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This study explores the neurofunctional correlates of the recognition of famous faces in patients with amnestic mild cognitive impairment (aMCI) and healthy controls depending on the genetic risk factor, Apolipoprotein E (ApoE) ε4. An event-related functional magnetic resonance imaging experiment was conducted while participants discriminated between famous and nonfamous faces. We compared the results of 32 healthy controls [17 ApoE ε4 carriers (E4+); 15 noncarriers (E4-)] with those of 30 patients with aMCI (16 E4+; 14 E4-). Despite comparable task performance, patients with aMCI, E4+ showed significantly less activation in a large cortical network including the left parahippocampal gyrus than patients with aMCI E4-. Furthermore, in the aMCI group, we found significantly reduced activation in the left parahippocampal gyrus and posterior cingulate cortex compared with the control group. Our results show that critical regions of the brain show functional decline associated with major risk factors, such as ApoE ε4 allele and neuropsychological signs of aMCI for the development of Alzheimer disease. Importantly, the ApoE genotype seems to influence cortical activation in patients with aMCI and to a lesser degree in healthy controls as well, who are without any cognitive symptoms. [ABSTRACT FROM AUTHOR]

Purpose: In patients with central visual field scotomata, a large part of visual cortex is not adequately stimulated. Patients often use a new eccentric fixation area on intact peripheral retina ("preferred retinal locus"-PRL) that functions as a pseudo-fovea. We used functional magnetic resonance imaging (fMRI) to examine whether stimulating this pseudo-fovea leads to increased activation or altered activation patterns in visual cortex in comparison to stimulating a comparable peripheral area in the opposite hemifield (OppPRL)., Methods: Nineteen patients with binocular central scotomata caused by hereditary retinal dystrophies and an age-matched control group were tested. The center of the visual field, PRL, and OppPRL were stimulated with flickering checkerboard stimuli and object pictures during fMRI measurement., Results: Results show that stimulation with pictures of everyday objects led to overall larger BOLD (blood oxygen level dependent) responses in visual cortex compared to that evoked by stimulation with flickering checkerboards. Patients showed this enhancement as early as in V1. When the PRL was directly stimulated with object pictures, the central representation area in early visual cortex was coactivated in the patients but not in the controls. In higher visual areas beyond retinotopic cortex, BOLD responses to stimulation of the PRL with object pictures were significantly enhanced in comparison to stimulation of the OppPRL area. Highly stable eccentric fixation with the PRL was associated with a higher BOLD signal in visual cortex in patients, and this effect was most pronounced in the conditions with object picture stimulation., Conclusions: The observed results suggest that naturalistic images are more likely to trigger top-down processes that regulate activation in early visual cortex in patients with central vision loss.

Objective: Intranasal oxytocin has been shown to affect human social and emotional processing, but its potential to affect pain remains elusive. This randomized, placebo-controlled, double-blind, crossover trial investigated the effect of intranasal oxytocin on the perception and processing of noxious experimental heat in 36 healthy male volunteers., Methods: Thermal thresholds were determined according to the Quantitative Sensory Testing protocol. A functional magnetic resonance imaging experiment including intensity and unpleasantness ratings of tonic heat was used to investigate the effects of oxytocin within the brain., Results: Thirty men (aged 18-50 years) were included in the study. Intranasal oxytocin had no significant effect on thermal thresholds, but significantly (t = -2.06, p = .046) reduced heat intensity ratings during functional magnetic resonance imaging. The effect on intensity ratings was small (-3.46 points on a 100-point visual analog scale [95% confidence interval {CI} = -6.86 to -0.07] and independent of temperature. No effects of oxytocin on stimulus- or temperature-related processing were found at the whole-brain level at a robust statistical threshold. A region of interest analysis indicated that oxytocin caused small but significant decreases in left (-0.045%, 95% CI = -0.087 to -0.003, t = -2.19, p = .037) and right (-0.051%, 95% CI = -0.088 to -0.014], t = -2.82, p = .008) amygdala activity across all temperatures., Conclusions: The present study provides evidence for a significant but subtle inhibitory effect of oxytocin on thermal stimulus ratings and concurrent amygdala activity. Neither of the two effects significantly depended of temperature; therefore, the hypothesis of a pain-specific effect of oxytocin could not be confirmed., Trial Registration: EUDRA-CT 2009-015115-40.

Recent evidence points to an overlap in the neural systems processing pain and social distress. In this functional MRI study we focus on the possible interplay between the processing of a psychosocial stressor and somatic pain within pain responsive brain regions, the latter being identified in an independent localizer experiment. A paradigm based on emotional induction (Hariri et al., 2000, Neuroreport 11(1):43-48) was combined with moderate heat pain to yield a factorial design with factor 'pain' as somatic stressor and factor 'faces' as nonpainful psychosocial stressor. Pain responsive regions of interest in the insula, SII cortex, and thalamus were activated by the factor 'faces' to a various extent. The hemodynamic response to both factors tends to aggregate in a compressive manner in these regions.

Investigating respiratory acts using motor imagery has the advantage that motion artifacts are much less likely to occur. To test whether motor imagery of voluntary coughing shows similar spatiotemporal activity patterns as compared to overt coughing, 12 participants underwent functional MRI scanning performing both tasks. We analyzed the data using a pattern classifier, that is, a support vector machine. Results showed that during imagined coughing, a number of brain areas reported previously to be involved in respiration showed more similarity in their spatiotemporal activity patterns with overt coughing than with a resting baseline. We conclude that motor imagery can be a suitable paradigm to investigate respiration, and that support vector machine analysis is potentially more sensitive and specific than a standard univariate analysis.

Blood oxygenation-level dependent changes in the cerebral cortex were measured using event-related functional magnetic resonance imaging in participants while they performed triple-step memory-guided saccades. To explore the role of dorsolateral prefrontal cortex in the manipulation of the contents of working memory, the sequence of saccade targets in the memory-guided task was either constant or was manipulated using coloured cues. The dorsolateral prefrontal cortex was significantly activated only during the period when participants had to reorder the locations of the saccade targets and not during the maintenance of spatial locations. This finding suggests that dorsolateral prefrontal cortex is primarily involved in the manipulation, and to a lesser extent, in the maintenance of the contents of working memory.

Using functional magnetic resonance imaging, we compared responses during visually guided saccades with those evoked during memory-guided saccades, in which participants executed saccades to remembered locations. Eye movements were recorded in the magnetic resonance tomograph. Significantly stronger activation during memory-guided saccades was observed in the posterior portion of the right inferior frontal gyrus, in the left inferior frontal eye field, in the posterior parietal cortex, as well as in the right posterior superior temporal gyrus. The posterior part of the dorsal anterior cingulum and a small voxel cluster in the dorsolateral prefrontal area, anterior to the left inferior frontal eye field, were only active in the memory-guided condition.

Using fMRI, we explored cortical responses to dichoptically presented random-dot (RD) stimuli which formed a checkerboard by means of horizontal disparity (Julesz). Depth reversals occurred every 800 ms by appropriate horizontal shifting of a subset of the RD pattern. We compared cortical blood oxygen level dependent (BOLD) responses of five subjects under conditions with and without binocular disparity. The results indicate that only extrastriate, but not striate, areas responded more to the stimuli with binocular disparity. We further found that the BOLD signal increased with increasing disparity level only in dorsal areas of occipito-parietal and prefrontal cortex. These results suggest that the fMRI BOLD response can reflect the processing of relative binocular disparity in extrastriate cortex.

Stimulus motion is a prominent feature that is used by the visual system to segment figure from ground and perceptually bind widely separated objects. Pursuit eye movements can be influenced by such perceptual grouping processes. We have examined the subjects' ability to detect small amounts of coherent motion in random dot kinematograms during pursuit. We compared performance on tests of coherent motion perception while subjects fixated a stationary spot or while they tracked a moving target. The results indicate that smooth pursuit can improve subjects' ability to detect the presence of coherent motion. We tentatively propose that an efference copy of the eye movement signal can enhance the ability of the visual system to detect correlations between sparsely placed targets among noisy distractors.

One of the major controversies in cognitive neuroscience is whether the primary visual cortex and nearby areas are involved in visual mental imagery. In an fMRI study we examined the brain activity of 10 healthy subjects under different task conditions: in the perception condition subjects saw complex geometrical shapes and had to decide whether other highlighted stimuli fell inside or outside the figure. In the imagery condition subjects saw only the highlighted stimuli and were instructed to imagine the previously studied geometrical shapes to solve the same task. Although the behavioral data show a distance effect that would be expected based on topographically organized mental images, the functional imaging data do not show increased activity in the primary visual cortex in the imagery condition. In the occipital cortex a slightly increased activity was found only in the visual association cortex (BA 19), whereas the highest activation was observed in the parietal cortex (BA 7 and 40). The results of the study do not support the assumption that the primary visual cortex is involved in visual mental imagery, but rather that a network of spatial subsystems and higher visual areas appears to be involved.

We have used fMRI to examine the nature of the changes that occur in the human visual cortex when an observer attends to a particular location in the visual image. Previous studies have shown that the magnitude of the response to a visual stimulus is increased when the observer attends to the stimulus. We show that, in addition, attention to a particular location results in a widespread suppression of activity levels at all other locations. This suggests that a key mechanism of attentional modulation may be that spontaneous (baseline) levels of neural activity are adjusted in a position-dependent manner across the entire visual field.

Experimental pain thresholds (electrical intracutaneous finger and dental pulp stimulation) and plasma hormone levels (beta-endorphin, cortisol, and catecholamines) were measured in ten healthy sportive men before, during, and after progressively more strenuous physical exercise. In a double-blind study conducted on two different days, 20 mg of the opioid-antagonist naloxone or placebo was administered prior to exercise. A significant pain threshold elevation was found during exercise for finger (ANOVA, P less than 0.004) and dental pulp stimulation (P less than 0.01). Pain threshold elevation was most pronounced during maximal exertion, at which time the subjects reported the greatest subjective fatigue. Thresholds remained elevated 10-15 min after the end of exercise, and, 60 min after exercise, thresholds returned to baseline values. The subjective magnitude estimation of suprathreshold stimuli was significantly reduced (P less than 0.0001) 5-10 min after exercise. Plasma beta-endorphin, cortisol, and catecholamines increased significantly (P less than 0.0005, all values) during exercise. Plasma beta-endorphin levels did not correlate significantly with pain thresholds (r = -0.37, NS). Naloxone failed to affect pain thresholds, although beta-endorphin and cortisol increased significantly more (P less than 0.02) during exercise after naloxone. It is concluded that short-term, exhaustive physical exercise can evoke a transient elevation in pain thresholds. This exercise-induced elevation in pain threshold does not, however, appear to be directly related to plasma endorphin levels.

Ischemic pain threshold and tolerance levels using the tourniquet pain technique and electrical cutaneous pain thresholds were measured in patients with asymptomatic ischemic heart disease. Thirty asymptomatic patients, who repeatedly exhibited no angina pectoris pain during the occurrence of exercise-induced coronary ischemia (greater than or equal to 0.1 mV ST segment depression in exercise ECG) were compared to 30 randomly selected symptomatic control patients. In a smaller patient group (6 symptomatic, 6 asymptomatic) the degree of forearm ischemia during the tourniquet test was determined non-invasively by monitoring transcutaneous pO2. Results indicated that asymptomatic patients needed significantly more time to reach pain threshold following occlusion of forearm blood flow and exhibited significantly lower tcpO2 values at threshold than symptomatic patients. Electrical pain thresholds were also elevated in the asymptomatic group. These findings indicate that the phenomenon of asymptomatic myocardial ischemia can be explained by an extracardiac pain modifying mechanism.