Modifications of thalamo-cortical circuitry in rats prenatally exposed to ethanol.

The present study aimed to investigate the organization of thalamo-cortical connections in adult rats exposed to ethanol during the last week of foetal life. Animals underwent thalamic injections of lectin-conjugated HRP. Results demonstrate that the thalamic-recipient zone of sensorimotor cortex is significantly thinner in ethanol-exposed than in control cases. Animals exposed to ethanol also display aberrant thalamo-cortical terminations in layer 5a. Neurones of origin of cortico-thalamic projections are normally located in layers 5 and 6; they appear quantitatively comparable in control and ethanol-exposed cases. Developmental alterations underlying the establishment of anomalous thalamo-cortical relationships are discussed.