Neonatal lead exposure impairs development of rodent barrel field cortex

Childhood exposure to low-level lead can permanently reduce intelligence, but the neurobiologic mechanism for this effect is unknown. We examined the impact of lead exposure on the development of cortical columns, using the rodent barrel field as a model. In all areas of mammalian neocortex, cortical columns constitute a fundamental structural unit subserving information processing. Barrel field cortex contains columnar processing units with distinct clusters of layer IV neurons that receive sensory input from individual whiskers. In this study, rat pups were exposed to 0, 0.2, 1, 1.5, or 2 g/liter lead acetate in their dam's drinking water from birth through postnatal day 10. This treatment, which coincides with the development of segregated columns in the barrel field, produced blood lead concentrations from 1 to 31 μg/dl. On postnatal day 10, the area of the barrel field and of individual barrels was measured. A dose-related reduction in barrel field area was observed (Pearson correlation = −0.740; P < 0.001); mean barrel field area in the highest exposure group was decreased 12% versus controls. Individual barrels in the physiologically more active caudoventral group were affected preferentially. Total cortical area measured in the same sections was not altered significantly by lead exposure. These data support the hypothesis that lead exposure may impair the development of columnar processing units in immature neocortex. We demonstrate that low levels of blood lead, in the range seen in many impoverished inner-city children, cause structural alterations in a neocortical somatosensory map.

Historical sketch of Mount Holyoke seminary. Founded at South Hadley, Mass., in 1837. Prepared in compliance with an invitation from the commissioner of education, representing the Department of the interior in matters relating to the national centennial of 1876.

Mode of access: Internet.

The life of Marie Antoinette,

At head of title: Crowned by the Académie française.

The life of Marie Antoinette,

Mode of access: Internet.

El teniente general don Pablo Morillo primer conde de Cartagena, marqués de La Puerta (1778-1837) Estudio biográfico documentado por Antonio Rodríguez Villa ...

t. I. Biografía. 1910.--t. II. Documentos justificativos: guerra de la independencia y primer año, 1815, de la expedición á Costa firme. 1908.--t. III. Documentos justificativos: Años 1816 á 1818 inclusives de la expedición á Costa firme. 1908.--t. IV. Documentos justificativos; Contiene los últimos años de la estancia de Morillo en América; su regreso á España; y los mandos que en ella obtuvo hasta 1837, en que falleció. 1908.

Yearbook for 1910 : administrative report and various economic and geological papers /

Administrative report -- Mineral production of Illinois in 1909 and 1910 by G.H. Cady -- Carlyle Oil Field and the surrounding territory by E.W. Shaw -- Carlinville oil and gas field by F.H. Kay -- Geology and mineral resources of the Springfield Quadrangle by T.E. Salvage -- Valuation of coal for gas manufacture by S.W. Parr -- Extinct lakes in Southern and Western Illinois and adjacent states by E.W. Shaw.

Geology in the field: the jubilee volume of the Geologists' Association (1858-1908)

Paged continuously.

Medical service in campaign; a handbook for medical officers in the field,

Mode of access: Internet.

Marmion, a tale of Flodden Field.

Mode of access: Internet.

Ferry Field Main Gate

[hand-colored post card, published by Geo. Wahr, Ann Arbor, Mich.]

University of Michigan football game at Regents Field, 1894

[looking north towards campus, University Hall dome on State St. in background)

University of Michigan football game at Regents Field, 1894

[Original grandstand, seated 400, burned in 1895, Sigma Alpha Epsilon House in background, at State and Park Place]

University of Michigan football game at Regents Field, 1894

[looking north toward campus, Museum Building Tower and University Hall dome in background]