Complex sentence: The second generation of CHAT moves beyond Vygotsky's, individually-focussed Activity to A.N. Leontiev-(with Luria, one of Vygotsky's pupils) -, who explicitly articulates the dialectical relationship between individual and collective.
Split into simpler sentences: The second generation of CHAT moves beyond Vygotsky's, individually-focussed, to A.N. Leontiev who, with Luria, was one of Vygotsky's pupils. Leontiev explicitly articulates the dialectical relationship between individual and collective.