The impact of body posture on intrinsic brain activity: The role of beta power at rest

Action and posture influence the retrieval of memory for objects

The embodied approach states that memory traces are retrieved, at least in part, through a sensorimotor simulation of the original events, i.e., during retrieval we use our body and its sensorimotor pathways to simulate what happened during encoding. Thus, body manipulations that are incongruent with the motor elements involved at encoding should modulate memory performance. To test this hypothesis, we devised two experiments. In Experiment 1, participants had to observe (observation task) or observe and also perform an action on (enactment task) a series of objects. At recognition, they recognised the enacted objects faster and more accurately than the observed ones. Crucially, in Experiment 2, we manipulated body posture during recognition: one group was asked to hold their hands/arms in front of them (non-interfering group), and the other group was asked to block their hands/arms behind their back (interfering group). The results on reaction times, but not those on accuracy, showed a critical interaction: while the noninterfering group recognised enacted objects faster than observed objects, this advantage disappeared for the interfering group. This suggests that adopting a posture inconsistent with action at encoding could influence the time needed to correctly recognise the objects, but not the accuracy of the recognition.

Crossing hands behind your back reduces recall of manual action sentences and alters brain dynamics

The embodied meaning approach posits that understanding action-related language recruits motor processes in the brain. However, the functional impact of these motor processes on cognition has been questioned. The present study aims to provide new electrophysiological (EEG) evidence concerning the role of motor processes in the comprehension and memory of action language. Participants read lists of sentences including manual-action or attentional verbs, while keeping their hands either in front of them or crossing them behind their back. Results showed that posture impacted selectively the processing of manual action sentence, and not of attentional sentences, in three different ways: 1) EEG fronto-central beta rhythms, a signature of motor processes, were desynchronized while reading action sentences in the hands-in-front posture compared to the hands-behind posture. The estimated source was the posterior cingulate cortex, involved in proprioceptive regulation. 2) Recall of nouns associated with manual sentences decreased when learning occurred in the hands-behind posture. 3) ERPs analysis revealed that the initial posture at learning modulates neural processes during subsequent recall of manual sentences in the left superior frontal gyrus, which is related to motor processes. These results provide decisive evidence for the functional involvement of embodied simulations in the encoding and retrieval of action-related language.