摘要:

AbstractInteractions between sentences and the individual words that comprise them are reviewed in studies using the event‐related brain potential (ERP). Results suggest that, for ambiguous words preceded by a biasing sentence context, context is used at an early stage to constrain the relevant sense of a word rather than select among multiple active senses. A study comparing associative single‐word context and sentence‐level context also suggests that sentence context influences the earliest stage of semantic analysis, but that the ability to use sentence context effectively is more demanding of working memory than the ability to use single‐word contexts. Another indication that sentence context has a dramatic effect on single‐word processing was the observation that high‐ and low‐frequency words elicit different ERPs at the beginnings of sentences but that this effect is suppressed by a meaningful sen

ISSN:0048-5772    

DOI:10.1111/j.1469-8986.1995.tb01228.x

出版商:Blackwell Publishing Ltd    

年代:1995

数据来源: WILEY

摘要:

AbstractThe somatosensory evoked potential negative components in the 100–150‐ms range were studied under conditions where attention was directed either toward or away from the probe stimulus. An N120 component, not sensitive to spatial attention, appeared in all conditions, including the no‐task condition. Its distribution was consistent with an origin in the second somatic area. A later N140 response, not recorded in neutral conditions, was highly sensitive to spatial attention and reached its maximum to stimulation of the attended hand; its behavior was consistent with that of a processing negativity. The N140 was bilaterally distributed, but the hemisphere contralateral to stimulation appeared to be involved earlier than the ipsilateral one. Although the exogenous N120 may be influenced by somatosensory awareness and perhaps tactile recognition, the N140 appears linked to the spatial components of attention and results from the activation of several areas in both hemisp

ISSN:0048-5772    

DOI:10.1111/j.1469-8986.1995.tb01229.x

出版商:Blackwell Publishing Ltd    

年代:1995

数据来源: WILEY

摘要:

AbstractIn this study, we examined the effects of psychological stress on calculated plasma volume, the relationship of these changes to changes in hematologic factors, and the time course of plasma volume changes. Plasma volume changes were assessed using mass densitometry techniques, which measured changes in blood and plasma density. Hematologic and hemodynamic variables were assessed in 40 healthy men and women during a mental arithmetic (math) or benign reading task and during postural change (standing). Results indicated that math and posture change produced a significant decrease in plasma volume (ps<.001) and increases in blood pressure (ps<.001), blood and plasma density (ps<.001), and total plasma protein (p<.001). Correlations were observed between plasma volume changes and changes in systolic (r= .55,p<.0001), diastolic (r= .61,p<.0001), and mean (r= .65,p<.0001) arterial pressure during math; plasma volume and blood pressure returned to baseline within 12 min following the math task. These results suggest that an important mechanism for stress‐induced decreases in plasma volume is increased blood pressure leading to increased fluid shifts from the vasculature into the interstitial space

ISSN:0048-5772    

DOI:10.1111/j.1469-8986.1995.tb01230.x

出版商:Blackwell Publishing Ltd    

年代:1995

数据来源: WILEY

摘要:

AbstractSeventeen children with attention deficit disorder (ADHD) and 10 normal controls performed two tasks while event‐related potentials were recorded. ADHD subjects took part in two more sessions under methylphenidate (MP) or placebo. In the spatial orienting task, invalidly cued targets elicited a longer reaction time (RT) and a P3that was longer in latency and greater in amplitude than did validly cued targets. Performance was similar for both groups, but the early portion of P3(300–400 ms) was lower in amplitude for invalidly cued targets in ADHD subjects. MP increased accuracy without affecting RT and shortened P3peak latency and increased the amplitude of its early portion. In the focused attention task, accuracy was greater for controls and MP, but there were no RT differenees. Attended stimuli elicited greater amplitude P1, N1, and P3than did nonattended stimuli, but these measures were unaffected by diagnosis or medicat

ISSN:0048-5772    

DOI:10.1111/j.1469-8986.1995.tb01231.x

出版商:Blackwell Publishing Ltd    

年代:1995

数据来源: WILEY

摘要:

AbstractThe purpose of this study was to determine whether the latencies of two event‐related potential (ERP) components, the NA and N400, were sensitive to semantic priming. Subjects performed a semantic judgment task, which was designed in such a way that the N400 could be examined without overlap from the P3. Priming effects on the latencies of both NA and N400 were most apparent at frontocentral sites. The amplitude of NA was not significantly affected by priming. The amplitude of N400 was smaller for primed than for unprimed words, but the effect was significant only at centroposterior sites. Current source density (CSD) analyses performed on the ERP data suggested the activation of multiple generators in the N400 time region. The ERP and CSD data were consistent with the existence of two types of N400, a frontal N400 that varies in latency as a function of semantic priming, and a posterior N400 that varies in amplitud

ISSN:0048-5772    

DOI:10.1111/j.1469-8986.1995.tb01232.x

出版商:Blackwell Publishing Ltd    

年代:1995

数据来源: WILEY

摘要:

AbstractIschemic pain was examined in adult males with and without a parental history of hypertension. Blood pressure and heart rate were recorded during baseline, cold pressor, and ischemia. Repeated pain ratings were obtained during cold pressor and ischemia, and the McGill Pain Questionnaire was completed after each stressor. A median split was used to identify high and low mean arterial pressure and heart rate reactors to cold pressor. Parental history of hypertension, high heart rate reactivity, and high mean arterial pressure reactivity were each associated with significantly lower ischemic pain ratings on the McGill Pain Questionnaire, suggesting that risk for hypertension is associated with hypoalgesia in normotensives.

ISSN:0048-5772    

DOI:10.1111/j.1469-8986.1995.tb01233.x

出版商:Blackwell Publishing Ltd    

年代:1995

数据来源: WILEY

摘要:

AbstractA decrease in the frontal lobes' efficiency is supposed to play a role in age‐related changes in cognitive function. If frontal lobes are involved in the maintenance of working memory, the elderly may require increased frontal activity because of more rapid memory decay. This is consistent with the fact that the P3 component of the eventrelated potential (ERP) has a more frontal orientation with increasing age. However, frontally distributed P3s are also observed in young people when novel stimuli are unexpectedly presented in an oddball paradigm. Young and old subjects were run in an auditory novelty oddball in which ERPs were recorded from 30 scalp sites. The young adults' P3s showed either a posterior (targets) or more frontally oriented (novels) scalp focus. The elderly were less accurate in their memory for the novel stimuli, and their P3s showed anterior and posterior foci to both targets and novels. The young adults' target P3s changed over time from a frontal to a posterior focus, whereas the old adults' did not. These results are consistent with decreased ability of the elderly to maintain the templates needed for stimulus categorizatio

ISSN:0048-5772    

DOI:10.1111/j.1469-8986.1995.tb01234.x

出版商:Blackwell Publishing Ltd    

年代:1995

数据来源: WILEY

摘要:

Images of MindBy Michael I. Posner and Marcus E. Raichle.Reviewed by Howard EichenbaumAttention and Brain FunctionBy R. Näätänen.Reviewed by M.‐H.

ISSN:0048-5772    

DOI:10.1111/j.1469-8986.1995.tb01235.x

出版商:Blackwell Publishing Ltd    

年代:1995

数据来源: WILEY

ISSN:0048-5772    

DOI:10.1111/j.1469-8986.1995.tb01236.x

出版商:Blackwell Publishing Ltd    

年代:1995

数据来源: WILEY

ISSN:0048-5772    

DOI:10.1111/j.1469-8986.1995.tb01237.x

出版商:Blackwell Publishing Ltd    

年代:1995

数据来源: WILEY