Regulation of visual attention in offspring of female monkeys treated chronically with delta 9-tetrahydrocannabinol.

Visual attention was studied in a group of rhesus monkey infants whose mothers received daily oral treatment with low levels of delta 9-tetrahydrocannabinol (THC, 2,4 mg/kg/day) prior to and during pregnancy and throughout lactation (3.5 postnatal months). Attention was measured at 1 and 2 years of age in a standardized test situation in which animals looked at projected slides. In comparison with controls (offspring of untreated mothers), THC offspring directed more attention at slides on the 1st trial of a session. The THC offspring also engaged in relatively longer individual periods of attention on the 1st vs 2nd trials of the session and during the 1st vs 2nd session in which a given slide was presented. Further experiments varying novelty and complexity of visual stimuli suggested that changes in visual attention of THC offspring can be characterized as a failure to limit the response to novel stimuli.