No, the SSRIs cross the blood brain barrier on a time scale of minutes and inhibit the re-uptake of serotonin leading to a massive spike of serotonin levels on a time scale of hours. But the claimed effect (depression cured) takes place on a time scale of weeks or even months.
Which is why this study is so interesting. It essentially replicated this exact effect. The mice had decreased motivation (locomotion speed) after directly tinkering the serotonin up, but over a longer time scale they had increased locomotion from their base levels. Essentially replicating the human experience, and providing a much more direct way to study the effects of this particular chemical. This is interesting science as we still have very little understanding about Serotonin.