D. B. Daly
D. M. Daly
Box 210855, Dallas, TX 75211
Ability to classify sets of certain synthetic sounds fluctuates with vigilance. In patients with genetic hypersomnia, performance can fluctuate from well-defined classes with narrow transitions to intervals with wide transitions where only stimuli at extremes are identified consistently. LRCs were used to measure whether performance differed from chance and if so, whether it differed from a composite of normals [Daly et al., J. Neurophysiol. 44, 200--222 (1980)]. In a group of subjects independently treated for genetic hypersomnia (11--13 yr old: IQ>120; meds: 15--20 mg methylphenidate, (tau)=2 h), rested untreated performance over 4-min periods in 24-min intervals changed ~100-fold (from normal to periods with wide transitions). At 10--12 min following dissolution of single, sublingual 10-mg doses, transitions narrowed and performance began to improve (re: normal composite). Performance continued to improve for 10--15 min, then remained relatively consistent (in some cases within normal limits for 40--50 min). Performance returned to untreated levels in an orderly fashion: Well-defined transition areas gradually widened, then spread toward extremes. Under similar conditions subsequent dose-response functions for an individual differed little. Name brand and generic preparations apparently dissolve at different rates; some differences among individuals may reflect variations in excipients or compounding.