Neural mechanisms supporting the formation and persistence of human motor memory

Motor learning involves both the acquisition of new motor programs such as those built while learning a new skill, and the recalibration of pre-existing motor programs through sensorimotor adaptation. The talk will focus on the mechanisms at the basis of the formation and persistence of these types of motor memories, and how they impact on human brain structure. The first part of the talk will focus on motor memory consolidation during wakefulness. It will be discussed work in which it is characterized the timescale of memory consolidation and the dynamics of functional connectivity supporting long-term memory in humans. The second part of the talk will centre on sleep consolidation. Contrary to its wellestablished role in declarative learning the impact of sleep on motor memory consolidation remains a subject of debate. 

Prof. Valeria Della Maggiore will present published and new EEG data from the Physiology of Action Lab@IFIBIO, University of Buenos Aires, indicating that when training occurs immediately before bedtime, so that sleep overlaps with the consolidation window, a 30% enhancement in motor performance emerges overnight along with a distinct modulation of neural markers of sleep consolidation well established in the declarative field. These results reconcile apparent conflicting viewpoints regarding the active role of sleep in procedural motor learning and may have translational implications in rehabilitation settings.

Finally, prof. Della Maggiore will show multimodal MRI evidence suggesting that motor learning induces both hippocampus-dependent memory reactivation and structural plasticity. The lab has shown that gains in performance during a motor skill learning task, like motor sequence learning (MSL), are linked to increased hippocampal activity and fast changes in mean diffusivity computed using the diffusion tensor model (DTI). Yet, DTI is not biologically specific. To overcome this limitation, we have implemented an approach combining the ultra-high gradients of the Connectome scanner (MGH) with a compartment-based model for apparent cell soma and neurite density imaging (SANDI) to identify the biological processes driving hippocampal changes in gray-matter microstructure during motor learning. We found that MSL induces a transient increase in the cell soma compartment of the hippocampus and cortical motor regions involved in MSL, and a persistent increase in the neurite fraction of the precuneus and the PPC.

Whereas the former may reflect a fast-homeostatic response such as astrocytic swelling associated with LTP-like processes, the latter may be compatible with structural remodeling of astrocytes and/or neurons. Together, the work supports the existence of common mechanisms at the basis of the formation of declarative and non-declarative memories.

Biosketch

Prof. Valeria Della Maggiore is a Biologist by training. After obtaining her Master of Science, she moved to Canada where she carried out a Ph.D in Experimental Psychology and Neuroscience at the University of Toronto, and a postdoctoral fellowship at the Montreal Neurological Institute (McGill University).

In 2006, she returned to Argentina, where she joined the Institute of Physiology and Biophysics (IFIBIO Houssay), School of Medicine, University of Buenos Aires (UBA) as the Head of the Physiology of Action Lab. She is currently a Principal investigator of CONICET (National Research Council) and the Scientific Director of the 3Tesla MRI Facility of the UBA, which holds a Siemens Tim Trio.

She is also an Associate Professor at the School of Science and Technology of the University of San Martin (UNSAM), where she is a scientific advisor of their MRI Facility (CEUNIM). Her research focuses on motor learning and plasticity. They use a variety of motor paradigms that tackle key aspects of motor skill acquisition and skill maintenance, together with non-invasive techniques such as MRI and EEG to study the mechanisms supporting memory encoding and consolidation at the functional and structural level during wakefulness and sleep. Through this multi-modal approach, they aim to understand how these mechanisms support gains in performance at different temporal scales from seconds to days.