Progressive failure of cerebral angiogenesis supporting neural plasticity in aging rats.

Previous work has demonstrated substantial formation of new synapses and capillary branches in visual cortex of young rats provided with complex experience. Synaptogenesis appears greatly weakened in old rats, however, perhaps because of an age-associated impairment of metabolic support. We have examined capillaries in visual cortex from eight 14-month-old and nine 24-month-old rats that had been kept for 50 days in either a complex environment with toys and other rats or in the standard laboratory condition they had been raised in.

Direct evidence that complex experience increases capillary branching and surface area in visual cortex of young rats.

Rats housed in complex environments with toys and other rats generate new synapses, and the expanding neuropil tends to spread apart existing blood vessels. Previous work demonstrated that weanling rats kept in complex environments had more closely packed capillaries, suggesting that new capillaries had sprouted into the newly added neuropil. The present study directly investigates the issue of new branching by using india ink perfusions of weanling rats kept for 30 days in a complex environment (EC), paired in standard caging (SC), or individual cages (IC) to examine the density of capillary branch points and the capillary surface area per unit tissue volume.

Complex experience promotes capillary formation in young rat visual cortex.

The metabolic support of neural plasticity was examined by comparing cerebral vasculature of weanling rats reared in complex environments (EC) to littermates reared individually (IC) or socially in pairs (SC). EC rats have a thicker occipital cortex, more synaptic contacts per neuron and larger dendritic arbors compared to SC or IC rats, potentially increasing local metabolic demands on microvasculature. Capillaries of EC rats were closer together than those of SC or IC rats and potentially filled a greater fraction of cortex with blood.

Experience and brain development.

This article considers how experience can influence the developing and mature brain and proposes a new categorization scheme based upon the type of information stored and the brain mechanisms that appear to be involved in storing it. In this scheme, experience-expectant information storage refers to incorporation of environmental information that is ubiquitous in the environment and common to all species members, such as the basic elements of pattern perception. Experience-expectant processes appear to have evolved as a neural preparation for incorporating specific information: in many sensory systems, synaptic connections between nerve cells are overproduced, and a subsequent selection process occurs in which aspects of sensory experience determine the pattern of connections that remains.

Lingual ectopia of the thyroid gland and autotransplantation.

A case of lingual ectopia of the thyroid gland in an adult patient is presented. The management by total excision and autotransplantation of the thyroid is described with a brief review of literature.