Event-related potentials reveal limited readiness to access phonetic details during word processing in dogs.

While dogs have remarkable abilities for social cognition and communication, the number of words they learn to recognize typically remains very low. The reason for this limited capacity is still unclear. We hypothesized that despite their human-like auditory abilities for analysing speech sounds, their word processing capacities might be less ready to access phonetic details. To test this, we developed procedures for non-invasive measurement of event-related potentials (ERPs) for language stimuli in awake dogs (n = 17). Dogs listened to familiar instruction words and phonetically similar and dissimilar nonsense words. We compared two different artefact cleaning procedures on the same data; they led to similar results. An early (200-300 ms; only after one of the cleaning procedures) and a late (650-800 ms; after both cleaning procedures) difference was present in the ERPs for known versus phonetically dissimilar nonsense words. There were no differences between the ERPs for known versus phonetically similar nonsense words. ERPs of dogs who heard the instructions more often also showed larger differences between instructions and dissimilar nonsense words. The study revealed not only dogs' sensitivity to known words, but also their limited capacity to access phonetic details. Future work should confirm the reported ERP correlates of word processing abilities in dogs.

Neural mechanisms for lexical processing in dogs.

During speech processing, human listeners can separately analyze lexical and intonational cues to arrive at a unified representation of communicative content. The evolution of this capacity can be best investigated by comparative studies. Using functional magnetic resonance imaging, we explored whether and how dog brains segregate and integrate lexical and intonational information. We found a left-hemisphere bias for processing meaningful words, independently of intonation; a right auditory brain region for distinguishing intonationally marked and unmarked words; and increased activity in primary reward regions only when both lexical and intonational information were consistent with praise. Neural mechanisms to separately analyze and integrate word meaning and intonation in dogs suggest that this capacity can evolve in the absence of language.

Visual cortical responses to the input from the amblyopic eye are suppressed during binocular viewing.

Amblyopia is a visual disorder caused by an anomalous early visual experience. It has been suggested that suppression of the visual input from the weaker eye might be a primary underlying mechanism of the amblyopic syndrome. However, it is still an unresolved question to what extent neural responses to the visual information coming from the amblyopic eye are suppressed during binocular viewing. To address this question we measured event-related potentials (ERP) to foveal face stimuli in amblyopic patients, both in monocular and binocular viewing conditions. The results revealed no difference in the amplitude and latency of early components of the ERP responses between the binocular and fellow eye stimulation. On the other hand, early ERP components were reduced and delayed in the case of monocular stimulation of the amblyopic eye as compared to the fellow eye stimulation or to binocular viewing. The magnitude of the amblyopic effect measured on the ERP amplitudes was comparable to that found on the fMRI responses in the fusiform face area using the same face stimuli and task conditions. Our findings showing that the amblyopic effects present on the early ERP components in the case of monocular stimulation are not manifested in the ERP responses during binocular viewing suggest that input from the amblyopic eye is completely suppressed already at the earliest stages of visual cortical processing when stimuli are viewed by both eyes.

[Effect of combined application of halothane and some central depressants (author's transl)]. / Beeinflussung der Halothannarkose durch zentral dämpfend Pharmaka

The combined effects of halothane and various central depressants were studied in mice by means of an isobolographic method which allows the statistical evaluation of interactions. A loss of the righting reflex for at least 2 min was taken as the criterion for the synchronisation of the peak time of drug effects. All interactions turned out to be supra-additive, more pronounced in the case of diazepam and flunitrazepam than in the case of medazepam, pentobarbitone or ethanol. The organic solvent used for the solution of diazepam and flunitrazepam was found to contribute to the observed interactions. The difficulties of estimating and classifying combined drug effects as well as their clinical relevance are discussed.

[Action of central depressants on the nitrous oxide anesthesia (author's transl)]. / Wirkung zentral dämpfender Pharmaka auf die Stickoxydul-Narkose

The synergistic action of seven central depressants three benzodiazepines, two neuroleptics on barbiturate and morphine on the anesthetic activity of nitrous oxide was studied in mice. The benzodiazipines and among them nitrazepam and flunitrazepam were found to be the most potent drugs in this respect; morphine on the other hand was innefective even in toxic doses. There was a significant difference in the slope of log dose-response curves; these curves were much steeper for pentobarbitone, droperidol and chlorpromazine than for nitrazepam, flunitrazepam, and diazepam. The theoretical and practical implications of this difference are discussed.