Effects of Acute Stress or Centrally Injected Interleukin-1beta on Neuropeptide Expression in the Immune System

Acute stress stimulates the expression and release of corticotropin-releasing hormone (CRH) and arginine vasopressin (AVP) from the hypothalamus, and the pro-opiomelanocortin products beta-endorphin and ACTH from the anterior pituitary. These neuropeptides are also expressed in immune tissues, and it has been proposed that they may modulate immune responses to stress through paracrine mechanisms. We subjected rats to restraint stress or central injection of interleukin (IL)-1beta to determine whether these acute stimuli can alter the expression of neuropeptides in the spleen and thymus. Restraint stress significantly increased the contents of all these neuropeptides in thymic, but not splenic, extracts. A single icv injection of IL-1beta increased contents of CRH, AVP, ACTH and beta-endorphin in the spleens of both sham-operated and adrenalectomised (ADX) rats. IL-1beta increased thymic contents of CRH and ACTH in sham-operated rats but these increases were not observed in ADX rats. These results suggest that the effects of IL-1beta on neuropeptide expression in the spleen are independent of glucocorticoids, whereas IL-1beta stimulation of neuropeptide expression in the thymus is dependent on circulating glucocorticoids. There were significant correlations between increases in CRH, ACTH and beta-endorphin in the spleen, and between CRH and ACTH in the thymus, consistent with the suggestion that IL-1beta-induced increases in ACTH and beta-endorphin may be mediated through CRH. These results provide evidence that stressors can directly influence neuropeptide expression in immune tissues. Thus stress may influence immune functions through paracrine mechanisms involving locally synthesised neuropeptides as well as through activation of the hypothalamo-pituitary-adrenal axis.     

Verb subcategorization frequencies: American English corpus data,methodological studies,and cross-corpus comparisons

Verb subcategorization frequencies (verb biases) have been widely studied in psycholinguistics and play an important role in human sentence processing. Yet available resources on subcategorization frequencies suffer from limited coverage, limited ecological validity, and divergent coding criteria. Prior estimates of verb transitivity, for example, vary widely with corpus size, coverage, and coding criteria. This article provides norming data for 281 verbs of interest to psycholinguistic research, sampled from a corpus of American English, along with a detailed coding manual. We examine the effect on transitivity bias of various coding decisions and methods of computing verb biases.     

Regulation of Peripheral Catecholamine Responses to Acute Stress in Young Adult and Aged F-344 Rats

Young adult (3-month-old) and aged (24-month-old) Fischer-344 male rats received i.v. infusions of 3H-labeled norepinephrine (NE) and epinephrine (EPI) to examine the effects of aging on the neuronal uptake of NE and sympathoadrenal release of NE and EPI. Spillovers of NE and EPI into plasma and their clearance from the circulation were estimated from plasma concentrations of endogenous and 3H-labeled NE and EPI. The efficiency of neuronal uptake was assessed from changes in plasma clearance of NE and concentrations of its intraneuronal metabolite, dihydroxyphenylglycol (DHPG), during immobilization stress or neuronal uptake blockade with desipramine. Stress-induced increases in plasma NE and higher plasma NE concentrations in aged compared to young adult rats were due to both decreases in NE clearance and increases in NE spillover. EPI spillover and clearance were reduced in aged compared to young adult rats, so that plasma EPI levels did not differ between groups. Young adult and aged rats had similar desipramine-induced decreases in NE clearance, whereas desipramine-sensitive decreases and stress-induced increases in plasma DHPG were larger in aged rats. This indicates that neuronal uptake is intact and that increased NE spillover at rest and during stress in aged rats reflects increased NE release from sympathetic nerves. The results show that aging is associated with divergent decreases in EPI release from the adrenal medulla and increases in NE release from sympathetic nerves. Increased plasma concentrations of NE in aged compared to young adult rats also result from decreased circulatory clearance of NE, but this does not reflect any age-related impairment of NE reuptake.     

A Probabilistic Model of Lexical and Syntactic Access and Disambiguation

The problems of access—retrieving linguistic structure from some mental grammar —and disambiguation—choosing among these structures to correctly parse ambiguous linguistic input—are fundamental to language understanding. The literature abounds with psychological results on lexical access, the access of idioms, syntactic rule access, parsing preferences, syntactic disambiguation, and the processing of garden-path sentences. Unfortunately, it has been difficult to combine models which account for these results to build a general, uniform model of access and disambiguation at the lexical, idiomatic, and syntactic levels. For example, psycholinguistic theories of lexical access and idiom access and parsing theories of syntactic rule access have almost no commonality in methodology or coverage of psycholinguistic data. This article presents a single probabilistic algorithm which models both the access and disambiguation of linguistic knowledge. The algorithm is based on a parallel parser which ranks constructions for access, and interpretations for disambiguation, by their conditional probability. Low-ranked constructions and interpretations are pruned through beam-search; this pruning accounts, among other things, for the garden-path effect. I show that this motivated probabilistic treatment accounts for a wide variety of psycholinguistic results, arguing for a more uniform representation of linguistic knowledge and for the use of probabilistically-enriched grammars and interpreters as models of human knowledge of and processing of language.     

Verb subcategorization frequencies: American English corpus data, methodological studies, and cross-corpus comparisons.

Verb subcategorization frequencies (verb biases) have been widely studied in psycholinguistics and play an important role in human sentence processing. Yet available resources on subcategorization frequencies suffer from limited coverage, limited ecological validity, and divergent coding criteria. Prior estimates of verb transitivity, for example, vary widely with corpus size, coverage, and coding criteria This article provides norming data for 281 verbs of interest to psycholinguistic research, sampled from a corpus of American English, along with a detailed coding manual. We examine the effect on transitivity bias of various coding decisions and methods of computing verb biases.     

Syntactic frame and verb bias in aphasia: plausibility judgments of undergoer-subject sentences

This study investigates three factors that have been argued to define "canonical form" in sentence comprehension: Syntactic structure, semantic role, and frequency of usage. We first examine the claim that sentences containing unaccusative verbs present difficulties analogous to those of passive sentences. Using a plausibility judgment task, we show that a mixed group of aphasics performed significantly better on unaccusatives than on passives. We then turn to the observation that passives are generally harder than actives for aphasics. We show that this effect is modulated by lexical bias, i.e., the likelihood that a verb appears in a given syntactic structure: Passives of passive-bias verbs were significantly easier than passives of active-bias verbs. More generally, sentences whose structure matches the lexical bias of the main verb are significantly easier than sentences in which structure and lexical bias do not match. These findings suggest that "canonical form" reflects frequency and lexical biases.