Identification and Characterization of GABAergic Projection Neurons from Ventral Hippocampus to Amygdala.

GABAergic local circuit neurons are critical for the network activity and functional interaction of the amygdala and hippocampus. Previously, we obtained evidence for a GABAergic contribution to the hippocampal projection into the basolateral amygdala. Using fluorogold retrograde labeling, we now demonstrate that this projection indeed has a prominent GABAergic component comprising 17% of the GABAergic neurons in the ventral hippocampus.

Comprehensive molecular, genomic and phenotypic analysis of a major clone of Enterococcus faecalis MLST ST40.

Background: Enterococcus faecalis is a multifaceted microorganism known to act as a beneficial intestinal commensal bacterium. It is also a dreaded nosocomial pathogen causing life-threatening infections in hospitalised patients. Isolates of a distinct MLST type ST40 represent the most frequent strain type of this species, distributed worldwide and originating from various sources (animal, human, environmental) and different conditions (colonisation/infection).

Axonal connections from posterior paralaminar thalamic neurons to basomedial amygdaloid projection neurons to the lateral entorhinal cortex in rats.

Stimulation of amygdaloid nuclei and emotionally relevant stimuli are known to influence the induction and maintenance of long-term potentiation in the hippocampal formation and the formation of long-term declarative memories. Because the thalamic projection from the posterior paralaminar thalamic nuclei is an important sensory afferent projection to amygdaloid nuclei mediating the fast acquisition of fear-potentiated behavior, we were interested in verifying whether this projection establishes synaptic contacts on amygdala neurons that project to the hippocampal formation. Thalamic afferents were labeled with the anterograde tracer Phaseolus vulgaris leucoagglutinin and amygdalo-hippocampal neurons were identified by injection of the retrograde tracer Fluorogold into the lateral entorhinal cortex.

Differential projection of the posterior paralaminar thalamic nuclei to the amygdaloid complex in the rat.

The thalamic paralaminar nuclei that border the medial and ventral edges of the medial geniculate body, viz. the suprageniculate nucleus (SG), the posterior intralaminar nucleus (PIN), the medial division of the medial geniculate nucleus (MGm), and the peripeduncular nucleus (PP), are regarded as important extralemniscal relay nuclei for sensory stimuli and as an important link for the direct transmission of sensory stimuli to the amygdala. Each of these thalamic nuclei receives a unique pattern of afferent input but an unresolved question is, how each of these thalamic nuclei project to the amygdala and whether there are zones of convergence and/or non-overlapping regions within amygdaloid target nuclei.

Convergent and complementary projections of the caudal paralaminar thalamic nuclei to rat temporal and insular cortex.

Thalamic nuclei adjacent to the medial geniculate body play a pivotal role in processing of sensory stimuli during emotional situations. These nuclei, which include the suprageniculate nucleus (SG), the posterior intralaminar nucleus (PIN), the peripeduncular nucleus (PP) and the medial division of the medial geniculate body (MGm), project to both cortex and amygdala, but target areas and the extent of the projection of individual nuclei are not known yet. The aim of the present study was to analyze the contribution of individual nuclei to the cortical projection with modern sensitive tracing techniques.

Organization of projections to temporal cortex originating in the thalamic posterior intralaminar nucleus of the rat.

Thalamic nuclei surrounding the medial geniculate body, among which the posterior intralaminar nucleus (PIN) is one of the largest, have great importance in fear-potentiated emotional behavior. Due to limited knowledge of the distribution of the cortical projections of the PIN, the connections between the temporal neocortex and the PIN were investigated by means of axonal transport of Phaseolus vulgaris leucoagglutinin or Mini-ruby. After iontophoretic injections of either tracer, anterogradely labeled terminals showed a broad, but not a diffuse, distribution in temporal and adjacent cortices (perirhinal, secondary auditory, visceral, secondary somatosensory, agranular insular cortices).

Direct synaptic connections of axons from superior colliculus with identified thalamo-amygdaloid projection neurons in the rat: possible substrates of a subcortical visual pathway to the amygdala.

The aim of the present study was to identify synaptic contacts from axons originating in the superior colliculus with thalamic neurons projecting to the lateral nucleus of the amygdala. Axons from the superior colliculus were traced with the anterograde tracers Phaseolus vulgaris leucoagglutinin or the biotinylated and fluorescent dextran amine "Miniruby." Thalamo-amygdaloid projection neurons were identified with the retrograde tracer Fluoro-Gold.