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The Cortical Physiology of Ipsilateral Limb Movements

2019; Elsevier BV; Volume: 42; Issue: 11 Linguagem: Inglês

10.1016/j.tins.2019.08.008

1878-108X

David T. Bundy, Eric C. Leuthardt,

EEG and Brain-Computer Interfaces

Unilateral limb movements are generally understood to be driven by the cortical hemisphere opposite to the moving limb, but there is increasing evidence that the hemisphere on the same side as the limb is also active during movements. These same-sided motor activations are robustly observed across numerous recording modalities and species and complex movement information can be decoded from the neural population activity. Ipsilateral motor activity has been proposed to represent a number of functions, including interhemispheric inhibition, maintaining an efferent copy of the state of the ipsilateral limb, and contributing to the planning and execution of voluntary movements. Growing evidence supports a complex role of the ipsilateral hemisphere in motor control, with the specific contributions varying according to task demands and timing. Whereas voluntary movements have long been understood to derive primarily from the cortical hemisphere contralateral to a moving limb, substantial cortical activations also occur in the same-sided, or ipsilateral, cortical hemisphere. These ipsilateral motor activations have recently been shown to be useful to decode specific movement features. Furthermore, in contrast to the classical understanding that unilateral limb movements are solely driven by the contralateral hemisphere, it appears that the ipsilateral hemisphere plays an active and specific role in the planning and execution of voluntary movements. Here we review the movement-related activations observed in the ipsilateral cortical hemisphere, interpret this evidence in light of the potential roles of the ipsilateral hemisphere in the planning and execution of movements, and describe the implications for clinical populations. Whereas voluntary movements have long been understood to derive primarily from the cortical hemisphere contralateral to a moving limb, substantial cortical activations also occur in the same-sided, or ipsilateral, cortical hemisphere. These ipsilateral motor activations have recently been shown to be useful to decode specific movement features. Furthermore, in contrast to the classical understanding that unilateral limb movements are solely driven by the contralateral hemisphere, it appears that the ipsilateral hemisphere plays an active and specific role in the planning and execution of voluntary movements. Here we review the movement-related activations observed in the ipsilateral cortical hemisphere, interpret this evidence in light of the potential roles of the ipsilateral hemisphere in the planning and execution of movements, and describe the implications for clinical populations. refers to on object on the opposite side of the body to the reference object. The cortical hemisphere on the opposite side of the body to a moving limb has the strongest neuroanatomical connections to the moving muscles and generates the majority of the outflow. on the opposite side of the body to a unilateral cortical lesion, such as a stroke or traumatic brain injury. The contralesional cortical hemisphere is the uninjured hemisphere and the contralesional limbs have more significant functional impairments. an internal cortical representation of the outflowing (efferent) motor command being executed by the limbs. electrodes used to record neural activity directly from the surface of the brain. ECoG recordings represent the summation of all ionic processes (i.e., fast action potentials, synaptic potentials, dendritic potentials, etc.) within a local area surrounding an electrode. Clinical electrodes are typically a few millimeters in diameter with an interelectrode spacing on the order of 1 cm. Because of their location directly on the cortical surface, ECoG signals record more focal representations of neural activity than electrodes placed on the surface of the scalp. electrodes used to record neural activity at the scalp. While noninvasive, EEG recordings suffer from poor spatial and spectral resolution because neural signals must past through the skull and scalp. recordings of the electrical activity associated with muscle contractions. a measurement of neural activity made using an MRI scanner. The MRI scanner is used to detect changes in local blood flow that are associated with increases and decreases in neural activity. refers to on object on the same side of the body as the reference object. The cortical hemisphere on the same side of the body as a moving limb has fewer direct neuroanatomical connections to the moving muscles than the contralateral hemisphere. on the same side of the body as a unilateral cortical lesion such as a stroke or traumatic brain injury. The ipsilesional cortical hemisphere is the injured hemisphere and the ipsilesional limbs are less impaired by the cortical lesion. the specific organization of different body parts. Within the motor cortex, representations of body parts are organized with lower-body representations in the most medial portions of the motor cortex, face and mouth representations in the most lateral portions of the motor cortex, and arm and hand representations located in between.