The basolateral amygdala is necessary for learning but not relearning extinction of context conditioned fear

Extinction of conditioned fear involves new learning that inhibits but does not eliminate the original fear memory. This inhibitory learning is thought to require activation of NMDA receptors (NMDAr) within the basolateral amygdala (BLA). However, once extinction has been learned, the role played by the BLA during subsequent extinction procedures remains unknown. The present study examined the role of neuronal activity and NMDAr activation in rats receiving their first or second extinction of context fear. We found that BLA infusion of DL-APV, a competitive antagonist of NMDAr, depressed fear responses at both the first and second extinction. It impaired learning extinction but spared and even facilitated relearning extinction. BLA infusion of muscimol, a GABA(A) agonist, produced a similar outcome, suggesting that DL-APV not only blocked NMDAr-dependent plasticity but also disrupted neuronal activity. In contrast, infusion of ifenprodil, a more selective antagonist of NMDAr containing the NR2B subunit, did not depress fear responses but impaired short- and long-term inhibition of fear at both the first and second extinction. Therefore, we suggest that relearning extinction normally requires NMDAr containing the NR2B subunit in the BLA. However, simultaneous blockade of these receptors and neuronal activity in the BLA results in compensatory learning that is able to promote long-term re-extinction. These data are consistent with a current model that attributes fear extinction to interactions between several neural substrates, including the amygdala and the medial prefrontal cortex.     

An evaluation of psychophysical models of auditory change perception

In many psychophysical experiments, the participant's task is to detect small changes along a given stimulus dimension or to identify the direction (e.g., upward vs. downward) of such changes. The results of these experiments are traditionally analyzed with a constant-variance Gaussian (CVG) model or a high-threshold (HT) model. Here, the authors demonstrate that for changes along three basic sound dimensions (frequency, intensity, and amplitude-modulation rate), such models cannot account for the observed relationship between detection thresholds and direction-identification thresholds. It is shown that two alternative models can account for this relationship. One of them is based on the idea of sensory quanta; the other assumes that small changes are detected on the basis of Poisson processes with low means. The predictions of these two models are then compared against receiver operating characteristics (ROCs) for the detection of changes in sound intensity. It is concluded that human listeners' perception of small and unidimensional acoustic changes is better described by a discrete-state Poisson model than by the more commonly used CVG model or by the less favored HT and quantum models.     

Conscious and Preconscious Uses of Memory in Patients with Depressive and Somatoform Disorders

This study investigated whether conscious and preconscious memory features contribute to discrimination between depressive and somatoform disorders. Thirty-one participants fulfilling the diagnostic criteria for a somatoform disorder and 28 participants fulfilling the criteria for depression were examined within the framework of the process–dissociation paradigm using neutral, health-threatening, and general threatening words in a lexical decision task. Parameters of conscious memory, preconscious memory, and chance were used to compare memory features of both the groups. There was an inverse relationship between conscious and preconscious memory effects for health-threatening stimuli in the group of patients with somatoform disorders but not in the group of depressive patients. Patients with somatoform disorders showed a significantly lower level of conscious memory for health-threatening stimuli than depressive participants. Compared to depressive patients, a more dynamic relationship between decreased conscious and increased preconscious memory for health-related stimuli seems to be characteristic for patients with somatoform disorders.     

Visual discrimination by heifers (Bos taurus) of their own species

Species discrimination has been described in several taxa but rarely in domestic animals. In contrast to wild species, domestic species present a great phenotypic variety. This study investigated whether 10 Prim'Holstein heifers (Bos taurus) could discriminate images of cows from images of other domestic animals. The experiment was based on simultaneous discrimination. Responses were obtained through instrumental conditioning using a food reward. In Experiment 1, the reward was associated with a cow face and, in the reversal learning task, with faces of other domestic species. The results showed that in both tasks, cows were able to reach the criterion in few sessions. Therefore, despite great phenotypic variety (a cognitive challenge) cows were able to visually discriminate their own species from other domestic species.     

Factor structure of patient and caregiver ratings on the dementia quality of life instrument

Preliminary evidence suggests that quality of life reports from patients diagnosed with mild cognitive impairment (MCI) and mild Alzheimer's disease (AD) are as reliable and valid as data provided by caregivers. To date, no studies compared the factor structure of data provided by caregivers and patients. Factor analyses are important to conduct because they are an indicator of validity. This study compared the factor structure of patient and caregiver reports on the Dementia Quality of Life scale (DQoL). Participants (N=67) were patients diagnosed with amnestic MCI or mild AD and their caregivers. Principal axis factor analyses were run separately on patient and caregiver report data. The three-factor solutions for patient and caregiver data were nearly identical. Three factors corresponding to positive affect, negative affect, and aesthetics emerged reliably from analyses. Thus, data from patients demonstrated a factor structure that was highly consistent with caregiver report data and conformed to meaningful psychological constructs.     

The Separate, relative, and joint effects of employee job performance domains on supervisors’ willingness to mentor

The purpose of our study was to further elucidate how employees should behave at work to increase their chances of being mentored by their immediate supervisor. To that end, we experimentally tested how three domains of employee performance [task performance (TP), organizational citizenship behavior (OCB) targeting the supervisor, and counterproductive work behavior (CWB) targeting coworkers] affect supervisors’ willingness to mentor. Each performance domain affected willingness to mentor. OCB had the weakest of the three main effects. Finally, the positive effect of TP was stronger when employees displayed less CWB.