Sensory and Motor Systems
Author: Guillermina Griffa | email: guillegriffa@gmail.com
Guillermina Griffa 1°, Florencia Jacobacci 1°, Valeria Della Maggiore 1°
1° CONICET Universidad de Buenos Aires. IFIBIO Houssay. Buenos Aires, Argentina.
The hippocampus has been long associated with the codification of declarative memories. Recently, however, a few studies have linked it to the encoding of non-declarative memories. Using magnetic resonance imaging (MRI) in humans, we found that learning a novel motor sequence (MSL) is associated with an increment in hippocampal activity as assessed with fMRI, and microstructural plasticity 30 min post learning, as assessed with diffusion MRI (DWI). Here, we carried out two additional DWI studies to establish further the role of the hippocampus in procedural learning. To assess whether its function relates to the sequencing of items in space/time, we trained subjects on a visuomotor adaptation (VMA) task involving no sequencing. Next, to assess whether it relates to processing the explicit component of the task typically engaged during early stages of learning, we trained a different group of subjects on an implicit version of the VMA task (IVMA). DWI were obtained before, 30 min and 24 hs after training. We found that training on either VMA or IVMA decreased MD in the left hippocampus 30 min post-learning. These changes returned to baseline values at 24 hs for VMA but persisted for IVMA. This difference may stem from the supremacy of the implicit component leading to stronger memory retention. Our results support a role of the hippocampus in procedural motor learning regardless of the task.