Neurocognitive Function and Suicide in U.S. Army Soldiers

This prospective cohort study used administrative data from the Army Study to Assess Risk and Resilience in Servicemembers to examine associations between neurocognitive functioning and subsequent suicidal events among Regular Army enlisted soldiers during the years 2004–2009. Cases were all soldiers who completed the Army's Automated Neuropsychological Assessment Metrics (ANAM) computerized testing battery prior to documented suicide attempt (n = 607), ideation (n = 955), or death (n = 57). Controls were an equal‐probability sample of 9,893 person‐months from other soldiers. Exploratory factor analysis of five ANAM tests identified a general neurocognitive factor that excluded the mathematic processing test (MTH). When examined separately in logistic regression analyses that controlled for sociodemographics and prior mental health diagnosis, both the general neurocognitive factor (logit [β] = ?.197 to ?.521; p < .01) and MTH (β = ?.024 to ?.064; p < .05) were associated with all outcomes. When both predictors were examined simultaneously, the general neurocognitive factor continued to be associated with all outcomes (β = ?.164 to ?.417; p < .05) and MTH continued to be associated with suicide attempt (β = ?.015; p = .046) and ideation (β = ?.014; p = .018). These small but robust associations suggest that future research must continue to examine the extent to which objective neurocognitive tests may enhance understanding and prediction of suicide risk.     

Electrophysiological evidence for age effects on sensory memory processing of tonal patterns

In older adults, difficulties processing complex auditory scenes, such as speech comprehension in noisy environments, might be due to a specific impairment of temporal processing at early, automatic processing stages involving auditory sensory memory (ASM). Even though age effects on auditory temporal processing have been well-documented, there is a paucity of research on how ASM processing of more complex tone-patterns is altered by age. In the current study, age effects on ASM processing of temporal and frequency aspects of two-tone patterns were investigated using a passive listening protocol. The P1 component, the mismatch negativity (MMN) and the P3a component of event-related brain potentials (ERPs) to tone frequency and temporal pattern deviants were recorded in younger and older adults as a measure of auditory event detection, ASM processing, and attention switching, respectively. MMN was elicited with smaller amplitude to both frequency and temporal deviants in older adults. Furthermore, P3a was elicited only in the younger adults. In conclusion, the smaller MMN amplitude indicates that automatic processing of both frequency and temporal aspects of two-tone patterns is impaired in older adults. The failure to initiate an attention switch, suggested by the absence of P3a, indicates that impaired ASM processing of patterns may lead to less distractibility in older adults. Our results suggest age-related changes in ASM processing of patterns that cannot be explained by an inhibitory deficit.     

Error monitoring dysfunction across the illness course of schizophrenia

Response monitoring abnormalities have been reported in chronic schizophrenia patients, but it is unknown whether they predate the onset of psychosis, are present in early stages of illness, or are late-developing abnormalities associated with illness progression. Response-synchronized event-related potentials (ERP) recorded during a picture-word matching task yielded error-related negativity (ERN), correct-response negativity (CRN), and error positivity (Pe) from 84 schizophrenia patients (SZ), 48 clinical high risk patients (CHR), and their age-matched healthy controls (HC; n = 110 and 88, respectively). A sub-sample of 35 early illness schizophrenia patients (ESZ) was compared to 93 age-matched HC and the CHR patients (after statistically removing the effects of normal aging). Relative to HC, 1) SZ, ESZ, and CHR had smaller ERNs, and 2) SZ and ESZ had larger CRNs and smaller Pes. Within the SZ, longer illness duration was associated with larger CRNs but was unrelated to ERN or Pe. CHR and ESZ did not differ on ERN or CRN, although Pe was smaller in ESZ than CHR. These results indicate that while ERN, CRN, and Pe abnormalities are present early in the illness, only the ERN abnormality is evident prior to psychosis onset, and only the CRN abnormality appears to worsen progressively over the illness course. Brain regions subserving response monitoring may be compromised early in the illness and possibly during its clinical prodrome.     

Dopamine regulation of human speech and bird song: a critical review

To understand the neural basis of human speech control, extensive research has been done using a variety of methodologies in a range of experimental models. Nevertheless, several critical questions about learned vocal motor control still remain open. One of them is the mechanism(s) by which neurotransmitters, such as dopamine, modulate speech and song production. In this review, we bring together the two fields of investigations of dopamine action on voice control in humans and songbirds, who share similar behavioral and neural mechanisms for speech and song production. While human studies investigating the role of dopamine in speech control are limited to reports in neurological patients, research on dopaminergic modulation of bird song control has recently expanded our views on how this system might be organized. We discuss the parallels between bird song and human speech from the perspective of dopaminergic control as well as outline important differences between these species.     

The Multidimensional Structure of ‘better than’

Axiomathes - According to the mixed lexicographic/additive account of ‘better than’ and similar aggregative value comparatives like ‘healthier than’, values are...