Poster Session E, Monday, March 25, 2:30 – 4:30 pm, Pacific Concourse
A functional role for primary motor cortex in memory for manipulable and handwritten words
Chelsea Gordon1, Alexandria Pabst1, Ramesh Balasubramaniam1; 1University of California, Merced
Processing manipulable words activate premotor and parietal cortices involved in the manipulation of that object despite the absence of movement. Previous work also indicates motor cortex involvement during the perception of handwritten and typed words. Primary motor cortex (M1) has been implicated in the formation and consolidation of implicit motor memories, however not much is known about its functional role in semantic memory. In the present study, we exposed participants to videos of 90 words, one at a time, to be encoded for later recognition. Half of the presented words had manipulable referents (e.g., spoon) while the other half had non-manipulable referents (e.g., opinion). One-third of each group of the words were handwritten, one-third typed, and one-third were static words. Finally, half of the participants (17) received continuous theta-burst stimulation (cTBS) to M1 to downregulate neural activity in this region, while the other half (17) received sham stimulation. Once the learning phase was complete, participants were asked to perform a recognition test for the previously viewed stimuli. We found that downregulating M1 led to decreased recognition for words with manipulable referents and greater recognition for words for nonmanipulable referents. We also found that while sham participants had the shortest reaction times when recognizing manipulable words that were learned as handwritten, M1 participants had higher reaction times when words were both handwritten and manipulable. These findings highlight the functional role of M1 in handwritten word perception, and in memory for certain kinds of semantic content.
Topic Area: LANGUAGE: Semantic