Growing up at the Nielsen; Keith Jarrett; 'Forbidden Broadway'

In its 20 years on Newbury Street, the Nielsen Gallery has become an integral element of the Boston arts scene. More low-key than many other galleries, and sometimes even downright publicity-shy, Nielsen has nevertheless established a stalwart reputation as a serious showplace for first-rate art.

To commemorate its 20th anniversary, Nielsen is holding what amounts to a gallery retrospective. Nina Nielsen, whose exuberant energy and sophisticated eye define the tone of the gallery, is calling the show ''Location,'' a title with both concrete and metaphysical meanings. It suggests the process by which artists nurture the roots of self and society, discovering a sense of place through a lifetime of creative work. The 21 artists Nielsen represents are each exhibiting a recent and an early work, a format designed to reveal the slow, instinctual progression of these artists as analogous to the organic development of the gallery itself. For the most part, it's an idea that works, and even when it doesn't, it still affords the opportunity to see some very fine paintings.

Not surprisingly, most of Nielsen's artists have moved from the third-generation Abstract Expressionism of the '60s toward the more expressionist mood of the '80s. It's a treat to see the expansion of the work of Joan Snyder, a well-known New York artist, from a sensitive '60s landscape to the full-blown, exploding passion of a huge 1983 portrayal of an angst-ridden, masklike head, a reflection of Snyder's growing interest in primitive and children's art. Jon Imber, Nielsen's most dynamic emerging artist, reverses the dominant trend toward distortion, moving from contorted figures toward rigorous, realistic self-examination. Staring with a piercing mixture of questioning and insight straight at the viewer, Imber's large-scale ''Self Portrait'' (1984) parallels the gallery's (and its artists') collective attempt to locate interior reality through the physical medium of paint.

While Nielsen has never limited itself to either abstract or representational styles, there's definitely a gallery ''look'' - a commonality of keen, disciplined energy that pervades diverse artists and modes. ''Location'' offers a glimpse at the growth of that intensity, as well as the welcome promise of its continued unfolding. Through Nov. 24.