Cognitive Brain Research
ISSN : 0926-6410
Published by: Elsevier BV (10.1016)
Total articles ≅ 1,334
Latest articles in this journal
Cognitive Brain Research, Volume 25, pp 833-850; https://doi.org/10.1016/j.cogbrainres.2005.09.008
Horizontal line bisection is a ubiquitous task in the investigation of visual neglect. Patients with left neglect typically make rightward errors that increase with line length and for lines at more leftward positions. For short lines, or for lines presented in right space, these errors may ‘cross over’ to become leftward. We have taken a new approach to these phenomena by employing a different set of dependent and independent variables for their description. Rather than recording bisection error, we record the lateral position of the response within the workspace. We have studied how this varies when the locations of the left and right endpoints are manipulated independently. Across 30 patients with left neglect, we have observed a characteristic asymmetry between the ‘weightings’ accorded to the two endpoints, such that responses are less affected by changes in the location of the left endpoint than by changes in the location of the right. We show that a simple endpoint weightings analysis accounts readily for the effects of line length and spatial position, including cross-over effects, and leads to an index of neglect that is more sensitive than the standard measure. We argue that this novel approach is more parsimonious than the standard model and yields fresh insights into the nature of neglect impairment.
Cognitive Brain Research, Volume 25, pp 963-981; https://doi.org/10.1016/j.cogbrainres.2005.09.021
Event-related brain potentials were recorded to morphologically correct and incorrect regular and irregular past tense verb forms presented in sentences and in lists. In the sentence context, all incorrect verb forms elicited a broadly distributed late posterior positivity, as well as a left anterior negativity (LAN) that was particularly pronounced for the incorrect irregulars. Using a single-word paradigm, we did not find a LAN for any of the incorrect verb forms but found an N400-like effect for all irregular verbs. In the sentence context, only the incorrect irregulars elicited a long-lasting, broadly distributed late positivity, reminiscent of the P600. For regular verbs, responses to incorrect forms produced smaller, more time restricted effects. These data show that morphological and syntactic violations produce similar patterns of brain activity, suggesting that these two systems engage cognitive processes with similar underlying neural substrates.
Cognitive Brain Research, Volume 25, pp 799-809; https://doi.org/10.1016/j.cogbrainres.2005.09.006
Neuronal operations associated with the top–down control process of shifting attention from one locus to another involve a network of cortical regions, and their influence is deemed fundamental to visual perception. However, the extent and nature of these operations within primary visual areas are unknown. In this paper, we used magnetoencephalography (MEG) in combination with magnetic resonance imaging (MRI) to determine whether, prior to the onset of a visual stimulus, neuronal activity within early visual cortex is affected by covert attentional shifts. Time/frequency analyses were used to identify the nature of this activity. Our results show that shifting attention towards an expected visual target results in a late-onset (600 ms postcue onset) depression of alpha activity which persists until the appearance of the target. Independent component analysis (ICA) and dipolar source modeling confirmed that the neuronal changes we observed originated from within the calcarine cortex. Our results further show that the amplitude changes in alpha activity were induced not evoked (i.e., not phase-locked to the cued attentional task). We argue that the decrease in alpha prior to the onset of the target may serve to prime the early visual cortex for incoming sensory information. We conclude that attentional shifts affect activity within the human calcarine cortex by altering the amplitude of spontaneous alpha rhythms and that subsequent modulation of visual input with attentional engagement follows as a consequence of these localized changes in oscillatory activity.
Cognitive Brain Research, Volume 25, pp 777-787; https://doi.org/10.1016/j.cogbrainres.2005.09.007
The feedback-related negativity (FRN) is an event-related brain potential component that is elicited by feedback stimuli indicating unfavorable outcomes. Until recently, the FRN has been studied primarily using experimental paradigms in which outcomes appeared to be contingent upon the participants' behavior. The present study further addressed the question whether an FRN can be elicited by outcomes that are not contingent on any preceding choice or action. Participants took part in a simple slot-machine task in which they experienced monetary gains and losses in the absence of responses. In addition, they performed a time estimation task often used to study the FRN and a flanker task known to elicit the error-related negativity. Outcomes in the slot-machine task elicited an FRN-like mediofrontal negativity whose amplitude correlated with the amplitude of the FRN associated with negative feedback in the time estimation task. However, the mediofrontal negativity was observed both for (unfavorable) outcomes that averted a gain and for (favorable) outcomes that averted a loss of money. The results are discussed in the framework of current conceptions of the FRN and related electrophysiological components.
Cognitive Brain Research, Volume 25, pp 788-798; https://doi.org/10.1016/j.cogbrainres.2005.09.005
Williams syndrome (WS) is a neurodevelopmental disorder of genetic origin that has been used as a model to understand visual cognition. We have investigated early deficits in the afferent magnocellular pathway and their relation to abnormal visual dorsal processing in WS. A spatiotemporal contrast sensitivity task that is known to selectively activate that pathway was used in six WS subjects. Additionally, we have compared visual performance in 2D and 3D motion integration tasks. A novel 3D motion coherence task (using spheres with unpredictable axis of rotation) was used in order to investigate possible impairment of occipitoparietal areas that are known to be involved in 3D structure from motion (SFM) perception. We have found a significant involvement of low-level magnocellular maps in WS as assessed by the contrast sensitivity task. On the contrary, no significant differences were observed between WS and the control groups in the 2D motion integration tasks. However, all WS subjects were significantly impaired in the 3D SFM task. Our findings suggest that magnocellular damage may occur in addition to dorsal stream deficits in these patients. They are also consistent with recently described genetic and neuroanatomic abnormalities in retinotopic visual areas. Finally, selective SFM coherence deficits support the proposal that there is a specific pathway in the dorsal stream that is involved in motion processing of 3D surfaces, which seems to be impaired in this disorder.
Cognitive Brain Research, Volume 25, pp 913-925; https://doi.org/10.1016/j.cogbrainres.2005.09.014
Aging is associated with changes in automatic processing of task-irrelevant stimuli, and this may lead to functional disturbances including repeated orienting to nonnovel events and distraction from task. The effect of age on automatic processing of time-dependent stimulus features was investigated by measurement of the auditory mismatch negativity (MMN) in younger (18–23) and older (55–85) adults. Amplitude of MMN recorded during a paradigm involving low-probability deviation in interstimulus interval (from 500 ms to 250 ms) was found to be reduced in the older group at fronto-central sites. This effect was paralleled by, and correlated to, decreased sensory gating efficiency for component N1 recorded during a separate paradigm involving alternate presentation of auditory stimuli at long (9 s) and short (0.5 s) interstimulus intervals. Further, MMN amplitude was correlated to behavioral performance on a small subset of neuropsychological tests, including the Rey Auditory Verbal Learning Test, within a group of healthy older adults. The results support the hypothesis that aging is associated with declines in automatic processing of time-dependent stimulus features, and this is related to cognitive function. These conclusions are considered in the context of age-related declines in prefrontal cortex function and associated increases in susceptibility to task-irrelevant stimuli.
Cognitive Brain Research, Volume 25, pp 891-899; https://doi.org/10.1016/j.cogbrainres.2005.09.023
According to the model hypothesized by Näätänen and Michie (Biol Psychol 1979; 8: 81–136), the generation of the mismatch negativity (MMN) requires a mismatch detection, taking place in temporal areas, followed by the activation of frontal generators, underlying attention switching toward the deviant stimulus. We aimed at verifying whether the activation of temporal and frontal regions is dependent on the amount of attentional resources allocable toward the deviant stimulus. We recorded event-related potentials (ERPs) in nine healthy subjects while reading and during a demanding visual task (Multiple Features Target Cancellation, MFTC). Raw data were further evaluated by Brain Electrical Source Analysis (BESA). During the Reading condition, distraction toward the unattended auditory stimuli was reflected by the enhancement of the N1 response to frequent stimuli and by the elicitation of a P3a response to deviant ones. The MMN distribution was explained by bilateral temporal dipoles. During the MFTC condition, no P3a was detected, while source analysis showed the activation of a right frontal generator. Temporal dipoles showed no change between the two conditions: we thus conclude that the earlier mismatch detection is independent on the attentional load. By contrast, the activation of a right frontal subcomponent occurred only during the high-load task, independently on any actual attention shift reflected by the P3a component. We thus discuss the hypothesis whether the right frontal MMN generator, rather than subserving a simple attention switching toward the deviant stimulus, plays a role in modulating the auditory change detection system (“contrast enhancement” model).
Cognitive Brain Research, Volume 25, pp 722-734; https://doi.org/10.1016/j.cogbrainres.2005.09.024
There is growing evidence that the visual processing of human body stimuli is particular and distinct from that of other objects. This is due to implicit knowledge of anatomical and biomechanical constraints of the human body. The question arises whether body stimuli in which biomechanical constraints are violated are processed in the same way as realistic bodies. This study investigated the neural mechanisms of anatomically plausible and implausible body stimuli. Event-related potentials (ERP) were recorded in healthy participants during mental rotation of body parts. Subjects were shown pictures of body parts or whole bodies in which one element (finger, arm) could be anatomically accurate or inaccurate (e.g., left forearm attached to right upper arm). Furthermore, the body parts were rotated in 7 different orientations, from 0° to 180° in 30° increments, resulting in some possible and some impossible positions of the body parts. Analysis of the 123-channel ERPs was carried out by determining the successive segments of stable map topographies and comparing them between conditions. A particular segment appeared in the case of anatomically impossible postures at 190–230 ms followed by a segment reflecting mental rotation at 310–380 ms. Anatomically implausible positions are thus detected at a very early stage, before mental rotation occurs. Source estimations derived from the topographic data indicated that left occipital, bilateral frontal and two medial areas were activated in the case of impossible postures, whereas left parietal regions were strongly activated during mental rotation. This result contrasts with mental rotation of objects, which is considered to be a right parietal process.
Cognitive Brain Research, Volume 25, pp 659-667; https://doi.org/10.1016/j.cogbrainres.2005.08.018
Questions regarding the appropriateness of facial expressions in particular situations arise ubiquitously in everyday social interactions. To determine the appropriateness of facial affect, first of all, we should represent our own or the other's emotional state as induced by the social situation. Then, based on these representations, we should infer the possible affective response of the other person. In this study, we identified the brain mechanism mediating special types of social evaluative judgments of facial affect in which the internal reference is related to theory of mind (ToM) processing. Many previous ToM studies have used non-emotional stimuli, but, because so much valuable social information is conveyed through nonverbal emotional channels, this investigation used emotionally salient visual materials to tap ToM. Fourteen right-handed healthy subjects volunteered for our study. We used functional magnetic resonance imaging to examine brain activation during the judgmental task for the appropriateness of facial affects as opposed to gender matching tasks. We identified activation of a brain network, which includes both medial frontal cortex, left temporal pole, left inferior frontal gyrus, and left thalamus during the judgmental task for appropriateness of facial affect compared to the gender matching task. The results of this study suggest that the brain system involved in ToM plays a key role in judging the appropriateness of facial affect in an emotionally laden situation. In addition, our result supports that common neural substrates are involved in performing diverse kinds of ToM tasks irrespective of perceptual modalities and the emotional salience of test materials.
Cognitive Brain Research, Volume 25, pp 632-640; https://doi.org/10.1016/j.cogbrainres.2005.08.020
Recent behavioural and neuroimaging studies have found that observation of human movement, but not of robotic movement, gives rise to visuomotor priming. This implies that the ‘mirror neuron’ or ‘action observation–execution matching’ system in the premotor and parietal cortices is entirely unresponsive to robotic movement. The present study investigated this hypothesis using an ‘automatic imitation’ stimulus–response compatibility procedure. Participants were required to perform a prespecified movement (e.g. opening their hand) on presentation of a human or robotic hand in the terminal posture of a compatible movement (opened) or an incompatible movement (closed). Both the human and the robotic stimuli elicited automatic imitation; the prespecified action was initiated faster when it was cued by the compatible movement stimulus than when it was cued by the incompatible movement stimulus. However, even when the human and robotic stimuli were of comparable size, colour and brightness, the human hand had a stronger effect on performance. These results suggest that effector shape is sufficient to allow the action observation–matching system to distinguish human from robotic movement. They also indicate, as one would expect if this system develops through learning, that to varying degrees both human and robotic action can be ‘simulated’ by the premotor and parietal cortices.