Language, culture and education

Californiaxiv, 239 p.: illus.; 23 c

Early postnatal nicotine exposure causes hippocampus-dependent memory impairments in adolescent mice: Association with altered nicotinic cholinergic modulation of LTP, but not impaired LTP

Fetal nicotine exposure from smoking during pregnancy causes long-lasting cognitive impairments in offspring, yet little is known about the mechanisms that underlie this effect. Here we demonstrate that early postnatal exposure of mouse pups to nicotine via maternal milk impairs long-term, but not short-term, hippocampus-dependent memory during adolescence. At the Schaffer collateral (SC) pathway, the most widely studied synapses for a cellular correlate of hippocampus-dependent memory, the induction of N-methyl-d-aspartate receptor-dependent transient long-term potentiation (LTP) and protein synthesis-dependent long-lasting LTP are not diminished by nicotine exposure, but rather unexpectedly the threshold for LTP induction becomes lower after nicotine treatment. Using voltage sensitive dye to visualize hippocampal activity, we found that early postnatal nicotine exposure also results in enhanced CA1 depolarization and hyperpolarization after SC stimulation. Furthermore, we show that postnatal nicotine exposure induces pervasive changes to the nicotinic modulation of CA1 activity: activation of nicotinic receptors no longer increases CA1 network depolarization, acute nicotine inhibits rather than facilitates the induction of LTP at the SC pathway by recruiting an additional nicotinic receptor subtype, and acute nicotine no longer blocks LTP induction at the temporoammonic pathway. These findings reflect the pervasive impact of nicotine exposure during hippocampal development, and demonstrate an association of hippocampal memory impairments with altered nicotinic cholinergic modulation of LTP, but not impaired LTP. The implication of our results is that nicotinic cholinergic-dependent plasticity is required for long-term memory formation and that postnatal nicotine exposure disrupts this form of plasticity

Challenges of multimodality: Language and the body in social interaction

This article reflects on recent challenges emerging from the study of language and the body in social interaction. There is a general interest in language and the body across disciplines that has invited a reconceptualization of the broader issues relative to action, cognition, culture, knowledge, social relations and identities, spatiality and temporality. The study of social interaction focuses on how multimodal resources - including language and bodily movements - are holistically and situatedly used in building human action. This article discusses some consequences and challenges of putting the body at the center of attention: it repositions language as one among other modalities, and invites us to consider the involvement of entire bodies in social interaction, overcoming a logo-centric vision of communication, as well as a visuo-centric vision of embodiment. These issues are developed through a series of conversation analytic studies, firstly of classic topics in linguistics like deixis, then of more recent topics, such as mobility and sensoriality