Biomedical subjects

Matthijs Vink

Publications and source records attributed to Matthijs Vink.

5 recordsLinked to original sources

PubMed2006

Striatal dysfunction in schizophrenia and unaffected relatives.

BACKGROUND: Schizophrenia has been frequently associated with impaired inhibitory control. Such control is known to involve the striatum. Here, we investigate whether impaired inhibitory control is associated with abnormal striatal activation in schizophrenia. First-degree relatives of patients were also tested to examine whether striatal abnormality is associated with schizophrenia, or with the risk for the illness. METHODS: Both functional MRI and behavioral data were acquired during a task designed to invoke inhibitory control in 21 patients, 15 unaffected siblings, and 36 matched controls. Subjects must refrain from responding to designated stop cues occurring within a series of motor cues. Subjects could anticipate the occurrence of stop cues as the likelihood of these cues increased in a linear fashion throughout the task. RESULTS: Control subjects showed striatal activation while responding to motor cues. This activation increased in a linear fashion when the likelihood of having to inhibit the response was increased. Both patients siblings did not show anticipation-related increase in either striatal activation. However, only patients showed behavioral impairments. CONCLUSIONS: Striatal abnormalities occur in schizophrenia patients and unaffected siblings. Thus striatal abnormalities may be related to an increased (genetic) risk to develop schizophrenia.

Adult↗

PubMed2005

Brain activation during antisaccades in unaffected relatives of schizophrenic patients.

BACKGROUND: Schizophrenia patients have difficulty inhibiting automatic saccades. Many studies have failed to resolve whether healthy first-degree relatives share the same deficit. Measures of brain activity may be more sensitive than behavioral measures. In patients, the saccadic inhibition deficit has been related to impaired frontostriatal functioning. This study attempts to establish whether this abnormality is also present in unaffected relatives of patients. METHODS: Functional brain images were acquired during prosaccades and antisaccades in 16 control subjects and 16 unaffected siblings of schizophrenia patients using an event-related functional magnetic resonance imaging design. Eye movements were measured during scanning. RESULTS: The task activated a network of regions corresponding to the oculomotor system. Siblings and control subjects did not differ during execution of prosaccades. During antisaccades, siblings did not activate the caudate nucleus. Siblings and control subjects did not differ on the percentage of antisaccade errors. CONCLUSIONS: Siblings did not appropriately activate the striatum during antisaccades, similar to what has been reported in patients. Siblings, however, did not make significantly more errors during antisaccades, indicating that they were able to compensate for the inactive caudate. Future research is needed to assess the potential of this striatal deficit as (genetic) risk factor for schizophrenia.

Adult↗

PubMed2005

Brain activation related to retrosaccades in saccade experiments.

In saccade experiments, each trial (e.g. prosaccade/antisaccade) is by definition followed by a saccade, which returns the gaze back to the center (retrosaccade). This event can complicate brain-imaging results when using a simple block-design. We used an event-related functional magnetic resonance imaging design involving prosaccades and antisaccades (testsaccades) to examine brain activation associated with retrosaccades. Testsaccades activated visual and oculomotor-related brain areas. During retrosaccades, these areas were less active than during testsaccades. In the supplementary eye fields, the insula, and striatum, the retrosaccades gave rise to negative blood oxygenation level-dependent responses. In the striatum, these negative responses were equal in size to the positive responses of the testsaccades. This could mask brain activity of testsaccades when not taken into account.

Brain↗

PubMed2005

Perceptual bias following visual target selection.

Attending to a relevant item in a visual display is thought to require not only selective attention to this item, but also active inhibition of surrounding distractor items. As a consequence of this spatial inhibition, selection of a relevant item in a previous distractor location is slowed (i.e., the spatial inhibition effect). The goal of this study is to identify brain regions that are involved in this spatial inhibition effect using functional magnetic resonance imaging (fMRI). Subjects had to select a target from a display which also included a distractor, while that target was presented in either a new location (control) or in a location previously occupied by a distractor (spatial inhibition). A region of interest analysis revealed decreased activation in the superior parietal lobe (SPL), but increased activation in the motor areas (supplementary motor area, putamen) when the target was presented in a previously inhibited compared to a new location. We take these results to suggest that presenting a target in a previously inhibited location negatively biases the selection of that target in favor of an accompanying distractor. This may result in an initially more efficient selection process, resulting in lower activation in the SPL. Counteracting this perceptual bias possibly requires additional motor activation. This study provides evidence for the notion that to make selection more efficient, prior information concerning an item is used. When this prior information conflicts with the current stimulus demands, compensatory motor actions are taken to correct this perceptual bias.

Adult↗

PubMed2005

Function of striatum beyond inhibition and execution of motor responses.

We used functional magnetic resonance imaging (fMRI) to study the role of the striatum in inhibitory motor control. Subjects had to refrain from responding to designated items (STOP trials) within a similar series of motor stimuli. Striatal activation was increased significantly compared to that when responding to all targets within a series of motor stimuli, indicating that the striatum is more active when inhibitory motor control over responses is required. The likelihood of a STOP trial was varied parametrically by varying the number of GO trials before a STOP trial. We could thus measure the effect of expecting a STOP trial on the fMRI response in the striatum. We show for the first time in humans that the striatum becomes more active when the likelihood of inhibiting a planned motor response increases. Our findings suggest that the striatum is critically involved in inhibitory motor control, most likely by controlling the execution of planned motor responses.

Adolescent↗