摘要:

AbstractIn this paper the similarities in the structural and functional organization of motor preparation and attension are discussed. A crucial structure in this organization is the thalamus, a complex of sensory and motor nuclei that transmits information from subcortical origins to the cortex. For the most part, the thalamus is overlapped by the nucleus reticularis, which has a local inhibitory influence on the underlying nuclei. This serves as a gating mechanism for the transmission of sensory information to the cortex. Skinner and Yingling (1977) have provided arguments in favor of a frontal control in the gating of sensory information. The present paper extends their suggestions to the motor system: a similar gating mechanism for the transmission of subcortical motor information to the cortex is hypothesized, also under frontal control. Slow potentials recorded during motor preparation and attention for an upcoming stimulus show a different distribution over the scalp. These distributions are interpreted as an indication of which thalamic gates are open to transmit information to the cortex. Probe responses (spinal reflexes, evoked potentials, and the startle reflex) can also be used to investigate which thalamocortical gates are open under certain experimental conditions. It is concluded that the sensory and motor input to the cortex are subjected to a similar control mechanism.

ISSN:0048-5772    

DOI:10.1111/j.1469-8986.1993.tb02054.x

出版商:Blackwell Publishing Ltd    

年代:1993

数据来源: WILEY

摘要:

AbstractThe time course of the facilitation of the acoustic startle reflex induced by anticipation of electric shocks was measured in 20 normal volunteers. Shocks could be administered during the last 10 s of 45‐s threat conditions but not during 50‐s no‐threat conditions, each condition being signaled by a different light. Consistent with previous data, overall eyeblink startle levels were higher during the threat than during the no‐threat conditions. However, the magnitude of this fear‐potentiated startle effect became progressively larger in the threat condition the longer the light was on and then abruptly decreased with the onset of the light signaling the no‐threat condition. These effects of the threat of shock on startle were interpreted in terms of anticipatory anxiety. Other interpretations, such as changes in selective or generalized attention, were also discussed. This paradigm provides a method to assess the time course of anticipatory anxiet

ISSN:0048-5772    

DOI:10.1111/j.1469-8986.1993.tb02055.x

出版商:Blackwell Publishing Ltd    

年代:1993

数据来源: WILEY

摘要:

AbstractPrepulse inhibition of the reflex blink by a weak stimulus shortly preceding a blink‐eliciting stimulus has been described as a sensorimotor gating phenomenon that may protect processing of the first stimulus. To determine how a stimulus configuration that elicits prepulse inhibition also affects exogenous evoked potentials and perceived loudness of the paired stimuli, the three types of response were recorded simultaneously under four conditions: tone pairs of 75–110 dB and 75–75 dB and single control tones of each intensity. Two studies using different intrapair intervals found that blinks and exogenous potentials peaking after 50 ms were smaller for the second tone of pairs than for equal‐intensity single tones. Pairing also reduced the loudness of 110‐dB second tones, but the loudness of 75‐dB first and second tones was unaffected or increased. These effects are discussed in terms of parallel processing of transient, unmodulated information in specific paths, steady‐state modulated information in nonspecific paths, and a context‐dependent effect on lou

ISSN:0048-5772    

DOI:10.1111/j.1469-8986.1993.tb02056.x

出版商:Blackwell Publishing Ltd    

年代:1993

数据来源: WILEY

摘要:

AbstractEvent‐related potentials (ERPs) were recorded from normal subjects who received random sequences of tone pips from loudspeakers located to the left and right of a central point. The task was to detect occasional higher pitched tones (targets) from one designated speaker. The negative difference (Nd) wave between ERPs for relevant and irrelevant tones was largest when subjects fixated on the relevant speaker, smallest when subjects fixated on the irrelevant speaker, and intermediate in a central fixation. In addition, the Nd modulation for the left tones was produced by the more negative (or less positive) shift of irrelevant‐stimulus ERPs and the less negative shift of relevant‐stimulus ERPs associated with fixating away from the relevant speaker. These findings suggest the possibility of both facilitatory and inhibitory effects of eye position on auditory spatial attention. The substantial modulation of ERPs due to eye position also indicated the necessity of fixation control in auditory attention ERP res

ISSN:0048-5772    

DOI:10.1111/j.1469-8986.1993.tb02057.x

出版商:Blackwell Publishing Ltd    

年代:1993

数据来源: WILEY

摘要:

AbstractThe purposes of the present study were to compare the cardiovascular response patterns evoked by three versions of the cold pressor test (either forehead stimulation or hand or foot immersion) and to determine the reproducibility of the responses over a 2‐week interval. Blood pressure, heart rate, stroke volume, cardiac output, total peripheral resistance, and systolic time intervals were obtained during rest and during the cold pressor test in 42 young men. Across conditions, the pressor response was supported by peripheral resistance increases with concomitant stroke volume decreases. Although the response panerns were generally similar across sites, exceptions were apparent for heart rate. Forehead stimulation was characterized by no significant change in heart rate, whereas limb (hand or foot) immersion was associated with significant heart rate acceleration. The responses elicited by the three cold pressor test conditions were reliable and showed little evidence of attenuation over the test‐retest inter

ISSN:0048-5772    

DOI:10.1111/j.1469-8986.1993.tb02058.x

出版商:Blackwell Publishing Ltd    

年代:1993

数据来源: WILEY

摘要:

AbstractA recently developed technique for examining thermal sensitivity during sleep was used to assess whether skin and core temperature responses to thermal stimulation were altered by sleep state. The technique was designed to probe thermal responsivity without altering core body temperature or inducing awakening. Twenty‐seven young men and women were studied during a sleep deprivation night and a sleep night three nights later. Cold water stimulation of the face alternated with an equal period of rewarming across a 40‐min cycle throughout the night. Skin temperature from the finger and rectal temperature were continuously assessed. Sleep continuity and architecture were largely uninfluenced by the thermal stimulation. Finger skin temperature decreased during cold facial stimulation in both sleep and waking states. Skin temperature changes during sleep were approximately one‐fifth the magnitude of those during waking. Core temperature was minimally influenced. REM sleep was associated with a greater amplitude decrease in finger temperature than was non‐REM (NREM) sleep. The results support the utility of the technique as a probe of thermal responsivity during sleep and suggest a reduction of thermal responsivity during sleep and, more tentatively, an altered responsivity during REM versus NRE

ISSN:0048-5772    

DOI:10.1111/j.1469-8986.1993.tb02059.x

出版商:Blackwell Publishing Ltd    

年代:1993

数据来源: WILEY

摘要:

AbstractEvent‐related brain potentials (ERPs) were recorded from young, middle‐aged, and older adults to infrequent target and novel stimuli during a version of the oddball paradigm. Analyses of scalp distribution suggested that the shift to a more frontally oriented topography with increasing age was confined to the P3 component (as compared to N1 and P2) elicited by both target and novel stimuli. This first demonstration of an age‐related shift in the scalp distribution of the novelty P3 elicited by auditory stimuli was associated with an age‐related increase in the false‐alarm rate to novel stimuli. These age‐associated differences in scalp distribution and false‐alarm rate are consistent with a change in frontal lobe activity with i

ISSN:0048-5772    

DOI:10.1111/j.1469-8986.1993.tb02060.x

出版商:Blackwell Publishing Ltd    

年代:1993

数据来源: WILEY

摘要:

AbstractFilter characteristics of the peak‐valley respiratory sinus arrhythmia estimation method are described. To identify filter characteristics of this method, models were generated that combined signals of different frequencies with trends of varying slopes. These models simulate the influence of trend and changing respiratory frequency on the accuracy of peak‐valley estimates. The transfer function of the peak‐valley method, unlike that of other time domain filters, is not solely dependent upon signal frequency. Two factors interact to determine the relative accuracy of the peak‐valley method: (a) slope of the signal component and (b) slope of the underlying trend. Combinations of these factors may result in significant distortion to the input signal. The direction of error is a function of the direction of the trend (i.e., overestimation with deceleration and underestimation with acceleration). In many situations when respiratory sinus arrhythmia amplitude is low in special populations (e.g., cardiovascular disorders, high‐risk infants, or human fetuses) or under conditions that greatly reduce respiratory sinus arrhythmia amplitude (e.g., exercise, drugs, pharmacological manipulations), use of the peak‐valley method may result in significant measurement error. The use of this method to evaluate respiratory sinus arrhythmia over short epochs (i.e., less than 2 min) or to quantify changes in respiratory sinus arrhythmia due to discrete stimulation (e.g., breath by breath) may result in inconsistent measurement error. Recommendations are made for detrending heart rate data prior to application of the peak‐

ISSN:0048-5772    

DOI:10.1111/j.1469-8986.1993.tb02061.x

出版商:Blackwell Publishing Ltd    

年代:1993

数据来源: WILEY

摘要:

AbstractMany researchers have used off‐line techniques for the automatic detection of electromyogram (EMG) onset. However, very little is known about the accuracy of these methods. In the present study, five such methods are evaluated and their accuracy is reported. Five subjects were asked to produce fast (ballistic) and slow (ramp) contractions with thumb and index finger of the right hand in a simple reaction time task. EMG was recorded from the first dorsal interosseus muscle, and onsets were visually determined in the raw EMG. These onsets were compared with the onsets produced by the automated methods on the rectified and low‐pass filtered EMG. Four of the automated methods produced very reliable estimates of the visually determined onsets, at least when additional constraints upon the initial estimates were made. Studies using automated methods for EMG onset detection should report findings about their accur

ISSN:0048-5772    

DOI:10.1111/j.1469-8986.1993.tb02062.x

出版商:Blackwell Publishing Ltd    

年代:1993

数据来源: WILEY

摘要:

Book Reviewed in this article:Psychophysiological Brain Research. Edited by C. H. M. Brunia, A. W. K. Gaillard, and A. Kok.Event‐Related Brain Research. Edited by C. H. M. Brunia, G. Mulder, and M. N. Verbate

ISSN:0048-5772    

DOI:10.1111/j.1469-8986.1993.tb02063.x

出版商:Blackwell Publishing Ltd    

年代:1993

数据来源: WILEY