The neurobiology of taboo language processing: fMRI evidence during spoken word production

Every language has words deemed to be socially inappropriate or ‘taboo’ to utter. Taboo word production appears prominently in language disorders following brain injury. Yet, we know little about the cognitive and neural mechanisms involved in processing taboo compared to neutral language. In the present study, we introduced taboo distractor words in the picture word interference paradigm during functional magnetic resonance imaging to investigate how these words influence spoken word production. Taboo distractor words significantly slowed picture-naming latencies compared to neutral words. This interference effect was associated with increased blood oxygen level dependent signal across a distributed thalamo-cortical network including bilateral anterior cingulate cortex and left inferior frontal gyrus, left posterior middle temporal gyrus and right thalamus. We interpret our findings as being consistent with an account integrating both domain-general attention-capture/distractor blocking and language-specific mechanisms in processing taboo words during spoken word production.

Neural Mechanisms for Monitoring and Halting of Spoken Word Production

During conversation, speakers monitor their own and others' output so they can alter their production adaptively, including halting it if needed. We investigated the neural mechanisms of monitoring and halting in spoken word production by employing a modified stop signal task during fMRI. Healthy participants named target pictures and withheld their naming response when presented with infrequent auditory words as stop signals. We also investigated whether the speech comprehension system monitors inner (i.e., prearticulatory) speech via the output of phonological word form encoding as proposed by the perceptual loop theory [Levelt, W. J. M. Speaking: From intention to articulation. Cambridge, MA: MIT Press, 1989] by presenting stop signals phonologically similar to the target picture name (e.g., cabbage-CAMEL). The contrast of successful halting versus naming revealed extensive BOLD signal responses in bilateral inferior frontal gyrus, preSMA, and superior temporal gyrus. Successful versus unsuccessful halting of speech was associated with increased BOLD signal bilaterally in the posterior middle temporal, frontal, and parietal lobes and decreases bilaterally in the posterior and left anterior superior temporal gyrus and right inferior frontal gyrus. These results show, for the first time, the neural mechanisms engaged during both monitoring and interrupting speech production. However, we failed to observe any differential effects of phonological similarity in either the behavioral or neural data, indicating monitoring of inner versus external speech might involve different mechanisms.

The locus of taboo context effects in picture naming

Speakers respond more slowly when naming pictures presented with taboo (i.e., offensive/embarrassing) than with neutral distractor words in the picture–word interference paradigm. Over four experiments, we attempted to localize the processing stage at which this effect occurs during word production and determine whether it reflects the socially offensive/embarrassing nature of the stimuli. Experiment 1 demonstrated taboo interference at early stimulus onset asynchronies of −150 ms and 0 ms although not at 150 ms. In Experiment 2, taboo distractors sharing initial phonemes with target picture names eliminated the interference effect. Using additive factors logic, Experiment 3 demonstrated that taboo interference and phonological facilitation effects do not interact, indicating that the two effects originate at different processing levels within the speech production system. In Experiment 4, interference was observed for masked taboo distractors, including those sharing initial phonemes with the target picture names, indicating that the effect cannot be attributed to a processing level involving responses in an output buffer. In two of the four experiments, the magnitude of the interference effect correlated significantly with arousal ratings of the taboo words. However, no significant correlations were found for either offensiveness or valence ratings. These findings are consistent with a locus for the taboo interference effect prior to the processing stage responsible for word form encoding. We propose a pre-lexical account in which taboo distractors capture attention at the expense of target picture processing due to their high arousal levels.

A quantitative comparison of the kidneys of the lanlocked sea lamprey of the Great Lakes and the anadromous sea lamprey of the Atlantic, Petromyzon marinus L

The length and cross-sectional area of the kidneys and the elongate renal corpuscles in both marine and freshwater lamprey, Petromyzon marinus L., increase proportionately as the animal increases in length. The paired kidneys are seldom identical, with one kidney usually longer and of greater cross-sectional area. Marine males demonstrate a larger cross-sectional area of their kidneys and renal corpuscles compared with marine females of similar size. The cross-sectional areas of the renal corpuscles of freshwater and marine animals are not significantly different and hence the amount of filtration surface is the same in the kidneys of both groups of animals. The evolution of the renal corpuscle and the involvement of this structure in osmoregulation in lampreys is discussed.