Biomaterial Database

Architectonics, somatotopic organization, and ipsilateral cortical connections of the primary motor area (M1) of owl monkeys. 1993

I Stepniewska, and T M Preuss, and J H Kaas

Department of Psychology, Vanderbilt University, Nashville, Tennessee 37240.

The ipsilateral cortical connections of primary motor cortex (M1) of owl monkeys were revealed by injecting WGA-HRP and fluorescent tracers into M1 sites identified by intracortical microstimulation. In some of the same animals, the extent and somatotopic organization of M1 was determined by making detailed microstimulation movement maps and relating the results to cortical architectonics. Thus, delineation of M1 was based on a combination of physiological and anatomical characteristics. M1 comprised most, but not all, of the cortex rostral to area 3a where movements were evoked at low levels of current (40 microA or less). Analysis of somatotopic patterns and architectonics placed some of the low-threshold sites in a ventral premotor field (PMV) and the dorsomedially situated supplementary motor area (SMA). Movements were also reliably elicited from a dorsal premotor area (PMD) at higher currents. M1 was characterized by a somatotopic global organization, representing hindlimb, trunk, forelimb, and face movements in a mediolateral sequence, and a mosaic local organization, with a given movement typically represented at several different sites. Architectonically, M1 was characterized by the absence of a granular layer IV and the presence of very large layer V pyramidal cells. However, M1 was not uniform in structure: pyramidal cells were larger caudally than rostrally, a feature we used to distinguish caudal (M1c) and rostral (M1r) subdivisions of the area. M1 resembles Brodmann's area 4, although the rostral subdivision has probably been considered as part of area 6 by some workers. Tracer injections of M1 revealed somatotopically distributed connections with motor areas PMD, PMV, and SMA, as well as in somatosensory areas 3a, 1, 2, and S2. Weaker connections were with area 3b, posterior parietal cortex, the parietal ventral area (PV), and cingulate cortex. M1r and M1c differed connectionally as well as architectonically, M1c being connected primarily with somatosensory areas, while M1r was strongly connected with both non-primary motor cortex and somatosensory cortex. These results indicate that M1 interacts directly with at least three non-primary motor areas and at least six somatosensory areas.

UI	MeSH Term	Description	Entries
D009044	Motor Cortex	Area of the FRONTAL LOBE concerned with primary motor control located in the dorsal PRECENTRAL GYRUS immediately anterior to the central sulcus. It is comprised of three areas: the primary motor cortex located on the anterior paracentral lobule on the medial surface of the brain; the premotor cortex located anterior to the primary motor cortex; and the supplementary motor area located on the midline surface of the hemisphere anterior to the primary motor cortex.	Brodmann Area 4,Brodmann Area 6,Brodmann's Area 4,Brodmann's Area 6,Premotor Cortex and Supplementary Motor Cortex,Premotor and Supplementary Motor Cortices,Anterior Central Gyrus,Gyrus Precentralis,Motor Area,Motor Strip,Precentral Gyrus,Precentral Motor Area,Precentral Motor Cortex,Premotor Area,Premotor Cortex,Primary Motor Area,Primary Motor Cortex,Secondary Motor Areas,Secondary Motor Cortex,Somatic Motor Areas,Somatomotor Areas,Supplementary Motor Area,Area 4, Brodmann,Area 4, Brodmann's,Area 6, Brodmann,Area 6, Brodmann's,Area, Motor,Area, Precentral Motor,Area, Premotor,Area, Primary Motor,Area, Secondary Motor,Area, Somatic Motor,Area, Somatomotor,Area, Supplementary Motor,Brodmann's Area 6s,Brodmanns Area 4,Brodmanns Area 6,Central Gyrus, Anterior,Cortex, Motor,Cortex, Precentral Motor,Cortex, Premotor,Cortex, Primary Motor,Cortex, Secondary Motor,Cortices, Secondary Motor,Gyrus, Anterior Central,Gyrus, Precentral,Motor Area, Precentral,Motor Area, Primary,Motor Area, Secondary,Motor Area, Somatic,Motor Areas,Motor Cortex, Precentral,Motor Cortex, Primary,Motor Cortex, Secondary,Motor Strips,Precentral Motor Areas,Precentral Motor Cortices,Premotor Areas,Primary Motor Areas,Primary Motor Cortices,Secondary Motor Area,Secondary Motor Cortices,Somatic Motor Area,Somatomotor Area,Supplementary Motor Areas
D009068	Movement	The act, process, or result of passing from one place or position to another. It differs from LOCOMOTION in that locomotion is restricted to the passing of the whole body from one place to another, while movement encompasses both locomotion but also a change of the position of the whole body or any of its parts. Movement may be used with reference to humans, vertebrate and invertebrate animals, and microorganisms. Differentiate also from MOTOR ACTIVITY, movement associated with behavior.	Movements
D010296	Parietal Lobe	Upper central part of the cerebral hemisphere. It is located posterior to central sulcus, anterior to the OCCIPITAL LOBE, and superior to the TEMPORAL LOBES.	Brodmann Area 39,Brodmann Area 40,Brodmann Area 5,Brodmann Area 7,Brodmann's Area 39,Brodmann's Area 40,Brodmann's Area 5,Brodmann's Area 7,Inferior Parietal Cortex,Secondary Sensorimotor Cortex,Superior Parietal Lobule,Angular Gyrus,Gyrus Angularis,Gyrus Supramarginalis,Intraparietal Sulcus,Marginal Sulcus,Parietal Cortex,Parietal Lobule,Parietal Region,Posterior Paracentral Lobule,Posterior Parietal Cortex,Praecuneus,Precuneus,Precuneus Cortex,Prelunate Gyrus,Supramarginal Gyrus,Area 39, Brodmann,Area 39, Brodmann's,Area 40, Brodmann,Area 40, Brodmann's,Area 5, Brodmann,Area 5, Brodmann's,Area 7, Brodmann,Area 7, Brodmann's,Brodmanns Area 39,Brodmanns Area 40,Brodmanns Area 5,Brodmanns Area 7,Cortex, Inferior Parietal,Cortex, Parietal,Cortex, Posterior Parietal,Cortex, Precuneus,Cortex, Secondary Sensorimotor,Cortices, Inferior Parietal,Gyrus, Angular,Gyrus, Prelunate,Gyrus, Supramarginal,Inferior Parietal Cortices,Lobe, Parietal,Lobule, Parietal,Lobule, Posterior Paracentral,Lobule, Superior Parietal,Paracentral Lobule, Posterior,Paracentral Lobules, Posterior,Parietal Cortex, Inferior,Parietal Cortex, Posterior,Parietal Cortices,Parietal Cortices, Inferior,Parietal Cortices, Posterior,Parietal Lobes,Parietal Lobule, Superior,Parietal Lobules,Parietal Lobules, Superior,Parietal Regions,Posterior Paracentral Lobules,Posterior Parietal Cortices,Precuneus Cortices,Region, Parietal,Secondary Sensorimotor Cortices,Sensorimotor Cortex, Secondary,Superior Parietal Lobules
D001931	Brain Mapping	Imaging techniques used to colocalize sites of brain functions or physiological activity with brain structures.	Brain Electrical Activity Mapping,Functional Cerebral Localization,Topographic Brain Mapping,Brain Mapping, Topographic,Functional Cerebral Localizations,Mapping, Brain,Mapping, Topographic Brain
D002540	Cerebral Cortex	The thin layer of GRAY MATTER on the surface of the CEREBRAL HEMISPHERES that develops from the TELENCEPHALON and folds into gyri and sulci. It reaches its highest development in humans and is responsible for intellectual faculties and higher mental functions.	Allocortex,Archipallium,Cortex Cerebri,Cortical Plate,Paleocortex,Periallocortex,Allocortices,Archipalliums,Cerebral Cortices,Cortex Cerebrus,Cortex, Cerebral,Cortical Plates,Paleocortices,Periallocortices,Plate, Cortical
D004525	Efferent Pathways	Nerve structures through which impulses are conducted from a nerve center toward a peripheral site. Such impulses are conducted via efferent neurons (NEURONS, EFFERENT), such as MOTOR NEURONS, autonomic neurons, and hypophyseal neurons.	Motor Pathways,Efferent Pathway,Pathway, Efferent,Pathways, Efferent
D004558	Electric Stimulation	Use of electric potential or currents to elicit biological responses.	Stimulation, Electric,Electrical Stimulation,Electric Stimulations,Electrical Stimulations,Stimulation, Electrical,Stimulations, Electric,Stimulations, Electrical
D004594	Electrophysiology	The study of the generation and behavior of electrical charges in living organisms particularly the nervous system and the effects of electricity on living organisms.
D005552	Forelimb	A front limb of a quadruped. (The Random House College Dictionary, 1980)	Forelimbs
D006614	Hindlimb	Either of two extremities of four-footed non-primate land animals. It usually consists of a FEMUR; TIBIA; and FIBULA; tarsals; METATARSALS; and TOES. (From Storer et al., General Zoology, 6th ed, p73)	Hindlimbs