Neural Mechanisms of Sustained Attention Are Rhythmic.
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ABSTRACT:
SUBMITTER: Helfrich RF
PROVIDER: S-EPMC6286091 | biostudies-literature | 2018 Aug
REPOSITORIES: biostudies-literature
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Project description:Background: Stress exacerbates symptoms of schizophrenia and attention deficit hyperactivity disorder, which are characterized by impairments in sustained attention. Yet how stress regulates attention remains largely unexplored. Here we investigated whether a 6-day variable stressor (VS) altered sustained attention and the cholinergic attention system in male and female rats. Methods: Sustained attention was tested with the sustained attention task (SAT). Successful performance on SAT relies on the release of acetylcholine (ACh) into the cortex from cholinergic neurons in the nucleus basalis of Meynert (NBM). Thus, we evaluated whether VS altered the morphology of these neurons with a novel approach using Cre-dependent virus in genetically modified ChAT::Cre rats, a species used for this manipulation only. Next, electrochemical recordings measured cortical ACh following VS. Finally, we used RNAseq to identify VS-induced transcriptional changes in the NBM. Results: VS impaired attentional performance in SAT and increased the dendritic complexity of NBM cholinergic neurons in both sexes. NBM cholinergic neurons are mainly under inhibitory control, so this morphological change could increase inhibition on these neurons, reducing downstream ACh release to impair attention. Indeed, VS decreased ACh release in the prefrontal cortex of males. Quantification of global transcriptional changes revealed that, although VS induced many sex-specific changes in gene expression, it increased several signaling molecules in both sexes.
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Project description:Human attention fluctuates across time, and even when stimuli have identical physical characteristics and the task demands are the same, relevant information is sometimes consciously perceived and at other times not. A typical example of this phenomenon is the attentional blink, where participants show a robust deficit in reporting the second of two targets (T2) in a rapid serial visual presentation (RSVP) stream. Previous electroencephalographical (EEG) studies showed that neural correlates of correct T2 report are not limited to the RSVP period, but extend before visual stimulation begins. In particular, reduced oscillatory neural activity in the alpha band (8-12 Hz) before the onset of the RSVP has been linked to lower T2 accuracy. We therefore examined whether auditory rhythmic stimuli presented at a rate of 10?Hz (within the alpha band) could increase oscillatory alpha-band activity and improve T2 performance in the attentional blink time window. Behaviourally, the auditory rhythmic stimulation worked to enhance T2 accuracy. This enhanced perception was associated with increases in the posterior T2-evoked N2 component of the event-related potentials and this effect was observed selectively at lag 3. Frontal and posterior oscillatory alpha-band activity was also enhanced during auditory stimulation in the pre-RSVP period and positively correlated with T2 accuracy. These findings suggest that ongoing fluctuations can be shaped by sensorial events to improve the allocation of attention in time.
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