Previous studies have implicated several brain areas as subserving numerical approximation. Most studies have examined brain correlates of adult numerical approximation and have not considered individual differences in mathematical ability. The present study examined non-symbolic numerical approximation in two groups of 10-year-olds: Children with low and high mathematical ability. The aims of this study were to investigate the brain mechanisms associated with approximate numerosity in children and to assess whether individual differences in mathematical ability are associated with differential brain correlates during the approximation task. The results suggest that, similarly to adults, multiple and distributed brain areas are involved in approximation in children. Despite equal behavioral performance, there were differences in the brain activation patterns between low and high mathematical ability groups during the approximation task. This suggests that individual differences in mathematical ability are reflected in differential brain response during approximation.

Several studies have independently suggested that patients with schizophrenia are more likely to have an enlarged cavum septum pellucidum (CSP) and an absent adhesio interthalamica (AI), respectively. However, neither finding has been consistently replicated and it is unclear whether there is an association between these two midline brain abnormalities. Thus, we compared the prevalence of absent AI and the prevalence, size and volume of CSP in 38 patients with schizophrenia and 38 healthy controls using magnetic resonance imaging (MRI). There were no between group differences in the presence or volume of CSP; however, an enlarged CSP was commoner among patients than controls. There was also a positive correlation between CSP ratings and volumes. No differences in the presence or absence of the AI were found between patients and controls; however, an absent AI was commoner in male patients with schizophrenia than females. There was absolutely no overlap between the presence of a large CSP and an absence of AI. In conclusion, our findings are in line with several case series and other MRI investigations that have shown a higher incidence of putatively developmental brain abnormalities in patients with schizophrenia, particularly in males, and support the neurodevelopmental model of this disorder.

Cognitive dysfunctioncan occur in some patients withamyotrophic lateral sclerosis (ALS)who are not suffering from dementia.The most striking and consistentcognitive deficit has beenfound using tests of verbal fluency.ALS patients with verbal fluencydeficits have shown functionalimaging abnormalities predominantlyin frontotemporal regionsusing positron emission tomography(PET). This study used automatedvolumetric voxel-basedanalysis of grey and white matterdensities of structural magneticresonance imaging (MRI) scans toexplore the underlying pattern ofstructural cerebral change in nondementedALS patients with verbalfluency deficits. Two groups of ALSpatients, defined by the presence orabsence of cognitive impairmenton the basis of the Written VerbalFluency Test (ALSi, cognitively impaired,n = 11; ALSu, cognitivelyunimpaired n = 12) were comparedwith healthy age matched controls(n = 12). A comparison of the ALSigroup with controls revealed significantly(p < 0.002) reduced whitematter volume in extensive motorand non–motor regions, includingregions corresponding to frontotemporalassociation fibres. Thesepatients demonstrated a correspondingcognitive profile of executiveand memory dysfunction.Less extensive white matter reductionswere revealed in the comparisonof the ALSu and control groupsin regions corresponding to frontalassociation fibres. White mattervolumes were also found to correlatewith performance on memorytests. There were no significant reductionsin grey matter volume inthe comparison of either patientgroup with controls. The structuralwhite matter abnormalities infrontal and temporal regions revealedhere may underlie the cognitiveand functional imaging abnormalitiespreviously reported innon–demented ALS patients. Theresults also suggest that extra–motorstructural abnormalities maybe present in ALS patients with noevidence of cognitive change. Thefindings support the hypothesis ofa continuum of extra–motor cerebraland cognitive change in thisdisorder.

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