One limitation of types of LTM is that there are conflicting findings about types of LTM and brain areas. Buckner and Petersen reviewed research findings and concluded that semantic memory is located on the left prefrontal cortex and episodic with the right prefrontal cortex. But other studies Tulving et al. found that semantic memory was associated with the right prefrontal cortex and the reverse for episodic memory. This challenges any neurophysiological evidence to support types of memory as there is poor agreement on where each type might be located