Sustained neuronal activity generated by glial plasticity

Astrocytes release gliotransmitters, notably glutamate, that can affect neuronal and synaptic activity. In particular, astrocytic glutamate release results in the generation of NMDA receptor (NMDA-R)-mediated slow inward currents (SICs) in neurons. However, factors underlying the emergence of SICs and their physiological roles are essentially unknown. Here we show that, in acute slices of rat somatosensory thalamus, stimulation of lemniscal or cortical afferents results in a sustained increase of SICs in thalamocortical (TC) neurons that outlasts the duration of the stimulus by 1 h. This long-term enhancement of astrocytic glutamate release is induced by group I metabotropic glutamate receptors and is dependent on astrocytic intracellular calcium. Neuronal SICs are mediated by extrasynaptic NR2B subunit-containing NMDA-Rs and are capable of eliciting bursts. These are distinct from T-type Ca2+ channel-dependent bursts of action potentials and are synchronized in neighboring TC neurons. These findings describe a previously unrecognized form of excitatory, nonsynaptic plasticity in the CNS that feeds forward to generate local neuronal firing long after stimulus termination.

Nicotinic acetylcholine receptor interaction with β-amyloid:molecular, cellular, and physiological consequences

Elevated amyloid-β peptide (Aβ) and loss of nicotinic acetylcholine receptors (nAChRs) stand prominently in the etiology of Alzheimer's disease (AD). Since the discovery of an Aβ - nAChR interaction, much effort has been expended to characterize the consequences of high versus low concentrations of Aβ on nAChRs. This review will discuss current knowledge on the subject at the molecular, cellular, and physiological levels with particular emphasis on understanding how Aβ - nAChR interaction may contribute to normal physiological processes as well as the etiology of AD. ©2010 Bentham Science Publishers Ltd.

When an intercultural business negotiation fails:comparing the emotions and behavioural tendencies of individualistic and collectivistic negotiators

This study explores the linkages between culture, emotions and behavioural tendencies in unsuccessful intercultural business negotiations. A set of novel research hypotheses are developed. They are tested using a negotiation scenario analysis involving 106 Finnish and 114 Indian study participants. Three key findings emerge from the statistical tests conducted. First, new empirical evidence suggesting that qualitatively different emotions (dejection vs. agitation) are experienced after a failed intercultural business negotiation by individualists and collectivists is provided. Second, the existence of the relationship between perspective-taking ability and emotional volatility in the context of failed intercultural business negotiation involving individualists and collectivists is revealed. Third, partial support is found for the idea that different types of negative emotions can lead to the same behavioural tendency (approach) among individualists and collectivists when intercultural business negotiation fails. The paper concludes by outlining a set of theoretical and managerial implications and suggestions for further research.