The cingulate cortex (CC) as a part of the "medial" pain subsystem is generally assumed to be involved in the affective and/or cognitive dimensions of pain processing, which are viewed as relatively slow processes compared with the sensory-discriminative pain coding by the lateral second somatosensory area (SII)-insular cortex. 
As part of an effort to describe the connections of the somatosensory system in Galago garnetti, a small prosimian primate, injections of tracers into cortex revealed that two somatosensory areas, the second somatosensory area (S2) and the parietal ventral somatosensory area (PV), project densely to the ipsilateral superior colliculus, while the primary somatosensory area (S1 or area 3b) does not.
Within the ferret AEV there were clusters of bimodal recording sites (somato-visual and audio-visual) that were located adjacent to surrounding unimodal cortical areas (such as the second somatosensory area and primary and secondary auditory areas).
Two dipoles in the bilateral insular cortex, one dipole in the anterior cingulate gyrus and two dipoles in the bilateral second somatosensory area were found.
In addition, the second somatosensory area, S2, and the parietal ventral area, PV, were probably present.
In addition to a primary somatosensory cortex (SI), the cerebral cortex of all mammals contains a second somatosensory area (SII); however, the functions of SII are largely unknown.
This persistent cortical hypometabolism occupies the somatosensory cortex, forelimb motor cortex, and second somatosensory area.
To gain insight into how cortical fields process somatic inputs and ultimately contribute to complex abilities such as tactile object perception, we examined the pattern of connections of two areas in the lateral sulcus of macaque monkeys: the second somatosensory area (S2), and the parietal ventral area (PV).
Somatosensory evoked potentials of 75 ms to 145 ms latency were recorded from the ictal onset zone, which was 2 cm caudal to the perisylvian area corresponding to the second somatosensory area. Seizures arising from the inferior parietal lobule including the angular and supuramarginal gyri can produce partial seizures whose ictal semiology and scalp electroencephalography are indistinguishable from the ones originating from the second somatosensory area..
OBJECTIVE: To record somatosensory evoked potentials (SEPs) to median nerve stimulation by chronically implanted electrodes in the parieto-rolandic opercular area of 9 epileptic patients, in order to evaluate whether somatosensory evoked responses could be generated in the second somatosensory area (SII) earlier than 40 ms after stimulus.
The dorsorostral belt (DRB) was subdivided into two zones on the basis of its projections: the more rostral part appears to overlap the second somatosensory area and be bimodal, while the caudal part has stronger auditory connections.
In the same animals, neuroanatomical tracers were placed into electrophysiologically identified sites in PV and/or the second somatosensory area (S2).
Area 3a has dense intrinsic connections and receives substantial inputs from the primary motor cortex (M1), the supplementary motor area (SMA), areas 1 and 2, the second somatosensory area (S2), and areas in posterior parietal cortex (PP).
Responsiveness of the first somatosensory area (SI) of the cerebral cortex was investigated in the marmoset monkey (Callithrix jacchus) in association with cooling-induced, reversible inactivation of the second somatosensory area, SII.
More sparse labeling was found in the medial agranular cortex (or MII), and the second somatosensory area.
The anterograde labeling of thalamocortical axons show that most "core cells" project to a single barrel column, whereas some "tail cells" give rise to branching axons that innervate the second somatosensory area and the dysgranular zone of the barrel field.
The earliest activated Sylvian dipolar sources did not change their location when the upper or lower limb was stimulated, as expected from the close projections of hand and foot in the second somatosensory area.
A second representation, the second somatosensory area (or S2), was found adjacent and caudolateral to S1 as a mirror image reversed along the representation of the glabrous snout.
Second, when activity patterns in the large central area resulting from stimulation of all body parts were considered, this region appeared to contain two fields that corresponded in location and somatotopic organization to the second somatosensory area (SII) and the parietal ventral area (PV).
Lateral to SI we found evidence for two further areas, the second somatosensory area (SII) and the parietal ventral area (PV).
Stimulation of the impaired hand resulted in activation of the ipsilateral parietal operculum (second somatosensory area [ SII]) and posterior parietal lobe (Brodmann's Area 7) in all cases, but no activation was elicited in the SI in any patient.
In addition, MEG can localize second somatosensory area (SII) over the superior bank of the Sylvian fissure as well as posterior parietal cortex (PPC), which are difficult to be detected by the EEG recording.
Corticocortical projections targeted areas projected to by both dorsal and ventral banks and also by second somatosensory area, first temporal cortical area, and striate cortex.
Lateral to SI, two fields were identified in the striped possum, the second somatosensory area (SII) and the parietal ventral area (PV); in the quoll, there appeared to be only one additional lateral field which we term SII/PV.
The findings were as follows: the areas in the lateral cortex activated by the stimuli were the primary sensory cortex (SI), the second somatosensory area (SII), the insula, the superior parietal lobule, and the retroinsular parietal operculum (RIPO).
A small, moderately myelinated area lateral to S1 was termed PV/S2 because it possessed features that were similar to both the parietal ventral area (PV) and the second somatosensory area (S2) in other mammals.
Responsiveness within the hand region of the second somatosensory area of cortex (SII) was investigated in the marmoset monkey (Callithrix jacchus) in association with cooling-induced, reversible inactivation of the primary somatosensory area, SI.
Corticostriatal and corticothalamic projections arising from the second somatosensory area in the rat were studied after labeling small pools of neurons in laminae V and VI with biocytin.
Insular connections between the second somatosensory area and retroinsular area of the parietal lobe have been documented.
We identified the more dorsal field as the second somatosensory area (S2) and the more ventral field as the parietal ventral area (PV).
Area 12m received somatosensory input from face, digit, or forelimb regions in the opercular part of area 1-2, in area 7b, in the second somatosensory area (SII), and in the anterior infraparietal area (AIP).
On the basis of cytoarchitectural criteria, the labeled regions include the second somatosensory area (SII), retroinsular area (Ri) and granular insula (Ig).
We term these fields the second somatosensory area (SII) and the parietal ventral area (PV) because of their similarities in position, internal organization, and relationship to anterior parietal fields, as described for SII and PV in other mammals.
Lesions of the second somatosensory area alone reduced the motor cortex responses on peripheral nerve stimulation by 10-20%.
In a recent study of the second somatosensory area (SmII) in the rat it was reported that the somatotopic map in the cortex lateral to the primary somatosensory area (SmI) is closely related to local features of the callosal pattern.
Responsiveness of neurons in the distal forelimb region of primary somatosensory cortex (SI) was examined in cat in association with the cooling-induced, reversible inactivation of the corresponding region of the second somatosensory area (SII).
This second set of stripes may be part of the second somatosensory area, S2.
The striatal projections of the cortex of the caudal portion of the cingulate gyrus (corresponding in part to the supplementary sensory area) and of the rostral parietal opercular region (corresponding in part to the second somatosensory area) are directed almost exclusively to the dorsal and ventral sectors of the putamen, respectively.
The cortical connections of the primary somatosensory area (SI or 3b), a caudal somatosensory field (area 1/2), the second somatosensory area (SII), the parietal ventral area (PV), the ventral somatosensory area (VS), and the lateral parietal area (LP) were investigated in grey headed flying foxes by injecting anatomical tracers into electrophysiologically identified locations in these fields.
Previous observations on the effect of ablation or inactivation of the primary somatosensory cortex (SI) on the responses of neurons within the second somatosensory area (SII) to tactile stimuli point to profound differences between monkeys and certain other mammals in the organization of thalamocortical systems.
These fields are: the primary somatosensory area, SI or area 3b; a field caudal to area 3b, area 1/2; the second somatosensory area, SII; the parietal ventral area, PV; and the ventral somatosensory area, VS. The second somatosensory area, SII, shared a congruent border with 3b at the representation of the nose.
The aim was to examine the responsiveness of individual neurons in the second somatosensory area (SII) in association with SI inactivation to evaluate the relative importance for tactile processing of the direct thalamocortical projection to SII and the indirect projection from the thalamus to SII via an intracortical path through SI.
The thalamic connections of the second somatosensory area in the anterior ectosylvian gyrus of cats have been investigated using the retrograde tracer horseradish peroxidase and the anterograde tracer Phaseolus vulgaris leucoagglutinin. Horseradish peroxidase was injected iontophoretically in several somatotopic zones of the second somatosensory area map of six cats. Neurons labeled in the ventrobasal complex were observed throughout the anteroposterior extent of the nucleus, while their mediolateral distribution varied with the site of horseradish peroxidase delivery in the body map of the second somatosensory area, which indicates that the projections from the ventrobasal complex to the second somatosensory area are somatotopically organized. In the cat in which the horseradish peroxidase injection involved both the second somatosensory area proper and the second somatosensory area medial, which lies in the lower bank of suprasylvian sulcus, labeled neurons were almost as numerous in the ventrobasal complex as in the posterior complex. In this case, patches of labeled fibers and terminals were distributed exclusively within the cytoarchitectonic borders of the second somatosensory area proper. Injection of Phaseolus vulgaris leucoagglutinin in the posterior complex labeled thalamocortical fibers in two distinct regions in the ipsilateral anterior ectosylvian gyrus, one lying laterally and the other medially, which correspond, respectively, to the fourth somatosensory area and the second somatosensory area medial. In this case, only rare fragments of labeled fibers were present in second somatosensory area proper, but no labeled terminals could be observed..
Recordings from the vicinity of the second somatosensory area, from the supplementary motor and sensory areas and from surface cortex other than sensorimotor cortex have not detected reliable short-latency activity, although some of these regions generate long-latency potentials.
In Tupaia belangeri and Galago senegalensis, microelectrode recordings immediately after ablation of the representation of the forelimb in the midportion of the first somatosensory area, S-I, revealed that all parts of the second somatosensory area, S-II, remained highly responsive to cutaneous stimuli.
There are indications in the literature that convergent ipsilateral and contralateral input to the second somatosensory area (SII) may interact.
The results indicate that two distinct somatosensory areas, SI and the dysgranular cortex, are interconnected with a further lateral somatosensory area referred to as the second somatosensory area (SII).
Considerably less overlap occurred after injections of the primary sensorimotor region (SI, MI) and second somatosensory area (SII), while the supplementary motor area, the auditory cortex and gyrus cinguli probably have no or very restricted access to the dorsal paraflocculus.
In addition, consistent abnormalities were observed in the pattern of callosal projections of the second somatosensory area of both hemispheres.
Partial ablations of specific parts of cortical areas 3b (SI proper) and 3a in marmosets were found to render somatotopically equivalent parts of two other cortical somatosensory fields, the second somatosensory area (SII) and the parietal ventral area (PV), unresponsive to peripheral stimulation.
This distribution suggests a tangential generator located in the upper wall of the SS in the second somatosensory area (SII).
This distribution suggests a tangential generator located in the upper wall of the SS in the second somatosensory area (SII).
Cytoarchitectonic evaluation of the perisylvian cortex in the three cases examined in detail indicated that labeled areas included the ventral premotor cortex (area 6V); the precentral opercular and orbitofrontal opercular areas (PrCO and OFO); the second somatosensory area (S-II); the opercular cortex immediately anterior to S-II, possibly corresponding to area 2 of the S-I complex; and the central part of the insular cortex, including portions of the granular and dysgranular insular fields (Ig, Idg).
We have reported that elimination of the representation of any body part in the primary (i.e., postcentral) somatosensory cortex of the adult macaque selectively eliminates the representation of that same body part in the second somatosensory area SII.
Poor interrelation between area 5 and areas SI (2, 3a, 3b) and no projection to SII (second somatosensory area of Wolsey) were observed.
Both resemble the second somatosensory area, S-II, enough to be identified as S-II in the absence of evidence for the other.
Removal of the representation of a specific body part in the postcentral cortex of the macaque resulted in the somatic deactivation of the corresponding body part in the second somatosensory area. In contrast, removal of the entire second somatosensory area had no grossly detectable effect on the somatic responsivity of neurons in the postcentral cortex.
Within the second somatosensory area one source was active; the P12 originated just lateral to the anterior aspect of the suprasylvian sulcus in the anterior ectosylvian gyrus..
Effects of electroacupuncture (EAP) on the character of spontaneous and evoked neuronal impulse activity changes in the second somatosensory area (S2) of the brain cortex by nociceptive and non-nociceptive stimulation were studied in acute experiments on cats.
Special attention was paid to the second somatosensory area (S2), the connections of which were also studied by means of thalamic isotope injections and retrograde degeneration.
The results show that the second somatosensory area (S2) is reciprocally connected with the retroinsular area (Ri), area 7b, and the granular (Ig) and dysgranular (Id) insular fields.
Within this second somatosensory area (SII), the following findings were made: A relatively large region is devoted to representations of the paws and face, especially the sinus hairs associated with the anterior upper lip and mystacial vibrissae.
Dense, uneven connections also characterized the second somatosensory area, S-II.
Threshold for evoking movements by microstimulation of the second somatosensory area of the cynomolgus monkey's cortex to intracortical microstimulation was examined.
Injections of the second somatosensory area (SmII) and the parietal association cortex (areas 5 and 7) gave moderate degrees of overlap.
Corticothalamic connections were shown between the second somatosensory area in primates and the ventroposterior nuclei of the thalamus.
In order to study the callosal connections of the hand sensory field of the second somatosensory area of the monkey, experiments were carried out by combining the method of retrograde neuronal tracing with microelectrode recording. Microelectrode recording from this hemisphere showed that the cortical zones of both the first and the second somatosensory area containing neurones excited by sensory stimulation of the contralateral hand also contained HRP-positive neurones..
It is suggested that brain research in the field of somatoform disorders look to the second somatosensory area (SII), which appears to be especially suited to the types of neurophysiological and neuropsychological dynamics that are generally presumed to underlie this class of maladies.
The second somatosensory area and the visual cortex both seem able to influence a small but significant proportion of cells projecting to crus II.
Two distinct patterns of terminal labeling were seen after injections of [ 3H]amino acids into the second somatosensory area (S2) and the retroinsular area (Ri).
The inferior parietal lobule was removed alone or together with the superior parietal lobule; the second somatosensory area (SII) was removed alone or together with posterior parietal surface cortex.
Microelectrode multiunit recording methods were used to determine the somatotopic organization of the second somatosensory area, S-II, in tree shrews.
The distribution of S1 (first somatosensory area) and S2 (second somatosensory area) neurons projecting to the contralateral S2 was studied with horseradish peroxidase in normal adult cats and in cats aged between 129 and 248 days in which the injected S2 area had been deprived of some of its input by an earlier lesion (on postnatal days 3 to 30; day of birth = day 1) of ipsilateral S1, alone or combined with a lesion of contralateral S2.
The second somatosensory area (SII) of awake, untrained cynomolgus monkeys was surveyed with recordings from nearly 1,000 single neurons.
Horseradish peroxidase (HRP) was injected unilaterally into the first and second visual areas (V1 and V2; areas 17 and 18) of 20 kittens aged between 2 and 90 days and into the second somatosensory area (S2) of 16 kittens aged between 1 and 52 days.
Habituation developed faster in the parietal cortex and in the focus of maximal activity of the first somatosensory areas as compared to the second somatosensory area.
Using the method of evoked potentials on chloralose-anesthetized and suxamethonium-immobilized cats, a comparative study was made of the effects of interaction of somatic and visceral afferent systems in the second somatosensory area and in the parietal cortex of the brain.
The second focus sometimes lay in area 2 of SI and sometimes in the second somatosensory area (SII)..
In neocortical regions ipsilateral to the lesion axonal degeneration was present in auditory subdivisions AI, AII, Ep, I, T, in the second somatosensory area (SII), in the anterior and middle suprasylvian gyrus, in the posteromedial suprasylvian and posterior lateral gyri, in the posterior splenial gyrus, in the anterior two-thirds of the cingulate gyrus and in the orbitofrontal regions.
The cells appeared concentration in the fore-and hindlimb regions of the sensorimotor cortex and, to a lesser extent, in the second somatosensory area contralateral to the injected side.
The second somatosensory area was simultaneously connected with the caudal portion of the posterior ventral nucleus and with the nuclei of the posterior group of the thalamus.
The second somatosensory area (S-II), showing bilateral representation without a precise topographical organization, was identified in the rostral portion of the ectosylvian gyrus.
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