The disruption of sentence production: some dissociations.

A patient (M.L.) with selective disruption of sentence production is described. M.L.'s sentence production performance is characterized by the omission (and occasional substitution) of free-standing and bound grammatical morphemes. In contrast to her impaired sentence production performance, M.L. has no difficulties in sentence comprehension or production of single words including functors. Her performance is interpreted as reflecting a functional lesion to the positional level of sentence production.