Acupuncture for pain relief during induced labour in nulliparae: a randomised controlled study.

OBJECTIVE: To assess the role of acupuncture for analgesia during labour. DESIGN: Double-blind study of manual, electro and sham acupuncture, and single-blind study comparing acupuncture with a control group for analgesia for labour induction. SETTING: A major obstetric unit in the UK. POPULATION: A cohort of 105 nulliparae undergoing labour induction at term. METHODS: Twenty-three subjects needed to be randomised to each group to have an 80% power of detecting a 50% relative reduction in epidural rate with an alpha value of 0.05. MAIN OUTCOME MEASURES: The primary end point was the rate of intrapartum epidural analgesia, and the secondary end points were parenteral analgesia requirement, labour length, delivery mode, neonatal condition and postpartum haemorrhage. RESULTS: There was no difference in epidural analgesia between acupuncture and sham acupuncture, relative risk 1.18 (95% CI 0.8-1.74), or between acupuncture and control, relative risk 0.88 (95% CI 0.66-1.19). There were no significant differences in the secondary end points between the acupuncture groups and the control group. Side effects or complications of acupuncture were not identified. CONCLUSIONS: Using the protocols studied, there was no analgesic benefit with acupuncture for pain relief during induced labour in nulliparae.

Associations with multiple pituitary hormone deficiency in patients with an ectopic posterior pituitary gland.

INTRODUCTION: The presence of an ectopic posterior pituitary gland (EPP) on magnetic resonance imaging (MRI) is associated with hypopituitarism with one or more hormone deficiencies. We aimed to identify risk factors for having multiple pituitary hormone deficiency (MPHD) compared to isolated growth hormone deficiency (IGHD) in patients with an EPP. METHODS: In 67 patients (45 male) with an EPP on MRI, the site (hypothalamic vs. stalk) and surface area (SA) [ x (maximum diameter/2) x (maximum height/2), mm(2)] of the EPP were recorded and compared in patients with IGHD and MPHD in relation to clinical characteristics. RESULTS: In MPHD (n = 32) compared to IGHD (n = 35) patients: age of presentation was younger (1.4 [0.1-10.7]vs. 4.0 [0.1-11.3] years, P = 0.005), major incidents during pregnancy were increased (47%vs. 20%, P = 0.02) as were admissions to a neonatal intensive care unit (NICU) (60%vs. 26%, P = 0.04), whilst EPP SA was lower (12.3 [2.4-34.6]vs. 25.7 [6.9-48.2] mm(2), P < 0.001). In patients with a hypothalamic (n = 56) compared to a stalk sited EPP (n = 11): prevalence of MPHD was greater (55%vs. 9%,P = 0.05) and EPP surface area was smaller (17.3 [2.4-48.2]vs. 25.3 [11.8-38.5] mm(2), P < 0.001). In regression analysis, after adjusting for age, presence of MPHD was associated with: major incidents during pregnancy (RR 6.8 [95%CI 1.2-37.7]), hypothalamic EPP site (RR 10.9 [1.0-123.9]) and small EPP SA (RR 2.5 [1.0-5.0] for tertiles of SA). CONCLUSION: In patients with an EPP, adverse antenatal events, size (small) and position (hypothalamic) of the posterior pituitary gland on MRI were associated with MPHD. These findings suggest that adverse factors during pregnancy may be important for the development of an EPP.

Efficacy of a monthly compared to 3-monthly depot GnRH analogue (goserelin) in the treatment of children with central precocious puberty.

AIMS: To compare the efficacy of goserelin 10.8 mg (Zoladex LA-ZLA) administered 9-12 weekly with 3.6 mg (Zoladex-Z) given monthly in suppressing pubertal development, and effect on body mass index (BMI). METHODS: Children with central precocious puberty (CPP) treated with Z (n = 34) or ZLA (n = 28) were studied retrospectively. Pubertal scores and BMI SDS during 24 months' treatment were compared. RESULTS: To attain adequate pubertal suppression, more patients on ZLA than Z required increase in injection frequency (p = 0.02) and this was so for 7/8 patients with a structural aetiology for CPP on ZLA and 2/8 on Z. A greater proportion of patients on ZLA had BMI >+2 SDS before (p = 0.05), and at 18 and 24 months (p = 0.02 and 0.04). BMI SDS transiently increased during the first 6 months on ZLA (p = 0.04). CONCLUSION: Both Z and ZLA were effective in suppressing puberty. To achieve adequate suppression, increased injection frequency was more likely with ZLA than Z, and particularly in patients with structural defects. Children with CPP had an elevated BMI at the onset of therapy and ZLA had a transient positive influence on BMI.

Progressive transneuronal changes in the brainstem and thalamus after long-term dorsal rhizotomies in adult macaque monkeys.

This study deals with a potential brainstem and thalamic substrate for the extensive reorganization of somatosensory cortical maps that occurs after chronic, large-scale loss of peripheral input. Transneuronal atrophy occurred in neurons of the dorsal column (DCN) and ventral posterior lateral thalamic (VPL) nuclei in monkeys subjected to cervical and upper thoracic dorsal rhizotomies for 13-21 years and that had shown extensive representational plasticity in somatosensory cortex and thalamus in other experiments. Volumes of DCN and VPL, number and sizes of neurons, and neuronal packing density were measured by unbiased stereological techniques. When compared with the opposite, unaffected, side, the ipsilateral cuneate nucleus (CN), external cuneate nucleus (ECN), and contralateral VPL showed reductions in volume: 44-51% in CN, 37-48% in ECN, and 32-38% in VPL. In the affected nuclei, neurons were progressively shrunken with increasing survival time, and their packing density increased, but there was relatively little loss of neurons (10-16%). There was evidence for loss of axons of atrophic CN cells in the medial lemniscus and in the thalamus, with accompanying severe disorganization of the parts of the ventral posterior nuclei representing the normally innervated face and the deafferented upper limb. Secondary transneuronal atrophy in VPL, associated with retraction of axons of CN neurons undergoing primary transneuronal atrophy, is likely to be associated with similar withdrawal of axons from the cerebral cortex and should be a powerful influence on reorganization of somatotopic maps in the somatosensory cortex.

Modification of visual callosal projections in rats.

The effects of a variety of developmental manipulations on the distribution of the callosal pathway to visual cortex were examined by using the Fink Heimer technique in adult rats. First, the callosal projections in albino and pigmented rats were compared and found to be similar. The callosal pathway was limited in area 17 to a region adjoining its lateral border with area 18a. Second, dark-reared rats were found to have normal callosal projections. Third, rats bilaterally enucleated at birth and expanded callosal inputs within area 17. Fourth, monocular enucleation at birth produced an expanded callosal pathway to area 17 contralateral to the enucleation and normal callosal projections to the opposite hemisphere. The expanded callosal inputs after enucleation showed a patchy distribution and usually avoided the most medial part of area 17. Fifth, a reduction in the callosal projections to the area 17/18a border was found after neonatal unilateral optic tract lesions. Sixth, expanded callosal inputs to area 17 were found following unilateral thalamic lesions at birth. The abnormal projection occupied mainly layers IV and III. The results of the different experiments indicate that the detailed distribution of the visual callosal projection within area 17 depends heavily on the organization of the retinogeniculocortical pathways to each hemisphere.

Connections between area 3b of the somatosensory cortex and subdivisions of the ventroposterior nuclear complex and the anterior pulvinar nucleus in squirrel monkeys.

The goal of this study was to determine whether somatosensory thalamic nuclei other than the ventroposterior nucleus proper (VP) have connections with area 3b of the postcentral cortex in squirrel monkeys. Small injections of the anatomical tracers wheat germ agglutinin conjugated to horseradish peroxidase (WGA-HRP) or 3H-proline were placed in electrophysiologically identified representations of body parts. The results indicate that, besides the well-established somatotopically organized connections with VP, area 3b has connections with three other nuclei of the somatosensory thalamus: the ventroposterior superior nucleus (VPS ["shell" of VP]), the ventroposterior inferior nucleus (VPI), and the anterior pulvinar nucleus (Pa). Injections confined to area 3b or involving adjacent parts of area 3a or area 1 indicate that connections between VPS, VPI, and Pa and the postcentral cortex are somatotopically organized. In VPS, connections related to the hand were found medially, and connections related to the foot were lateral. In VPI, connections with the cortical representations of the mouth, hand, and foot were successively more lateral. In Pa, connections related to the mouth, hand, and foot were successively more ventral, lateral, and caudal, and the trunk region was caudomedial. The findings suggest that VPI contains a representation of all parts of the body, including the face. The connections of Pa with the primary somatosensory cortex, area 3b, the location of Pa relative to the ventroposterior nucleus, and the high degree of topographic order in the connections of Pa with the postcentral cortex suggest that Pa is an integral part of the somatosensory thalamus in monkeys and is homologous to the medial nucleus of the posterior group (Pom) in other mammals. Overall, the results contribute to the growing evidence that individual somatosensory cortical areas in monkeys receive inputs from multiple thalamic sources, and that a single thalamic nucleus has several cortical targets.

Neurochemical subdivisions of the inferior pulvinar in macaque monkeys.

The architecture of the pulvinar of rhesus monkeys was investigated by acetylcholinesterase (AChE) histochemistry, and by immunocytochemistry for calbindin-D28k and the SMI-32 antibody. The presence of four inferior subdivisions, comparable to those found in architectonic-connectional studies in squirrel monkeys (C.G. Cusick, J.L. Scripter, J.G. Darensbourg, and J.T. Weber, 1993, J. Comp. Neurol. 336:1-30), provided a basis for a proposed revised terminology for visual sectors of the macaque pulvinar. In the present study, the inferior pulvinar (PI) was identified as a neurochemically distinct region that included the traditional cytoarchitectonic nucleus PI and adjacent portions of the lateral and medial pulvinar nuclei, PL and PM. In calbindin-D28k stains, the lateral subdivision of the inferior pulvinar (PIL) had less intense neuropil staining than the adjacent central division, PIC. The PIL was characterized by large, intensely immunopositive neurons seldom found within PIC. PIL occupied the traditional PL and PI and exhibited a narrow shell zone, PIL-S, restricted to PL. The medial division of the inferior pulvinar (PIM) was in a location previously shown to be strongly connected with the middle temporal visual area (MT) in macaques. PIM was found in the medial one-half of the traditional PI and extended into adjacent portions of the traditional PM and PL. PIM was distinguished by less intense neuropil staining for calbindin and many cells stained with the SMI-32 antibody for neurofilament protein. In AChE stains, PIL was moderately dark, PIC appeared lighter, and PIM was characterized by small, intensely stained patches. The small posterior division (PIP) stained darkly for calbindin, lightly for AChE, and was unstained with the SMI-32 antibody. Thus, neurochemical, and perhaps connectional, subdivisions exist within PI, the region of the pulvinar that relays information to striate, "lower order" extrastriate, and inferotemporal visual cortex.

Neurochemical organization of inferior pulvinar complex in squirrel monkeys and macaques revealed by acetylcholinesterase histochemistry, calbindin and Cat-301 immunostaining, and Wisteria floribunda agglutinin binding.

To investigate whether the inferior pulvinar complex has a common organization in different primates, the chemoarchitecture of the visual thalamus was re-examined in squirrel monkeys (Saimiri sciureus) and macaques (Macaca mulatta). The inferior pulvinar (PI) complex consisted of multiple subdivisions and encompassed the classic PI, and adjacent ventral parts of the lateral and medial pulvinar (PL and PM, respectively). In keeping with nomenclature suggested previously for macaques, the PI subdivisions were termed the posterior, medial, central, lateral, and lateral-shell (PI(P), PI(M), PI(C), PI(L), and PI(L-S)). In both species, PI(P) was intense for calbindin, light for acetylcholinesterase (AChE), and very light for Wisteria floribunda agglutinin (WFA) histochemistry. The PI(M) was calbindin poor, AChE rich, and moderate for WFA. The PI(C) was calbindin intense, lighter for AChE, and exhibited little WFA binding. PI(L) and PI(L-S) contained populations of large calbindin or WFA cells that were more numerous in PI(L-S). Although staining with the monoclonal antibody Cat-301 differed between macaques and squirrel monkeys, the same subdivisions were displayed. Moderately dense, patchy Cat-301 stain was found in PI(M) of macaques, whereas in squirrel monkeys PI(M) was light. Connections of the rostral dorsolateral (DLr) and middle temporal (MT) areas of visual cortex in squirrel monkeys were compared with PI subdivisions revealed by the newer histochemical methods in the same cases. The major connections of DLr were with PI(C) and of MT were with PI(M).

Protein kinase C-delta in rat brain: association with sensory neuronal hierarchies.

Originally characterized as the calcium- and phospholipid-dependent protein kinases, the protein kinases C include at least eight separate isoforms, some of which are calcium-independent and all of which are highly enriched in brain. Of the calcium-independent isoforms, the delta subspecies of protein kinase C has the most restricted complement of lipid activators and substrate specificity, suggesting that it may have a unique role in cell signalling pathways. Using immunocytochemistry, we report that the distribution of protein kinase C-delta immunoreactivity in rat brain is also restricted, being present in all sensory systems. Moreover, it is found in alternating hierarchies of sensory pathways: in all sensory systems except auditory, it is found in first- and third-order neurons, while in the auditory system, it is found in second- and fourth-order neurons. Thalamocortical systems are intensely immunoreactive, including barrel fields of the rat parietal cortex. Outside of sensory systems, protein kinase C-delta is present in cerebellum within longitudinal stripes in Purkinje neurons, and in the caudate-putamen, it appears to be associated with the striosome (patch) compartment. In contrast to all other protein kinase C isoforms, protein kinase C-delta is absent from hippocampus. These findings suggest that protein kinase C-delta may have a unique role in signal transduction in the central nervous system (CNS), especially in sensory systems.

Chemoarchitectonics and corticocortical terminations within the superior temporal sulcus of the rhesus monkey: evidence for subdivisions of superior temporal polysensory cortex.

Cortex of the upper bank of the superior temporal sulcus (STS) in macaque monkeys, termed the superior temporal polysensory (STP) region, corresponds largely to architectonic area TPO and is connectionally distinct from adjacent visual areas. To investigate whether or not the STP region contains separate subdivisions, immunostaining for parvalbumin and neurofilament protein (using the SMI-32 antibody) was compared with patterns of corticocortical terminations in the STS. Chemoarchitectonic results provided evidence for three caudal-to-rostral subdivisions: TPOc, TPOi, and TPOr. Area TPOc was characterized by patchy staining for parvalbumin and SMI-32 in cortical layers IV/III and III, respectively. Area TPOi had more uniform chemoarchitectonic staining, whereas area TPOr had a thicker layer IV than TPOi. 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. In TPOc, columns of frontal connections showed a periodicity similar to that of the SMI-32 staining. The caudal inferior parietal lobule (area 7a) and superior temporal gyrus projected to each subdivision of area TPO, displaying either panlaminar or fourth-layer terminations. In addition to STP cortex, parvalbumin and SMI-32 immunostaining allowed identification of caudal visual areas of the STS, including MT, MST, FST, and V4t. These areas received first- and sixth-layer projections from prefrontal cortex and area 7a.

Studies on the evolution of multiple somatosensory representations in primates: the organization of anterior parietal cortex in the New World Callitrichid, Saguinus.

Because members of the New World family, Callithricidae, are generally regarded as the most primitive of monkeys, we studied the organization of somatosensory cortex in the tamarin (Saguinus) in hopes of better understanding differences in the organization of anterior parietal cortex in primates and how these differences relate to phylogeny. In most prosimian primates only one complete representation of cutaneous receptors has been found in the region of primary cortex, S-I, while in all Old and New World monkeys studied to date, two cutaneous representations exist in distinct architectonic fields, areas 3b and 1. In detailed microelectrode mapping studies in anesthetized tamarins, only one complete representation responsive to low-threshold cutaneous stimulation was evident in the S-I region. This topographic representation was in a parietal koniocortical field that architectonically resembles area 3b of other monkeys, and the general somatotopic organization of the field was similar to that of area 3b of other monkeys. Cortex rostral to the single representation was generally unresponsive to somatosensory stimuli, or required more intense stimulation for neural activation. Cortex caudal to the representation, in the region of area 1 of other monkeys, was generally either unresponsive or responded to only high-threshold stimulation, although some recording sites were activated by low-threshold tactile stimulation. The present evidence, together with that from previous studies, suggests that the single, complete body surface representation in Saguinus is homologous to the S-I representation found in some prosimians (Galago, Perodicticus) and the area 3b cutaneous representation found in New World Cebidae (Aotus, Saimiri, and Cebus) and Old World Macaca. Cortex rostral to S-I in Saguinus has the appearance of areas 3a and 4 of other primates. The cortex caudal to S-I in Saguinus, while resembling area 1 in some ways, does not have all of the features of area 1 of other monkeys. In particular, the field was not easily activated by low-threshold cutaneous stimuli, as area 1 is in other monkeys, and therefore a second cutaneous representation of all body parts was not demonstrated. Thus, cortex in the expected location of area 1 of Saguinus was not as responsive as area 1 of other monkeys, and it somewhat resembled the high-threshold fringe zones found caudal to S-I in anesthetized prosimians and some nonprimates. The results raise the possibility that the area 1 cutaneous representation that is characteristic of other New World monkeys and Old World monkeys evolved from a less responsive precursor along the caudal border of S-I in early monkeys.

Neurochemical and connectional organization of the dorsal pulvinar complex in monkeys.

To investigate the organization of the dorsal pulvinar complex, patterns of neurochemical staining were correlated with cortico-pulvinar connections in macaques (Macaca mulatta). Three major neurochemical subdivisions of the dorsal pulvinar were identified by acetylcholinesterase (AChE) histochemistry, as well as immunostaining for calbindin-D(28K) and parvalbumin. The dorsal lateral pulvinar nucleus (PLd) was defined on histochemical criteria as a distinct AChE- and parvalbumin-dense, calbindin-poor wedge that was found to continue caudally along the dorsolateral edge of the pulvinar to within 1 mm of its caudal pole. The ventromedial border of neurochemical PLd with the rest of the dorsal pulvinar, termed the medial pulvinar (PM), was sharply defined. Overall, PM was lighter than PLd for AChE and parvalbumin and displayed lateral (PMl) and medial (PMm) histochemical divisions. PMm contained a central "oval" (PMm-c) that stained darker for AChE and parvalbumin than the surrounding region. The neurochemically defined PLd was labeled by tracer injections in the inferior parietal lobule (IPL) and dorsolateral prefrontal cortex but not the superior temporal gyrus (STG). Label within PMl was found after prefrontal and IPL and, to a lesser extent, after STG injections. The PMm was labeled after injections of the IPL and STG, but only sparsely following prefrontal injections. The histochemically distinct subregion or module of PMm, PMm-c, was labeled only by STG injections. Overlapping labeling was found in dorsal pulvinar divisions PMl and PLd following paired IPL/prefrontal, but not IPL/STG or these particular STG/prefrontal, injections. Thus, PLd may be a visuospatially related region whereas PM appears to contain several types of territories, some related to visual or auditory inputs, and others that receive directly converging input from posterior parietal and prefrontal cortex and may participate in a distributed cortical network concerned with visuospatial functions.

Interhemispheric connections of visual cortex of owl monkeys (Aotus trivirgatus), marmosets (Callithrix jacchus), and galagos (Galago crassicaudatus).

Interhemispheric connections of visual cortex were studied in owl monkeys, marmosets, and galagos after multiple injections of horseradish peroxidase into one cerebral hemisphere. Areal patterns of connections were revealed in sections of cortex that was flattened and cut parallel to the surface. Results were related to the locations of known visual areas, especially in owl monkeys, in which more visual areas have been established. The connection patterns in owl monkeys and marmosets are very similar, suggesting that the organization of visual cortex differs little in these two New World simians. Galagos have a basically similar pattern, but the connections are more widespread. In all three primates, connections are not restricted to cortex representing the line of decussation of the retina, and even striate cortex has connections displaced from the border. These connections extend up to 2 mm into area 17 in owl monkeys, and they are most extensive in galagos, where they form foci that are coextensive with regions of high cytochrome oxidase activity. Connections are concentrated in the caudal half of area 18, but protrusions of connections cross of the width of the field. The middle temporal visual area (MT) has unevenly distributed connections throughout, with some increase in density along the border. The dorsomedial visual area (DM) of owl monkeys has connections restricted to the rostral border, and a similar region of sparse connections identifies the probable location of DM in marmosets and galagos. Caudal parts of the dorsolateral visual area (DL) of owl monkeys have dense interhemispheric connections. Other visual areas are characterized by unevenly distributed clumps of connections, suggesting that functions are not uniformly distributed, and that semiregular processing modules exist. The results indicate that most extrastriate visual neurons are subject to interhemispheric influences and support the conclusion that callosal connections are functionally heterogeneous.

Cortical connections of the caudal subdivision of the dorsolateral area (V4) in monkeys.

Evidence suggests that all primates have rostral and caudal subdivisions in the region of visual cortex identified as the dorsolateral area (DL) or V4. However, the connections of DL/V4 have not been examined in terms of these subdivisions. To determine the cortical connections of the caudal subdivision of DL (DLC) in squirrel monkeys, injections of the neuroanatomical tracers wheat germ agglutinin conjugated to horseradish peroxidase, Diamidino Yellow, and Fluoro-Gold were made in cortex rostral to V II. To aid in delineating the borders of DLC, cortex was also evaluated architectonically. Based on similar patterns of connections, DLC extends from dorsolateral to ventrolateral cortex. DLC receives strong, feedforward input from V II and projects in a feedforward fashion to the rostral subdivision of DL (DLR) and caudal inferior temporal (IT) cortex, including a separate location in the inferior temporal sulcus. DLC has weaker connections with V I, the middle temporal area (MT), cortex rostral to MT in the location of the fundal superior temporal area (FST), cortex dorsal to DLC, ventral cortex rostral to V II, and cortex in the frontal lobe, lateral to the inferior arcuate sulcus. Only lateral DLC has connections with V I, and only dorsolateral DLC has connections with cortex dorsal to DLC. The topographic organization of DLC was inferred from its connections with V II. Thus, dorsolateral DLC represents the lower field, lateral DLC represents central vision, and ventrolateral DLC represents the upper field. Limited observations were made on DLR. Confirming earlier observations (Cusick and Kaas: Visual Neurosci. 1:211, 1988), DLR is paler than DLC myeloarchitectonically. DLR receives only sparse feedforward input from V II, but stronger input from DLC. DLR has strong connections with cortex just rostral to dorsal V II, ventral posterior parietal cortex in the sylvian fissure, MT, the medial superior temporal area, FST, and the inferior temporal sulcus. DLR also shares connections with IT cortex. Thus, while both DLC and DLR are involved in the pathway relaying visual information to IT cortex, an area specialized for object vision, DLR also projects densely to areas such as MT involved in the pathway relaying to posterior parietal cortex, a region specialized for spatial localization and motion perception.

Cortical connections of dorsal cortex rostral to V II in squirrel monkeys.

A region of dorsal cortex along the rostral border of V II has been described as comprising a visual area or areas separate from more lateral cortex in both New and Old World primates. To evaluate these possibilities in squirrel monkeys, we studied patterns of cortical connections by injecting Fast Blue, Fluoro-Gold, horseradish peroxidase, and wheat germ agglutinin conjugated to horseradish peroxidase into the dorsal region and related results to distinctions in myeloarchitecture. Our major conclusions are as follows. 1) The dorsal region (D) has distinctly different connections from the area found laterally, the caudal subdivision of the dorsolateral area (DLC). These include major connections with the rostral subdivision of the dorsolateral area (DLR), ventral posterior parietal cortex in the Sylvian fissure, the middle temporal area (MT), the medial superior temporal area (MST), ventral cortex just rostral to V II, and cortex in the inferior temporal sulcus. Weaker connections are with V I, V II, DLC, the fundal superior temporal area (FST), and the frontal lobe. In contrast, DLC has strong connections with V II and inferior temporal (IT) cortex, weaker connections with DLR, and lacks connections with ventral posterior parietal cortex (Steele et al: J Comp Neurol 306:495-520, 1991). 2) Caudal and rostral aspects of dorsal cortex differ in the magnitude of connections with V I, V II, DLR, and FST. These differences are consistent with the previous proposal that at least two visual areas, caudal and rostral, occupy the dorsal region in squirrel monkeys (Krubitzer and Kaas: Visual Neurosci 5:165, 1990), but they could also reflect regional differences in the connections of a single visual area. 3) The dorsal region is more densely myelinated than surrounding cortex; however, rostral aspects of dorsal cortex are less myelinated than caudal aspects, again suggesting the existence of at least two areas. 4) The distinctiveness of connections between dorsal cortex and rostral as compared to caudal dorsolateral cortex provides further evidence for dividing the region of DL into two visual areas, DLC and DLR (Cusick and Kaas: Visual Neurosci 1:211, 1988; Steele et al: J Comp Neurol 306:495-520, 1991).

Interhemispheric connections of cortical sensory areas in tree shrews.

Interhemispheric connections were studied in tree shrews (Tupaia belangeri) after multiple injections of horseradish peroxidase or horseradish peroxidase conjugated to wheat germ agglutinin into the cortex of one cerebral hemisphere. After an appropriate survival period, the areal pattern of connections was revealed by flattening the other hemisphere, cutting sections parallel to the cortical surface, and staining with tetramethylbenzidine. Architectonic boundaries were identified by using sections stained for myelinated fibers. Labeled cells and axon terminations formed largely overlapping distributions that covaried in density, although labeled cells appeared to be more evenly distributed than labeled terminations. Connections were concentrated along the border of area 17 (V-I) with area 18 (V-II). However, connections also extended as far as 2 mm into area 17 to include cortex representing parts of the visual field 10 degrees or more from the zero vertical meridian. Clusters of dense connections spanned the width of area 18, where they alternated with regions of fewer connections. These clusters roughly corresponded in location to regions with heavier myelination. In the visually responsive temporal cortex, connections were also unevenly distributed. The organization of most of this cortex is not understood, but one subdivision, the temporal dorsal area (TD), has been identified on the basis of reciprocal connections with area 17. The central part of the TD had few interhemispheric connections, while most of the outer border had dense connections. The auditory cortex had dense and patchy connections throughout. The pattern in the primary somatosensory cortex (S-I) varied according to the representation of body parts, so that the cortex related to the forepaw had sparse connections, while connections were dense but uneven over much of the representation of the face, nose, and mouth. A focus of connections was found at the border of the forepaw and face representations, where the myelination of S-I cortex is interrupted. Dense, uneven connections also characterized the second somatosensory area, S-II. The motor cortex was densely connected, with only slightly fewer terminations rostral to the forepaw region of S-I. Other parts of frontal cortex had dense connections. The distribution of cortical connections varied with depth for at least some areas, so that clusters of cells and terminations were found in supragranular layers in S-I, S-II, and TD, while infragranular labeled cells were more evenly distributed.(ABSTRACT TRUNCATED AT 400 WORDS)

Cortical organization after treatment of a peripheral nerve with ricin: an evaluation of the relationship between sensory neuron death and cortical adjustments after nerve injury.

The present study was designed to assess whether cortical changes after peripheral nerve damage are related to the degree of death of primary sensory neurons in the damaged nerve. The cytotoxin ricin was injected into the sciatic nerves of adult rats to kill primary sensory neurons with axons through the injection site. Following periods of 6-101 days, the S-I hindpaw map was evaluated with neurophysiological techniques and compared with the hindpaw maps of previously studied normal adult rats and adult rats that had undergone adult or neonatal sciatic section at a comparable level of the nerve. These comparisons allowed evaluation of cortical functional organization following different degrees of sensory neuron loss after sciatic nerve injury. There were three main results. 1) The comparison of ricin-treated and normal adult rats indicated that ricin treatment interrupted inputs from the sciatic skin territory on the hindpaw and caused a limited increase in the size of the cortical area that was activated by stimulation of hindpaw skin innervated by the remaining saphenous nerve. 2) The cortical maps of rats that had undergone adult ricin treatment (relatively large primary neuron loss) or section during adulthood (small to moderate primary neuron loss) were similar. In both groups, only the saphenous hindpaw skin was represented in cortex, and the cortical area that was activated by stimulation of the saphenous hindpaw skin had undergone a comparable limited enlargement. 3) The comparison of ricin-treated adult rats (relatively large primary neuron loss) and adult rats that had undergone neonatal section (relatively large primary neuron loss) indicated that cortical organization differed after these treatments. In particular, after ricin treatment the cortical area that was activated by stimulation of the saphenous hindpaw skin was larger than the comparable area in neonatal denervates, and the topographical progressions between the hindpaw and adjacent body representations were not as variable as after neonatal section. These findings indicate that cortical maps are altered after injection of ricin into a nerve. The similarity in cortical organization after ricin treatment (relatively large sensory neuron loss) and nerve section in adults (relatively small sensory neuron loss) and the differences in cortical organization after ricin treatment and nerve section in neonates (both relatively large sensory neuron loss) indicate cortical changes do not covary as a simple function of the degree of peripheral neuron death.

The relationship of corpus callosum connections to electrical stimulation maps of motor, supplementary motor, and the frontal eye fields in owl monkeys.

Microstimulation and anatomical techniques were combined to reveal the organization and interhemispheric connections of motor cortex in owl monkeys. Movements of body parts were elicited with low levels of electrical stimulation delivered with microelectrodes over a large region of precentral cortex. Movements were produced from three physiologically defined cortical regions. The largest region, the primary motor field, M-I, occupied a 4-6-mm strip of cortex immediately rostral to area 3a. M-I represented body movements from tail to mouth in a grossly somatotopic mediolateral cortical sequence. Specific movements were usually represented at more than one location, and often at as many as six or seven separate locations within M-I. Although movements related to adjoining joints typically were elicited from adjacent cortical sites, movements of nonadjacent joints also were produced by stimulation of adjacent sites. Thus, both sites producing wrist movements and sites producing shoulder movements were found next to sites producing digit movements. Movements of digits of the forepaw were evoked at several locations including a location rostral to or within cortex representing the face. Overall, the somatotopic organization did not completely correspond to previous concepts of M-I in that it was neither a single topographic representation, nor two serial or mirror symmetric representations, nor a "nesting about joints" representation. Instead, M-I is more adequately described as a mosaic of regions, each representing movements of a restricted part of the body, with multiple representations of movements that tend to be somatotopically related. A second pattern of representation of body movements, the supplementary motor area (SMA), adjoined the rostromedial border of M-I. SMA represented the body from tail to face in a caudorostral cortical sequence, with the most rostral portion related to eye movements. Movements elicited by near-threshold levels of current were often restricted to a single muscle or joint, as in M-I, and the same movement was sometimes multiply represented. Typically, more intense stimulating currents were required for evoking movements in SMA than in M-I. A third motor region, the frontal eye field (FEF), bordered the representation of eyelids and face in M-I. Eye movements elicited from this cortex consisted of rapid horizontal and downward deviation of gaze into the contralateral visual hemifield.

Chemoarchitectonic subdivisions of the visual pulvinar in monkeys and their connectional relations with the middle temporal and rostral dorsolateral visual areas, MT and DLr.

The organization of the inferior pulvinar complex (PI) in squirrel monkeys was studied with histochemical localization of the calcium binding proteins calbindin-D28k and parvalbumin, and of cytochrome oxidase. With each of these markers, the inferior pulvinar complex can be subdivided into four distinct regions. Calbindin-D28k immunoreactivity is densely distributed in cells and neuropil within PI, except for a distinct centromedially located gap. This calbindin-poor zone, termed the medial division of the inferior pulvinar (PIM), corresponds precisely to a region that contains elevated cytochrome oxidase activity and parvalbumin immunostaining. The PIM extends slightly above and behind the classically defined limit of the inferior pulvinar, the corticotectal tract. Regions of inferior pulvinar with intense immunostaining for calbindin-D28k were the posterior division of the inferior pulvinar (PIP, medial to PIM) and the central division (PIC, lateral to PIM). A newly recognized lateral region, PIL, adjoins the lateral geniculate nucleus and stains more lightly for calbindin and parvalbumin immunoreactivity and for cytochrome oxidase. Staining patterns for calbindin, parvalbumin, and cytochrome oxidase in the pulvinar of rhesus monkeys closely resemble those shown in squirrel monkey inferior pulvinar, suggesting that a common organization exists in all primates. In order to examine cortical connection patterns of the histochemically defined compartments in the inferior pulvinar, injections of up to five neuroanatomical tracers (wheat germ agglutinin conjugated to horseradish peroxidase and fluorescent retrograde tracers) were placed in the same cerebral hemisphere. Single injection sites were in the middle temporal area (MT), and several separate injections were placed in a strip corresponding to the rostral subdivision of the dorsolateral area (DLr). Injections that involved only DLr and not MT labeled principally the PIC, and more sparsely PIP and PIL. DLr connections occupied a "shell" region dorsal to PIM that extended from PIC into the lateral and medial divisions of the pulvinar, PL and PM. Injection sites that included MT or were largely restricted to MT produced dense label in PIM and moderate label in PIC and PIL. The retinotopic organization within the inferior pulvinar was inferred from patterns of connections. Connections with cortex related most closely to central vision were found posteriorly in PIM and in adjacent portions of PIC as it wraps around the caudal pole of PIM. Cortex related to more peripheral locations in the lower visual field connected with more rostral PIM and PIC. Patterns of label within the portions of PL and PM that were immediately adjacent to PIM roughly paralleled those in PIM and PIC.(ABSTRACT TRUNCATED AT 400 WORDS)

Somatotopic organization of the lateral sulcus of owl monkeys: area 3b, S-II, and a ventral somatosensory area.

Multiunit microelectrode recordings and injections of horseradish peroxidase (HRP) were used to reveal neuron response properties, somatotopic organization, and interconnections of somatosensory cortex in the lateral sulcus (sylvian fissure) of New World owl monkeys. There were a number of main findings. 1) Representations of the face and head in areas 3b, 1, and S-II are found on the upper bank of the lateral sulcus. Most of the mouth and lip representations of area 3b were found in a rostral extension along the lip of the lateral sulcus. Adjacent cortex deeper in the lateral sulcus represented the nose, eye, ear, and scalp. 2) S-II was located on the upper bank of the lateral sulcus and extended past the fundus onto the deepest part of the lower bank. The face was represented most superficially in the sulcus, with the hand, foot, and trunk located in a rostrocaudal sequence deeper in the sulcus. The orientation of S-II is "erect," with the limbs pointing away from area 3b. 3) Neurons in S-II were activated by light tactile stimulation of the contralateral body surface. Receptive fields were several times larger than for area 3b neurons. 4) A 1-2-mm strip of cortex separating the face and hand representations in S-II was consistently responsive to the stimulation of deep receptors but was unresponsive to light cutaneous stimulation. 5) Injections of horseradish peroxidase in the electrophysiologically identified hand or foot representations of area 3b revealed somatotopically matched interconnections with mapped hand and foot representations in S-II. 6) A systematic representation of the body, termed the "ventral somatic" area, VS, was found extending laterally from S-II on the lower bank of the lateral sulcus. Within VS, the hand and foot were represented deep in the sulcus along the hand and foot regions of S-II, and the face was lateral near the ventral lip of the sulcus. 7) Neurons at most recording sites in the VS region were activated by contralateral cutaneous stimuli. However, a few sites had neurons with bilateral receptive fields. Receptive field sizes were comparable to those in S-II. In addition, neurons in islands of cortex in the VS region had properties that suggested that they were activated by pacinian receptors, while other regions were difficult to activate by light tactile stimuli but responded to stimuli that would activate deep receptors. 8) A few recording sites caudal to S-II on the upper bank of the lateral sulcus were responsive to somatic stimuli.(ABSTRACT TRUNCATED AT 400 WORDS)