Frontal and temporal contributions to understanding the iconic co-speech gestures that accompany speech

In everyday conversation, listeners often rely on a speaker's gestures to clarify any ambiguities in the verbal message. Using fMRI during naturalistic story comprehension, we examined which brain regions in the listener are sensitive to speakers' iconic gestures. We focused on iconic gestures that contribute information not found in the speaker's talk, compared with those that convey information redundant with the speaker's talk. We found that three regions-left inferior frontal gyrus triangular (IFGTr) and opercular (IFGOp) portions, and left posterior middle temporal gyrus (MTGp)--responded more strongly when gestures added information to nonspecific language, compared with when they conveyed the same information in more specific language; in other words, when gesture disambiguated speech as opposed to reinforced it. An increased BOLD response was not found in these regions when the nonspecific language was produced without gesture, suggesting that IFGTr, IFGOp, and MTGp are involved in integrating semantic information across gesture and speech. In addition, we found that activity in the posterior superior temporal sulcus (STSp), previously thought to be involved in gesture-speech integration, was not sensitive to the gesture-speech relation. Together, these findings clarify the neurobiology of gesture-speech integration and contribute to an emerging picture of how listeners glean meaning from gestures that accompany speech.

Maintenance of the DNA puff expanded state is independent of active replication and transcription

The maintenance of the expanded state of DNA puffs II/2B and II/9A in polytene chromosomes from stage 14 x 7 Sciara coprophila salivary glands was assayed after inhibition of RNA synthesis, DNA synthesis, or both processes together. Heat shock conditions were established in order to inhibit transcription. Polypeptides of Mr 72,000 and 36,000 were produced in Sciara after heat shock. The gene encoding the Mr 72,000 polypeptide, the homolog of Drosophila hsp70, was cloned. In situ hybridization detected Sciara hsp70 at bands 4A and 17C on chromosome IV. Sciara hsp70 encodes a 2.3 kb heat shock mRNA. DNA puffs (e.g., DNA puffs 2B and 9A on chromosome II) remained fully expanded even after inhibition of transcription by heat shock or actinomycin D, or after inhibition of DNA replication by aphidicolin, or inhibition of both RNA synthesis and DNA synthesis together by actinomycin D plus aphidicolin. Therefore, maintenance of the DNA puff expanded state in Sciara does not require ongoing transcription and/or replication. Mechanisms for initiation and for maintenance of puffs (open chromatin structure) are discussed.