Neuroreport
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The primary mechanism by which cocaine induces stereotypy has been difficult to discern because cocaine has three high-affinity targets: the reuptake transporters for dopamine (DAT), norepinephrine, and serotonin. To dissect out the role of DAT in cocaine effects, we generated a knock-in mouse line with a cocaine-insensitive DAT (DAT-CI mice). DAT-CI mice provide a powerful tool that can directly test whether DAT inhibition is important for cocaine-induced stereotypy. ⋯ In fact, 40 mg/kg cocaine suppressed stereotypy in DAT-CI mice but produced profound stereotypy in wild-type mice. These findings suggest that DAT inhibition is necessary for cocaine-induced stereotypy. Furthermore, mechanisms independent of DAT inhibition appear to inhibit stereotypy.
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We describe the characterization of a partial saphenous nerve injury (PSNI) model of neuropathic pain in the mouse. PSNI resulted in significant mechanical allodynia in mice with no behavioural change to temperature stimulation. ⋯ In galanin knockout mice, PSNI failed to induce allodynia as previously reported in other neuropathic pain models. PSNI can be used to simultaneously study behavioural and neurophysiological changes in wild-type and transgenic mice.
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The evaluation of whether an outcome is good or bad is reflected in feedback-related negativity (FRN), which is an event-related brain potential (ERP) component that is elicited by bad events. It is still, however, unclear how the FRN reflects the evaluation of outcomes induced by others. ⋯ FRN was elicited not only by the losses of another in a cooperative situation but also by the gains of another in an antagonistic situation. These results indicate that FRN reflects the evaluation on the basis of one's own evaluative criteria, regardless of the monetary outcome for another.
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In event-related brain potential studies using a visual S1-S2 matching task, stimulus changes elicit change-related positivity, which reflects the detection of visual changes. To investigate the effects of attention on change detection, we tested the elicitation of change-related positivity in response to changes in color and spatial frequency under three attention conditions: (i) changes in an unattended feature at an attended location, (ii) in an attended feature at an unattended location, and (iii) in an unattended feature at an unattended location. The results suggest that stimulus changes can be detected even when both feature and spatial attention are withdrawn, but change detection can also be inhibited, which might be because of biased-competition determined by the combination of feature and spatial attention conditions.
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Randomized Controlled Trial
Theta burst stimulation of the motor cortex reduces laser-evoked pain perception.
Repetitive transcranial magnetic stimulation over the primary motor cortex (M1) was recently introduced to modulate pain perception. The aim of this double-blind cross-over study was to investigate the effect of a modified rTMS paradigm, called cTBS on experimentally induced laser-evoked pain applied over the left M1. cTBS inhibits the cortical excitability of the M1 for approximately 1 h. Subjective pain was measured using the verbal analogue scale prior to, immediately after and 30 min post-stimulation. cTBS, and not the sham stimulation resulted in a significant decrease in pain perception on both hands, accentuated on the right hand. Further studies are needed using motor cortex TBS in chronic pain to pave the way towards a therapeutic tool.