Preservation and compensation: The functional neuroanatomy of insight and working memory in schizophrenia

Abstract

BackgroundPoor insight in schizophrenia has been theorised to reflect a cognitive deficit that is secondary to brain abnormalities, localized in the brain regions that are implicated in higher order cognitive functions, including working memory (WM). This study investigated WM-related neural substrates of preserved and poor insight in schizophrenia.MethodForty stable schizophrenia outpatients, 20 with preserved and 20 with poor insight (usable data obtained from 18 preserved and 14 poor insight patients), and 20 healthy participants underwent functional magnetic resonance imaging (fMRI) during a parametric ‘n-back’ task. The three groups were preselected to match on age, education and predicted IQ, and the two patient groups to have distinct insight levels. Performance and fMRI data were analysed to determine how groups of patients with preserved and poor insight differed from each other, and from healthy participants.ResultsPoor insight patients showed lower performance accuracy, relative to healthy participants (p = 0.01) and preserved insight patients (p = 0.08); the two patient groups were comparable on symptoms and medication. Preserved insight patients, relative to poor insight patients, showed greater activity most consistently in the precuneus and cerebellum (both bilateral) during WM; they also showed greater activity than healthy participants in the inferior–superior frontal gyrus and cerebellum (bilateral). Group differences in brain activity did not co-vary significantly with performance accuracy.ConclusionsThe precuneus and cerebellum function contribute to preserved insight in schizophrenia. Preserved insight as well as normal-range WM capacity in schizophrenia sub-groups may be achieved via compensatory neural activity in the frontal cortex and cerebellum.

Stimulating cognition in schizophrenia: A controlled pilot study of the effects of prefrontal transcranial direct current stimulation upon memory and learning

“…Similarly, bilateral cerebellum showed increased activity with load for both verbal and abstract stimuli, [43] and in participants with schizophrenia, Sapara demonstrated greater activation of bilateral cerebellum during a WM task, relative to healthy controls [57]. These data support the concept of a necessary compensatory activation in regions such as the There are some limitations to this study.…”

Voxel-based magnetic resonance imaging investigation of poor and preserved clinical insight in people with schizophrenia

“…Compared to anterior cortical regions, much less is known about the involvement of posterior medial cortices due to the dearth of research into the contributions of these brain regions to various aspects of psychotic disorders[ 25 ]. In our recent study, we found further evidence of functional contributions from the precuneus, as well as the cerebellum, in supporting neural activities sub-serving the preservation of insight in schizophrenia patients[ 49 ].…”

“…Since then, several studies[ 26 , 30 , 31 , 47 ], including this one, have reported frontal neuroanatomical abnormalities in relation to impaired clinical insight in schizophrenia. Some functional imaging studies have further associated aberrant frontal functional MRI activity with impaired clinical insight during working memory[ 49 ], self-reflection[ 50 ], self-monitoring[ 51 ] and self-awareness tasks[ 52 ] in schizophrenia. In addition, earlier correlational VBM studies have also reported associations between smaller superior and middle temporal lobe grey matter volumes and impaired clinical insight[ 23 , 48 ].…”

Insight in schizophrenia spectrum disorders: relationship with behavior, mood and perceived quality of life, underlying causes and emerging treatments

“…In terms of functional imaging studies, converging evidence has now linked poor insight to activity in central midline structures, including basal ganglia 104 , prefrontal cortex 103,104,[115][116][117] , cingulate cortex 103 , insula 117 , inferior parietal lobule 103 and the precuneus 116 . Functional resting state studies also suggest that insight may be related to the default mode network, particularly in the left hemisphere 102 .…”