Habenular and mediodorsal thalamic connectivity predict persistent weight loss after laparoscopic sleeve gastrectomy.

OBJECTIVE: The aim of this study was to investigate laparoscopic sleeve gastrectomy (LSG)-induced changes in connectivity between regions involved with reward/antireward and cognitive control and the extent to which these changes persist after surgery and predict sustainable weight loss. METHODS: Whole-brain local functional connectivity density (lFCD) was studied in 25 participants with obesity who underwent resting-state functional MRI before (PreLSG), 1 month after (PostLSG1 ), and 12 months after (PostLSG12 ) LSG and compared with 25 normal-weight controls. Regions with significant time effects of LSG on functional connectivity density were identified for subsequent seed-based connectivity analyses and to examine associations with behavior. RESULTS: LSG significantly increased lFCD in the mediodorsal thalamic nucleus (MD) and in the habenula (Hb) at PostLSG12 compared with PreLSG/PostLSG1 , whereas it decreased lFCD in the posterior cingulate cortex/precuneus (PCC/PreCun) at PostLSG1 /PostLSG12 , and these changes were associated with reduction in BMI. In contrast, controls had no significant lFCD differences between baseline and repeated measures. MD had stronger connectivity with PreCun and Hb at PostLSG12 compared with PreLSG/PostLSG1 , and the increased MD-left PreCun and Hb-MD connectivity correlated with decreases in hunger and BMI, respectively. PCC/PreCun had stronger connectivity with the insula at PostLSG1-12 . CONCLUSIONS: The findings highlight the importance of reward and interoceptive regions as well as that of regions mediating negative emotions in the long-term therapeutic benefits of LSG.

The anterior and medial thalamic nuclei and the human limbic system: tracing the structural connectivity using diffusion-weighted imaging.

The limbic system is a phylogenetically old, behaviorally defined system that serves as a center for emotions. It controls the expression of anger, fear, and joy and also influences sexual behavior, vegetative functions, and memory. The system comprises a collection of tel-, di-, and mesencephalic structures whose components have evolved and increased over time. Previous animal research indicates that the anterior nuclear group of the thalamus (ANT), as well as the habenula (Hb) and the adjacent mediodorsal nucleus (MD) each play a vital role in the limbic circuitry. Accordingly, diffusion imaging data of 730 subjects obtained from the Human Connectome Project and the masks of six nuclei (anterodorsal, anteromedial, anteroventral, lateral dorsal, Hb, and MD) served as seed regions for a direct probabilistic tracking to the rest of the brain using diffusion-weighted imaging. The results revealed that the ANT nuclei are part of the limbic and the memory system as they mainly connect via the mammillary tract, mammillary body, anterior commissure, fornix, and retrosplenial cortices to the hippocampus, amygdala, medio-temporal, orbito-frontal and occipital cortices. Furthermore, the ANT nuclei showed connections to the mesencephalon and brainstem to varying extents, a pattern rarely described in experimental findings. The habenula-usually defined as part of the epithalamus-was closely connected to the tectum opticum and seems to serve as a neuroanatomical hub between the visual and the limbic system, brainstem, and cerebellum. Finally, in contrast to experimental findings with tracer studies, directly determined connections of MD were mainly confined to the brainstem, while indirect MD fibers form a broad pathway connecting the hippocampus and medio-temporal areas with the mediofrontal cortex.

Arterial Supply of the Thalamus: A Comprehensive Review.

The thalamus is a deep cerebral structure that is crucial for proper neurological functioning as it transmits signals from nearly all pathways in the body. Insult to the thalamus can, therefore, result in complex syndromes involving sensation, cognition, executive function, fine motor control, emotion, and arousal, to name a few. Specific territories in the thalamus that are supplied by deep cerebral arteries have been shown to correlate with clinical symptoms. The aim of this review is to enhance our understanding of the arterial anatomy of the thalamus and the complications that can arise from lesions to it by considering the functions of known thalamic nuclei supplied by each vascular territory.

Topographic organization of connections between prefrontal cortex and mediodorsal thalamus: Evidence for a general principle of indirect thalamic pathways between directly connected cortical areas.

Our ability to act flexibly, according to goals and context, is known as cognitive control. Hierarchical levels of control, reflecting different levels of abstraction, are represented across prefrontal cortex (PFC). Although the mediodorsal thalamic nucleus (MD) is extensively interconnected with PFC, the role of MD in cognitive control is unclear. Tract tracer studies in macaques, involving subsets of PFC areas, have converged on coarse MD-PFC connectivity principles; but proposed finer-grained topographic schemes, which constrain interactions between MD and PFC, disagree in many respects. To investigate a unifying topographic scheme, we performed probabilistic tractography on diffusion MRI data from eight macaque monkeys, and estimated the probable paths connecting MD with each of all 19 architectonic areas of PFC. We found a connectional topography where the orderly progression from ventromedial to anterior to posterolateral PFC was represented from anteromedial to posterolateral MD. The projection zones of posterolateral PFC areas in MD showed substantial overlap, and those of ventral and anteromedial PFC areas in MD overlapped. The exception was cingulate area 24: its projection zone overlapped with projections zones of all other PFC areas. Overall, our data suggest that nearby, functionally related, directly connected PFC areas have partially overlapping projection zones in MD, consistent with a role for MD in coordinating communication across PFC. Indeed, the organizing principle for PFC projection zones in MD appears to reflect the flow of information across the hierarchical, multi-level PFC architecture. In addition, cingulate area 24 may have privileged access to influence thalamocortical interactions involving all other PFC areas.

The Mediodorsal Thalamus: An Essential Partner of the Prefrontal Cortex for Cognition.

Deficits in cognition are a core feature of many psychiatric conditions, including schizophrenia, where the severity of such deficits is a strong predictor of long-term outcome. Impairment in cognitive domains such as working memory and behavioral flexibility has typically been associated with prefrontal cortex (PFC) dysfunction. However, there is increasing evidence that the PFC cannot be dissociated from its main thalamic counterpart, the mediodorsal thalamus (MD). Since the causal relationships between MD-PFC abnormalities and cognitive impairment, as well as the neuronal mechanisms underlying them, are difficult to address in humans, animal models have been employed for mechanistic insight. In this review, we discuss anatomical, behavioral, and electrophysiological findings from animal studies that provide a new understanding on how MD-PFC circuits support higher-order cognitive function. We argue that the MD may be required for amplifying and sustaining cortical representations under different behavioral conditions. These findings advance a new framework for the broader involvement of distributed thalamo-frontal circuits in cognition and point to the MD as a potential therapeutic target for improving cognitive deficits in schizophrenia and other disorders.

Finding prefrontal cortex in the rat.

The prefrontal cortex of the rat. I. Cortical projection of the mediodorsal nucleus. II. Efferent connections The cortical projection field of the mediodorsal nucleus of the thalamus (MD) was identified in the rat using the Fink-Heimer silver technique for tracing degenerating fibers. Small stereotaxic lesions confined to MD were followed by terminal degeneration in the dorsal bank of the rhinal sulcus (sulcal cortex) and the medial wall of the hemisphere anterior and dorsal to the genu of the corpus callosum (medial cortex). No degenerating fibers were traced to the convexity of the hemisphere. The cortical formation receiving a projection from MD is of a relatively undifferentiated type which had been previously classified as juxtallocortex. A study of the efferent fiber connections of the rat׳s MD-projection cortex demonstrated some similarities to those of monkey prefrontal cortex. A substantial projection to the pretectal area and deep layers of the superior colliculus originates in medial cortex, a connection previously reported for caudal prefrontal (area 8) cortex in the monkey. Sulcal cortex projects to basal olfactory structures and lateral hypothalamus, as does orbital frontal cortex in the monkey. The rat׳s MD-projection cortex differs from that in the monkey in that it lacks a granular layer and appears to have no prominent direct associations with temporal and juxtahippocampal areas. Furthermore, retrograde degeneration does not appear in the rat thalamus after damage to MD-projection areas, suggesting that the striatum or thalamus receives a proportionally larger share of the MD-projection in this animal than it does in the monkey. Comparative behavioral investigations are in progress to investigate functional differences between granular prefrontal cortex in the primate and the relatively primitive MD-projection cortex in the rat. © 1969. This article is part of a Special Issue entitled SI:50th Anniversary Issue.

Thalamocortical connections between the mediodorsal nucleus of the thalamus and prefrontal cortex in the human brain: a diffusion tensor tractographic study.

PURPOSE: The elucidation of thalamocortical connections between the mediodorsal nucleus (MD) of thalamus and the prefrontal cortex (PFC) is important in the clinical fields of neurorehabilitation and psychiatry. However, little is known about these connections in human brain. We attempted to identify and investigate the anatomical characteristics of the thalamocortical connection between MD and PFC in human brain using diffusion tensor tractography (DTT). MATERIALS AND METHODS: Thirty-two healthy volunteers were recruited for this study. Diffusion tensor images were scanned using a 1.5-T. A seed region of interest was placed at the MD of the thalamus on coronal images, and target regions of interest were placed on the dorsolateral prefrontal cortex (DLPFC), the ventrolateral prefrontal cortex (VLPFC), and the orbitofrontal cortex (OFC), respectively. The three thalamocortical connections found were reconstructed using Functional Magnetic Resonance Imaging of the Brain (FMRIB) software. RESULTS: The three thalamocortical connections were arranged in subcortical white matter in the following order from upper to lower levels: the DLPFC, the VLPFC, and the OFC. In terms of fractional anisotropy and mean diffusivity values, no significant differences were observed between the DLPFC, VLPFC and OFC (p>0.05). In contrast, the OFC tract volume was higher than those of the DLPFC and the VLPFC (p<0.05). CONCLUSION: Three thalamocortical connections were reconstructed between MD and PFCs in human brain using DTT. We believe that the results of this study would be helpful to clinicians in treating frontal network syndrome and psychiatric diseases.

Thalamocortical Connections between the Mediodorsal Nucleus of the Thalamus and Prefrontal Cortex in the Human Brain: A Diffusion Tensor Tractographic Study

PURPOSE: The elucidation of thalamocortical connections between the mediodorsal nucleus (MD) of thalamus and the prefrontal cortex (PFC) is important in the clinical fields of neurorehabilitation and psychiatry. However, little is known about these connections in human brain. We attempted to identify and investigate the anatomical characteristics of the thalamocortical connection between MD and PFC in human brain using diffusion tensor tractography (DTT). MATERIALS AND METHODS: Thirty-two healthy volunteers were recruited for this study. Diffusion tensor images were scanned using a 1.5-T. A seed region of interest was placed at the MD of the thalamus on coronal images, and target regions of interest were placed on the dorsolateral prefrontal cortex (DLPFC), the ventrolateral prefrontal cortex (VLPFC), and the orbitofrontal cortex (OFC), respectively. The three thalamocortical connections found were reconstructed using Functional Magnetic Resonance Imaging of the Brain (FMRIB) software. RESULTS: The three thalamocortical connections were arranged in subcortical white matter in the following order from upper to lower levels: the DLPFC, the VLPFC, and the OFC. In terms of fractional anisotropy and mean diffusivity values, no significant differences were observed between the DLPFC, VLPFC and OFC (p>0.05). In contrast, the OFC tract volume was higher than those of the DLPFC and the VLPFC (p<0.05). CONCLUSION: Three thalamocortical connections were reconstructed between MD and PFCs in human brain using DTT. We believe that the results of this study would be helpful to clinicians in treating frontal network syndrome and psychiatric diseases.

Mediodorsal thalamic nucleus receives a direct retinal input in marmoset monkey (Callithrix jacchus): a subunit B cholera toxin study.

The mediodorsal thalamic nucleus is a prominent nucleus in the thalamus, positioned lateral to the midline nuclei and medial to the intralaminar thalamic complex in the dorsal thalamus. Several studies identify the mediodorsal thalamic nucleus as a key structure in learning and memory, as well as in emotional mechanisms and alertness due to reciprocal connections with the limbic system and prefrontal cortex. Fibers from the retina to the mediodorsal thalamic nucleus have recently been described for the first time in a crepuscular rodent, suggesting a possible regulation of the mediodorsal thalamic nucleus by visual activity. The present study shows retinal afferents in the mediodorsal thalamic nucleus of a new world primate, the marmoset (Callithrix jacchus), using B subunit of cholera toxin (CTb) as an anterograde tracer. A small population of labeled retinofugal axonal arborizations is consistently labeled in small domains of the medial and lateral periphery of the caudal half of the mediodorsal nucleus. Retinal projections in the mediodorsal thalamic nucleus are exclusively contralateral and the morphology of the afferent endings was examined. Although the functional significance of this projection remains unknown, this retina-mediodorsal thalamic nucleus pathway may be involved in a wide possibility of functional implications.

Connections of the marmoset rostrotemporal auditory area: express pathways for analysis of affective content in hearing.

The current hierarchical model of primate auditory cortical processing proposes a core of 'primary-like' areas, which is surrounded by secondary (belt) and tertiary (parabelt) regions. The rostrotemporal auditory cortical area (RT) remains the least well characterized of the three proposed core areas, and its functional organization has only recently come under scrutiny. Here we used injections of anterograde and retrograde tracers in the common marmoset (Callithrix jacchus) to examine the connectivity of RT and its adjacent areas. As expected from the current model, RT exhibited dense core-like reciprocal connectivity with the ventral division of the medial geniculate body, the rostral core area and the auditory belt, but had weaker connections with the parabelt. However, RT also projected to the ipsilateral rostromedial prefrontal cortex (area 10), the dorsal temporal pole and the ventral caudate nucleus, as well as bilaterally to the lateral nucleus of the amygdala. Thus, RT has connectivity with limbic structures previously believed to connect only with higher-order auditory association cortices, and is probably functionally distinct from the other core areas. While this view is consistent with a proposed role of RT in temporal integration, our results also indicate that RT could provide an anatomical 'shortcut' for processing affective content in auditory information.

Laminar and modular organization of prefrontal projections to multiple thalamic nuclei.

The prefrontal cortex projects to many thalamic nuclei, in pathways associated with cognition, emotion, and action. We investigated how multiple projection systems to the thalamus are organized in prefrontal cortex after injection of distinct retrograde tracers in the principal mediodorsal (MD), the limbic anterior medial (AM), and the motor-related ventral anterior/ventral lateral (VA/VL) thalamic nuclei in rhesus monkeys. Neurons projecting to these nuclei were organized in interdigitated modules extending vertically within layers VI and V. Projection neurons were also organized in layers. The majority of projection neurons to MD or AM originated in layer VI ( approximately 80%), but a significant proportion ( approximately 20%) originated in layer V. In contrast, prefrontal neurons projecting to VA/VL were equally distributed in layers V and VI. Neurons directed to VA/VL occupied mostly the upper part of layer V, while neurons directed to MD or AM occupied mostly the deep part of layer V. The highest proportions of projection neurons in layer V to each nucleus were found in dorsal and medial prefrontal areas. The laminar organization of prefrontal cortico-thalamic projections differs from sensory systems, where projections originate predominantly or entirely from layer VI. Previous studies indicate that layer V cortico-thalamic neurons innervate through some large terminals thalamic neurons that project widely to superficial cortical layers. The large population of prefrontal projection neurons in layer V may drive thalamic neurons, triggering synchronization by recruiting several cortical areas through widespread thalamo-cortical projections to layer I. These pathways may underlie the synthesis of cognition, emotion and action.

Functional connectivity between the thalamus and visual cortex under eyes closed and eyes open conditions: a resting-state fMRI study.

The thalamus and visual cortex are two key components associated with the alpha power of electroencephalography. However, their functional relationship remains to be elucidated. Here, we employ resting-state functional MRI to investigate the temporal correlations of spontaneous fluctuations between the thalamus [the whole thalamus and its three largest nuclei (bilateral mediodorsal, ventrolateral and pulvinar nuclei)] and visual cortex under both eyes open and eyes closed conditions. The whole thalamus show negative correlations with the visual cortex and positive correlations with its contralateral counterpart in eyes closed condition, but which are significantly decreased in eyes open condition, consistent with previous findings of electroencephalography desynchronization during eyes open resting state. Furthermore, we find that bilateral thalamic mediodorsal nuclei and bilateral ventrolateral nuclei have remarkably similar connectivity maps, and resemble to those of the whole thalamus, suggesting their crucial contributions to the thalamus-visual correlations. The bilateral pulvinar nuclei are found to show distinct functional connectivity patterns, compatible with previous findings of the asymmetry of anatomical and functional organization in the nuclei. Our data provides evidence for the associations of intrinsic spontaneous neuronal activity between the thalamus and visual cortex under different resting conditions, which might have implications on the understanding of the generation and modulation of the alpha rhythm.

Individual variability in the structural asymmetry of the dorsomedial nucleus of the thalamus in men and women.

Quantitative neurohistochemical parameters were used to study the structure of the dorsomedial nucleus of the thalamus. The study set consisted of 10 specimens from the collection of the Institute of the Brain, Russian Academy of Medical Sciences and included seven men and three women aged 19-59 years, all right-handed, who died suddenly and had no neurological or mental diseases during life. The following parameters were measured: neuron density, total and satellite glia densities, the density of satellite-surrounded neurons, and the ratios of satellite glia to all glia and neurons surrounded by satellite glia to all neurons. On a background of individual variability in these measures, a number of gender-related and interhemisphere differences were found. Thus, neuron density in both men and women showed no asymmetry and individual variability was less marked in women. Glial cell density in men was greater on the right, while in women it was greater on the left; satellite glial cell density, conversely, was greater on the left in men and more variable in women. Significant asymmetry with greater values on the left in men was seen for the density of neurons surrounded by satellite glia, while this was more variable in women, though the ratio of neurons with satellite glia to all neurons was greater on the left in men and women, as was the ratio of satellite glia to all glial cells. Overall, there was a tendency to rather greater asymmetry in this structure in men and a tendency to greater individual variability in women.

Comparative study of the effects of electrical stimulation in the nucleus accumbens, the mediodorsal thalamic nucleus and the bed nucleus of the stria terminalis in rats with schedule-induced polydipsia.

In the schedule-induced polydipsia model, hungry rats receiving a food pellet every minute will display excessive drinking behaviour (compulsive behaviour). We aimed 1) to evaluate if electrical stimulation in the nucleus accumbens (N ACC), the mediodorsal thalamic nucleus (MD) or the bed nucleus of the stria terminalis (BST) can decrease water intake in the schedule-induced polydipsia model; 2) to compare water intake between these groups for different stimulation amplitudes; and 3) to compare the effect of low frequency (2 Hz) with high frequency (100 Hz) stimulation. Rats were randomly divided into four groups: electrode implanted in the 1) N ACC (n=7), 2) MD (n=8), 3) BST (n=8), or 4) a sham-operated control group (n=7). Postoperatively, each rat of group 1, 2 and 3 was randomly tested in the model using pulses with a frequency of 2 Hz and 100 Hz, each at an amplitude of 0.1, 0.2, 0.3, 0.4 and 0.5 mA, or without stimulation. Group 4 was tested 11 times without stimulation. Each day the rats were tested in random order. High-frequency electrical stimulation in all three brain areas decreased water intake significantly at an amplitude of 0.2 mA or higher, however, without differences between the brain areas. Based on these results, we expect a decrease in compulsions in patients suffering from treatment-resistant obsessive-compulsive disorder during electrical stimulation in the N ACC, the MD and the BST. However, we foresee no difference in energy consumption to decrease symptoms during electrical stimulation between these brain areas.

Development of the human dorsal nucleus of the vagus.

The dorsal nucleus of the vagus nerve plays an integral part in the control of visceral function. The aim of the present study was to correlate structural and chemical changes in the developing nucleus with available data concerning functional maturation of human viscera and reflexes. The fetal development (ages 9 to 26 weeks) of the human dorsal nucleus of the vagus nerve has been examined with the aid of Nissl staining and immunocytochemistry for calbindin and tyrosine hydroxylase. By 13 weeks, the dorsal vagal nucleus emerges as a distinct structure with at least two subnuclei visible in Nissl stained preparations. By 15 weeks, three subnuclei (dorsal intermediate, centrointermediate and ventrointermediate) were clearly discernible at the open medulla level with caudal and caudointermediate subnuclei visible at the level of the area postrema. All subnuclei known to exist in the adult were visible by 21 weeks and cytoarchitectonic differentiation of the nucleus was largely completed by 25 weeks. The adult distribution pattern of calbindin and tyrosine hydroxylase immunoreactive neurons was also largely completed by 21 weeks, although morphological differentiation of labeled neurons continued until the last age examined (26 weeks). The structural development of the dorsal nucleus of the vagus nerve appears to occur in parallel with functional maturation of the cardiovascular and gastric movements, which the nucleus controls.

High-frequency deep brain stimulation of the nucleus accumbens region suppresses neuronal activity and selectively modulates afferent drive in rat orbitofrontal cortex in vivo.

High-frequency deep-brain stimulation (DBS) of the nucleus accumbens (NAc) region is an effective therapeutic avenue for patients with treatment-resistant obsessive-compulsive disorder (OCD). Imaging studies suggest that DBS acts by suppressing the aberrant metabolism in the orbitofrontal cortex (OFC) that is a hallmark of OCD; however, little is known about the mechanisms by which this occurs. We examined the effects of 30 min NAc DBS at 130 Hz on spontaneously active OFC neurons and local field potentials (LFPs) in addition to evoked responses elicited by single-pulse stimulation of the NAc or mediodorsal thalamus (MD) in urethane-anesthetized rats. NAc DBS reduced the mean firing rate of OFC neurons, although neurons receiving monosynaptic input from MD were less affected and some putative interneurons were excited by DBS. Single-pulse stimulation of the NAc produced a robust inhibition in OFC neurons that was attenuated after DBS, whereas excitatory responses were unchanged. In contrast, after DBS inhibitory responses evoked from MD were unchanged, whereas excitatory responses were enhanced. NAc-evoked LFP responses were potentiated after DBS, whereas MD-evoked LFP responses were unchanged. NAc DBS also enhanced OFC spontaneous LFP oscillatory activity in the slow (0.5-4 Hz) frequency band. These results suggest that DBS of the NAc region may alleviate OCD symptoms by reducing activity in subsets of OFC neurons, potentially by driving recurrent inhibition though antidromic activation of corticostriatal axon collaterals. Moreover, selective potentiation of input to these inhibitory circuits may also contribute to the therapeutic effects produced by DBS in OCD patients.

Distinct, parallel pathways link the medial mammillary bodies to the anterior thalamus in macaque monkeys.

Mammillary body neurons projecting to the thalamus were identified by injecting retrograde tracers into the medial thalamus of macaque monkeys. The source of the thalamic projections from the medial mammillary nucleus showed strikingly different patterns of organization depending on the site of the injection within the two anterior thalamic nuclei, anterior medialis and anterior ventralis. These data reveal at least two distinct modes by which the primate medial mammillary bodies can regulate anterior thalamic function. Projections to the thalamic nucleus anterior medialis arise mainly from the pars lateralis of the medial mammillary nucleus. A particularly dense source is the dorsal cap in the posterior half of the pars lateralis, a subregion that has not previously been distinguished. In contrast, neurons spread evenly across the medial mammillary nucleus gave rise to projections more laterally in the anterior thalamic nuclei. A third pattern of medial mammillary neurons appeared to provide the source of projections to the rostral midline thalamic nuclei. In contrast, the labeled cells in the lateral mammillary nucleus were evenly spread across that nucleus, irrespective of injection site. In addition to the established projection to anterior dorsalis, the lateral mammillary nucleus appears to project lightly to a number of other thalamic nuclei, including lateralis dorsalis, anterior medialis, anterior ventralis, and the rostral midline nuclei, e.g. nucleus reuniens. These anatomical findings not only reveal novel ways of grouping the neurons within the medial mammillary nucleus, but also indicate that the mammillothalamic connections support cognition in multiple ways.

[Individual variability and structural asymmetry of the dorsal medial nucleus of the thalamus in men and women].

Using quantitative neurohistological indices, a structure of the dorsal medial nucleus of the thalamus has been studied in 10 cases from the collection of the Institute of Brain, Russian Academy of Medical Sciences. The sample included 7 men and 3 women aged from 19 to 59 years, right-handed, who died suddenly and did not suffer lifetime neurological or mental disorders. The following indices have been determined: neuronal density, density of total and satellite glia, density of neurons surrounded by the satellite glia as well as portion of the satellite glia to the total one and portion of satellite-surrounded neurons to their total amount. Some sex and hemisphere differences were found against the background of individual variability of the indices studied. No asymmetry was observed for neuronal density both in men and women, individual variability in women being less expressed. The density of glial cells was dominated on the right side in men and on the left side in women and that of satellite ones, on the contrary, was higher on the left side in men and more variable in women. There was a significant asymmetry of the density of neurons surrounded by the satellite glia with higher indices on the left side in men and higher variability in women. However the portion of neurons with satellite glia to their total amount as well as the portion of the satellite glia to the total one was larger on the left side both in men and women. In total, there was a trend to a larger asymmetry of the dorsal medial nucleus structure in men and to individual variability in women.

Projections from bed nuclei of the stria terminalis, dorsomedial nucleus: implications for cerebral hemisphere integration of neuroendocrine, autonomic, and drinking responses.

The overall projection pattern of a tiny bed nuclei of the stria terminalis anteromedial group differentiation, the dorsomedial nucleus (BSTdm), was analyzed with the Phaseolus vulgaris-leucoagglutinin anterograde pathway tracing method in rats. Many brain regions receive a relatively moderate to strong input from the BSTdm. They fall into eight general categories: humeral sensory-related (subfornical organ and median preoptic nucleus, involved in initiating drinking behavior and salt appetite), neuroendocrine system (magnocellular: oxytocin, vasopressin; parvicellular: gonadotropin-releasing hormone, somatostatin, thyrotropin-releasing hormone, corticotropin-releasing hormone), central autonomic control network (central amygdalar nucleus, BST anterolateral group, descending paraventricular hypothalamic nucleus, retrochiasmatic area, ventrolateral periaqueductal gray, Barrington's nucleus), hypothalamic visceromotor pattern-generator network (five of six known components), behavior control column (ingestive: descending paraventricular nucleus; reproductive: lateral medial preoptic nucleus; defensive: anterior hypothalamic nucleus; foraging: ventral tegmental area, along with interconnected nucleus accumbens and substantia innominata), orofacial motor control (retrorubral area), thalamocortical feedback loops (paraventricular, central medial, intermediodorsal, and medial mediodorsal nuclei; nucleus reuniens), and behavioral state control (subparaventricular zone, ventrolateral preoptic nucleus, tuberomammillary nucleus, supramammillary nucleus, lateral habenula, and raphé nuclei). This pattern of axonal projections, and what little is known of its inputs suggest that the BSTdm is part of a striatopallidal differentiation involved in coordinating the homeostatic and behavioral responses associated thirst and salt appetite, although clearly it may relate them to other functions as well. The BSTdm generates the densest known inputs directly to the neuroendocrine system from any part of the cerebral hemispheres.

Projections from bed nuclei of the stria terminalis, magnocellular nucleus: implications for cerebral hemisphere regulation of micturition, defecation, and penile erection.

The basic structural organization of axonal projections from the small but distinct magnocellular and ventral nuclei (of the bed nuclei of the stria terminalis) was analyzed with the Phaseolus vulgaris leucoagglutinin anterograde tract tracing method in adult male rats. The former's overall projection pattern is complex, with over 80 distinct terminal fields ipsilateral to injection sites. Innervated regions in the cerebral hemisphere and brainstem fall into nine general functional categories: cerebral nuclei, behavior control column, orofacial motor-related, humorosensory/thirst-related, brainstem autonomic control network, neuroendocrine, hypothalamic visceromotor pattern-generator network, thalamocortical feedback loops, and behavioral state control. The most novel findings indicate that the magnocellular nucleus projects to virtually all known major parts of the brain network that controls pelvic functions, including micturition, defecation, and penile erection, as well as to brain networks controlling nutrient and body water homeostasis. This and other evidence suggests that the magnocellular nucleus is part of a corticostriatopallidal differentiation modulating and coordinating pelvic functions with the maintenance of nutrient and body water homeostasis. Projections of the ventral nucleus are a subset of those generated by the magnocellular nucleus, with the obvious difference that the ventral nucleus does not project detectably to Barrington's nucleus, the subfornical organ, the median preoptic and parastrial nuclei, the neuroendocrine system, and midbrain orofacial motor-related regions.