Variability in the stereotaxic position of cerebral points in the albino rat.

An analysis of variability in the stereotaxic position of five cerebral points in rats revealed: (1) that variability was less from the bregma skull point than from ear-bar-zero or the lambda skull point, (2) that high correlations exist between the position of skull points and cerebral structures, and (3) that the use of two external landmarks for predicting the position of cerebral targets produces a greater than 40% reduction in errors over that resulting from the use of single (ear-bar-zero or skull landmark) predictors.