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Critique of “strengthening of horizontal cortical connection following skill Learning”

Critique of “strengthening of horizontal cortical connection following skill Learning”. Group B4: Premraj Yogarajah Ruth Pedrosa Shawn Thadeaus Netra Malhotra. Schedule of Events. Summary of article Factors affecting MEP amplitude Control for Variables LTP and Memory

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Critique of “strengthening of horizontal cortical connection following skill Learning”

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  1. Critique of “strengthening of horizontal cortical connection following skill Learning” Group B4: PremrajYogarajah Ruth Pedrosa Shawn Thadeaus NetraMalhotra

  2. Schedule of Events • Summary of article • Factors affecting MEP amplitude • Control for Variables • LTP and Memory • Effects of Aging on LTP • Motor learning in humans • What we know today

  3. RUTH Brief Summary METHOD: • Trained rats in skilled reaching task (3-5 days) • Coronial brain slices prepared • Examined effect of training on strength of horizontal intracortical connections (layer II/III)

  4. Results: • Skill learning changes strength of connections in M1 • First direct evidence - plasticity of intracortical connections associated with learning a new motor skill

  5. PREM Factors Affecting MEP Amplitude • Age • Resting motor threshold Muller-Dahlhaus, J.F.M, et al. 2007. Iterindividual variability and age-dependency of motor cortical plasticity induced by paired associative stimulation. Exp Brain Res. 187: 467-475

  6. PREM Age Figure 1. Age of individual vs. the amplitude of the motor-evoked potential of individual. Muller-Dahlhaus, J.F.M, et al. 2007. Iterindividual variability and age-dependency of motor cortical plasticity induced by paired associative stimulation. Exp Brain Res. 187: 467-475

  7. PREM Resting Motor Threshold Figure 3. Resting motor threshold of individual vs. the amplitude of the motor-evoked potential of individual. Muller-Dahlhaus, J.F.M, et al. 2007. Iterindividual variability and age-dependency of motor cortical plasticity induced by paired associative stimulation. Exp Brain Res. 187: 467-475

  8. Control for Variability • Design of experiment eliminates most variables found among the test subjects • Individual served as both control and test subject Hodgson R.A., et al. 2004. Training-induced and electrically induced potentiation in the neocortex. Neurobiology of Learning and Memory. 83: 22-23.

  9. LTP and Memory • Trained hemisphere less amenable to further LTP induction • Absence of LTP and the affect on learning Hodgson R.A., et al. 2004. Training-induced and electrically induced potentiation in the neocortex. Neurobiology of Learning and Memory. 83: 22-23.

  10. Age-related changes in anatomy and neurophysiology in aged rats • Loss of functional synapses • Decreased strength of NMDA-receptor response: ↑ in threshold for LTP induction • Calcium dyregulation - ↑ threshold in LTP induction, ↓ threshold in LTD induction

  11. Effects of Aging on LTP • ↑ age leads to LTP induction impairment • Tasks- learned slower, forgotten quickly • LTP in adult rats may induce LTD in aged rats

  12. Effects of Aging on Relationships between Physiology, Plasticity, and Cognition

  13. Sequential Neural Changes during Motor Learning in Schizophrenia • Same methodology METHOD: • Neural changes from learning a motor task • Visual guided reaching • PET Rowland, L.M., Shadmehr, R., Kravitz, D. & Holcomb, H. H. (2008). Sequential Neural Changes during motor learning in schizophrenia. Psychiatry Res. 163(1): 1-12

  14. Schizophrenics and Healthy Volunteers • Schizophrenic – deficiency constructing representations • Do they use the same brain regions as healthy individuals ? Rowland, L.M., Shadmehr, R., Kravitz, D. & Holcomb, H. H. (2008). Sequential Neural Changes during motor learning in schizophrenia. Psychiatry Res. 163(1): 1-12

  15. Found: Rowland, L.M., Shadmehr, R., Kravitz, D. & Holcomb, H. H. (2008). Sequential Neural Changes during motor learning in schizophrenia. Psychiatry Res. 163(1): 1-12

  16. What we know today… • MSL operates as the interaction of two orthogonal connections - intracortical serial connections (horizontal arrows) - cortico–BG/cortico–CB loop circuits (vertical arrows)

  17. Figure 3: Motor sequence is learned through cortex–Basil Ganglia and cortex–Cerebellum loop circuits independently, and in different coordinates (spatial and motor).

  18. Basal Ganglia • Spatial sequence • Reversible blockade of the anterior striatum (associative region) deficits in learning new sequences • Blockade of the posterior striatum (motor region)disruptions in the execution of learned sequences

  19. Cerebellum • Blockade disrupts learning of complex goal directed behaviors • Cerebellar lesions impair motor sequence learning • Long-term memories for motor skills may be stored in the CB

  20. CONCLUSION

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