The effect of Escitalopram on tonic and phasic alertness in healthy volunteers
Von der Medizinischen Fakulta¨ t derRheinisch-Westf¨alischenTechnischenHochschuleAachen zur Erlangung des akademischen Grades einer Doktorin der Medizin genehmigte Dissertation
1networks: alerting, orienting and executive control (fromAnantomy of three attentional Posner & Rothbart, 2007).. . . . . . . . . . . . . . . . . . . . . . .. . . . . . . 2Simplified image of the mechanism of action of SSRIs on 5-HT neurons in the brain. A. In depressed state there is an up regulation of 5-HT1Aautoreceptors, which inhibits 5-HT firing rate B. When SSRI treatment is initiated, 5-HT rises to a much higher level at the cell body area of the raphe nucleus than in the area where the axon terminates. At first this decreases the firing rate of 5-HT neurons even more. C. Subchronic treat-ment leads to a desensitization of 5-HT1Aautoreceptors and other adaptive changes as well as a down regulation of terminal autoreceptors, allowing the firing rate of the cell to recover in the presence of the drug and more 5-HT to be released per impulse reaching the terminal.. . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 3Structure of Escitalopram (www.lexapro.com).. . . . . . . . . . . . . . . . . . . . 4The three ANT target conditions: (a) neutral, (b) congruent, (c) incongruent.. . . . . 5The four ANT warning conditions: (a) no cue, (b) centre cue, (c) double cue, (d) spatial cue.. . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 6Posner & Fan, 2007): The cue provides information ofTrial event in the ANT (from when and where the target will occur. The target is a central arrow that indicated a left or right response surrounded by congruent or incongruent flankers.. . . . . .. 7Procedure of one session.. . . . . . . . . . . . . . . . . . . . . . .. . . . . . . 8No cue and double cue reaction times (ANT) under administration of Escitalopram (E) or placebo (P).. . . . . . . . . . . . . . . . . . . . . . . . . .. . . . . . . . 9(ANT) for the challenge as well as theNo cue and double cue mean reaction times steady-state group.. . . . . . . . . . . . . . . . . . . . . . . . . .. . . . . . . . 10reaction time under administration of Escitalopram (E) or placebo (P).Mean . . . . 11Mean reaction time for the challenge as well as steady-state group.. . . . . . . . . 12Training effect comparing results of the ANT from session 1 (s1) and session 2 (s2).