Functional connectivity analyses revealed that for the comparison subjects, but not the patients with MDD, rostral ACC and medial PFC activation 80 milliseconds after committing an error predicted left dorsolateral PFC (Brodmann area 8/9) activation 472 milliseconds after committing an error. 
Two other areas occupy the ventral prearcuate convexity cortex, a caudal one-area 8r-located just rostral to area 8/FEF and a rostral one-area 45A-which extends as far as the inferior frontal sulcus.
The improvement of UPDRS motor score by DBS correlated with the metabolic activities of rostral supplementary motor area (Brodmann's area 8; BA8), anterior cingulate cortex (BA32), and prefrontal cortex (BA9).
Voxel-to-voxel mapping of each subject's performance showed that the lateral and posterior portion of the SFG (mostly Brodmann area 8, rostral to the frontal eye field) was the subregion that contributed the most to the WM impairment.
The intermediate subdivision of area 8 (8Ad) has efferent projections to area 7, while the dorsomedial subdivision (8B) has few or no connections with extrastriate cortex. Area 46, located rostrolateral to area 8Av, has substantial connections with the medial extrastriate areas (DM, DA, and area 7) and with MT, while the cortex lateral to 8Av (area 12/45) projects primarily to MT and to the MTc.
We found that axons from areas 46 and rostral 8 terminated heavily in layers I-III of all intraparietal areas, as did caudal area 8 to area LIPv, suggesting 'feedback' communication. However, contrary to previous assumptions, axons from caudal area 8 terminated mostly in layers IV-V of LIPd and 7a, suggesting 'feedforward' communication.
Additional functional connectivity analyses using inferior frontal activation clusters (right area 44, left area 47) as seed volumes showed connectivity with superior frontal area 8 and anterior cingulate gyrus, suggesting that the role of inferior frontal cortex was related to response conflict and inhibition.
In addition, the integration of inconsistent emotional information engaged the dorsal frontomedial cortex (Brodmann's area 8/9), whereas the integration of inconsistent temporal information required the lateral prefrontal cortex bilaterally.
Compared to the NSTM task (delay period), the STM task enhanced cortical responses in bilateral dorsolateral prefrontal (Brodmann area 8-9 (BA 8-9)), lateral premotor (BA 6L), medial premotor (BA 6M), inferior parietal (BA 40), and superior parietal (BA 7) areas.
On the third day, cortical labeling extended into the rostral motor-related areas and, also, prearcuate area 8.
The heterotopic connections of F7 originate mainly from F2, with smaller contingent from pre-supplementary motor area (pre-SMA, F6), area 8 (frontal eye fields), and prefrontal cortex (area 46), while those of F2 originate from F7, with smaller contributions from ventral premotor areas (F5, F4), SMA-proper (F3), and primary motor cortex (M1).
RESULTS: A linear regression model, controlling for the effects of cognitive deficits, revealed a significant relationship between severity of delusional thought and the metabolic rates in three frontal regions: the right superior dorsolateral frontal cortex (Brodmann's area 8), the right inferior frontal pole (Brodmann's area 10), and the right lateral orbitofrontal region (Brodmann's area 47).
RESULTS: STN stimulation significantly changed rCBF in the right pre-supplementary motor area (pre-SMA), anterior cingulate cortex, and dorsolateral prefrontal cortex and in the medial Brodmann's area 8 (BA8) as defined in the atlas of Talairach and Tournoux (P < 0.05 corrected for multiple comparisons).
The maintenance in working memory of spatial locations and their temporal order was associated with activation of area 8 and intraparietal cortex.
The mid-dorsolateral prefrontal region receives visuospatial input from the posterior dorsolateral region (areas 8 and 6) and from the cortex within the middle part (sulcal area 46) and the caudal part (area 8) of the sulcus principalis.
In contrast, maintenance was associated with activation of prefrontal area 8 and the intraparietal cortex.
As for mPFC ablation, the lesioned area involved the agranular precentral region (Brodmann's area 8), the anterior cingulate cortex (Brodmann's area 24) and the prelimbic area (Brodmann's area 32).
Standing with eyes closed activated the prefrontal cortex (Brodmann area 8/9).
Its distant connections are with area 44; the dorsal portion of area 8 and the ventral portion of area 46; as well as CMAr, SMA, and the supplementary sensory area.
An attempt was made to clarify the laminar distributions of neurons activated during a symmetrically reinforced, visually guided GO/NO-GO task with visual cues for which Brodmann's area 8 (Walker, 1940) is considered an essential region (cf. We systematically recorded single unit activities in area 8 in 200 microns steps from the surface to the bottom of the cortex, using a glass-coated microelectrode that contained a carbon fiber. Activities of GO cue-coupled neurons, intermediate neurons and movement-coupled neurons in GO trials were recorded in layers II-VI, layers II-VI and layers III-VI of the area 8, respectively.
The anterior and inferior frontal structures (and also the eye field, area 8) belong to the prefrontal region.
The connectional results showed prefrontal cortex in the location of the frontal eye fields (area 8) and dorsal area 46 projected in a columnar pattern to all cortical layers of area TPOc, to layer IV of TPOi, and in a columnar fashion, with a moderate increase in density in layer IV, to TPOr.
Thus, area 8 can be subdivided into dorsal and ventral regions on the basis of the distribution of GABAA, muscarinic and serotonin receptors.
Errors in performance increased 10-60 min after injection into 10 of 33 sites in area 9, 9 of 25 sites in area 8, 20 of 34 sites in area 6, and 2 of 10 sites in area 4.
Patients with idiopathic torsion dystonia showed significant overactivity in the contralateral lateral premotor cortex, rostral supplementary motor area, Brodmann area 8, anterior cingulate area 32, ipsilateral dorsolateral prefrontal cortex, and bilateral lentiform nucleus.
These cell types are similar to those previously found in the more dorsal anterior cingulate cortex (area 24) and frontal eyefields (area 8).
Responses of hypothalamic neurons to single (1/s, 20 impulses) stimulation of the prefrontal (area 8), cingulum (area 24), periamygdaloideus (RPA) cortex and hippocampus (field CA3) were studied on experimental cats anesthetized with ketamine.
The density of innervation is highest in areas 1 and 6, intermediate in area 8, and lowest in area 17.
In contrast, highly differentiated prefrontal area 8 projects to the most lateral sector of the mediodorsal nucleus, the multiformis subdivision.
Evoked potentials (EPs) and neuronal responses of the medial (MPO) and lateral (LPO) preoptic region (RPO) and adjacent areas of the anterior hypothalamus to serial (6-300 s) stimulation of the prefrontal (area 8), cingulum (area 24), periamygdaloideus (RPA) cortex and hippocampus (field CA3) were studied on experimental cats anesthetized by ketamine. Prevalence of inhibitory responses over excitatory ones was minimal (ratio 1.7:1), when the neocortex (area 8) was stimulated and it was more pronounced (ratio 1.9:1) during stimulation of the evolutionary intermediate cortex (area 24).
Evoked potentials (EPs) and neuronal responses of the medial (MPO) and lateral (LPO) preoptic region (RPO) and adjacent areas of the hypothalamus to stimulation of the prefrontal (area 8), cingulum (area 24), periamigdaloideus (RPA) cortex and hippocampus (area CA3) have been studied on cats anesthetized with ketamine.
The mediodorsal regions included portions of medial areas 25, 32, 14, and dorsal area 8.
Local injection of a GABA (gamma-aminobutyric acid) antagonist, bicuculline, into Brodmann's area 8 (Walker's areas 8A and 45) of the monkey prefrontal cortex induced movements of the contralateral forelimb in 4 monkeys that were well-trained to perform a two-choice visual discrimination GO/NO-GO task by appropriate release of the hand from a lever. These results indicate that, during learning of the task, a new structure responsible for learned movement of the forelimb was made in area 8 and was disinhibited by bicuculline and, furthermore, they suggest that inhibitory GABA neurons suppress tonically efferent neurons associated with the initiation of movement..
The last group includes the caudal part of ventral area 46 and ventral area 8. The last group includes the caudal part of dorsal area 46 and dorsal area 8. Periallo- and proisocortices have widespread intrinsic connections, whereas isocortices situated at a distance from limbic areas, such as area 8, have restricted connections.
The corticocortical connections between the arcuate area (Walker's areas 8A and 45 or Brodmann's area 8) and the premotor and supplementary motor areas (Vogts' area 6) in the brain of the macaque monkey were studied microscopically with wheat germ agglutinin-conjugated horseradish peroxidase (WGA-HRP), which was injected into Brodmann's area 8 primarily to elucidate the projections of area 8 into area 6. After injection of WGA-HRP into area 8A, labeled terminals and cells appeared predominantly in the superior premotor area (a region of the premotor area above the arcuate spur, Vogt and Vogt's upper areas 6a alpha and 6a beta), forming one, two, or three bands of label in the anteroposterior direction, whereas labeling occurred to a lesser extent in the inferior premotor area (a region of the premotor area below the arcuate spur, Vogt and Vogt's areas 4c, lower 6a alpha and 6b).
The mediodorsal regions included portions of medial area 32 and the caudal part of dorsal area 8. The cells of origin were located in rostromedial visual cortices after injection of retrograde tracers in area 32 and in more caudal medial and dorsolateral visual areas after injection in caudal area 8.
The GABA infusion has partial anticonvulsant effects when applied to the motor cortex, reticular magnocellular nucleus (RMC), or substantia nigra (SN), but when directed to the prefrontal cortex (area 8) it has no effect.
Similarly, if cerebellar programs are used in some prefrontal areas (e.g., area 8 and the inferior frontal convolution), mental and language manipulations could be effected rapidly and skillfully.
Monkeys with bilateral removal of caudal prefrontal cortex (area 8) or dorso-lateral parietal cortex (areas 5 and 7) or the inferior temporal cortex (area TE) were presented with two versions of a go-left/go-right visuo-spatial discrimination.
There were no significant connections with prearcuate area 8 or the granular frontal (prefrontal) cortex.
After HRP injections restricted primarily to the superficial layers of the colliculus, labelled cells were found in visual cortex (areas 17, 18, and 19) and both in the frontal eye field (area 8) and the adjacent part of premotor cortex (area 6).
In area 8, a fairly large proportion of the 49 recorded neurons responded in both the visual discrimination (37%) and motor initiation (35%) phases. Some functional heterogeneity seems evident within area 8 since visual discrimination responses were rostral, visuokinesis was central and motor initiation was in the caudal bank of the arcuate sulcus.
Four additional capuchin monkeys, one rhesus (Macaca mulatta), and one cynomolgus (Macaca fascicularis) monkey, received HRP gel implants in premotor (area 6), frontal eye field (FEF, area 8), superior (area 5), and inferior (area 7) parietal lobules to orthogradely label the course and termination of corticopontine projections, and thus to confirm the retrograde studies. Premotor (area 6) frontal cortex and FEF (area 8) were found to be the main sources of cortical inputs to the ipsilateral paramedian basilar pons, whereas FEF, dorsal prefrontal convexity, and dorsal medial prefrontal (granular frontal association) cortex were the main sources of bilateral projections to the paramedian pontine tegmentum.
For example, area 8 receives many fibers from both the rostral part of area 9 and a small area adjacent to the inferior branch of the arcuate sulcus. Thus, the caudal half of the STs area projects to area 8 and a small adjacent part of area 9.
The sources of ipsilateral afferents to subdivisions of one frontal eye field (Walker, '40a area 8) were studied with horseradish peroxidase (HRP) in macaque monkeys. There were major differences in the distribution of cells projecting to the caudal and rostral parts of area 8. In contrast, rostral area 8 had a much lower percentage of its cortical input originating in visual association areas (5%) or in the ventral bank of the intraparietal sulcus (8%). After HRP injection in this rostral part, 21% of labeled cells were in auditory association areas and 13% in paralimbic regions, whereas labeling in these two types of cortex was negligible after HRP administration to caudal parts of area 8. The results suggest that caudal area 8 may be involved in head and eye movements in response to visual stimuli, while its anterior subdivisions may be involved in directing the head and eyes in response to auditory stimuli.
Because of the location of these preoculomotor trajectories, stimulation and lesion experiments affecting ocular motility may be explained by having involved prefrontal projections which have their origin in sulcus principalis or prearcuate area 8 (frontal eye field) cortex..
Implants of horseradish peroxidase gel6 in the sulcus principalis and/or area 8 "frontal eye field" cortex of macaque and cebus monkeys, processed with tetramethyl benzidine (TMD) neurohistochemistry9, resulted in anterograde labeling of a prominent "prefrontal oculomotor bundle" which traversed the medial subthalamic region at the diencephalic-mesencephalic junction to terminate directly in accessory and principal oculomotor nuclear groups.
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