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271.
An extension of G. L. Cates et al. (2003) investigation was conducted to determine if students’ cumulative learning rates would be superior for words read under a traditional drill and practice condition (as they were for spelling in the previous study) than under interspersal conditions of varying ratios of unknown to known words. Participants consisted of three intermediate grade students who were delayed readers. They received a less challenging ratio of unknown to known word (High-P sequencing) interspersal procedure, a more challenging ratio of unknown to known word interspersal training procedure, and a traditional drill and practice procedure in an alternating fashion across several tutoring sessions. Cumulative words read with mastery and cumulative rates of words read with mastery were measured across sessions for each participant under each instructional condition. Findings were consistent with the Cates et al., study revealing that children learn more words per minute of instructional time under the traditional drill and practice condition. These results further support examining instructional efficiency as well as effectiveness when making decisions about selecting and implementing interventions. 相似文献
272.
PurposeThe heart is a complex system and many researchers have been recently studying cardiac behavior using the theory of nonlinear dynamical systems. One of the most appealing tools for analyzing heart function is the heart rate variability (HRV) signal. This study aimed to elucidate the HRV dynamics of six distinct states: spontaneous normal breathing (SNB) and metronomic breathing (MB), as non-meditator groups, before Chinese Chi meditation (CCM), during CCM, before Kundalini yoga meditation (KYM), and during KYM, as meditator groups.MethodsThe HRV data were obtained from the Physionet database. Lagged Poincare indices, Lyapunov exponent (LE), Lempel-Ziv complexity (LZ), and 4 types of entropy were calculated.ResultsThe results showed the greatest discrepancies in the lagged Poincare indices for KYM and CCM. In contrast, the least variations were achieved for MB. Compared to SNB, an enhancement in the log energy entropy and a reduction in the LZ and other entropies were concluded during KYM and CCM practices. In contrast, a reverse pattern was observed for MB. Using support vector machine, HRV dynamics were classified with average accuracies of 99.14 and 98.2% and average sensitivities of 99.87 and 99.57% for pre-KYM and during KYM, respectively.ConclusionIt was shown that the HRV dynamics were significantly different in meditators and non-meditators. 相似文献
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276.
Oliver Stiedl Michael Meyer MD PhD 《Integrative psychological & behavioral science》2002,37(4):311-345
Non-linear fractal analysis of cardiac interbeat time series was performed in corticotropin-releasing factor receptor subtype
2 (CRFR2) deficient mice. Heart rate dynamics in mice constitutes a self-similar, scale-invariant, random fractal process
with persistent intrinsic long-range correlations and inverse power-law properties. We hypothesized that the sustained tachycardic
response elicited by intraperitoneal (ip) injection of human/rat CRF (h/rCRF) is mediated by CRFR2. In wildtype control animals,
heart rate was increased to about maximum levels (~ 750 bpm) while in CRFR2-deficient animals baseline values were retained
(~ 580 bpm). The tachycardic response elicited by ip-application is mediated by CRFR2 and is interpreted to result from sympathetic
stimulation. However, the functional integrity of CRFR2 would not present a prerequisite to maintaining the responsiveness
and resiliency of cardiac control to external environmental perturbations experimentally induced by extrinsic ip-application
of h/rCRF or under physiological conditions that may be associated with an increased peripheral release of CRF. Under stressful
physiological conditions achieved by novelty exposure, CRFR2 is not involved in the cardiodynamic regulation to external short-term
stress. While the hypothesis of involvement of CRFR2 in cardiac regulation upon pharmacological stimulation cannot be rejected,
the present findings suggest that the mechanism of action is by sympathetic stimulation, but would not unambiguously allow
to draw any conclusions as to the physiological role of CRFR2 in the control of cardiac dynamics. 相似文献
277.
Dissociable patterns of brain activity during comprehension of rapid and syntactically complex speech: evidence from fMRI 总被引:7,自引:0,他引:7
Sentence comprehension is a complex task that involves both language-specific processing components and general cognitive resources. Comprehension can be made more difficult by increasing the syntactic complexity or the presentation rate of a sentence, but it is unclear whether the same neural mechanism underlies both of these effects. In the current study, we used event-related functional magnetic resonance imaging (fMRI) to monitor neural activity while participants heard sentences containing a subject-relative or object-relative center-embedded clause presented at three different speech rates. Syntactically complex object-relative sentences activated left inferior frontal cortex across presentation rates, whereas sentences presented at a rapid rate recruited frontal brain regions such as anterior cingulate and premotor cortex, regardless of syntactic complexity. These results suggest that dissociable components of a large-scale neural network support the processing of syntactic complexity and speech presented at a rapid rate during auditory sentence processing. 相似文献
278.
Nava E Landau D Brody S Linder L Schächinger H 《Neurobiology of learning and memory》2004,81(3):167-171
Experimental evidence has linked increased arousal to enhanced memory retention. There is also evidence that procedures reducing arousal, i.e., mental relaxation, might improve memory, but conflicting results have been reported. To clarify this issue, we studied the effects of a single session of relaxation training on incidental visual long-term memory. Thirty-two relaxation-naive subjects viewed 280 slides without being told that there would be subsequent memory testing. Afterwards, subjects listened to a 12 min relaxation tape; 16 subjects relaxed by following the instructions (relaxation group), and the other 16 subjects pressed a button whenever a body part was mentioned (control group). While listening to the relaxation tape, high frequency heart rate variability (HRV) was greater and low frequency HRV was lower in the relaxation group, implying effective relaxation and increasing parasympathetic activation. The relaxation group had superior memory retention 4 weeks later (p = .004), indicating enhancement of long-term memory performance. This effect could not be explained by retroactive interference experienced in the control group because short-term memory performance immediately after the tape was slightly better in the control group. Retention of materials acquired after the relaxation session remained unaffected, suggesting relaxation has retrograde effects on memory consolidation. Our data demonstrate a favorable influence of relaxation on at least this aspect of learning. Our data also extend previous knowledge on the beneficial effects of ascending parasympathetic stimulation on memory retention in that enhanced long-term memory consolidation may also occur in the presence of central and descending parasympathetic activation triggered by willful psychomotor activity. 相似文献
279.
Linda?M.?Rorick Peter?R.?Finn Joseph?E.?SteinmetzEmail author 《Integrative psychological & behavioral science》2004,39(1):24-41
Recently, we reported that High-Alcohol-Drinking (HAD) rats exhibited selective deficits in active avoidance learning under
alcohol-naive conditions, and that administration of moderate doses of alcohol (0.5 and 1.0 g/kg) facilitated learning in
these rats (Blankenship et al., 2000; Rorick et al., 2003b). We hypothesized that the deficits resulted from excessive fear
in the aversive learning context and that the anxiolytic properties of alcohol may have contributed to the improved learning
that was observed after alcohol administration. This hypothesis was supported by a recent study in which prolonged freezing
in HAD rats was seen after a classical fear conditioning procedure (Rorick et al., 2003a). To provide additional evidence
that HAD rats indeed exhibit behaviors consistent with the expression of increased fear in aversive learning contexts, we
employed a Pavlovian fear conditioning task to measure heart rate in HAD and Low-Alcohol-Drinking (LAD) rats. In this study,
HAD (HAD-1 and HAD-2) and LAD (LAD-1 and LAD-2) rats were assigned to one of three pre-exposure conditions: Context Only,
Context/Tone, or Sequential (Context Only followed by Context/Tone) Pre-Exposure. Following pre-exposure, fear conditioning
acquisition and extinction procedures were identical for all groups. Results indicated that although no baseline differences
were observed between HAD and LAD rats, HAD rats receiving Context-Only pre-exposure exhibited excessive heart rate reactivity
to the tone conditional stimulus during fear conditioning acquisition, compared to LAD rats receiving the same pre-exposure
conditions. These findings support the hypothesis that HAD rats exhibit behaviors consistent with increased fear in aversive
learning contexts, as measured by autonomic conditioning. 相似文献
280.
Effects of reinforcer magnitude on responding under differential-reinforcement-of-low-rate schedules of rats and pigeons 下载免费PDF全文
Experiment I investigated the effects of reinforcer magnitude on differential-reinforcement-of-low-rate (DRL) schedule performance in three phases. In Phase 1, two groups of rats (n = 6 and 5) responded under a DRI. 72-s schedule with reinforcer magnitudes of either 30 or 300 microl of water. After acquisition, the water amounts were reversed for each rat. In Phase 2, the effects of the same reinforcer magnitudes on DRL 18-s schedule performance were examined across conditions. In Phase 3, each rat responded unider a DR1. 18-s schedule in which the water amotnts alternated between 30 and 300 microl daily. Throughout each phase of Experiment 1, the larger reinforcer magnitude resulted in higher response rates and lower reinforcement rates. The peak of the interresponse-time distributions was at a lower value tinder the larger reinforcer magnitude. In Experiment 2, 3 pigeons responded under a DRL 20-s schedule in which reinforcer magnitude (1-s or 6-s access to grain) varied iron session to session. Higher response rates and lower reinforcement rates occurred tinder the longer hopper duration. These results demonstrate that larger reinforcer magnitudes engender less efficient DRL schedule performance in both rats and pigeons, and when reinforcer magnitude was held constant between sessions or was varied daily. The present results are consistent with previous research demonstrating a decrease in efficiency as a function of increased reinforcer magnituide tinder procedures that require a period of time without a specified response. These findings also support the claim that DRI. schedule performance is not governed solely by a timing process. 相似文献