NEUROIMAGING AND COGNITION IN MS
1. Structural MRI
Cognitive impairment in MS has been shown to correlate with different indices of brain pathology as revealed by MRI.
Lesions and atrophy:
Studies have shown that global markers of impaired cognition have been linked to total hyper- and hypo-intense lesion volume (Rovaris et al., 1998; Lazeron et al., 2005; Sperling et al., 2001; Rao et al., 1989). This may be due to the lesions disrupting cortical-cortical connections (Lezak, Howieson& Loring, 2004).
Brain atrophy is found to be a more powerful predictor of cognitive impairment than lesion volume (Benedict et al., 2004). Studies have shown that third ventricle width, related to atrophy of the thalamus, has been shown to explain significant variance in neuropsychological outcomes. Other MRI parameters include brain parenchymal fraction (Benedict et al., 2004) and neocortical gray matter volume (Benedict et al., 2006). Cortical lesions/ demyelination (Roosendaal et al., 2009) and cortical …show more content…
Functional MRI studies are increasing now for they can study the neuronal plasticity and functional reorganization, present at least in the early stages of the disease. The research findings using functional MRI in MS cases show not only increased activation of the same areas as healthy subjects while performing a cognitive task, but also recruitment of ancillary regions as well (Bonzano et al., 2009; Penner et al., 2003; Bobholz et al., 2006; Forn et al., 2006; Cader et al., 2006) This is because of the compensatory mechanisms i:e the brain having to work harder – and less efficiently – in managing cognitive demand. This may be via the use of redundant neural pathways, or axonal sprouting that can compensate for the destruction of axon and through the mediating role of cholinergic system (Parry et al., 2003, Cader, Palace & Matthews.,
1. Structural MRI
Cognitive impairment in MS has been shown to correlate with different indices of brain pathology as revealed by MRI.
Lesions and atrophy:
Studies have shown that global markers of impaired cognition have been linked to total hyper- and hypo-intense lesion volume (Rovaris et al., 1998; Lazeron et al., 2005; Sperling et al., 2001; Rao et al., 1989). This may be due to the lesions disrupting cortical-cortical connections (Lezak, Howieson& Loring, 2004).
Brain atrophy is found to be a more powerful predictor of cognitive impairment than lesion volume (Benedict et al., 2004). Studies have shown that third ventricle width, related to atrophy of the thalamus, has been shown to explain significant variance in neuropsychological outcomes. Other MRI parameters include brain parenchymal fraction (Benedict et al., 2004) and neocortical gray matter volume (Benedict et al., 2006). Cortical lesions/ demyelination (Roosendaal et al., 2009) and cortical …show more content…
Functional MRI studies are increasing now for they can study the neuronal plasticity and functional reorganization, present at least in the early stages of the disease. The research findings using functional MRI in MS cases show not only increased activation of the same areas as healthy subjects while performing a cognitive task, but also recruitment of ancillary regions as well (Bonzano et al., 2009; Penner et al., 2003; Bobholz et al., 2006; Forn et al., 2006; Cader et al., 2006) This is because of the compensatory mechanisms i:e the brain having to work harder – and less efficiently – in managing cognitive demand. This may be via the use of redundant neural pathways, or axonal sprouting that can compensate for the destruction of axon and through the mediating role of cholinergic system (Parry et al., 2003, Cader, Palace & Matthews.,