Cerebellum Purkinje cell vulnerability in aged rats with memory impairment.

The cerebellum is involved in higher order cognitive function and is susceptible to age-related atrophy. However, limited evidence has directly examined the cerebellum's role in cognitive aging. To interrogate potential substrates of the relationship between cerebellar structure and memory in aging, here we target the Purkinje cells (PCs). The sole output neurons of the cerebellum, PC loss and/or degeneration underlie a variety of behavioral abnormalities. Using a rat model of normal cognitive aging, we immunostained sections through the cerebellum for the PC-specific protein, calbindin-D28k. Although morphometric quantification revealed no significant difference in total PC number as a function of age or cognitive status, regional cell number was a more robust correlate of memory performance in the young cerebellum than in aged animals. Parallel biochemical analysis of PC-specific protein levels in whole cerebellum additionally revealed that calbindin-D28k and Purkinje cell protein-2 (pcp-2) levels were lower selectively in aged rats with spatial memory impairment compared to both young animals and aged rats with intact memory. These results suggest that cognitive aging is associated with cerebellum vulnerability, potentially reflecting disruption of the cerebellum-medial temporal lobe network.

Malignant and Nonmalignant Lesions of the Oral Cavity.

There is a broad spectrum of pathology that occurs in the oral cavity. Knowledge of the different anatomic subsites and contents of each is important for accurate diagnosis and treatment. Oral cavity tumors are predominantly malignant in nature, but there are many nonmalignant lesions of which the practicing clinician should be aware. This article will discuss the anatomy, imaging approaches, and imaging characteristics of nonmalignant and malignant pathology in the oral cavity.