Central auditory processing in adults with chronic stroke without hearing loss: A magnetoencephalography study

ObjectiveStroke lesions in non-auditory areas may affect higher-order central auditory processing. We sought to characterize auditory functions in chronic stroke survivors with unilateral arm/hand impairment using auditory evoked responses (AERs) with lesion and perception metrics.MethodsThe AERs in 29 stroke survivors and 14 controls were recorded with single tones, active and passive frequency-oddballs, and a dual-oddball with pitch-contour and time-interval deviants. Performance in speech-in-noise, mistuning detection, and moving-sound detection was assessed. Relationships between AERs, behaviour, and lesion overlap with functional networks, were examined.ResultsDespite their normal hearing, eight patients showed unilateral AER in the hemisphere ipsilateral to the affected hand with reduced amplitude compared to those with bilateral AERs. Both groups showed increasing attenuation of later components. Hemispheric asymmetry of AER sources was reduced in bilateral-AER patients. The N1 wave (100 ms latency) and P2 (200 ms) were delayed in individuals with lesions in the basal-ganglia and white-matter, while lesions in the attention network reduced the frequency-MMN (mismatch negativity) responses and increased the pitch-contour P3a response. Patients’ impaired speech-in-noise perception was explained by AER measures and frequency-deviant detection performance with multiple regression.ConclusionAERs reflect disruption of auditory functions due to damage outside of temporal lobe, and further explain complexity of neural mechanisms underlying higher-order auditory perception.SignificanceStroke survivors without obvious hearing problems may benefit from rehabilitation for central auditory processing.     

Non-sympathetic FRN responses to drops in others’ stocks

Previous neuroeconomic studies have observed that people display sympathetic neural responses toward others’ misfortunes. We argue that the reverse emotions, such as gloating or schadenfreude, may also emerge in certain circumstances. To examine this theory, we recorded feedback-related negativity (FRN) toward others’ large or small gains or losses in a stock market context. We adopted the framework of social distance, according to which we hypothesized that because others in the stock market are far away, unidentified, and indistinct, people would show less sympathy or even schadenfreude toward others’ large losses. The results indicated that FRN at Fz was significantly less negative when observing larger decreases in others’ stock, indicating that others’ large losses are not unexpected negative events in the stock market and suggesting the existence of schadenfreude. Our research contributes to the understanding of social neurofinance by demonstrating the schadenfreude effect in relation to the stock market. This study also provides new information regarding the relationship between FRN and the social emotions that form the expectations of gain and loss.     

Neural dynamics of inflectional and derivational morphology processing in the human brain

We investigated neural distinctions between inflectional and derivational morphology and their interaction with lexical frequency using the mismatch negativity (MMN), an established neurophysiological index of experience-dependent linguistic memory traces and automatic syntactic processing. We presented our electroencephalography (EEG) study participants with derived and inflected words of variable lexical frequencies against their monomorphemic base forms in a passive oddball paradigm, along with acoustically matched pseudowords. Sensor space and distributed source modelling results showed that at 100–150 msec after the suffix onset, derived words elicited larger responses than inflected words. Furthermore, real derived words showed advantage over pseudo-derivations and frequent derivations elicited larger activation than less frequent ones. This pattern of results is fully in line with previous research that explained lexical MMN enhancement by an activation of strongly connected word-specific long-term memory circuits, and thus suggests stronger lexicalisation for frequently used complex words. At the same time, a strikingly different pattern was found for inflectional forms: higher response amplitude for pseudo-inflections than for real inflected words, with no clear frequency effects. This is fully in line with previous MMN results on combinatorial processing of (morpho)syntactic stimuli: higher response to ungrammatical morpheme strings than grammatical ones, which does not depend on the string's surface frequency. This pattern suggests that, for inflectional forms, combinatorial processing route dominates over whole-form storage and access. In sum, our results suggest that derivations are more likely to form unitary representations than inflections which are likely to be processed combinatorially, and imply at least partially distinct brain mechanisms for the processing and representation of these two types of morphology. These dynamic mechanisms, underpinned by perisylvian networks, are activated rapidly, at 100–150 msec after the information arrives at the input, and in a largely automatic fashion, possibly providing neural basis for the first-pass morphological processing of spoken words.     

Detection of K-<Emphasis Type="Italic">ras</Emphasis> mutations in the plasma DNA of pancreatic cancer patients

Background In pancreatic cancers, K-ras mutations have been found frequently (80%–100%), and they could be a good marker to detect tumor DNA in the plasma. Several studies have indicated that polymerase chain reaction/restriction fragment length polymorphism (PCR/RFLP) analysis of K-ras mutation was a useful method for the detection of hepatic and lymph node metastasis of pancreatic cancer. However, this method sometimes exhibited false-positive results, and the rate of K-ras mutation might thus be overestimated in these tissues. To diagnose pancreatic cancer correctly at an early stage, we attempted to detect tumor DNA in the plasma of pancreatic cancer patients using a more sensitive and specific method.Methods We examined 28 pancreatic cancer patients using a sensitive mutation-specific mismatch ligation assay for K-ras gene mutations in primary tumors and paired plasma samples.Results K-ras gene mutations were detected in 26 of the 28 (93%) pancreatic cancers. We also found the same mutations in 9 of these 26 (35%) patients in their plasma DNA. This mutation was found even in the plasma of patients with TNM stage II cancer.Conclusions Genetic alterations present in the tumors of pancreatic cancer patients can be detected in their plasma, and this approach is potentially applicable for cancer screening and the monitoring of this deadly disease.