G. Wilson Shaffer’s scientific contributions

... Later, German psychiatrists [4,5] supported the notion that mania was the basic mental illness and that excitement was underpinned by neural tissue excitatory processes (astonishing intuition, given that Camillo Golgi's neuronal doctrine at these times was still to come forth); this was reflected by Heinroth's classification of melancholia saltans among the manias [4]. These views were increasingly strengthened in mid-20 th Century literature [6]. Athanasios Koukopoulos with his life-long collaborator Daniela Reginaldi observed that when lithium reduced manic phenomena, it suppressed the expression of subsequent depressions. ...

Reference:

Neurobiological Evidence for the Primacy of Mania Hypothesis