Cerebellar contributions to the processing of saccadic errors.

Department of Neuroscience, Erasmus MC, Rotterdam 3000 CA, The Netherlands.
The Cerebellum (Impact Factor: 2.6). 06/2009; 8(3):403-15. DOI: 10.1007/s12311-009-0116-6
Source: PubMed

ABSTRACT Saccades are fast eye movements that direct the point of regard to a target in the visual field. Repeated post-saccadic visual errors can induce modifications of the amplitude of these saccades, a process known as saccadic adaptation. Two experiments using the same paradigm were performed to study the involvement of the cerebrum and the cerebellum in the processing of saccadic errors using functional magnetic resonance imaging and in-scanner eye movement recordings. In the first active condition, saccadic adaptation was prevented using a condition in which the saccadic target was shifted to a variable position during the saccade towards it. This condition induced random saccadic errors as opposed to the second active condition in which the saccadic target was not shifted. In the baseline condition, subjects looked at a stationary dot. Both active conditions compared with baseline evoked activation in the expected saccade-related regions using a stringent statistical threshold [the frontal and parietal eye fields, primary visual area, MT/V5, and the precuneus (V6) in the cerebrum; vermis VI-VII; and lobule VI in the cerebellum, known as the oculomotor vermis). In the direct comparison between the two active conditions, significantly more cerebellar activation (vermis VIII, lobules VIII-X, left lobule VIIb) was observed with random saccadic errors (using a more relaxed statistical threshold). These results suggest a possible role for areas outside the oculomotor vermis of the cerebellum in the processing of saccadic errors. Future studies of these areas with, e.g., electrophysiological recordings, may reveal the nature of the error signals that drive the amplitude modification of saccadic eye movements.

  • [Show abstract] [Hide abstract]
    ABSTRACT: Potentially dangerous events in the environment evoke automatic ocular responses, called reactive saccades. Adaptation processes, which maintain saccade accuracy against various events (e.g. growth, aging, neuro-muscular lesions), are to date mostly relayed to cerebellar activity. Here we demonstrate that adaptation of reactive saccades also involves cerebral cortical areas. Moreover, we provide the first identification of the neural substrates of adaptation of voluntary saccades, representing the complement to reactive saccades for the active exploration of our environment. An fMRI approach was designed to isolate adaptation from saccade production: an adaptation condition in which the visual target stepped backward 50 ms after saccade termination was compared to a control condition where the same target backstep occurred 500 ms after saccade termination. Subjects were tested for reactive and voluntary saccades in separate sessions. Multi-voxel pattern analyses of fMRI data from previously-defined regions of interests (ROIs) significantly discriminated between adaptation and control conditions for several ROIs. Some of these areas were revealed for adaptation of both saccade categories (cerebellum, frontal cortex), whereas others were specifically related to reactive saccades (temporo-parietal junction, hMT+/V5) or to voluntary saccades (medial and posterior areas of intra-parietal sulcus). These findings critically extend our knowledge on brain motor plasticity by showing that saccadic adaptation relies on a hitherto unknown contribution of the cerebral cortex.
    NeuroImage 03/2012; 61(4):1100-12. DOI:10.1016/j.neuroimage.2012.03.037 · 6.13 Impact Factor
  • Source
    [Show abstract] [Hide abstract]
    ABSTRACT: The cerebellum applies an internal forward-model to predict the sensory consequences of actions. This forward-model is updated based on on-line performance monitoring. A previous study has shown that performance monitoring is altered in patients with focal vascular cerebellar lesions, but altered neural responses are not paralleled by impaired behaviour, and the critical cerebellar sites have yet to be identified. The present study investigated if saccadic performance monitoring is more severely altered in patients with cerebellar degenerative disease relative to the previously examined patients with focal vascular cerebellar lesions, and which cerebellar regions support performance monitoring. 16 patients and 16 healthy controls performed an antisaccade task while an electroencephalogram (EEG) was recorded. Error rates were increased, and the error-related negativity (ERN), an event-related potential (ERP) component associated with error processing/performance monitoring, was reduced while the error positivity (Pe), a later ERP component related to more conscious aspects of error processing, was preserved in patients. Thus, performance monitoring is altered in patients with cerebellar degeneration, confirming a critical role of the cerebellum for fast classification of saccadic accuracy. In contrast to patients with focal lesions, post-acute functional reorganization and compensation presumably is hampered by disease progression, resulting in altered neural processing and impaired behavioural performance. Voxel-based morphometry (VBM) indicated the strongest effects for behavioural performance, with correlations between gray matter volume reduction in bilateral posterolateral regions (left Crus II and right lobule VI) and increased error rates. Moreover, somewhat smaller correlations were found for volume loss in left lobule VIIb/VIIIa and right lobule V and ERN amplitude, and in right Crus I and Pe amplitude. The present findings are consistent with involvement of posterolateral cerebellar regions in motor and cognitive functions.
    Neuropsychologia 02/2015; 68. DOI:10.1016/j.neuropsychologia.2015.01.017 · 3.45 Impact Factor
  • [Show abstract] [Hide abstract]
    ABSTRACT: Using functional MRI, we assessed activity in the human cerebellum related to the properties of post-saccadic visual errors that drive the plasticity of saccadic eye movements. In the scanner subjects executed blocks of saccadic eye movements toward a target that could be randomly displaced during the saccade. Such an intra-saccadic shift was randomly forward or backward, and could be either small or large. Post-saccadic visual errors induced activation in several cerebellar areas. These areas included, but were not limited to, the oculomotor vermis which is known for its role in saccadic control. Large errors yielded more activation in the cerebellar hemispheres, whereas small errors induced more activation in the vermis. Forward shifts induced more activation than backward shifts. Our results suggest that the differences in cerebellar activation patterns for different sizes and directions of post-saccadic errors could underlie the behavioral differences observed between various saccadic adaptation paradigms. In addition, the outcome argues for an extended range of cerebellar target areas in electrophysiological studies on saccadic eye movement control.
    The Cerebellum 09/2012; DOI:10.1007/s12311-012-0417-z · 2.60 Impact Factor

Full-text (2 Sources)

Available from
May 30, 2014