Do neural systems for planning motor actions play a func-tional role in understanding action language? Across multi-ple neuroimaging studies, processing action verbs correlateswith somatotopic activity in premotor cortex (PMC). Yet, onlyone neurostimulation study supports a functional role for PMCin action verb understanding: paradoxically, inhibiting PMCmade people respond faster to action verbs. Here we investi-gated effects of PMC excitation and inhibition on action verbunderstanding using tDCS. Right-handers received excitatoryor inhibitory stimulation to left PMC hand areas, then madelexical decisions on unimanual action verbs and abstract verbs.tDCS polarity selectively affected how accurately participantsresponded to unimanual action verbs. Inhibitory stimulationto left PMC caused a relative improvement in performance forright-hand responses, whereas excitatory left PMC stimulationcaused a relative impairment. tDCS polarity did not differ-entially affect responses to abstract verbs. Premotor areas thatsubserve planning actions also support understanding languageabout these actions.

Using space to think about time appears to be a human universal, but the specifics of people’s space-time mappings vary across individuals and groups. What determines how people spatialize time in their minds? Here we hypothesized that motor experience contributes to individuals’ space-time mappings, independent of linguistic and cultural factors. Many everyday motor actions require using the hands in a particular sequence (e.g., positioning a nail with the nondominant hand before swinging the hammer with the dominant hand), establishing a correlation between space (left hand, right hand) and time (earlier action, later action) that reverses with handedness. These action sequences reinforce Westerners’ typical left-to-right mental timeline for right-handers, but contradict this timeline for left-handers. Accordingly, we find that right-handers associate leftward space with earlier times and rightward space with later times more strongly than left-handers, for whom cultural and bodily experiences present contrasting relationships between space and time.

When people understand language about their own actions they activate premotor regions they use to perform these actions.Do people understand language about other peoples actions by imagining how they perform these actions themselves, orhow they perceive others performing them? Here, we recorded BOLD fMRI while left- and right-handers read about andthen imagined their own unimanual actions (e.g. you write) or others actions (e.g. she writes). When imagining theirown manual actions, participants preferentially activated PMC circuits controlling their dominant hand. By contrast, whenimagining others actions, participants PMC activity reflected both how they perform actions themselves and how theytypically see actions performed by right-handers (about 90% of people they see). Language-induced motor imagery forour own actions reflects how we use our own bodies, whereas imagery for others actions also reflects how others use theirbodies, even if their bodies differ from our own.