Stress-induced Fos-like Immunoreactivity in the Pons and the Medulla Oblongata of Rats

Immunoreactivity of the immediate early gene c-fos was used to investigate changes in the activity of brainstem neurons in response to acute stressors like immobilization, formalin-induced pain, cold exposure, hemorrhage and insulin-induced hypoglycemia. Different stressors induced Fos-like immunoreactivity in different pontine and medullary neurons. A single, 3 hour immobilization was found to be a very strong stimulus that activated brainstem catecholaminergic (tyrosine hydroxylase-immunopositive) neurons and cells in the raphe and certain pontine tegmental nuclei, as well as in the reticular formation. Pain, induced by a subcutaneous injection of formalin was also effective on catecholamine-synthesizing neurons and on others cells in the nucleus of the solitary tract. Cold exposure activated cells mainly in the sensory spinal trigeminal and parabrachial nuclei and in the so-called "pontine thermoregulatory area". Moderate Fos-like immunoreactivity was induced by a hypotonic (25%) hemorrhage in medullary catecholaminergic neurons, the nucleus of the solitary tract and the Barrington nucleus. Among stressful stimuli used, insulin-induced hypoglycemia elicited the smallest Fos activation in the lower brainstem. The present observations indicate that different stressors may use different neuronal pathways in the central organization of the stress response.     

Visual skills in airport-security screening

Abstract— An experiment examined visual performance in a simulated luggage-screening task. Observers participated in five sessions of a task requiring them to search for knives hidden in x-ray images of cluttered bags. Sensitivity and response times improved reliably as a result of practice. Eye movement data revealed that sensitivity increases were produced entirely by changes in observers' ability to recognize target objects, and not by changes in the effectiveness of visual scanning. Moreover, recognition skills were in part stimulus-specific, such that performance was degraded by the introduction of unfamiliar target objects. Implications for screener training are discussed.     

Age-related differences in localized attentional interference

Attentional selection of an object in the visual field degrades processing of neighboring stimuli in young adults. A pair of experiments examined the effects of aging on such localized attentional interference. In Experiment 1, younger and older observers made speeded same-different judgments of target shapes that varied in spatial separation. Performance declined for both age groups as the distance between targets decreased, but an Age x Distance interaction indicated that the magnitude of this effect was larger for older adults. Experiment 2 ruled out sensory masking as an explanation for these findings. Results indicate that older observers experience losses in the ability to attend to multiple spatially proximal stimuli within the visual field.     

The View from the Driver's Seat: What Good Is Salience?

A set of experiments gauged the value of salient and non‐salient visual information to drivers' decision making. Stimuli were images of traffic scenes viewed from a drivers' approximate perspective, and the subjects' task was to make stop‐or‐go driving judgments. Under some experimental conditions (Experiment 1), subjects viewed only the salient information from within each scene. Under other conditions (Experiments 2–3), they viewed only the non‐salient information. A signal detection measure of sensitivity served as the primary dependent measure. Data indicated that an above‐chance amount of the information needed for accurate judgments was contained within salient image regions and that some information was available only from the salient regions. Other critical information, however, was contained exclusively within non‐salient regions. Results suggest that an attentional bias toward visual salience would serve as an economical information‐seeking strategy for drivers but by itself would overlook many task‐critical cues. Copyright © 2013 John Wiley & Sons, Ltd.     

Connectivity among semantic associates: an fMRI study of semantic priming

Semantic priming refers to a reduction in the reaction time to identify or make a judgment about a stimulus that has been immediately preceded by a semantically related word or picture and is thought to result from a partial overlap in the semantic associates of the two words. A semantic priming lexical decision task using spoken words was presented in event-related fMRI and behavioral paradigms. Word pairs varied in terms of semantic relatedness and the connectivity between associates. Thirteen right-handed subjects underwent fMRI imaging and 10 additional subjects were tested in a behavioral version of the semantic priming task. It was hypothesized priming would be greatest, reaction time fastest, and cortical activation reduced the most for related word pairs of high connectivity, followed by related word pairs of low connectivity, and then by unrelated word pairs. Behavioral and fMRI results confirmed these predictions. fMRI activity located primarily in bilateral posterior superior and middle temporal regions showed modulation by connectivity and relatedness. The results suggest that these regions are involved in semantic processing.     

Spatial interference between attended items engenders serial visual processing

A pair of experiments investigated the architecture of visual processing, parallel versus serial, across high and low levels of spatial interference in a divided attention task. Subjects made speeded judgments that required them to attend to a pair of color-cued objects among gray filler items, with the spatial proximity between the attended items varied to manipulate the strength of interference between attended items. Systems factorial analysis (Townsend & Nozawa, Journal of Mathematical Psychology 39:321-359, 1995) was used to identify processing architecture. Experiment 1, using moderately dense displays, found evidence of parallel processing whether attended objects were in low or high proximity to one another. Experiment 2, using higher-density displays, found evidence of parallel selection when attended stimuli were widely separated but serial processing when they were in high proximity. Divided visual attention can operate in parallel under conditions of low or moderate spatial interference between selected items, but strong interference engenders serial processing.     

Attentional cues in chronic schizophrenia: abnormal disengagement of attention.

Posner's (1980) reaction time (RT) paradigm was used to examine the engagement and disengagement operations of visual selective attention in patients with schizophrenia. In the 1st experiment, 14 medicated, chronic schizophrenic subjects (diagnosed by criteria of the Diagnostic and Statistical Manual of Mental Disorders; American Psychiatric Association, 1987) and 15 age-matched normal control subjects made a speeded response to a target preceded by a valid, an invalid, or no cue. Control subjects showed the expected advantage and disadvantage in RT for valid and invalid cues, which suggests intact engagement and disengagement operations. For schizophrenic patients, valid cues also enhanced RT, but invalid cues did not slow RT. Similar results were found in the 2nd experiment. The failure of unpredictable, invalid cues to inhibit RT in chronic schizophrenia may be related to an abnormality in the disengagement operation of selective attention.     

Significance of violence in stories of young children

Stories told by 72 5-yr.-old children were scored for themes of violence and correlated with their mothers' reports of aggressive or fearful behaviors. Values for the entire sample were not significant. However, when data for Hispanic children were removed from the sample the correlation of violent stories to ratings of children's aggression was significant (r = .27) and for a count of violent words r = .30. The correlation of violent words to fearfulness was .28 and for girls only .35. The count of violent words was also correlated with African-American children's ratings of fearfulness (r = .64).     

Age at earliest reported memory: associations with personality traits, behavioral health, and repression

The present study examined relationships between the age at earliest memory and the personality traits and behavioral health of 107 undergraduates. Participants answered questions on their earliest memory and completed the Myers-Briggs Type Indicator (MBTI) and a medical history form. Analyses indicated that continuous scores on two MBTI scales (Sensing-Intuition and Judging-Perceiving) were inversely related to age at earliest memory as were participant's self-reported drug and alcohol problems, emotional and psychological symptoms, accident rates, physical symptoms, and satisfaction with health. Respondents who reported first memories at or after 7 years of age (i.e., approximately 1 SD above the mean age at recalled memory) were classified as repressors. Repressors scored in the Sensing and Judging directions on the MBTI and reported significantly fewer emotional symptoms, accidents, psychological symptoms, and less health satisfaction than nonrepressors. Results are consistent with the age at earliest memory and repression literature and support the use of earliest memory age as an index of repression.     

Attentional templates regulate competitive interactions among attended visual objects

In two experiments, we examined the mechanisms responsible for creating a zone of interference surrounding an attended visual object (see, e.g., Mounts & Gavett, 2004). In Experiment 1, the similarity between attended stimuli and noise items was manipulated in order to contrast an account based on competitive interactions between attended items with an account based on inefficient filtering of unattended stimuli. Consistent with the competitive interaction account, the data revealed that similarity between attended items increased the strength of localized interference, whereas similarity of noise items to the attended stimuli did not. Experiment 2 showed that the interference observed between attended items was determined by their match to attentional templates.