Meaning selection and the subcortex: Evidence of reduced lexical ambiguity repetition effects following subcortical lesions

Recent research indicates that individuals with nonthalamic subcortical (NS) lesions call experience difficulties processing lexical ambiguities in a variety of contexts. This study examined how prior processing of a lexical ambiguity influences subsequent meaning activation in 10 individuals with NS lesions and 10 matched healthy controls. Subjects made speeded lexical decisions oil related or unrelated targets following homophone primes. Homophones were repealed with different targets biasing the same or different meanings oil the second presentation. The effects of prime-target relatedness, interstimulus interval (200 or 1250 ms), and same vs different meaning repetition were examined Both the patient and control groups showed printing when the same homophone meaning was biased oil repetition. When a different meaning was biased on the second presentation. no priming was evident in the controls, while facilitation remained present for the NS group, consistent with aberrant meaning selection and deactivation processes. These findings are discussed in terms of age and task-related repetition effects and current conceptions of frontal-subcortical involvement in cognition.

Of snakes and flowers: Does preferential detection of pictures of fear-relevant animals in visual search reflect on fear-relevance?

Previous research in visual search indicates that animal fear-relevant deviants, snakes/spiders, are found faster among non fear-relevant backgrounds, flowers/mushrooms, than vice versa. Moreover, deviant absence was indicated faster among snakes/spiders and detection time for flower/mushroom deviants, but not for snake/spider deviants, increased in larger arrays. The current research indicates that the latter 2 results do not reflect on fear-relevance, but are found only with flower/mushroom controls. These findings may reflect on factors such as background homogeneity, deviant homogeneity, or background-deviant similarity. The current research removes contradictions between previous studies that used animal and social fear-relevant stimuli and indicates that apparent search advantages for fear-relevant deviants seem likely to reflect on delayed attentional disengagement from fear-relevance on control trials.

Phosphoinositide regulation of neuroexocytosis: adding to the complexity

Exocytosis of neurotransmitter containing vesicles supports neuronal communication. The importance of molecular interactions involving specific lipids has become progressively more evident and the lipid composition of both the synaptic vesicle and the pre-synaptic plasma membrane at the active zone has significant functional consequences for neurotransmitter release. Several classes of lipids have been implicated in exocytosis including polyunsaturated fatty acids and phosphoinositides. This minireview will focus on recent developments regarding the role of phosphoinositides in neurosecretion.

Relationship between bicarbonate retention and bone characteristics in broiler chickens

Determination of the bicarbonate retention factor (BRF) is an important step during development of the indicator amino acid oxidation technique for use in a new model. A series of 4-h oxidation experiments were performed to determine the BRF of broilers aged 7, 14, 21, 28, 35, and 42 d using 4 birds per age group. A priming dose of 1.2 mu Ci of (NaHCO3)-C-14, followed by eight half-hourly doses of 1 mu Ci of (NaHCO3)-C-14 were given orally to each of 4 birds per age. The percentage of 14 C dose expired by the bird at a steady state was measured. These birds, as well as 12 additional birds matched for age and BW, were killed, and femur bone mineral density was measured by quantitative computed tomography to determine the relationship between bone development and bicarbonate retention at each age. There was a correlation (r = 0.50; P < 0.05) between total cross-sectional femur bone mineral density and bicarbonate retention at each age. A prediction equation (Y = 6.95 x 10(-2) X - 3.51 x 10(5)X(2) + 27.58; P < 0.0001, R-2 = 0.79) where Y = bicarbonate retention and X = BW was generated to predict Y as a function of X. Bicarbonate retention values peaked at 28 d, during the stage of the most rapid bone deposition and the highest growth rate. A constant BRF was found from 1,900 to 2,700 g of BW of 35.15 +/- 1.095% (mean SEM). This retention factor will allow the accurate correction of oxidation of C-14-labeled substrates in broilers of different ages and BW in future indicator amino acid oxidation studies.

Signal integration between IFN gamma and TLR signalling pathways in macrophages

Macrophages are major effector cells of the innate immune system, and appropriate regulation of macrophage function requires the integration of multiple signalling inputs derived from the recognition of host factors (e.g. interferon-gamma/IFN gamma) and pathogen products (e.g. toll-like receptor/TLR agonists). The profound effects of IFN gamma pre-treatment (priming) on TLR-induced macrophage activation have long been recognised, but many of the mechanisms underlying the priming phenotype have only recently been identified. This review summarises the known mechanisms of integration between the IFN gamma and TLR signalling pathways. Synergy occurs at multiple levels, ranging from signal recognition to convergence of signals at the promoters of target genes. In particular, the cross-talk between the IFN gamma and LPS and CpG DNA signalling pathways is discussed. (c) 2006 Elsevier GmbH. All rights reserved.

Top-down influences on lexical selection during spoken word production: A 4T fMRI investigation of refractory effects in picture naming

Spoken word production is assumed to involve stages of processing in which activation spreads through layers of units comprising lexical-conceptual knowledge and their corresponding phonological word forms. Using high-field (4T) functional magnetic resonance imagine (fMRI), we assessed whether the relationship between these stages is strictly serial or involves cascaded-interactive processing, and whether central (decision/control) processing mechanisms are involved in lexical selection. Participants performed the competitor priming paradigm in which distractor words, named from a definition and semantically related to a subsequently presented target picture, slow picture-naming latency compared to that with unrelated words. The paradigm intersperses two trials between the definition and the picture to be named, temporally separating activation in the word perception and production networks. Priming semantic competitors of target picture names significantly increased activation in the left posterior temporal cortex, and to a lesser extent the left middle temporal cortex, consistent with the predictions of cascaded-interactive models of lexical access. In addition, extensive activation was detected in the anterior cingulate and pars orbitalis of the inferior frontal gyrus. The findings indicate that lexical selection during competitor priming is biased by top-down mechanisms to reverse associations between primed distractor words and target pictures to select words that meet the current goal of speech.

Searching for the trace: The influence of age, lexical activation and working memory on sentence processing

To investigate the stability of trace reactivation in healthy older adults, 22 older volunteers with no significant neurological history participated in a cross-modal priming task. Whilst both object relative center embedded (ORC) and object relative right branching (ORR) sentences is-ere employed, working memory load was reduced by limiting the number of wordy separating the antecedent front the gap for both sentence types. Analysis of the results did not reveal any significant trace reactivation for the ORC or ORR sentences. The results did reveal, however, a positive correlation between age and semantic printing at the pre-gap position and a negative correlation between age and semantic printing at the gap position for ORC sentences. In contrast, there was no correlation between age and priming effects for the ORR sentences. These results indicated that trace reactivation may be sensitive to a variety of age related factors, including lexical activation and working memory. The implications of these results for sentence processing in the older population arc discussed.

The influence of dopamine on semantic activation in Parkinson's disease: Evidence from a multipriming task

Research has suggested that semantic processing deficits in Parkinson's disease (PD) are related to striatal dopamine deficiency. As an investigation of the influence of dopamine on semantic activation in PD, 7 participants with PD performed a lexical-decision task when on and off levodopa medication. Seven healthy controls matched to the participants with PD in terms of sex, age, and education also participated in the study. By use of a multipriming paradigm, whereby 2 prime words were presented prior to the target word, semantic priming effects were measured across stimulus onset asynchronies (SOAs) of 250 Ins and 1,200 Ins. The results revealed a similar pattern of priming across SOAs for the control group and the PD participants on medication. In contrast, within-group comparisons revealed that automatic semantic activation was compromised in PD participants when off medication. The implications of these results for the neuromodulatory influence of dopamine on semantic processing in PD are discussed.

Anterior lamella actinic changes as a factor in involutional eyelid malposition

Purpose: We conducted a noncomparative, retrospective chart review of 45 patients and 51 eyelids with the diagnosis of involutional entropion or ectropion that underwent full-thickness lower eyelid shortening between June 2001 and February 2004, in whom the severity of actinic damage was analyzed in relation to the eyelid position. Patients with any different surgical approach or other primary causes of abnormal eyelid position, such as paralytic, congenital, or mechanical factors, were excluded. Methods: After excision, all eyelid specimens were examined by a single anatomic pathologist, who was masked to the type of eyelid malposition. The extent of dermal actinic change was evaluated under light microscopy, according to a previously validated grading system. Results: Fifty-one eyelids from 26 male and 19 female patients were analyzed. The mean age at the surgery was 76 +/- 10 years (range, 52 to 92 years), affecting one side in 39 cases and both sides in 6 cases. The most frequent eyelid malposition was ectropion, which affected two thirds of the cases (35 eyelids). Half of the patients presented with mild actinic skin changes; however, the severity of the histologic skin actinic changes was significantly worse in patients with ectropion in comparison to those with entropion (p < 0.0001). Conclusions: Actinic damage affecting the anterior lamella of the lower eyelid contributes as an additional factor in final eyelid position in patients with involutional eyelid changes. More severe and extensive actinic changes were present in eyelids with ectropion.

Attention vs. emotion: Affective learning and the startle reflex

The eye-blink startle reflex can be modulated by attentional and emotional processes. The reflex is facilitated during stimuli that engage attention. A linear pattern of emotional modulation has also been consistently demonstrated: the reflex is facilitated during unpleasant stimuli and attenuated during pleasant stimuli. However, during anticipation of pleasant or unpleasant stimuli it is unclear whether emotion or attention drives startle reflex modulation. This study used a differential learning procedure to investigate whether startle modulation during anticipation of a salient stimulus reflected emotional or attentional processes. In acquisition, a CS+ was paired with a pleasant or unpleasant US and a CS- was presented alone. In extinction, blink startle magnitude was measured during CS+ and CS-. Post-acquisition valence ratings and affective priming showed that CS+ had acquired the same affective value as the pleasant or unpleasant US with which it was paired. No differences in modulation of blink startle reflexes during pleasant CS+ and unpleasant CS+ were found throughout extinction. Blink startle facilitation occurred during CS+ but not CS- across the first third of extinction. Thus, attentional rather than emotional processes appeared to facilitate blink startle during anticipation of salient stimuli.

The good and the bad: Acquisition of likes and dislikes in affective learning

Affective learning, the acquisition of likes and dislikes, was investigated in two experiments using verbal ratings and affective priming as indices of affective change. In both experiments, neutral geometric shapes were paired with pleasant or unpleasant pictures in a picture-picture conditioning procedure to acquire positive and negative valence. Experiment 1 found the acquisition of positive valence; however, this valence change was lost after extinction training. Experiment 2 used more salient pictures as unconditioned stimuli. Positive and negative valence was acquired during paired presentations and retained across extinction training. The results of Experiment 2 are consistent with dual process accounts, which claim that evaluative conditioning is distinct from Pavlovian conditioning because it is resistant to extinction.