Premotor cortex

The premotor cortex occupies the part of Brodmann area 6 that lies on the lateral surface of the cerebral hemisphere.Second, the primary motor cortex is agranular: it lacks a layer IV marked by the presence of granule cells.In the study of neurolinguistics, the ventral premotor cortex has been implicated in motor vocabularies in both speech and manual gestures.A mental syllabary — a repository of gestural scores for the most highly used syllables in a language — has been linked to the ventral premotor cortex in a large-scale meta-analysis of functional imaging studies[citation needed].A recent prospective fMRI study that was designed to distinguish phonemic and syllable representations in motor codes provided further evidence for this view by demonstrating adaptation effects in the ventral premotor cortex to repeating syllables[citation needed].Electrical stimulation of these neurons causes an apparent defensive movement as if protecting the body surface.[19][20] This premotor region may be part of a larger circuit for maintaining a margin of safety around the body and guiding movement with respect to nearby objects.Instead M1 was considered to be a single map of the body, perhaps with complex properties, arranged along the central sulcus.Roland and colleagues[31][32] studied the dorsal premotor cortex and the supplementary motor area in humans while blood flow in the brain was monitored in a positron emission scanner.When people made complex sensory-guided movements such as following verbal instructions, more blood flow was measured in the dorsal premotor cortex.When people made internally paced sequences of movements, more blood flow was measured in the supplementary motor area.When people made simple movements that required little planning, such as palpating an object with the hand, the blood flow was more limited to the primary motor cortex.[4][22] By implication, at least three different cortical fields may exist, each one performing its own special function in relation to the fingers and wrist.In this alternative proposal, the motor cortex is organized as a map of the natural behavioral repertoire.In contrast the simpler parts of the movement repertoire that tend to focus more on the distal musculature are emphasized in the more posterior cortex.In this alternative view, though movements of lesser complexity are emphasized in the primary motor cortex and movements of greater complexity are emphasized in the caudal premotor cortex, this difference does not necessarily imply a control hierarchy.
Some commonly accepted divisions of the cortical motor system of the monkey
Brodmann area 6ArteryNeuroNamesAnatomical terms of neuroanatomymotor cortexfrontal lobeprimary motor cortexspinal cordtrunk musclessupplementary motor areaBetz cellscytoarchitectureparietal cortexprefrontal cortexstriatumthalamusMirror neuronsPenfieldGrazianoposterior cortexVogt, C.Vogt, O.BibcodeGraziano, M.S.A.Graziano, M.S.ABrodmann, KPenfield, W.cerebral cortexhuman brainPrefrontalSuperior frontal gyrusMiddle frontal gyrusInferior frontal gyrusPars orbitalisBroca's areaPars opercularisPars triangularisSuperior frontal sulcusInferior frontal sulcusPrecentralPrecentral gyrusPrecentral sulcusMedial frontal gyrusParaterminal gyrusParaolfactory areaStraight gyrusOrbital gyriOrbitofrontal cortexVentromedial prefrontal cortexSubcallosal areaOlfactory sulcusOrbital sulcusParacentral lobuleParacentral sulcusSupplementary eye fieldFrontal eye fieldsParietal lobeSuperior parietal lobuleInferior parietal lobuleSupramarginal gyrusAngular gyrusParietal operculumIntraparietal sulcusPrecuneusMarginal sulcusPostcentral gyrusPrimary somatosensory cortex3, 1 and 2Secondary somatosensory cortexPosterior parietal cortexOccipital lobeOccipital gyriLateral occipital gyrusLunate sulcusTransverse occipital sulcusVisual cortexCuneusLingual gyrusCalcarine sulcusTemporal lobeTransverse temporal gyrusAuditory cortex41 and 42Superior temporal gyrusWernicke's areaPlanum temporaleSuperior temporal sulcusMiddle temporal gyrusOccipitotemporal sulcusFusiform gyrusMedial temporal lobeInferior temporal sulcusInferior temporal gyrusInterlobarsulci/fissuresCentral (frontal+parietal)Lateral (frontal+parietal+temporal)Parieto-occipitalPreoccipital notchLongitudinal fissureCingulate (frontal+cingulate)Collateral (temporal+occipital)Callosal sulcusLimbic lobeParahippocampal gyrusEntorhinal cortexPerirhinal cortexPostrhinal cortexPosterior parahippocampal gyrusPrepyriform areaCingulate cortexSubgenual areaAnterior cingulatePosterior cingulateIsthmus of cingulate gyrusRetrosplenial cortexHippocampal formationHippocampal sulcusFimbria of hippocampusDentate gyrusRhinal sulcusIndusium griseumAmygdalaInsular cortexOperculumBrodmann areas