Maternal immune activation alters the sequential structure of ultrasonic communications in male rats

Abstract

Maternal immune activation (MIA) is a risk factor for schizophrenia and many of the symptoms and neurodevelopmental changes associated with this disorder have been modelled in the rodent. While several previous studies have reported that rodent ultrasonic vocalizations (USVs) are affected by MIA, no previous study has examined whether MIA affects the way that individual USVs occur over time to produce vocalisation sequences. The sequential aspect of this behaviour may be particularly important because changes in sequencing mechanisms have been proposed as a core deficit in schizophrenia. The present research generates MIA with POLY I:C administered to pregnant Sprague-Dawley rat dams at GD15. Male pairs of MIA adult offspring or pairs of their saline controls were placed into a two-chamber apparatus where they were separated from each other by a perforated plexiglass barrier. USVs were recorded for a period of 10 ​min and automated detection and call review were used to classify short call types in the nominal 50 ​kHz band of social affiliative calls. Our data show that the duration of these 50-kHz USVs is longer in MIA rat pairs and the time between calls is shorter. Furthermore, the transition probability between call pairs was different in the MIA animals compared to the control group, indicating alterations in sequential behaviour. These results provide the first evidence that USV call sequencing is altered by the MIA intervention and suggest that further investigations of these temporally extended aspects of USV production are likely to reveal useful information about the mechanisms that underlie sequence generation. This is particularly important given previous research suggesting that sequencing deficits may have a significant impact on both behaviour and cognition.

Maternal immune activation affects socio-communicative behavior in adult rats

“…However, these communication de cits did not persist until adulthood, as our current study did not demonstrate any poly(I:C)-evoked quantitative changes in the call number in adult animals. In line with our data, the study by Scott et al 52 also did not reveal signi cant changes in the total number of calls or the proportion of call type categories in poly(I:C) male rats. A similar conclusion emerges from another MIA model based on administering the bacterial endotoxin lipopolysaccharide (LPS).…”

“…Accordingly, signi cant increases in the duration and bandwidth of high frequency modulated calls were observed in poly(I:C) males. The result of Scott et al 52 con rms our observation demonstrating that calls from poly(I:C) animals were longer in duration than control calls. These changes in call duration were speci c to highly modulated USV categories, including complex and trill subtypes 52 .…”

“…The result of Scott et al 52 con rms our observation demonstrating that calls from poly(I:C) animals were longer in duration than control calls. These changes in call duration were speci c to highly modulated USV categories, including complex and trill subtypes 52 . The latter authors concluded that the extended call duration might affect temporary call distributions, revealed as a tendency for poly(I:C) animals to generate pairs of calls with short inter-call intervals.…”

“…The latter authors concluded that the extended call duration might affect temporary call distributions, revealed as a tendency for poly(I:C) animals to generate pairs of calls with short inter-call intervals. Interestingly, the sequential structure of USV communications of MIA animals was also changed in that study 52 . Whether these aspects of communication are also affected in our experimental conditions awaits further studies.…”

Developmental vitamin D-deficiency produces autism-relevant behaviours and gut-health associated alterations in a rat model

“…These ndings are consistent with two recent studies showing increased USVs in DVD-de cient rats at P9 [11] and P12 [49]. Many other animal models of autism have also demonstrated altered USVs (either increased or decreased) [50][51][52]. However, the mechanisms involved in USVs remain poorly de ned.…”