Search results for "campus"

Multiple-unit responses to pitch changes in rabbits

1996

Multiple-unit activity (MUA) was recorded from the hippocampus (Hc), the visual cortex (VCx) and the cerebellar cortex (CerCx) in rabbits when pitch deviant tones were presented in a series of standard tones (oddball situation) and when standard tones were absent (deviant-alone situation). Significant MMN-like responses (deviant responses minus standard responses in the oddball situation) occurred in Hc, reflecting a MUA increase to the standards and its decrease to the deviants. In accordance with parallel ERPs reported earlier, the MMN-like responses reflected responses only to different presentation frequencies of stimuli. Non-selectivity in the pitch of such responses in VCx and a lack …

Regular theta-firing neurons in the nucleus incertus during sustained hippocampal activation

2015

This paper describes the existence of theta-coupled neuronal activity in the nucleus incertus (NI). Theta rhythm is relevant for cognitive processes such as spatial navigation and memory processing, and can be recorded in a number of structures related to the hippocampal activation including the NI. Strong evidence supports the role of this tegmental nucleus in neural circuits integrating behavioural activation with the hippocampal theta rhythm. Theta oscillations have been recorded in the local field potential of the NI, highly coupled to the hippocampal waves, although no rhythmical activity has been reported in neurons of this nucleus. The present work analyses the neuronal activity in t…

The human brain subventricular zone: stem cells in this niche and its organization.

2007

The human brain harbors stem cells in the subventricular zone (SVZ). The authors have collected postmortem and intraoperative tissue from adult human patients and found that it contains a unique ribbon of astrocytes that proliferate in vivo and can function as neural stem cells in vitro. Furthermore, they have conducted an anatomic, cytoarchitectural, and ultrastructural study in complete postmortem brains to define the precise organization of the lateral walls of the human lateral ventricles. With immunohistochemistry, the authors mapped a proliferative glial fibrillary acidic protein (GFAP)--positive ribbon of astrocytic cells in the human SVZ. In this article, the authors report on four …

Hippocampal evoked potentials to pitch deviances in an auditory oddball situation in the rabbit: no human mismatch-like dependence on standard stimul…

1995

Hippocampal auditory evoked potentials (AEP) were recorded in 10 rabbits when pitch deviant tones occurred in a series of standard tones (oddball situation). In control recordings, deviant tones were presented without intervening standard tones (deviant-alone situation). All AEP deflections observed in the oddball situation were found also in the deviant-alone situation. Thus, it appeared that none of the AEP deflections to deviant tones in the oddball situation was specific to a memory trace of preceding standard tones. This observation was in contradiction to such a specificity of the mismatch negativity (MMN) found in humans. Instead, a connection to a neuronal orienting reaction interpr…

The effect of rewarding hypothalamic stimulation on behavioral and neural hippocampal responses during trace eyeblink conditioning in rabbit (Oryctol…

2005

Rabbits were trace-conditioned with a tone as a conditioned stimulus and an airpuff as an unconditioned stimulus. Electrical stimulation to the medial forebrain bundle in the lateral hypothalamus was delivered either before or after the tone-airpuff pair. The purpose of the present study was to test whether the effect of post-trial hypothalamic stimulation differed from the effect of pre-trial hypothalamic stimulation on trace conditioning in the same subjects. Additionally, hippocampal responses were measured during sessions to see if hypothalamic stimulation activated dopaminergic fibres and affected hippocampal cell functioning and thus learning. The results showed that behavioral nictit…

On the cellular mechanisms underlying working memory capacity in humans

2016

The cellular processes underlying individual differences in the Working Memory Capacity (WMC) of humans are essentially unknown. Psychological experiments suggest that subjects with lower working memory capacity (LWMC), with respect to subjects with higher capacity (HWMC), take more time to recall items from a list because they search through a larger set of items and are much more susceptible to interference during retrieval. However, a more precise link between psychological experiments and cellular properties is lacking and very difficult to investigate experimentally. In this paper, we investigate the possible underlying mechanisms at the single neuron level by using a computational mod…

The vomeronasal cortex - afferent and efferent projections of the posteromedial cortical nucleus of the amygdala in mice

2013

Most mammals possess a vomeronasal system that detects predominantly chemical signals of biological relevance. Vomeronasal information is relayed to the accessory olfactory bulb (AOB), whose unique cortical target is the posteromedial cortical nucleus of the amygdala. This cortical structure should therefore be considered the primary vomeronasal cortex. In the present work, we describe the afferent and efferent connections of the posteromedial cortical nucleus of the amygdala in female mice, using anterograde (biotinylated dextranamines) and retrograde (Fluorogold) tracers, and zinc selenite as a tracer specific for zinc-enriched (putative glutamatergic) projections. The results show that t…

Hippocampal theta activity, learning and behavioral tendencies

2014

Trace eyeblink conditioning is a method that models a declarative, awareness-dependent form of learning. Hippocampal theta activity, an approximately 3.5 - 8.5 Hz oscillatory pattern in rabbits, has been associated with learning-related phenomena: arousal, attentional processes and association forming. In some studies theta-contingent training, given during a brain state rich in hippocampal theta oscillation, has improved the initial learning in trace eyeblink conditioning. However, other laboratories have failed to replicate this effect. This study explored the effects of theta-contingent conditioning and extinction on learning, and the connection between the magnitude of spontaneous hippo…

2015

Oxidative stress is thought to be one of the main mediators of neuronal damage in human neurodegenerative disease. Still, the dissection of causal relationships has turned out to be remarkably difficult. Here, we have analyzed global protein oxidation in terms of carbonylation of membrane proteins and cytoplasmic proteins in three different mammalian species: aged human cortex and cerebellum from patients with or without Alzheimer's disease, mouse cortex and cerebellum from young and old animals, and adult rat hippocampus and cortex subjected or not subjected to cerebral ischemia. Most tissues showed relatively similar levels of protein oxidation. However, human cortex was affected by sever…

Endoplasmic Reticulum Stress Inhibition Protects against Excitotoxic Neuronal Injury in the Rat Brain

2007

Elevated brain glutamate with activation of neuronal glutamate receptors accompanies neurological disorders, such as epilepsy and brain trauma. However, the mechanisms by which excitotoxicity triggers neuronal injury are not fully understood. We have studied the glutamate receptor agonist kainic acid (KA) inducing seizures and excitotoxic cell death. KA caused the disintegration of the endoplasmic reticulum (ER) membrane in hippocampal neurons and ER stress with the activation of the ER proteins Bip, Chop, and caspase-12. Salubrinal, inhibiting eIF2α (eukaryotic translation initiation factor 2 subunit α) dephosphorylation, significantly reduced KA-induced ER stress and neuronal deathin vivo…