Left posterior BA37 is involved in object recognition: a TMS study

Functional imaging studies have proposed a role for left BA37 in phonological retrieval, semantic processing, face processing and object recognition. The present study targeted the posterior aspect of BA37 to see whether a deficit, specific to one of the above types of processing could be induced. Four conditions were investigated: word and nonword reading, colour naming and picture naming. Repetitive transcranial magnetic stimulation (rTMS) was delivered over posterior BA37 of the left and right hemispheres (lBA37 and rBA37, respectively) and over the vertex. Subjects were significantly slower to name pictures when TMS was given over lBA37 compared to vertex or rBA37. rTMS over lBA37 had no significant effect on word reading, nonword reading or colour naming. The picture naming deficit is suggested to result from a disruption to object recognition processes. This study corroborates the finding from a recent imaging study, that the most posterior part of left hemispheric BA37 has a necessary role in object recognition.