Clinical-neuroendocrinological syndromes due to lesions of the cingulate gyrus in humans

Understanding the mechanisms of callosal development through the use of transgenic mouse models

The cerebral cortex is the area of the brain where higher-order cognitive processing occurs. The 2 hemispheres of the cerebral cortex communicate through one of the largest fiber tracts in the brain, the corpus callosum. Malformation of the corpus callosum in human beings occurs in 1 in 4000 live births, and those afflicted experience an extensive range of neurologic disorders, from relatively mild to severe cognitive deficits. Understanding the molecular and cellular processes involved in these disorders would therefore assist in the development of prognostic tools and therapies. During the past 3 decades, mouse models have been used extensively to determine which molecules play a role in the complex regulation of corpus callosum development. This review provides an update on these studies, as well as highlights the value of using mouse models with the goal of developing therapies for human acallosal syndromes.

Aging and alexithymia: association with reduced right rostral cingulate volume

OBJECTIVES

Previous studies have linked alexithymia to an inability to process emotions appropriately. Older persons show changes in emotion processing and have higher alexithymia scores. Because the anterior cingulate cortex (ACC) is one of the regions showing earlier decline in late-life, and alexithymia seems to be related to a dysfunction in right hemisphere regions including the ACC subserving affective processes, the present study sought to test the hypothesis that reduced ACC volume accounts for the association between older age and alexithymia.

DESIGN

Correlation analyses between functionally distinct ACC subregions, age and alexithymia features.

SETTING

University of Iowa.

PARTICIPANTS

Twenty-four healthy volunteers aged between 24 and 79 years.

MEASUREMENTS

Psychiatric and neuropsychological assessment and assessment of alexithymia using the 20-item Toronto Alexithymia Scale. High-resolution magnetic resonance imaging, and in-house developed methods for ACC parcellation.

RESULTS

Older age directly correlated with higher overall alexithymia and reduced bilateral rostral and right dorsal ACC gray matter volume. Furthermore, higher alexithymia scores correlated with reduced right rostral ACC volume. This correlation seems to be influenced primarily by Factor 3 of the alexithymia scale measuring diversion of attention to external details in place of internal feelings.

CONCLUSIONS

These results suggest that alexithymia in older age may be a result of structural changes in the right rostral ACC.