How the brain's blue spot helps us focus our attention
The neurotransmitter noradrenaline regulates our brain's sensitivity to relevant information

Date:
January 7, 2022
Source:
Max Planck Institute for Human Development
Summary:
How can we shift from a state of inattentiveness to one of highest
attention? The locus coeruleus, literally the 'blue spot,' is
a tiny cluster of cells at the base of the brain. As the main
source of the neurotransmitter noradrenaline, it helps us control
our attentional focus. Synthesizing evidence from animal and human
studies, scientists have now developed a novel framework describing
the way the blue spot regulates our brain's sensitivity to relevant
information in situations requiring attention.



FULL STORY ==========================================================================
How can we shift from a state of inattentiveness to one of highest
attention? The locus coeruleus, literally the "blue spot," is a tiny
cluster of cells at the base of the brain. As the main source of the neurotransmitter noradrenaline, it helps us control our attentional
focus. Synthesizing evidence from animal and human studies, scientists
at the Max Planck Institute for Human Development and the University
of Southern California have now developed a novel framework describing
the way the blue spot regulates our brain's sensitivity to relevant
information in situations requiring attention. Their findings have
been published in an opinion article in the journal Trends in Cognitive Sciences.


==========================================================================
Our attention fluctuates. Sometimes, we are distracted and things slip
by our awareness, while at other times we can easily focus on what
is important.

Imagine you are walking home after a day at work; perhaps you are
preparing the list of groceries to buy for dinner in your mind --
you are in a state of inattentiveness. However, when a car you did not
notice suddenly honks, you are readily able to redirect your attention
and respond to this new situation. But how does the brain shift from a
state of inattentiveness to one of focused attention? During states of inattentiveness, our brains are governed by slow, rhythmic fluctuations of neural activity. In particular, neural rhythms at a frequency around 10
Hertz, termed alpha oscillations, are thought to suppress the active
processing of sensory inputs during inattentiveness. Thus, alpha
oscillations can be understood as a filter that regulates our brain's sensitivity for external information. "While the link between the waxing
and waning of alpha oscillations and attention has been established for
some time, less is known about what makes these rhythmic firing patterns
come and go," says Markus Werkle-Bergner, Senior Scientist at the Center
for Lifespan Psychology at the Max Planck Institute for Human Development
and coauthor on the opinion article.

To explore this question, the researchers focused on the blue spot (locus coeruleus), a tiny cell structure that is located in the brainstem, hidden
deep under the cortex. This cell cluster is only about 15 millimeters in
size, but it is connected to most of the brain via an extensive network
of long-ranging nerve fibers. The blue spot is made up of neurons that
are the main source of the neurotransmitter noradrenaline. By regulating
neural communication, noradrenaline contributes to the control of stress, memory, and attention.

"Due to its small size and its location deep in the brainstem, it was previously almost impossible to investigate the noradrenergic nucleus non- invasively in living humans. Fortunately, over the past years, animal
research has revealed that fluctuations in pupil size are linked to the activity of the blue spot. Thus, our eyes can be regarded as a window
to a brain region that long seemed inaccessible," says Mara Mather,
professor of Gerontology at the University of Southern California and
coauthor on the opinion article.

To study whether the blue spot's noradrenaline could be one factor
regulating alpha oscillations, the researchers combined recordings
of pupil size and neural oscillations while participants solved a
demanding attention task. As expected, during moments of larger pupil
size, indicative of higher noradrenergic activity, alpha oscillations disappeared. Moreover, participants who showed stronger pupil and alpha responses were better at solving the attention task. These findings,
that were published 2020 in an article in the Journal of Neuroscience,
suggest that by modulating alpha oscillations, the blue spot can help
us focus our attention.

What remained unanswered in this study is hownoradrenaline influences
alpha oscillations. To approach this question, the authors additionally
turned to previous animal research that recorded neural activity
directly from neurons in the thalamus, a region in the middle of the
brain that functions as a pacemaker of the alpha rhythm. Importantly,
the rhythmic firing of these neurons at rest gives rise to the cortical
alpha oscillations seen during states of inattentiveness. However,
adding noradrenaline to these neurons abolishes their rhythmicity.

"Assembling the findings across studies, we were able to describe how noradrenaline and the thalamus might interact to control alpha rhythmic activity. We suggest that the blue spot's noradrenaline regulates our
brain's sensitivity to process relevant information by suppressing alpha generators in the thalamus," says Martin Dahl, postdoctoral researcher
at the Center for Lifespan Psychology, Max Planck Institute for Human Development, and the University of Southern California and first author
on the opinion article.

Thus, during situations requiring a sudden shift in attention, a surge of noradrenaline helps us refocus -- and quickly dodge the approaching car.

Further long-term studies that assess both the locus coeruleus and
thalamus in the same participants may be able to shed new light on the
neural mechanisms of attention and its decline in aging and disease.

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========================================================================== Journal Reference:
1. Martin J. Dahl, Mara Mather, Markus Werkle-Bergner. Noradrenergic
modulation of rhythmic neural activity shapes selective
attention. Trends in Cognitive Sciences, 2022; 26 (1): 38 DOI:
10.1016/j.tics.2021.10.009 ==========================================================================

Link to news story: https://www.sciencedaily.com/releases/2022/01/220107121453.htm
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