Repeated stimulus presentation leads to neural adaptation and consequent amplitude reduction in vowel-evoked envelope following responses (EFRs)-a response that reflects neural activity phase-locked to envelope periodicity.EFRs are elicited by vowels presented in isolation or in the context of other phonemes such as consonants in syllables. While context phonemes could exert some forward influence on vowel-evoked EFRs, they may reduce the degree of adaptation. Here, we evaluated whether the properties of context phonemes between consecutive vowel stimuli influence adaptation. EFRs were elicited by the low-frequency first formant (resolved harmonics) and middleto-high-frequency second and higher formants (unresolved harmonics) of a male-spoken /i/ when the presence, number and predictability of context phonemes (/s/, /a/, / Ð / and /u/) between vowel repetitions varied. Monitored over four iterations of /i/, adaptation was evident only for EFRs elicited by the unresolved harmonics. EFRs elicited by the unresolved harmonics decreased in amplitude by $16-20 nV (10%-17%) after the first presentation of /i/ and remained stable thereafter. EFR adaptation was reduced by the presence of a context phoneme, but the reduction did not change with their number or predictability. The presence of a context phoneme, however, attenuated EFRs by a degree similar to that caused by adaptation ($21-23 nV). Such a trade-off in the short-and long-term influence of context phonemes suggests that the benefit of interleaving EFR-eliciting vowels with other context phonemes depends on whether the use of consonant-vowel syllables is critical to improve the validity of EFR applications.

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Throughout the past decades, there has been growing concern about society's increasing dependence on technology, especially regarding cell phone usage and brain tumors. Despite the numerous case studies and meta-analyses published, the contradicting conclusions on the topic have led to insufficient scientific data to support or refute this claim. Since cell phones are so widespread, even a small increase in risk of brain tumors could have large adverse effects on public health. This meta-analysis will examine these studies to determine a possible conclusion. All studies were obtained from PubMed, published from 2001 to 2013, included unadjusted odds ratios, and investigated the relationship between subjects' incidences of brain tumors and their cell phone usage. Odds ratios (ORs) and confidence intervals (CIs) were calculated for each brain tumor subtype, laterality of tumor location, and each individual study. A pooled OR was found using Comprehensive Meta-Analysis Software. After careful consideration, 19 case studies were chosen to be in this meta-analysis. In total, this included 84,226 patients, 61,845 controls, and 15 countries. 100-1.559). Ultimately, the pooled OR was found to be 0.963 (0.904 -1.027). This meta-analysis confirms no relationship between use of handheld cellular telephones and increased risk of brain tumor occurrence. However, the effects of persisting exposure on subjects' health warrants further evaluation in prospective long-term epidemiological studies.

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