Subcortical connections of the perirhinal, postrhinal, and entorhinal cortices of the rat. I. afferents.

In this study the subcortical afferents for the rat PER areas 35 and 36, POR, and the lateral and medial entorhinal areas (LEA and MEA) were characterized. We analyzed 33 retrograde tract-tracing experiments distributed across the five regions. For each experiment, we estimated the total numbers, percentages, and densities of labeled cells in 36 subcortical structures and nuclei distributed across septum, basal ganglia, claustrum, amygdala, olfactory structures, thalamus, and hypothalamus.

Subcortical connections of the perirhinal, postrhinal, and entorhinal cortices of the rat. II. efferents.

This is the second of two studies detailing the subcortical connections of the perirhinal (PER), the postrhinal (POR) and entorhinal (EC) cortices of the rat. In the present study, we analyzed the subcortical efferents of the rat PER areas 35 and 36, POR, and the lateral and medial entorhinal areas (LEA and MEA). Anterograde tracers were injected into these five regions, and the resulting density of fiber labeling was quantified in an extensive set of subcortical structures.

Head west or left, east or right: interactions between memory systems in neurocognitive aging.

Cognitive aging is accompanied by decline in multiple domains of memory. Here, we developed a T-maze task that required rats to learn competing hippocampal, and striatal navigation strategies in succession, across days. A final session increased demands on cognitive flexibility and required within-day switching between strategies, emphasizing capacities that engage the prefrontal cortex.

Using the spatial learning index to evaluate performance on the water maze.

The Morris water maze was developed in 1981 and quickly became the standard task for assessing spatial memory and spatial navigation. Twenty years ago, Gallagher, Burwell, and Burchinal (1993) reported new variables and measures, including a spatial learning index, that greatly enhanced the utility of the Morris water maze for assessing subtle differences in performance on the task. The learning index provided a single number that could be used to elucidate neurobiological measures of hippocampal dysfunction, for example, correlation of learning performance with a biomarker of aging.

CREB-binding protein levels in the rat hippocampus fail to predict chronological or cognitive aging.

Normal cognitive aging is associated with deficits in memory processes dependent on the hippocampus, along with large-scale changes in the hippocampal expression of many genes. Histone acetylation can broadly influence gene expression and has been recently linked to learning and memory. We hypothesized that CREB-binding protein (CBP), a key histone acetyltransferase, may contribute to memory decline in normal aging.