NRSC 4132 Blog

You just finished your 30 mile bike ride or just finished that triathlon you always wanted in great time.. Now your exhaustedâ?¦ now what why canâ??t you finish your thought? Is it possible that the muscle fatigued you experiences can impacted you mentally? Studies indicate that the mental and actual movements share overlapping neural substrates (Jeannerod, 2001; Fadiga and Craighero, 2004; Munzert et al., 2009) and preserve the same spatiotemporal characteristics according to Demougeot. Demougeot suggested that if the two components are related that one will have to mentally prepare or exercise the mind to have optimal performance. ..â??Appropriate mental training can enhance motor performance.â?? Demougeot seek to find the answer to have much physically activity or muscle fatigue will start to have an effect on the mental stabilization of oneâ??s cognitions? In their study they measured the temporal features of actual and mental movements before and after muscle fatigueâ?¦ â??A strong prediction is that duration of mental actions should be sensitive to muscle fatigue, because the forward model receives as input the efferent copy of inappropriate motor commands and the perturbed state of the arm, both caused by muscle fatigue.â??

To conduct their study they used seventeen adults who were all health with no neurological problems who they used as participates. The participates then were asked to move their arms, physically and then mentally at different angles in a conducted sequence. They then tested the participate before and after the muscle fatigue.

They discovered that muscle fatigue significantly influenced the mental aspect of the experiment. Demougeot discovered that muscle fatigue significantly influenced alterations in the signaling used in mental cognition. They also discovered actual movements were in general slower immediately after fatigue, but progressively returned to prefatigue values. When applied to their study they discovered that mental movements were faster immediately after fatigue and gradually returned to prefatigue values. Demougeot studied the motor effent outflow signals to justify their thesis and this is what the concluded â??However, its efferent copy is available to the forward model, which naturally predicts very fast movements. Since during mental movements there is not sensory information, and state estimation derives from forward model alone, the brain continues to simulate faster mental movements after fatigue based on inappropriate (large) neural drives. This explains why mental movements were consistently faster than actual movements after fatigue, at least until their complete adaptation. This process, i.e., state estimation without sensory feedback, also explains the slower update of motor controller (i.e., motor commands) during mental compared to actual movements after fatigue. â??

Though neuroimaging Demougeot discovered that muscle fatigue can greatly impact oneâ??s ability to mentally function as proven above. One can also conclude that next time you stay up to study all night for an exam (muscle fatigue) that it could be detrimental to our test grade. Demougeot proved that muscle fatigue influences motor performance and action planning. Itâ??s no longer enough for physically training but mentally training is required now too.

To read full article please follow https://cuvpn.colorado.edu/content/31/29/,DanaInfo=www.jneurosci.org+10712.full

Reconsolidation theory states that the reactivation of memories destabilizes them unless they are reconsolidated within a certain amount of time. A study by Susanne Diekelmann shows that memory reactivation actually serves different purposed when we are awake and when we are asleep. Apparently memory reactivation during slow wave sleep results in an immediate stabilization while reactivation during wakefulness still results in destabilization. Diekelmann and her lab reactivated memories by presenting subjects with odors, and used fMRI technology to image the brain during reactivation. Participants in this study learned during the evening in the presence of an experimental odor in order to establish a connection between the odor and the material being learned.

During slow wave sleep, the participants were presented with the odor and then awoken a few minutes later to be started learning an interference object location task. Reactivating memories using the presented odor during waking lead to a reduced ability to recall the original object location task when interference preceeded. Using the fMRI, they found that reactivation during slow wave sleep activated hippocampal and posterior cortical regions whereas reactivation during wakefulness activated activated prefrontal cortical areas. Their findings indicate that the reactivations of memory traces have opposite effects on memory during slow wave sleep and awake times.

This study makes me think about Jim Carey in Sunshine of the Spotless Mind, where he undergoes a procedure while sleeping to erase all of his memories of his ex-girlfriend. While this plot seems totally unrealistic, it may be something that will be plausible in the future. But according to this study, wouldn't it be more effective to try and erase memories while people are awake? Imagine. What would the world be like if we could selectively choose the things we want to remember and those we want to be erased from our lives? We build our personalities and choices off of previous experiences, and learn from our mistakes. If we erase our mistakes, aren't we just likely to make them again? I mean Jim Carey went looking for his ex-girlfriend again in the movie.

For more information or to read this study check out "Labile or Stable: Opposing Consequences for Memory While Reactivated during Waking and Sleep" in Nature Neuroscience.