Brain Deactivation in the Outperformance in Bimodal Tasks: An fMRI Study

Abstract

While it is known that some individuals can effectively perform two tasks simultaneously, other individuals cannot. How the brain deals with performing simultaneous tasks remains unclear. In the present study, we aimed to assess which brain areas corresponded to various phenomena in task performance. Nineteen subjects were requested to sequentially perform three blocks of tasks, including two unimodal tasks and one bimodal task. The unimodal tasks measured either visual feature binding or auditory pitch comparison, while the bimodal task required performance of the two tasks simultaneously. The functional magnetic resonance imaging (fMRI) results are compatible with previous studies showing that distinct brain areas, such as the visual cortices, frontal eye field (FEF), lateral parietal lobe (BA7), and medial and inferior frontal lobe, are involved in processing of visual unimodal tasks. In addition, the temporal lobes and Brodmann area 43 (BA43) were involved in processing of auditory unimodal tasks. These results lend support to concepts of modality-specific attention. Compared to the unimodal tasks, bimodal tasks required activation of additional brain areas. Furthermore, while deactivated brain areas were related to good performance in the bimodal task, these areas were not deactivated where the subject performed well in only one of the two simultaneous tasks. These results indicate that efficient information processing does not require some brain areas to be overly active; rather, the specific brain areas need to be relatively deactivated to remain alert and perform well on two tasks simultaneously. Meanwhile, it can also offer a neural basis for biofeedback in training courses, such as courses in how to perform multiple tasks simultaneously.

Stimulation in the Dorsolateral Prefrontal Cortex Changes Subjective Evaluation of Percepts

“…Based on this model, a hypothesis can be developed that, in the case of uncertainty or overloading of object-level processing, the prefrontal cortices will become more active in order to modulate signals and noise. This hypothesis is supported by a recent fMRI study [6] showing that the PFC (Brodmann area 9, BA9) was activated when subjects were overloaded in a bimodal attentional task, compared to a unimodal task. Here, we report a study showing that applying repetitive transmagnetic stimulation (rTMS) over the BA9 in order to interfere with its functional activity resulted in significant increas in guessed responses, compared to three other control conditions (i.e., no-TMS, sham TMS on BA9, and rTMS on Cz).…”

“…Based on this model, a hypothesis can be developed that, given uncertainty or overloading of object-level processing, the prefrontal cortices will be more active in modulating signals and noise. This hypothesis is supported by a recent fMRI study [6] showing that the dorsolateral PFC (BA9) was more active when subjects performed bimodal tasks than in a combination of unimodal tasks. Here, we report a study showing that applying repetitive transcranial magnetic stimulation (rTMS) over the BA9 can reproduce the uncertainty effect while subjects perform a feature binding task.…”

“…This suggests that it may be involved in the process of visual awareness and working memory. Our hypothesis is that object-level processing in the parietal lobe is more efficient when the dorsolateral PFC is in a functional state, which also results in more confident responses in our feature binding task [6]. If in the meantime, we deliver rTMS over the dorsolateral PFC, compared to the other two control sites, it will disturb the recurrent feedback routes to the object processing and result in an increase in guessed responses.…”

The Influence of Levetiracetam in Cognitive Performance in Healthy Individuals: Neuropsychological, Behavioral and Electrophysiological Approach

“…The anterior region of the cerebral cortex, also known as frontopolar cortex (Brodmann area-10) has been linked to extremely complex executive functions. 52 – 54 ) The electrophysiological data for the pair of electrodes FP1 and FP2, located in the anterior prefrontal cortex region, showed a similar pattern for the main effect condition. A decrease in theta power between the placebo and LEV conditions was observed.…”

Functional neuroanatomy of auditory scene analysis in Alzheimer's disease

“…Together these profiles suggest that AD may lead to abnormally enhanced activation (or failed deactivation) of inferior parietal cortex during analysis of the incoming sound stream. Dynamic activity shifts in inferior parietal components of the default mode network may normally act to maximise processing efficiency; such shifts might maintain sensitivity to aberrant sensory stimuli that are more difficult to match against stored templates ( Chiang et al, 2013 ; Newman and Twieg, 2001 ), whereas this sensitivity may be blunted in AD. Modulation of inferior parietal cortex activity could facilitate overall network responsivity to salient auditory and other environmental events, consistent with the proposed ‘sentinel’ function of the default mode network in the healthy brain and its blighting in AD ( Buckner et al, 2008 ; Gilbert et al, 2007 ).…”