Oxytocin and vasopressin levels are decreased in the plasma of male schizophrenia patients.

OBJECTIVE: Impaired social functioning and autistic symptoms are characteristics of schizophrenia. The social hormones oxytocin (OT) and arginine-vasopressin (AVP) both modulate social interaction and therefore may be involved in the pathogenesis of schizophrenia. We investigated whether men with schizophrenia show altered OT and AVP levels compared with healthy controls (HC) and whether autism symptoms are associated with OT levels. METHODS: Forty-one men with non-acute schizophrenia and 45 matched HC were enrolled. Schizophrenia was assessed with the Positive and Negative Syndrome Scale (PANSS). Blood samples were collected on 2 days, and plasma OT and AVP levels were measured by ELISA immunoassay. RESULTS: The schizophrenia patients had significantly lower plasma OT levels than the HC; a similar trend was found for AVP. Plasma OT levels were associated with severe life events, fewer important attached persons, and a higher score on the PANSS negative scale; the most dominant PANSS items were 'preoccupation', 'emotional withdrawal', and 'passive/apathetic social withdrawal'. CONCLUSION: These findings support an association between the social hormones OT and AVP and schizophrenia. We suggest that OT metabolism may be altered in schizophrenia, but other possible causes for decreased plasma OT levels in schizophrenia patients include decreased OT synthesis, mRNA expression, and translation. Especially the 'autistic' symptoms of schizophrenia seem to be closely linked to an altered metabolism of OT, the 'attachment' hormone.

With the past behind and the future ahead: back-to-front representation of past and future sentences.

Several studies support the psychological reality of a mental timeline that runs from the left to the right and may strongly affect our thinking about time. Ulrich and Maienborn (Cognition 117:126-138, 2010) examined the linguistic relevance of this timeline during the processing of past- and future-related sentences. Their results indicate that the timeline is not activated automatically during sentence comprehension. While no explicit reference of temporal expressions to the left-right axis has been attested (e.g., *the meeting was moved to the left), natural languages refer to the back-front axis in order to encode temporal information (e.g., the meeting was moved forward). Therefore, the present study examines whether a back-frontal timeline becomes automatically activated during the processing of past- and future-related sentences. The results demonstrate a clear effect on reaction time that emerges from a time-space association along the frontal timeline (Experiment 1). However, this activation seems to be nonautomatic (Experiment 2), rendering it unlikely that this frontal timeline is involved in comprehension of the temporal content of sentences.

How strongly linked are mental time and space along the left-right axis?

Different lines of research suggest that our mental representations of time and space are linked, though the strength of this linkage has only recently been addressed for the front-back mental timeline (Eikmeier, Schröter, Maienborn, Alex-Ruf, & Ulrich, 2013). The present study extends this investigation to the left-right mental timeline. In contrast to what was found in the cited previous study, the obtained space-time congruency effects were smaller than benchmark stimulus-response congruency effects in control conditions. This pattern of results suggests that the representations of time and space are less strongly linked for the left-right axis than for the back-front axis.

Do we map remembrances to the left/back and expectations to the right/front of a mental timeline? Space-time congruency effects with retrospective and prospective verbs.

Recent experimental studies have shown that people code time in terms of a mental timeline which typically runs from left to right or from back to front. Determining the cognitive function of this mental timeline for language processing, however, is still an unsettled issue. Whereas the studies of Ulrich and Maienborn (2010) and Ulrich et al. (2012) argue against an automatic activation of the mental timeline for the interpretation of tense and temporal adverbials at sentence level, Sell and Kaschak (2011) observe an automatic activation for the processing of past- and future-related sentences in small stories. The present paper reports the results of three experiments which examine the processing of sentences with retrospective and prospective verbs (e.g., to remember, to regret vs. to expect, to announce) in present tense, which locate a second, embedded event in the past or the future. When temporal information was task-relevant, a space-time congruency effect emerged (Experiment 1). This suggests that the mental timeline is not only linked to overtly deictic linguistic material but may also be construed in a more intricate way through the compositional construction of sentence meaning. The congruency effect disappeared, however, when temporal information was task-irrelevant (Experiments 2 and 3), suggesting that the mental timeline is not functionally involved in the cognitive processing of these especially demanding two-event sentences. The results of the present study support the conclusion that the relevant factor driving an automatic activation of the mental timeline is not the number of linguistically expressed events, but might rather be the number of sentential units.

Dimensional overlap between time and space.

Several pieces of evidence suggest that our mental representations of time and space are linked. However, the extent of this linkage between the two domains has not yet been assessed. We present the results of two experiments that draw on the predictions of the dimensional overlap model (Kornblum, Hasbroucq, & Osman, Psychological Review 97:253-270, 1990). The stimulus and response sets in these reaction time experiments were related to either time or space. The obtained stimulus-response congruency effects were of about the same size for identical stimulus-response sets (time-time or space-space) and for different stimulus-response sets (time-space or space-time). These results support the view that our representations of time and space are strongly linked.