex and thalamus (p < 0.04). In conclusion, in the light of decreased hippocampus function in aMCI, inter-hemispheric hippocampus FC and hippocampal FC with brain regions predominantly included in the DMN may contribute to residual primacy recall in aMCI.

Paper here.

Advertisements
Posted in Aging, Cognition, Dementia, Memory, Psychology | Tagged , , ,

PhD Opportunity

We are seeking a UK/EU candidate for a PhD position in the School of Natural Sciences and Psychology at Liverpool John Moores University to start before November 2016. The PhD will focus on Memory and Neurodegeneration, with the specific aim of identifying and developing sensitive cognitive markers for early detection. A 2.1/First degree (or equivalent) in Psychology is required; an MSc in Psychology is desirable; knowledge of cognitive/experimental psychology, cognitive/clinical neuroscience and/or neuropsychology is also desirable. The prospective student must be highly proficient in English, written and spoken. The post will be funded for three years, pending progression.

Please direct inquires and applications to Dr Davide Bruno, d.bruno@ljmu.ac.uk.

Deadline for applications is September 1.

P1010216

Posted in Aging, Cognition, Dementia, Memory, Psychology | Tagged , , , , , , , , , , , ,

Integrity

We have a paper about to come out on Neuroreport where a novel measure of hippocampal integrity is compared to more standard hippocampal volumetrics, for the purpose of prediction of future cognitive ability.

The abstract: The risk of Alzheimer’s disease can be predicted by volumetric analyses of MRI data in the medial temporal lobe. The present study compared a volumetric measurement of the hippocampus with a novel measure of hippocampal integrity (HI) derived from the ratio of parenchyma volume over total volume. Participants were cognitively intact and aged 60 years or older at baseline, and were tested twice, roughly 3 years apart. Participants had been recruited for a study on late-life major depression (LLMD) and were evenly split between depressed patients and controls. Linear regression models were applied to the data with a cognitive composite score as the outcome, and HI and volume, together or separately, as predictors. Subsequent cognitive performance was predicted well by models that included an interaction between HI and LLMD status, such that lower HI scores predicted more cognitive decline in depressed patients. More research is needed, but tentative results from this study appear to suggest that the newly introduced measure HI is an effective tool for the purpose of predicting future changes in general cognitive ability, and especially so in individuals with LLMD.

2016-06-09 19.34.43

Photo: Il gufo di Papa’.

Posted in Aging, Cognition, Dementia, Depression, Memory, Psychology | Tagged , , , , , , , ,

Introducing the Recency Ratio

Individuals with Alzheimer’s disease have been found to present a typical serial position
curve in immediate recall tests, showing poor primacy performance and exaggerated
recency recall. However, the recency advantage is usually lost after a delay. On this basis,
we examined whether the recency ratio (Rr), calculated by dividing recency performance
in an immediate memory task by recency performance in a delayed task, was a useful risk
marker of cognitive decline. We tested whether change in Mini-Mental State Examination
(MMSE) performance between baseline and follow-up was predicted by baseline Rr and
found this to be the case (N = 245). From these analyses, we conclude that participants
with high Rr scores, who show disproportionate recency recall in the immediate test
compared to the delayed test, present signs of being at risk for cognitive decline or
dysfunction.

The rest is here. (Wife-photo-credit :)))

P1010118

Posted in Aging, Cognition, Dementia, Memory, Psychology | Tagged , , , , , , , , , ,

Is there progress?

“Major depressive disorder (MDD) contributes to a significant worldwide disease burden, expected to be second only to heart disease by 2050. However, accurate diagnosis has been a historical weakness in clinical psychiatry. (…) Over the past two decades, literature on a growing number of (…) biomarkers for MDD increasingly suggests that MDD patients have significantly different biological profiles compare d to healthy controls. However, difficulty in elucidating their exact relationships within depression patrhology renders individual markers inconsistent diagnostic tools.”

Read more here.

 

Posted in Depression, Emotions, Psychology | Tagged ,

On the way out (part 2)

After three and a half years at Liverpool Hope University, which I thoroughly enojoyed mainly due to the warmth and professionalism of my colleagues, I have made the decision to seek out a new challenge. As of yesterday, I am now at Liverpool John Moores University. Not a big move, geographically speaking, since I am only a few miles down the road, but a move nonetheless; and, in that respect, a move that I have made with a hefty mixture of excitement and sadness. The excitement, obviously, comes from the prospect of working in a vibrant and strong School, and as part of a University that is trying to put itself on the map with clear vision and ambition. The sadness, on the other hand, comes with leaving behind my old Department, and my old students, albeit with the knowledge that the latter will be well looked after in my absence by the former.

I learned a lot during my time at Hope and I must say that I do feel transformed. Looking back, I had no idea what I was really getting myself into when I moved over from New York in 2012 to become a Lecturer; I feel that I have become, through some good and some bad experiences, a much better scientist and teacher, but also a better husband and hopefully person.

And I know Oskar (pictured) meaow-grees (wife photo credit).

h

Posted in Psychology

On the way out (part 1)

The input order of free recall has long been a subject of research in psychology (…). (I)tems presented at the beginning of the list (primacy) and items presented at the end of the list (recency) are remembered better than middle items (…). In this paper, (in contrast) we attempt to shed some light on (…) the output order of free recall (…) i.e., the order in which items are reported at test (…).

To read more, click here.

P1000662.JPG

Posted in Aging, Cognition, Dementia, Memory, Psychology | Tagged , , , , , , , , , , ,