July 3, 2022

The Cortico-Cerebellar System

The primary motor cortex and prefrontal cortex each connect with distinct areas of the cerebellar cortex. This connectivity confers distinct functional properties to these areas.
The cerebellum contains upwards of 50% of the brains neurons. It communicates with the cerebral cortex through increasingly well-understood connections, forming the cortico-cerebellar system – one of the largest anatomical systems in the primate brain. Despite the prominence of this system, and the fact that its properties are becoming well understood, its contributions to behaviour remain elusive.
Motor skills

The cerebellum can influence a variety of motor control centres in the brain, including the motor cortex, through its output pathways. Inputs to the cerebellum provide it with access to sensory information that serves as feedback to guide learning.  Computational models of its circuitry, and evidence from neurophysiological studies, show that cerebellar circuits are capable of plasticity that could support the storage of ‘motor memory’. Our work uses functional MRI to investigate the cerebellar mechanisms of motor skill in the human brain by studying its responses to error feedback and charting the dynamics of its activity while people acquire motor skills in the scanner.

Cognitive skills

Plasticity in the human cerebellar cortex as subjects learn first-order rules to automaticity. From Balsters and Ramnani (2011).

Other parts of the primate cerebellar cortex are connected with association areas of the cerebral cortex including the prefrontal cortex and posterior parietal cortex which are known for their roles in higher cognitive functions such as the abstraction and processing of rules (see below). This raises interesting questions about the roles that the cerebellum might play beyond motor learning. We have tested hypotheses about the ways in which this system is engaged in the automatic processing of cognitive information. Our work has used functional MRI to test the hypotheses that these parts of the cerebellar cortex are engaged in the acquisition of cognitive skills, such as the automatic execution of rules.  Specifically, we ask whether the critical parts of the cerebellum show dynamic changes in activity as human volunteers learn during scanning. We also examine the interactions between connected cerebellar and prefrontal areas and examine how these interactions change during learning.

Review papers

  • Ramnani N (2006) “The Primate Cortico-Cerebellar System”, Nature Reviews Neuroscience, 7(7):511-22
  • Ramnani N and Owen AM (2004), “The Anterior Prefrontal Cortex: What can functional imaging tell us about function?” Nature Reviews: Neuroscience 5, 184-194.
  • Ramnani N (2011), “Frontal Lobe and Posterior Parietal Contributions to the Cortico-cerebellar System.”, Cerebellum (in press)

Research papers

  • Balsters JH, Whelan C, Roberston I and Ramnani N (2012), “Cerebellum and cognition: Evidence for the encoding of higher-order rules”, Cerebral Cortex (in press).
  • Balsters JH and Ramnani N (2011), “Cerebellar plasticity and the automation of first-order rules”, Journal of Neuroscience, 31(6):2305-12.
  • Balsters JH, Cussans E, Diedrichsen J, Phillips KA, Preuss TM, Rilling JK, Ramnani N (2010) Evolution of the cerebellar cortex: The selective expansion of prefrontal-projecting cerebellar lobules. Neuroimage, 43:388-98.
  • Jill X. O’Reilly, Christian F. Beckmann, Valentina Tomassini, Narender Ramnani and Heidi Johansen-Berg (2010). “Distinct and overlapping functional zones in the cerebellum defined by resting state functional connectivity”, Cerebral Cortex, 20:953-65.
  • Balsters JH and Ramnani N (2009), “Symbolic Representations of Action in the Human Cerebellum”, NeuroImage 43(2), 388-98.
  • Sakai K, Ramnani N and Passingham RE (2002), “Learning of sequences of finger movements and timing: Frontal lobe and action-oriented representation”, Journal of Neurophysiology, 8: 2035-2046.
  • Ramnani N and Miall RC (2001), ”Expanding cerebellar horizons”, Trends in Cognitive Sciences, 5(4): 135-136.
  • Ramnani N and Passingham RE (2001), “Changes in the human brain during rhythm learning: A PET study”. Journal of Cognitive Neuroscience, 13(7): 952-66.
  • Ramnani N, Toni I, Passingham, RE and Haggard, P (2001), “The Cerebellum and Parietal Cortex play a specific role in coordination: A PET Study”. NeuroImage, 14(4):899-911.
  • Toni I, Ramnani N, Josephs O, Ashburner J and Passingham RE (2001), ”Learning arbitrary visuo-motor associations: I. Temporal dynamics of brain activity”. NeuroImage, 14:1048-1057.
  • Ramnani N, Toni I, Josephs O, Ashburner J and Passingham RE (2000), “Learning- and expectation-related changes in the human brain during motor learning”. Journal of Neurophysiology, 84: 3026-3036.
  • Ramnani N and Yeo CH (1996), “Reversible inactivations of the cerebellum prevent the extinction of conditioned responses in rabbits”. Journal of Physiology (Lond), 495: 159-68.
  • Hardiman MJ, Ramnani N, and Yeo CH (1996). “Reversible inactivations of the cerebellum with muscimol prevent the acquisition and extinction of conditioned nictitating membrane responses in the rabbit”. Experimental Brain Res. 110(2): 235-47.

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