Functional Magnetic Resonance Imaging Of Working Memory Among Multiple Sclerosis Patients
Sweet LH, Rao SM, Primeau M, Mayer AR, Cohen RA
J NeuroImaging 2004 Apr;14(2):150-7
Medical College of Wisconsin, USA
Background And Purpose
Verbal Working Memory (VWM) deficits have been a well-replicated finding among patients with Multiple Sclerosis (MS).
Functional Magnetic Resonance Imaging (fMRI) studies have described a VWM system in healthy samples; however, Functional NeuroImaging of this system among MS patients is just beginning to appear.
Fifteen MS patients and 15 sex-, age-, education-, and IQ-matched Healthy Control (HC) participants completed a 2-Back VWM task as Whole-Brain FMRI was conducted.
Each group exhibited increased Brain activity compared to the O-Back control task in regions associated with the 2-Back in previous NeuroImaging Studies.
These included Broca's Area, Supplementary Motor Area (SMA), PreMotor Cortices (PMC), and DorsoLateral PreFrontal Cortices (DLPFC).
MS patients exhibited greater Cortical activity than did HC participants in Left Primary Motor and SomatoSensory Cortices, PMC, DLPFC, Anterior Cingulate, and BiLateral SMA.
MS patients exhibited relatively less activation in Broca's Area, BiLateral Cerebellum, and other regions not typically associated with the 2-Back (e.g., Right Fusiform Gyrus, Left Lingual Gyrus, Right Hippocampus).
Performance accuracy and reaction time did not differ between groups.
Normal performance of a challenging VWM task among high-functioning MS patients is associated with a shift toward greater activity in regions related to SensoriMotor functions and Anterior Attentional/Executive components of the VWM System.
Posterior Memory Storage Systems appeared unaffected, while portions of the Visual Processing and SubVocal Rehearsal Systems were less active.
Although a shift in Neural activity was noted relative to HC participants, deviation from regions normally involved in VWM function was not observed in this patient sample.
fMRI Evidence Of Brain Reorganization During Attention And Memory Tasks In Multiple Sclerosis
Mainero C, Caramia F, Pozzilli C, Pisani A, Pestalozza I, Borriello G, Bozzao L, Pantano P
NeuroImage 2004 Mar;21(3):858-67
University of Rome "La Sapienza", Section of Clinical Neurology, Department of Neurological Sciences, Rome, Italy
Functional Magnetic Resonance Imaging (fMRI) data on Motor Function have shown Adaptive Functional Changes related to Brain Injury in Multiple Sclerosis (MS).
We investigated whether patients with MS have altered fMRI activation patterns during Attention and Memory Tasks, and whether functional changes in the Brain correlate with the extent of overall tissue damage on conventional MRI.
Twenty-two right-handed patients with Relapsing/Remitting MS (RRMS) and no or only mild deficits at NeuroPsychological Testing and 22 matched healthy subjects were scanned during the Paced Auditory Serial Addition Test (PASAT) and a recall task.
fMRI data were analyzed using Statistical Parametric Mapping (SPM99). The relation between fMRI changes during both tasks and T2 lesion load was investigated.
During both tasks, patients exhibited significantly greater Brain Activation than controls and recruited additional Brain Areas.
Task-related functional changes were more significant in patients whose performance matched that of controls than in patients with a lower performance.
During the PASAT, Brain functional changes involved the Right Supplementary Motor Area and Cingulate, the BiLateral PreFrontal, Temporal and Parietal Areas.
Whereas during the Recall Task, they involved the PreFrontal and Temporal Cortex and Basal Ganglia BiLaterally, and the Left Thalamus.
In patients, activation in specific Brain areas during performance of both tasks positively correlated with T2 Brain lesions.
Patients with RRMS exhibit altered patterns of activation during tasks exploring Sustained Attention, Information Processing and Memory.
During these tasks, fMRI activity is greater in patients with better Cognitive function than in those with lower Cognitive function.
Functional changes in specific Brain areas increase with increasing tissue damage suggesting that they may also represent adaptive mechanisms that reflect underlying Neural disorganization or disinhibition, possibly associated with MS.
A Functional MRI Study Of Cortical Activations Associated With Object Manipulation In Patients With MS
Filippi M, Rocca MA, Mezzapesa DM, Falini A, Colombo B, Scotti G, Comi G
NeuroImage 2004 Mar;21(3):1147-54
Scientific Institute and University Ospedale San Raffaele, NeuroImaging Research Unit, 20132 Milan, Italy
Previous functional Magnetic Resonance Imaging (fMRI) studies of Simple Motor Tasks have shown that in patients with Multiple Sclerosis (MS), there is an increased recruitment of several regions part of a complex SensoriMotor Network.
These studies have suggested that this might be the case because patients tend to activate, when performing a Simple Motor Task, regions that are usually activated in healthy subjects during the performance of more Complex Tasks due to the presence of SubCortical structural damage.
In this study, we tested this hypothesis by comparing the patterns of Cortical Activations during the performance of two tasks with different levels of complexity from 16 MS patients and 16 age- and sex-matched controls.
The first task (Simple) consisted of flexion-extension of the last four fingers of the right hand, and the second task (Complex) consisted of object manipulation.
During the simple task, MS patients had, when compared to controls, more significant activations of the Supplementary Motor Area (SMA), Secondary Sensorimotor Area, Posterior Lobe of the Cerebellum, Superior Parietal Gyrus (SPG), and Inferior Frontal Gyrus (IFG).
These three latter regions are part of a Fronto-Parietal Circuit, whose activation occurs typically in the ContraLateral Hemisphere of healthy subjects during object manipulation, as shown also by the present study.
During the performance of the complex task, MS patients showed an increased BiLateral recruitment of several areas of the Fronto-Parietal Circuit associated with object manipulation.
As well of several other areas, which were mainly in the Frontal Lobes.
This study confirms that some of the regions that are activated by MS patients during the performance of Simple Motor Tasks are part of more complex pathways, recruited by healthy subjects when more Complex and difficult tasks have to be performed.
Filippi M, Rocca MA, Mezzapesa DM, Ghezzi A, Falini A, Martinelli V, Scotti G, Comi G
Hum Brain Mapp 2004 Feb;21(2):108-17
Scientific Institute and University Ospedale San Raffaele, NeuroImaging Research Unit, Milan, Italy
Using functional Magnetic Resonance Imaging (fMRI), we investigated whether movement-associated functional changes of the Brain are present in patients who are, most likely, at the earliest stage of Multiple Sclerosis (MS).
Functional MRI exams were obtained from 16 patients at presentation with Clinically Isolated Syndromes (CIS) suggestive of MS and 15 sex- and age-matched healthy volunteers.
During, the performance of three simple and one more complex motor tasks with fully normal functioning extremities. fMRI analysis was performed using Statistical Parametric Mapping (SPM99).
Compared to healthy volunteers, CIS patients had increased activations of the ContraLateral Primary SensoriMotor Cortex (SMC), Secondary SomatoSensory Cortex (SII), and Inferior Frontal Gyrus (IFG), when performing a Simple Motor Task with the dominant hand.
The increased recruitment of the ContraLateral Primary SMC was also found during the performance of the same Motor Task with the non-dominant hand and with the dominant foot.
In this latter case, an anterior shift of the center of activation of this region was detected.
During the performance of a Complex Motor Task with the dominant upper and lower limbs, CIS patients had an increased recruitment of a widespread network.
Including the Frontal Lobe, The Insula, The Thalamus, usually considered to function in Motor, Sensory, and multimodal Integration Processing.
The comparison of Brain activations during the performance of simple vs. complex Motor Tasks showed that the movement-associated Somatotopic organization of the Cerebral and Cerebellar Cortices was retained in patients with CIS.
Cortical reorganization occurs in patients at presentation with CIS highly suggestive of MS.
Local synaptic reorganization, recruitment of parallel existing pathways, and reorganization of distant sites are all likely to contribute to the observed functional changes.
Hum. Brain Mapping 21:106-115, 2004. Copyright 2003 Wiley-Liss, Inc.