Sensitivity of prefrontal cortex to changes in target probability: A functional MRI study

Sackler Institute for Developmental Psychobiology, Weill Medical College of Cornell University, New York, New York 10021, USA.
Human Brain Mapping (Impact Factor: 5.97). 05/2001; 13(1):26-33. DOI: 10.1002/hbm.1022
Source: PubMed


Electrophysiological studies suggest sensitivity of the prefrontal cortex to changes in the probability of an event. The purpose of this study was to determine if subregions of the prefrontal cortex respond differentially to changes in target probabilities using functional magnetic resonance imaging (fMRI). Ten right-handed adults were scanned using a gradient-echo, echo planar imaging sequence during performance of an oddball paradigm. Subjects were instructed to respond to any letter but "X". The frequency of targets (i.e., any letter but X) varied across trials. The results showed that dorsal prefrontal regions were active during infrequent events and ventral prefrontal regions were active during frequent events. Further, we observed an inverse relation between the dorsal and ventral prefrontal regions such that when activity in dorsal prefrontal regions increased, activity in ventral prefrontal regions decreased, and vice versa. This finding may index competing cognitive processes or capacity limitations. Most importantly, these findings taken as a whole suggest that any simple theory of prefrontal cortex function must take into account the sensitivity of this region to changes in target probability.

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    • "Seem to be of particular importance for cognitive estimation. fMRI studies of healthy adults engaged in tasks requiring probability show activation in dlPFC (Casey et al., 2001). An fMRI study examining the neural correlates of tactile estimation showed greater levels of activation in dlPFC during a texture estimation task as compared to a nearly identical task not requiring any estimation (Kitada et al., 2005). "
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    ABSTRACT: We often estimate an unknown value based on available relevant information, a process known as cognitive estimation. In this study, we assess the cognitive and neuroanatomic basis for quantitative estimation by examining deficits in patients with focal neurodegenerative disease in frontal and parietal cortex. Executive function and number knowledge are key components in cognitive estimation. Prefrontal cortex has been implicated in multilevel reasoning and planning processes, and parietal cortex has been associated with number knowledge required for such estimations. We administered the Biber cognitive estimation test (BCET) to assess cognitive estimation in 22 patients with prefrontal disease due to behavioral variant frontotemporal dementia (bvFTD), to 17 patients with parietal disease due to corticobasal syndrome (CBS) or posterior cortical atrophy (PCA) and 11 patients with mild cognitive impairment (MCI). Both bvFTD and CBS/PCA patients had significantly more difficulty with cognitive estimation than controls. MCI were not impaired on BCET relative to controls. Regression analyses related BCET performance to gray matter atrophy in right lateral prefrontal and orbital frontal cortices in bvFTD, and to atrophy in right inferior parietal cortex, right insula, and fusiform cortices in CBS/PCA. These results are consistent with the hypothesis that a frontal-parietal network plays a crucial role in cognitive estimation.
    Frontiers in Human Neuroscience 06/2015; 9(317). DOI:10.3389/fnhum.2015.00317 · 3.63 Impact Factor
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    • "During this task, we observed reduced activation in inferior frontal/insular regions in the HFA group compared with the control group. These regions of VLPFC have been strongly implicated in attention (Gitelman et al., 1999; LaBar et al., 1999) and response inhibition (Casey et al., 2001; Rubia et al., 2001; Shafritz et al., 2005). It is conceivable that lack of inferior frontal/insular activation in the HFA group reflects a more efficient neural processing of response inhibition, as performance was equivalent with controls. "
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    ABSTRACT: Autism is marked by impairments in social reciprocity and communication, along with restricted, repetitive and stereotyped behaviors. Prior studies have separately investigated social processing and executive function in autism, but little is known about the brain mechanisms of cognitive control for both emotional and nonemotional stimuli. We used functional magnetic resonance imaging to identify differences in neurocircuitry between individuals with high functioning autism (HFA) and neurotypical controls during two versions of a go/no-go task: emotional (fear and happy faces) and nonemotional (English letters). During the letter task, HFA participants showed hypoactivation in ventral prefrontal cortex. During the emotion task, happy faces elicited activation in ventral striatum, nucleus accumbens and anterior amygdala in neurotypical, but not HFA, participants. Response inhibition for fear faces compared with happy faces recruited occipitotemporal regions in HFA, but not neurotypical, participants. In a direct contrast of emotional no-go and letter no-go blocks, HFA participants showed hyperactivation in extrastriate cortex and fusiform gyrus. Accuracy for emotional no-go trials was negatively correlated with activation in fusiform gyrus in the HFA group. These results indicate that autism is associated with abnormal processing in socioemotional brain networks, and support the theory that autism is marked by a social motivational deficit. Copyright © 2015. Published by Elsevier Inc.
    Progress in Neuro-Psychopharmacology and Biological Psychiatry 03/2015; 60. DOI:10.1016/j.pnpbp.2015.03.001 · 3.69 Impact Factor
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    • "In view of the limitations of EEG methods in determining the source of brain activity, functional magnetic resonance imaging (fMRI) has been used to study neural processes evoked by standard and deviant acoustic stimuli (event-related fMRI) [31–36]. This technique is based on blood-oxygen level-dependent (BOLD) contrast, discovered by Ogawa [37], and is used to map neural activity in the brain with a high spatial resolution (a few millimeters). "
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    ABSTRACT: Background The neural underpinnings of auditory information processing have often been investigated using the odd-ball paradigm, in which infrequent sounds (deviants) are presented within a regular train of frequent stimuli (standards). Traditionally, this paradigm has been applied using either high temporal resolution (EEG) or high spatial resolution (fMRI, PET). However, used separately, these techniques cannot provide information on both the location and time course of particular neural processes. The goal of this study was to investigate the neural correlates of auditory processes with a fine spatio-temporal resolution. A simultaneous auditory evoked potentials (AEP) and functional magnetic resonance imaging (fMRI) technique (AEP-fMRI), together with an odd-ball paradigm, were used. Material/Methods Six healthy volunteers, aged 20–35 years, participated in an odd-ball simultaneous AEP-fMRI experiment. AEP in response to acoustic stimuli were used to model bioelectric intracerebral generators, and electrophysiological results were integrated with fMRI data. Results fMRI activation evoked by standard stimuli was found to occur mainly in the primary auditory cortex. Activity in these regions overlapped with intracerebral bioelectric sources (dipoles) of the N1 component. Dipoles of the N1/P2 complex in response to standard stimuli were also found in the auditory pathway between the thalamus and the auditory cortex. Deviant stimuli induced fMRI activity in the anterior cingulate gyrus, insula, and parietal lobes. Conclusions The present study showed that neural processes evoked by standard stimuli occur predominantly in subcortical and cortical structures of the auditory pathway. Deviants activate areas non-specific for auditory information processing.
    Medical science monitor: international medical journal of experimental and clinical research 01/2014; 20:35-46. DOI:10.12659/MSM.889712 · 1.43 Impact Factor
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