Organization of the forelimb area in squirrel monkey motor cortex: representation of digit, wrist, and elbow muscles

  title={Organization of the forelimb area in squirrel monkey motor cortex: representation of digit, wrist, and elbow muscles},
  author={John P. Donoghue and Stephen J. Leibovic and Jerome N. Sanes},
  journal={Experimental Brain Research},
SummaryThe EMG in 8 to 14 hand, forearm, and arm muscles evoked by intracortical electrical stimulation was recorded at 433 sites in layer V in the region of the forelimb area of the primary motor cortex (MI) of three squirrel monkeys during ketamine anesthesia. At each site, the EMG was recorded at movement threshold (T) and at 1.5T and 2T at each site (but ≤60 μA), and the threshold movement was noted. In the animals examined, the total MI forelimb area identified by movements or EMG occupied… 

Properties of primary motor cortex output to forelimb muscles in rhesus macaques.

M1 output effects showed many similarities with red nucleus output although red nucleus effects were generally weaker and showed a strong bias toward facilitation of extensor muscles and a greater tendency to facilitate synergies involving muscles at noncontiguous joints.

Integrated motor cortical control of task-related muscles during pointing in humans.

A large body of compelling but indirect evidence suggests that the motor cortex controls the different forelimb segments as a whole rather than individually. The purpose of this study was to obtain

The reorganization of the motor system in primates after the loss of a limb.

  • J. KaasH. Qi
  • Biology, Psychology
    Restorative neurology and neuroscience
  • 2004
In two of the macaque monkeys, injections in M1 reveal more widespread intrinsic connections than in normal M1, and in several monkeys and galagos, injections of tracers in muscles of the stump, shoulder, or hip labeled spinal cord motor neurons that normally project to the distal limb suggest that the functional changes in M2 are mediated in part by the formation of new connections.

Complex Movements Evoked by Microstimulation of Precentral Cortex

9 A map of complex movements in motor cortex of primates

It is suggested that primary motor and lateral premotor cortex might not be arranged in a hierarchy, but instead might operate in parallel, serving different parts of the workspace.

Arm movements evoked by electrical stimulation in the motor cortex of monkeys.

It is suggested that at least some of the stimulation-evoked movements reflect relatively high-level, adaptable motor plans, as well as to a weight added to the hand, which indicates adaptability to differing circumstances.

Double representation of the wrist and elbow in human motor cortex

The purpose was to document and simultaneously provide evidence that would extend the presence of double representation of the wrist to that of the elbow and to observe double wrist and elbow representation that bracketed finger fMRI responses in M1 and the SMA.

The organization of the forelimb representation of the C57BL/6 mouse motor cortex as defined by intracortical microstimulation and cytoarchitecture.

The mouse motor cortex has homologies with the rat in having 2 forelimb representations and an OL but is distinct in the predominance of digit representations, consistent with the primary motor-somatosensory overlap zone characterized in rats.

The comparable size and overlapping nature of upper limb distal and proximal muscle representations in the human motor cortex

Results show that commonly used proximal and distal upper limb muscles, taken individually, are controlled by motor cortical territories of approximately equal size that significantly overlap despite differences in the location of their optimal points.

Mapping of direction and muscle representation in the human primary motor cortex controlling thumb movements

It appears that one of the organizing principles for the human corticospinal motor system is based on a spatially segregated representation of movement directions and that the representation of individual somatic structures, such as the hand muscles, overlap.



Digit-muscle responses evoked from multiple intracortical foci in monkey precentral motor cortex.

The data suggest that the digit area of motor cortex does not have a simple organization in which each muscle is represented by a single focus, rather, each muscle has multiple foci that have varying degrees of efficacy in producing responses and with variable overlap onto foci of other muscles.

Patterns of facilitation and suppression of antagonist forelimb muscles from motor cortex sites in the awake monkey.

Patterns of excitatory and inhibitory effects were produced in antagonistic forelimb muscles by single intracortical microstimuli applied to motor cortex sites in macaque monkeys performing ramp-and-hold wrist movements, suggesting that the cortically evoked suppression is mediated by polysynaptic relays.

Organization of the face representation in macaque motor cortex

The face representation in precentral motor cortex in macaque monkeys was stimulated with microelectrodes with the most commonly evoked muscle response in zygomaticus, which retracts the corners of the mouth in expressions of fear and anger.

Topographic organization of baboon primary motor cortex: face, hand, forelimb, and shoulder representation.

The results suggest that the baboon motor cortex is topographically organized; however, embedded within this overall pattern lies a fine-grained mosaic incorporating multiple representations of the same muscle.

Microstimulation mapping of precentral cortex during trained movements.

Both excitation and inhibition of muscles could be produced with ICMS of precentral cortex when the animal was performing a task involving the muscles being mapped, and different types of movements involving a single muscle are represented at different locations within this region.

The relationship of corpus callosum connections to electrical stimulation maps of motor, supplementary motor, and the frontal eye fields in owl monkeys

The somatotopic organization of M‐I was neither a single topographic representation, nor two serial or mirror symmetric representations, nor a “nesting about joints” representation, and is more adequately described as a mosaic of regions, each representing movements of a restricted part of the body, with multiple representations of movements that tend to be somatOTopically related.

Postspike facilitation of forelimb muscle activity by primate corticomotoneuronal cells.

In macaque monkeys making rampand-hold wrist movements against elastic loads, activity of task-related motor cortex cells and specific wrist and finger muscles was recorded and postspike facilitation (PSF) of average EMG activity was recorded.

Dynamic organization of primary motor cortex output to target muscles in adult rats II. Rapid reorganization following motor nerve lesions

The results indicated that the output circuits of MI can be quickly reorganized by nerve lesions in adult mammals.

Dynamic organization of primary motor cortex output to target muscles in adult rats I. Long-term patterns of reorganization following motor or mixed peripheral nerve lesions

The results indicate that the amount of cortex controlling a group of muscles and the strength of the relationship between a cortical locus with its target muscles is modified by nerve lesions in adult mammals.

Relationship of intrinsic connections to forelimb movement representations in monkey motor cortex: a correlative anatomic and physiological study.

Data suggest that extensive, horizontally oriented, intrinsic axon collaterals provide inputs to many different Forelimb movement representations and may be recruited during complex movements to coordinate the activity of motor cortical zones whose predominant output is to forelimb muscle groups acting synchronously.