Impact of early exposure to a cafeteria diet on prefrontal cortex monoamines and novel object recognition in adolescent rats.

The prefrontal cortex (PFC) undergoes protracted postnatal development such that its structure and behavioural function may be profoundly altered by environmental factors. Here we investigate the effect of lactational dietary manipulations on novel object recognition (NOR) learning and PFC monoamine neurotransmitter metabolism in early adolescent rats. To this end, Wistar rat dams were fed a high caloric cafeteria diet (CD) during lactation and resultant 24-26 day old offspring exposed to NOR testing and simultaneous PFC dopamine and serotonin metabolism measurement. In the second NOR choice trial where one familiar and one novel object were presented controls explored the novel preferentially to the familiar object both after a 5 min (P < 0.001) or 30 min (P < 0.05) inter-trial intervals (ITI). By contrast, offspring from dams fed on lactational CD failed to show any significant preference for the novel object at either time point. Compared with chow fed controls, their average exploration ratio of the novel object was lower after the 5 min ITI (P < 0.05). Following a 60 min ITI, neither CD nor control offspring showed a preference for the novel object. PFC dopamine metabolism was significantly reduced in the CD group (P < 0.001), whereas serotonin metabolism was increased (P < 0.001). These results suggest that an obesogenic lactational diet can have a detrimental impact on cognition in adolescent offspring associated with aberrant PFC serotonin and dopamine metabolism.

Modeling global and focal hyperarticulation during human-computer error resolution.

When resolving errors with interactive systems, people sometimes hyperarticulate--or adopt a clarified style of speech that has been associated with increased recognition errors. The primary goals of the present study were: (1) to provide a comprehensive analysis of acoustic, prosodic, and phonological adaptations to speech during human-computer error resolution after different types of recognition error; and (2) to examine changes in speech during both global and focal utterance repairs. A semi-automatic simulation method with a novel error-generation capability was used to compare speech immediately before and after system recognition errors. Matched original-repeat utterance pairs then were analyzed for type and magnitude of linguistic adaption during global and focal repairs. Results indicated that the primary hyperarticulate changes in speech following all error types were durational, with increases in number and length of pauses most noteworthy. Speech also was adapted toward a more deliberate and hyperclear articulatory style. During focal error repairs, large durational effects functioned together with pitch and amplitude to provide selective prominence marking of the repair region. These results corroborate and generalize the computer-elicited hyperarticulate adaptation model (CHAM). Implications are discussed for improved error handling in next-generation spoken language and multimodal systems.