Synaptic connections of callosal projection neurons in the vibrissal region of mouse primary motor cortex: An electron microscopic/horseradish peroxidase study

1986 ◽  
Vol 248 (4) ◽  
pp. 573-587 ◽  
Author(s):  
Linda L. Porter ◽  
Edward L. White
Keyword(s):  
Motor Cortex ◽  
Horseradish Peroxidase ◽  
Primary Motor Cortex ◽  
Projection Neurons ◽  
Synaptic Connections ◽  
Electron Microscopic ◽  
Callosal Projection

Organization of the primate face motor cortex as revealed by intracortical microstimulation and electrophysiological identification of afferent inputs and corticobulbar projections

1988 ◽  
Vol 59 (3) ◽  
pp. 796-818 ◽  
Author(s):  
C. S. Huang ◽  
M. A. Sirisko ◽  
H. Hiraba ◽  
G. M. Murray ◽  
B. J. Sessle
Keyword(s):  
Motor Cortex ◽  
Single Neuron ◽  
Primary Motor Cortex ◽  
General Pattern ◽  
Emg Activity ◽  
Projection Neurons ◽  
Intracortical Microstimulation ◽  
Facial Musculature ◽  
The Face ◽  
Afferent Inputs

1. The technique of intracortical microstimulation (ICMS), supplemented by single-neuron recording, was used to carry out an extensive mapping of the face primary motor cortex. The ICMS study involved a total of 969 microelectrode penetrations carried out in 10 unanesthetized monkeys (Macaca fascicularis). 2. Monitoring of ICMS-evoked movements and associated electromyographic (EMG) activity revealed a general pattern of motor cortical organization. This was characterized by a representation of the facial musculature, which partially enclosed and overlapped the rostral, medial, and caudal borders of the more laterally located cortical regions representing the jaw and tongue musculatures. Responses were evoked at ICMS thresholds as low as 1 microA, and the latency of the suprathreshold EMG responses ranged from 10 to 45 ms. 3. Although contralateral movements predominated, a representation of ipsilateral movements was found, which was much more extensive than previously reported and which was intermingled with the contralateral representations in the anterior face motor cortex. 4. In examining the fine organizational pattern of the representations, we found clear evidence for multiple representation of a particular muscle, thus supporting other investigations of the motor cortex, which indicate that multiple, yet discrete, efferent microzones represent an essential organizational principle of the motor cortex. 5. The close interrelationship of the representations of all three muscle groups, as well as the presence of a considerable ipsilateral representation, may allow for the necessary integration of unilateral or bilateral activities of the numerous face, jaw, and tongue muscles, which is a feature of many of the movement patterns in which these various muscles participate. 6. In six of these same animals, plus an additional two animals, single-neuron recordings were made in the motor and adjacent sensory cortices in the anesthetized state. These neurons were electrophysiologically identified as corticobulbar projection neurons or as nonprojection neurons responsive to superficial or deep orofacial afferent inputs. The rostral, medial, lateral, and caudal borders of the face motor cortex were delineated with greater definition by ICMS and these electrophysiological procedures than by cytoarchitectonic features alone. We noted that there was an approximate fit in area 4 between the extent of projection neurons and field potentials anti-dromically evoked from the brain stem and the extent of positive ICMS sites.(ABSTRACT TRUNCATED AT 400 WORDS)

scholarly journals A computational model based on cortico-spinal fMRI for asymmetrically organized motor corticospinal networks in humans

2021 ◽  
Author(s):  
Eiji Takasawa ◽  
Mitsunari Abe ◽  
Kenji Takagishi ◽  
Hirotaka Chikuda ◽  
Takashi Hanakawa
Keyword(s):  
Motor Cortex ◽  
Primary Motor Cortex ◽  
Hand Movement ◽  
Hand Preference ◽  
Synaptic Connections ◽  
Spinal Motoneurons ◽  
Functional Magnetic Resonance ◽  
Hand Dexterity ◽  
Spinal Fmri ◽  
Dexterous Hand

Abstract Evolution of the direct connection from primary motor cortex to motoneurons in the spinal cord parallels acquisition of hand dexterity and lateralization of hand preference. Recent studies indicated that the phylogenetically older pathway consisting of multi-synaptic connections from primary motor cortex to spinal motoneurons also participate in controlling dexterous hand movement. However, it remains unknown how the two corticospinal pathways work in concert to control unilateral hand movement with lateralized preference. Using corticospinal functional magnetic resonance imaging, we discovered the asymmetric organization of the two corticospinal networks that modelled monosynaptic or polysynaptic control from primary motor cortices over spinal motoneurons. Moreover, the degree of the involvement of the two corticospinal networks paralleled the lateralization of hand preference. The present results pointed to the functionally lateralized motor nervous system that underlies the behavioural asymmetry of handedness, a uniquely human trait which could have phylogenetically differentiated humans from other primates.

Differential activity patterns of putaminal neurons with inputs from the primary motor cortex and supplementary motor area in behaving monkeys

2011 ◽  
Vol 106 (3) ◽  
pp. 1203-1217 ◽  
Author(s):  
Sayuki Takara ◽  
Nobuhiko Hatanaka ◽  
Masahiko Takada ◽  
Atsushi Nambu
Keyword(s):  
Motor Cortex ◽  
Primary Motor Cortex ◽  
Supplementary Motor Area ◽  
Activity Patterns ◽  
Motor Area ◽  
Projection Neurons ◽  
Related Activity ◽  
Cortical Inputs ◽  
Behaving Monkeys ◽  
Increased Activity

Activity patterns of projection neurons in the putamen were investigated in behaving monkeys. Stimulating electrodes were implanted chronically into the proximal (MIproximal) and distal (MIdistal) forelimb regions of the primary motor cortex (MI) and the forelimb region of the supplementary motor area (SMA). Cortical inputs to putaminal neurons were identified by excitatory orthodromic responses to stimulation of these motor cortices. Then, neuronal activity was recorded during the performance of a goal-directed reaching task with delay. Putaminal neurons with inputs from the MI and SMA showed different activity patterns, i.e., movement- and delay-related activity, during task performance. MI-recipient neurons increased activity in response to arm-reach movements, whereas SMA-recipient neurons increased activity during delay periods, as well as during movements. The activity pattern of MI + SMA-recipient neurons was of an intermediate type between those of MI- and SMA-recipient neurons. Approximately one-half of MIproximal-, SMA-, and MI + SMA-recipient neurons changed activities before the onset of movements, whereas a smaller number of MIdistal- and MIproximal + distal-recipient neurons did. Movement-related activity of MI-recipient neurons was modulated by target directions, whereas SMA- and MI + SMA-recipient neurons had a lower directional selectivity. MI-recipient neurons were located mainly in the ventrolateral part of the caudal aspect of the putamen, whereas SMA-recipient neurons were located in the dorsomedial part. MI + SMA-recipient neurons were found in between. The present results suggest that a subpopulation of putaminal neurons displays specific activity patterns depending on motor cortical inputs. Each subpopulation receives convergent or nonconvergent inputs from the MI and SMA, retains specific motor information, and sends it to the globus pallidus and the substantia nigra through the direct and indirect pathways of the basal ganglia.

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