The comparative developmental neurotoxicity of lead in humans and animals

Chronic low-level lead toxicity in the rat. I. Maternal toxicity and perinatal effects.

Enormous effort has been focused over the last decade and a half on characterizing the behavioral effects of lead in the developing organism. While age-appropriate standardized measures of intelligence (IQ) have been the dependent variable most often used to assess lead-induced cognitive impairment in epidemiologic studies, researchers have also used a variety of other methods designed to assess specific behavioral processes sensitive to lead. Increased reaction time and poorer performance on vigilance tasks associated with increased lead body burden suggest increased distractibility and short attention span. Assessment of behavior on teachers' rating scales identified increased distractibility, impulsivity, nonpersistence, inability to follow sequences of directions, and inappropriate approach to problems as hallmarks of lead exposure. Robust deficits in learned skills such as reading, spelling, math, and word recognition have also been found. Spatial organizational perception and abilities seem particularly sensitive to lead-induced impairment. Assessment of complex tasks of learning and memory in both rats and monkeys has revealed overall deficits in function over a variety of behavioral tasks. Exploration of behavioral mechanisms responsible for these deficits identified increased distractibility perseveration, inability to inhibit inappropriate responding, and inability to change response strategy as underlying deficits. Thus, there is remarkable congruence between the epidemiologic and experimental literatures with regard to the behavioral processes identified as underlying the deficits inflicted by developmental lead exposure. However, careful behavioral analysis was required from researchers in both fields for such understanding to emerge.

Behavioral effects of lead: commonalities between experimental and epidemiologic data.

Chronic low-level lead toxicity in the rat. II. Effects on postnatal physical and behavioral development.

Lead neurotoxicity: a review of the biochemical, neurochemical and drug induced behavioural evidence.

The effects of lead acetate and aging on temporally-spaced responding (differential reinforcement of low rate or DRL-20 seconds) were studied. Three groups of animals were considered along with their respective controls. Neonate-treated Long-Evans

D. D. Dietz

Papers

Effects of lead on temporally-spaced responding in rats.