A redrawn map for the human motor cortex

Abstract

The human brain’s motor cortex is often regarded as a linear map with discrete sections, each controlling different parts of the body. The discovery that portions of the motor cortex have other functions points to a different type of map.

Keywords: Brain; Computational biology and bioinformatics; Neuroscience.

Figure 1.. Two models for the motor cortex.

a, In conventional models of the human brain, discrete portions of the motor cortex send neural projections to particular regions of the brainstem or spinal cord to control certain parts of the body (colour coding reflects motor-cortex regions that control different body parts). As a result, the motor cortex can be thought of as a continuous map of the regions that it controls, often illustrated as a homunculus (shown to the left of the motor cortex). b, Gordon et al.1 propose an alternative model. Here, the movement map is centred around three effector regions (coloured segments), each with a concentric organization (so in the hand region, for instance, neurons controlling the fingers are sandwiched between those controlling the wrist, then the elbow). The effector regions are interleaved with inter-effector regions involved in action coordination. These inter-effector regions lack the body-part specificity of the effector regions, are interconnected with the cingulo-opercular network (which controls action initiation) and have the potential to regulate a range of body functions beyond basic movements.