Progressive changes in a recognition memory network in Parkinson's disease
- Bàrbara Segura1,
- Naroa Ibarretxe-Bilbao1,2,3,
- Roser Sala-Llonch1,
- Hugo Cesar Baggio1,
- María Jose Martí2,4,5,
- Francesc Valldeoriola2,4,5,
- Pere Vendrell1,2,4,
- Nuria Bargalló4,6,
- Eduard Tolosa2,4,5,
- Carme Junqué1,2,4
- 1Department of Psychiatry and Clinical Psychobiology, University of Barcelona, Barcelona, Spain
- 2Centro de Investigación en Red de Enfermedades Neurodegenerativas (CIBERNED), Hospital Clínic de Barcelona, Barcelona, Spain
- 3Department of Methods and Experimental Psychology, Faculty of Psychology and Education, University of Deusto, Bilbao, Spain
- 4Institute of Biomedical Research August Pi i Sunyer (IDIBAPS), Barcelona, Spain
- 5Parkinson's Disease and Movement Disorders Unit, Neurology Service, Institut Clínic de Neurociències (ICN), Hospital Clínic de Barcelona, Barcelona, Spain
- 6Centre de Diagnòstic per la Imatge Hospital Clinic de Barcelona (CDIC), Hospital Clínic de Barcelona, Barcelona, Spain
- Correspondence to Professor C Junque, Department of Psychiatry and Clinical Psychobiology, University of Barcelona, Casanova 143, Barcelona 08036, Spain;
- Received 21 March 2012
- Revised 31 August 2012
- Accepted 20 September 2012
- Published Online First 31 October 2012
Background In a previous functional MRI (fMRI) study, we found that patients with Parkinson's disease (PD) presented with dysfunctions in the recruitment of recognition memory networks. We aimed to investigate the changes in these networks over time.
Methods We studied 17 PD patients and 13 age and sex matched healthy subjects. In both groups fMRI (recognition memory paradigm) and neuropsychological assessments were obtained at baseline and at follow-up. To analyse changes over time in functional networks, model free (independent component analysis) analyses of the fMRI data were carried out. Then, a cross correlation approach was used to assess the changes in the strength of functional connectivity.
Results At follow-up, patients showed reduced recruitment of one network, including decreased activation in the orbitofrontal cortices, middle frontal gyri, frontal poles, anterior paracingulate cortex, superior parietal lobes and left middle temporal gyrus, as well as decreased deactivation in the anterior paracingulate gyrus and precuneus. Cross correlation analyses over time showed a decrease in the strength of functional connectivity between the middle frontal gyrus and the superior parietal lobe in PD patients.
Conclusions Model free fMRI and cross correlation connectivity analyses were able to detect progressive changes in functional networks involved in recognition memory in PD patients at early disease stages and without overt clinical deterioration. Functional connectivity analyses could be useful to monitor changes in brain networks underlying neuropsychological deficits in PD.