AN ELECTROPHYSIOLOGICAL ANALYSIS OF THE AMYGDALOID AND SUBICULAR PROJECTIONS TO THE VENTROMEDIAL NUCLEUS OF THE HYPOTHALAMUS IN THE RABBIT

Electrophysiological experiments were performed on 96 male New Zealand white rabbits, anesthetized with urethane. Glass electrodes, filled with 2M NaCl, were used for microstimulation of three fiber pathways projecting from "limbic" centers to the ventromedial nucleus of the hypothalamus (VMH). Unitary and field potential recordings were made in the VMH after stimulation.^ Stimulation of the lateral portion of the fimbria, which carries fibers from the ventral subiculum of the hippocampal formation, evokes predominantly an inhibition of neurons medially in the VMH, and excitation of neurons located laterally.^ Stimulation of the dorsal portion of the stria terminalis, which carries fibers from the cortical nucleus of the amygdala, also produces predominantly an inhibition of cells medially and excitation laterally.^ Stimulation of the ventral component of the stria terminalis, which carries fibers from the medial nucleus of the amygdala, evokes excitation of cell medially, with little or no response seen laterally.^ Cells recorded medially in the VMH received convergent inputs from each of the three fiber systems: inhibition from fimbria and dorsal stria stimulation, excitation from ventral stria stimulation.^ The excitatory unitary responses recorded medially to ventral stria stimulation and laterally to fimbria and dorsal stria stimulation were subjected to a series of threshold stimulus intensities. From these tests it was determined that each of these three projections terminates monosynaptically on VMH neurons.^ The evidence for convergence upon single VMH neurons of projections from the amygdala and the hippocampal formation suggests this area of the brain to be important for integration of information from these two limbic centers. The VMH has been implied in a number of behavioral states: eating, reproduction, defense and aggression; it has further been linked to control of the anterior pituitary. These data provide a functional circuit through which the amygdaloid complex and the hippocampal formation can channel information from higher cortical centers into a hypothalamic area capable of coordinating behavioral and hormonal responses. ^

Grey matter volumetric changes related to recovery from hand paresis after cortical sensorimotor stroke

Preclinical studies using animal models have shown that grey matter plasticity in both perilesional and distant neural networks contributes to behavioural recovery of sensorimotor functions after ischaemic cortical stroke. Whether such morphological changes can be detected after human cortical stroke is not yet known, but this would be essential to better understand post-stroke brain architecture and its impact on recovery. Using serial behavioural and high-resolution magnetic resonance imaging (MRI) measurements, we tracked recovery of dexterous hand function in 28 patients with ischaemic stroke involving the primary sensorimotor cortices. We were able to classify three recovery subgroups (fast, slow, and poor) using response feature analysis of individual recovery curves. To detect areas with significant longitudinal grey matter volume (GMV) change, we performed tensor-based morphometry of MRI data acquired in the subacute phase, i.e. after the stage compromised by acute oedema and inflammation. We found significant GMV expansion in the perilesional premotor cortex, ipsilesional mediodorsal thalamus, and caudate nucleus, and GMV contraction in the contralesional cerebellum. According to an interaction model, patients with fast recovery had more perilesional than subcortical expansion, whereas the contrary was true for patients with impaired recovery. Also, there were significant voxel-wise correlations between motor performance and ipsilesional GMV contraction in the posterior parietal lobes and expansion in dorsolateral prefrontal cortex. In sum, perilesional GMV expansion is associated with successful recovery after cortical stroke, possibly reflecting the restructuring of local cortical networks. Distant changes within the prefrontal-striato-thalamic network are related to impaired recovery, probably indicating higher demands on cognitive control of motor behaviour.

Modulation of anticipatory emotion and perception processing by cognitive control.

Strategies of cognitive control are helpful in reducing anxiety experienced during anticipation of unpleasant or potentially unpleasant events. We investigated the associated cerebral information processing underlying the use of a specific cognitive control strategy during the anticipation of affect-laden events. Using functional magnetic resonance imaging, we examined differential brain activity during anticipation of events of unknown and negative emotional valence in a group of eighteen healthy subjects that used a cognitive control strategy, similar to "reality checking" as used in psychotherapy, compared with a group of sixteen subjects that did not exert cognitive control. While expecting unpleasant stimuli, the "cognitive control" group showed higher activity in left medial and dorsolateral prefrontal cortex areas but reduced activity in the left extended amygdala, pulvinar/lateral geniculate nucleus and fusiform gyrus. Cognitive control during the "unknown" expectation was associated with reduced amygdalar activity as well and further with reduced insular and thalamic activity. The amygdala activations associated with cognitive control correlated negatively with the reappraisal scores of an emotion regulation questionnaire. The results indicate that cognitive control of particularly unpleasant emotions is associated with elevated prefrontal cortex activity that may serve to attenuate emotion processing in for instance amygdala, and, notably, in perception related brain areas.

Michel decay spectrum for a muon bound to a nucleus

The spectrum of electrons from muons decaying in an atomic bound state is significantly modified by their interaction with the nucleus. Somewhat unexpectedly, its first measurement, at the Canadian laboratory TRIUMF, differed from basic theory. We show, using a combination of techniques developed in atomic, nuclear, and high-energy physics, that radiative corrections eliminate the discrepancy. In addition to solving that outstanding problem, our more precise predictions are potentially useful for interpreting future high-statistics muon experiments that aim to search for exotic interactions at 10−16 sensitivity.

Co-culture of Notochordal Cells with Nucleus pulposus and Annulus fibrosus cells under normoxia and hypoxia

Introduction Notochordal cells (NC) are shifted back into focus due to their apparent action of activating other disc cells via indirect release of yet unknown factors into the medium (conditioned medium = CM).1,2 Recent evidence confirms the results from the late 1990s.3,4 Here, we test porcine (p) NC cultured in 3D and the influence of adding serum or using serum-free medium onto the culture on NC cells and its stimulating effects for subsequent coculture with primary bovine (b) nucleus pulposus (bNPC) and annulus fibrous cells (bAFC). Materials and Methods Primary pNC, bNPC, and bAFC were isolated from porcine tails (< 6-12 months age) or bovine tails (∼1 year age), which were obtained from the food chain (N = 4 repeats) within 4 hours postmortem. All cells were seeded into 1.2% alginate, each with a density of 4 × 106/mL. NC were then either cultured for 7 days in serum free medium (SFM = Dulbecco modified eagle medium [DMEM] supplied with ITS+, 50 µg/mL vitamin C and nonessential amino acids) or DMEM + 10% fetal calf serum (FCS). CM was produced from NC collecting 4 mL SFM and keeping approximately 30 beads for 7 days. Then, a coculture was set up in SFM for 14 days using indirect cell-cell contact (culture insert, high density pore, 0.4 µm) using a 50:50% ratio5 of pNC:bNP or bAF, or by addition of CM, respectively. The cell activity, glycosaminoglycan per DNA (GAG/DNA) ratio, and real-time RT-PCR of IVD relevant genes were monitored. Mass spectrometry was performed on the SFM and the cocultured medium as well as the CM of the pNC to identify possible key cytokines to the stimulatory effects. Results The results for cell activity confirmed that pNC are highly responsive on the nutritional condition in the culture (K-W test, p = 0.048) after 7 days of coculture. bNPC and bAFC did not respond significantly different to coculture or addition of CM with respect to cell activity. However, GAG/DNA ratio of pNC was significantly upregulated if they were initially pre-exposed to FCS and in coculture with bNPC after 14 days, for both normoxia and hypoxia (K-W, p = 0.03). The bNPC were stimulated by both, 1:1 coculture with pNC but also by addition of CM only, which resulted in approximately 200% increased GAG/DNA values relative to the day 0 state. However, this doubling of the GAG/DNA ratio was nonsignificant after 14 days. The aggrecan/collagen type 2 ratio as quantified from real-time RT-PCR pointed to a beneficial state of the bNPC if cultured either in indirect coculture with pNC or by the addition of CM (Fig. 1). The mass spectrometric analysis of the CM revealed that there was connecting tissue growth factor present (CTGF) among the cytokine CLC11, a cytokine that has been found to be expressed in skeletal tissues including bone marrow and chondrocytes among other factors that might have immunoregulatory and cell proliferative functions.

A Thalamic-Fronto-Parietal Structural Covariance Network Emerging in the Course of Recovery from Hand Paresis after Ischemic Stroke.

AIM To describe structural covariance networks of gray matter volume (GMV) change in 28 patients with first-ever stroke to the primary sensorimotor cortices, and to investigate their relationship to hand function recovery and local GMV change. METHODS Tensor-based morphometry maps derived from high-resolution structural images were subject to principal component analyses to identify the networks. We calculated correlations between network expression and local GMV change, sensorimotor hand function and lesion volume. To verify which of the structural covariance networks of GMV change have a significant relationship to hand function, we performed an additional multivariate regression approach. RESULTS Expression of the second network, explaining 9.1% of variance, correlated with GMV increase in the medio-dorsal (md) thalamus and hand motor skill. Patients with positive expression coefficients were distinguished by significantly higher GMV increase of this structure during stroke recovery. Significant nodes of this network were located in md thalamus, dorsolateral prefrontal cortex, and higher order sensorimotor cortices. Parameter of hand function had a unique relationship to the network and depended on an interaction between network expression and lesion volume. Inversely, network expression is limited in patients with large lesion volumes. CONCLUSION Chronic phase of sensorimotor cortical stroke has been characterized by a large scale co-varying structural network in the ipsilesional hemisphere associated specifically with sensorimotor hand skill. Its expression is related to GMV increase of md thalamus, one constituent of the network, and correlated with the cortico-striato-thalamic loop involved in control of motor execution and higher order sensorimotor cortices. A close relation between expression of this network with degree of recovery might indicate reduced compensatory resources in the impaired subgroup.