Nonlinear Regression in Parametric Activation Studies

doi:10.1006/nimg.1996.0029

NeuroImage

Volume 4, Issue 1, August 1996, Pages 60-66

https://doi.org/10.1006/nimg.1996.0029 Get rights and content

Abstract

Parametric study designs can reveal information about the relationship between a study parameter (e.g., word presentation rate) and regional cerebral blood flow (rCBF) in functional imaging. The brain's responses in relation to study parameters might be nonlinear, therefore the (linear) correlation coefficient as often used in the analysis of parametric studies might not be a proper characterization. We present a noninteractive method, which fits nonlinear functions of stimulus or task parameters to rCBF responses, using second-order polynomial expansions. This technique is implemented in the context of the general linear model and statistical parametric mapping. We also consider the usefulness of statistical inferences, based onFfields, about similarities and differences of these nonlinear responses in different groups. This approach is illustrated with a 12-run H₂¹⁵O PET activation study using an auditory paradigm of increasing word presentation rates. A patient who had recovered from severe aphasia and a normal control were studied. We demonstrate the ability of this new technique to identify brain regions where rCBF is closely related to increasing word presentation rate in both subjects without constraining the nature of this relationship and where these nonlinear responses differ.

References (0)

Cited by (140)

A distributed dynamic brain network mediates linguistic tone representation and categorization
2021, NeuroImage
Citation Excerpt :
Brain maps were initially thresholded at voxel-level P = 0.001, and all reported brain areas were corrected at the cluster-level P = 0.05 using the FWE rate approach implemented in the SPM package. The relationship between the pitch salience (i.e., IRN iteration steps) and the level of brain activation was examined using the trial-by-trial parametric modulation analysis (Buchel et al., 1996). We aimed to identify brain regions that systematically vary with pitch salience.
Successful categorization requires listeners to represent the incoming sensory information, resolve the “blooming, buzzing confusion” inherent to noisy sensory signals, and leverage the accumulated evidence towards making a decision. Despite decades of intense debate, the neural systems underlying speech categorization remain unresolved. Here we assessed the neural representation and categorization of lexical tones by native Mandarin speakers (N = 31) across a range of acoustic and contextual variabilities (talkers, perceptual saliences, and stimulus-contexts) using functional magnetic imaging (fMRI) and an evidence accumulation model of decision-making. Univariate activation and multivariate pattern analyses reveal that the acoustic-variability-tolerant representations of tone category are observed within the middle portion of the left superior temporal gyrus (STG). Activation patterns in the frontal and parietal regions also contained category-relevant information that was differentially sensitive to various forms of variability. The robustness of neural representations of tone category in a distributed fronto-temporoparietal network is associated with trial-by-trial decision-making parameters. These findings support a hybrid model involving a representational core within the STG that operates dynamically within an extensive frontoparietal network to support the representation and categorization of linguistic pitch patterns.
How context features modulate the involvement of the working memory system during discourse comprehension
2018, Neuropsychologia
Using functional magnetic resonance imaging (fMRI), we investigated the effects of context features on the involvement of the working memory (WM) system during discourse comprehension. During the fMRI scan, participants were asked to read two-sentence discourses in which the topic of the second sentence was either maintained, or was shifted from, the topic of the first. Changes in the level of coherence between the two sentences as well as context length were also investigated across discourse items. The WM system was identified with a verbal N-back task. Analysis of the reading comprehension task revealed that within the WM system, stronger activation in the left inferior frontal gyrus corresponded with increased bridging coherence demands between sentences, while greater activation in the left inferior and middle frontal gyri, bilateral superior frontal gyri, and bilateral inferior parietal lobules corresponded with increased context length. Topic variation showed no effect on activation of the WM system. These results provide new insights into understanding how different levels of context features modulate activation of the subcomponents of the WM system and indicate a role for the left inferior frontal gyrus as a core component of the WM system supporting discourse processing.
Changes in Male Rat Sexual Behavior and Brain Activity Revealed by Functional Magnetic Resonance Imaging in Response to Chronic Mild Stress
2018, Journal of Sexual Medicine
Citation Excerpt :
For the improvement of the normality of the correlation coefficients, a Fisher z-transformation was applied. To improve the specificity of the FC, the 2 motion parameters caused by the reposition and the global signal time course were regressed out in this analysis.24 A 2-sample t-test was performed to identify whether there were significant differences in FC between the CMS and control groups.
Non-organic erectile dysfunction (noED) at functional imaging has been related to abnormal brain activity and requires animal models for further research on the associated molecular mechanisms.
To develop a noED animal model based on chronic mild stress and investigate brain activity changes.
We used 6 weeks of chronic mild stress to induce depression. The sucrose consumption test was used to assess the hedonic state. The apomorphine test and sexual behavior test were used to select male rats with ED. Rats with depression and ED were considered to have noED. Blood oxygen level-dependent–based resting-state functional magnetic resonance imaging (fMRI) studies were conducted on these rats, and the amplitude of low-frequency fluctuations and functional connectivity were analyzed to determine brain activity changes.
The sexual behavior test and resting-state fMRI were used for outcome measures.
The induction of depression was confirmed by the sucrose consumption test. A low intromission ratio and increased mount and intromission latencies were observed in male rats with depression. No erection was observed in male rats with depression during the apomorphine test. Male rats with depression and ED were considered to have noED. The possible central pathologic mechanism shown by fMRI involved the amygdaloid body, dorsal thalamus, hypothalamus, caudate-putamen, cingulate gyrus, insular cortex, visual cortex, sensory cortex, motor cortex, and cerebellum. Similar findings have been found in humans.
The present study provided a novel noED rat model for further research on the central mechanism of noED.
The present study developed a novel noED rat model and analyzed brain activity changes based at fMRI. The observed brain activity alterations might not extend to humans.
The present study developed a novel noED rat model with brain activity alterations related to sexual arousal and erection, which will be helpful for further research involving the central mechanism of noED.
Chen G, Yang B, Chen J, et al. Changes in Male Rat Sexual Behavior and Brain Activity Revealed by Functional Magnetic Resonance Imaging in Response to Chronic Mild Stress. J Sex Med 2018;15:136–147.
Variability in behavior that cognitive models do not explain can be linked to neuroimaging data
2017, Journal of Mathematical Psychology
It is known that behavior is substantially variable even across nearly identical situations. Many cognitive models are not able to explain this intraindividual variability but focus on explaining interindividual differences captured in model parameters. In sequential sampling models of decision making, for instance, one single threshold parameter value is estimated for every person to quantify how much evidence must be accumulated for committing to a choice. However, this threshold may vary across trials even within subjects and experimental conditions. Neuroimaging tools such as functional magnetic resonance imaging (fMRI) or electroencephalography (EEG) can reveal moment-to-moment fluctuations in the neural system that are likely to contribute to fluctuations in behavior. We propose that neural and behavioral variability could be linked to each other by assuming and estimating trial-by-trial variability in model parameters. To illustrate our proposal, we first highlight recent studies in model-based cognitive neuroscience that have gone beyond correlating model predictions with neuroimaging data. These studies made use of variance in behavior that remained unexplained by cognitive modeling but could be linked to specific fMRI or EEG signals. Second, we specify in a tutorial a novel and efficient approach, how to extract such variance and to apply it to neuroimaging data. Our proposal shows how the variability in behavior and the neural system can provide a fruitful source of theory development in cognitive neuroscience.
Age-related differences in resolving semantic and phonological competition during receptive language tasks
2016, Neuropsychologia
Receptive language (e.g., reading) is largely preserved in the aging brain, and semantic processes in particular may continue to develop throughout the lifespan. We investigated the neural underpinnings of phonological and semantic retrieval in older and younger adults during receptive language tasks (rhyme and semantic similarity judgments). In particular, we were interested in the role of competition on language retrieval and varied the similarities between a cue, target, and distractor that were hypothesized to affect the mental process of competition. Behaviorally, all participants responded faster and more accurately during the rhyme task compared to the semantic task. Moreover, older adults demonstrated higher response accuracy than younger adults during the semantic task. Although there were no overall age-related differences in the neuroimaging results, an Age×Task interaction was found in left inferior frontal gyrus (IFG), with older adults producing greater activation than younger adults during the semantic condition. These results suggest that at lower levels of task difficulty, older and younger adults engaged similar neural networks that benefited behavioral performance. As task difficulty increased during the semantic task, older adults relied more heavily on largely left hemisphere language regions, as well as regions involved in perception and internal monitoring. Our results are consistent with the stability of language comprehension across the adult lifespan and illustrate how the preservation of semantic representations with aging may influence performance under conditions of increased task difficulty.
Anticipating conflict: Neural correlates of a Bayesian belief and its motor consequence
2015, NeuroImage
Previous studies have examined the neural correlates of proactive control using a variety of behavioral paradigms; however, the neural network relating the control process to its behavioral consequence remains unclear. Here, we applied a dynamic Bayesian model to a large fMRI data set of the stop signal task to address this issue. By estimating the probability of the stop signal – p(Stop) – trial by trial, we showed that higher p(Stop) is associated with prolonged go trial reaction time (RT), indicating proactive control of motor response. In modeling fMRI signals at trial and target onsets, we distinguished activities of proactive control, prediction error, and RT slowing. We showed that the anterior pre-supplementary motor area (pre-SMA) responds specifically to increased stop signal likelihood, and its activity is correlated with activations of the posterior pre-SMA and bilateral anterior insula during prolonged response times. This directional link is also supported by Granger causality analysis. Furthermore, proactive control, prediction error, and time-on-task are each mapped to distinct areas in the medial prefrontal cortex. Together, these findings dissect regional functions of the medial prefrontal cortex in cognitive control and provide system level evidence associating conflict anticipation with its motor consequence.

View all citing articles on Scopus

View full text

Regular ArticleNonlinear Regression in Parametric Activation Studies

Abstract

Regular Article
Nonlinear Regression in Parametric Activation Studies