Download Coming to Attention How the brain decides what to focus conscious

Coming to Attention
How the brain decides what to focus conscious attention on
Adapted from Andreas K. Engel, Stefan Debener and Cornelia Kranczioch,
Scientific American.com , July 30, 2006
1. Cognitive neuroscientists would like to know what is behind such phenomena: What
happens in our brains when we deliberately concentrate on something? Does some
mechanism inside our heads decide which information reaches our consciousness--and
which does not? And do our intentions, needs and expectations influence what we perceive?
Recent research offers some fascinating insights.
2. Psychologists began seeking answers to such questions as long ago as 1890, when
American philosopher and psychologist William James wrote about important characteristics
of attention in The Principles of Psychology. James concluded that the capacity of
consciousness is limited, which is why we cannot pay attention to everything at once.
3. James and others distinguished between types of attention. Some of them are "selfcreated": a penetrating odor, a loud siren, a woman in a bright red dress among people
wearing black. (Many researchers now call this process "bottom-up," because the stimuli
battle their way into our consciousness automatically because they are so striking.)
Alternatively, we can actively and deliberately control our focus (called "top-down," because
higher brain regions are involved at the outset). For example, at a noisy party, we can tune
out background noise to listen to the conversation at the next table.
4. Neuroscience did not deal with this topic until much later. In 1985 a research team led by
Robert Desimone at the National Institute of Mental Health was first to observe how single
neurons in the visual region of rhesus monkeys changed their activity depending on what the
primates were looking at. Desimone and his colleague Jeffrey Moran discovered that certain
neurons in the V4 area of the visual region -- an area important for the perception of color -responded more frequently when the test animal gazed fixedly at a colored target. The same
nerve cells (also called neurons) exhibited much weaker activity when the ape noticed the
target but did not look right at it.
5. All these studies linked attention to an increase in the activity of neurons. Now the latest
neurobiological research points to another significant factor in attention: huge numbers of
neurons synchronize their activity. Many neuroscientists believe that study of this
phenomenon will provide the answer to one of the biggest riddles of attention research, the
so-called binding problem.
6. Imagine that a grasshopper suddenly lands on the table in front of you. Before the insect
can arrive in your consciousness as a fully realized, three-dimensional entity, several
different areas of the brain must be active. One processes the insect's color, another its size,
yet another its location, and so on. How does the brain bind all these individual
characteristics together into a single impression of a green grasshopper?
7. Twenty years ago Christoph von der Malsburg, a computer scientist and brain theorist,
suggested a solution. By synchronizing their activities, nerve cells could join into effectively
cooperating units--so-called assemblies. Then, in the early 1990s Francis Crick Christof Koch
expanded on Malsburg's hypothesis. The two scientists proved that only signals from "teams"
of neurons that cooperated especially well possessed enough strength to reach the
consciousness. Recent findings lend empirical support to the Crick-Koch hypothesis. In the
experiments done between 1995 and 1998 Fries, Singer and Engel demonstrated that the
degree of neuronal synchronization decisively influences which incoming signals are further
processed and thus becomes relevant to the consciousness's perception.
8. Fries also showed that active, intentional control of
attention can influence
synchronization. He worked with macaques that had learned to direct their attention to a
particular spot on the monitor screen in response to a signal; a stimulus would appear at that
location after a short delay. If this stimulus appeared at the expected location, the
synchronization was clearly stronger. Synchronization immediately weakened, however, as
soon as the research animals switched their attention to other stimuli.
Expectant Neurons
9.
The effect of expectation reveals itself especially clearly in an experiment using acoustic
stimuli. The researchers asked listeners to pay particular attention to high tones in a series of
more or less similar tones. When they heard the target tone, a high-frequency
synchronization activity appeared in the brain; in contrast, unexpected loud noises, which
automatically call attention to themselves, did not elicit this effect.
10. Regardless of which sensory system is involved, the reinforced rhythmic synchronization
that the researchers measured seems to be a good indicator of active attention. When a
person deliberately directs attention to a stimulus, not only does the activity of individual
neurons in the brain change, but the synchronization also improves for all the neurons taking
part in the coding for the same stimulus. The effect may be compared to a symphony
orchestra that soon arrives at a common tempo after the individual instruments begin playing.
11.
In what ways might intentions and needs influence attention? With the help of
functional magnetic resonance imaging (fMRI), the researchers wanted to locate brain
regions involved in conscious perception of a target stimulus. To do so, they needed a
research technique to compare two conditions: one that led from active attention to conscious
awareness of a stimulus, and a second, in which the same stimulus did not penetrate the
consciousness. They used a phenomenon called attention blink. In the experiment they once
again displayed a series of letters to subjects and observed them with fMRI. This time,
however, only a single green letter appeared among rapidly changing black letters, and the
subject had to tell at the end of the test whether or not it was a vowel. At the same time, the
subject was to look for a black X that popped up at different times after the green -letter.
12. During the experiment, the attention of the subjects showed clear gaps--the "blinks"--as
a result of their intentional, conscious focus on the task. If the black X appeared very soon-within a third of a second--after the green letter, about half the time the participants did not
notice it. If there was a longer period after the first stimulus, their recognition rate improved.
13. At the end of the experiment, they compared the fMRI values for each procedure in
which the subjects perceived the X with those in which it was shown but not noticed. They
saw clear differences in activity in a few brain regions. Scientists have been aware of these
regions' importance in controlling attention for a long time. The researchers were surprised,
however, when they found a difference in the system, which is normally involved in
processing emotional reactions. The state of our emotional system probably influences the
control of attention and which sensory signals are allowed to reach consciousness.
14. Therefore, the neuronal synchronization that is closely associated with conscious
perception does not just depend on external stimuli but also on the flexible inner dynamic of
the brain. The scientists theorize that neurons are constantly and actively predicting where
the visual stimuli they expect will appear. All incoming stimuli set their own temporal coupling
patterns in motion. If these stimuli correspond to those that the expectation has created, the
incoming signals are reinforced and advance onward. If the expectations are not met,
however, the brain suppresses the incoming neuronal messages.
15. Neuronal synchronization brings order to the chaotic mental world. In fact, cognitive
deficits and disordered thoughts among schizophrenic patients appear to be connected to
disturbed neuronal synchronization. On the other hand, a healthy brain is an active receiver
of news from the environment. It is an active system, one that controls itself via a complex
internal dynamic. Our experiences, intentions, expectations and needs affect this dynamic
and thus determine how we perceive and interpret our environment.
QUESTIONS
1. Who are the people interested in answers to the questions in paragraph 1?
______________________________________________________________
2. Why, according to William James, can we not focus conscious attention on everything at
once?
______________________________________________________________
3. A. Name the two main types of attention distinguished by psychologists:
a. ________________________
b. ________________________
B. What does the example of listening to a conversation at a noisy party illustrate?
______________________________________________________________
4. Studies such as the one described in paragraph 4 showed the following correlation:
__________________ is related to ______________________________________
5. What may provide an answer to the “binding problem”?
______________________________________________________________
6. What is the relation between paragraphs 5 and 6?
a. Par 6 illustrates an idea presented in par 5.
b. Par 6 contrasts par 5.
c. Par 6 is in a cause and effect relationship with par 5.
d. Par 6 adds information to par 5.
7. In par. 7 it says “Christoph von der Malsburg suggested a solution”. A solution to what?
________________________________________________
______________________________________________________________
8. Only assemblies of nerve cells which work together effectively can send messages to the
consciousness. True / False
Justify your answer from the text:
__________________________________________________________________________
__________________________________________________
9. In his experiment with macaques Fries discovered that if the animal didn’t focus on the
stimuli, the synchronization became (weaker/ stronger).
10. What does the experiment described in paragraph 9 illustrate?
Complete the sentence:
The experiment described in paragraph 9 illustrates the ______________
_________________________.
11. What does the writer compare the process of neuron synchronization to?
Write ONE word in each space.
In par 10, the synchronization of neurons in our brain is compared to a ______________
______________ . Like the individual instruments in the latter, the individual ______________
in the former start acting together, i.e. become synchronized.
12. (par 11) "To do so, they needed a research technique…"
a. Who needed a research technique? ____________________________
b. What did they want to do? _____________________________________
_____________________________________________________________
13. What were the scientists' findings from the fMRI study, described in paragraphs 11-13?
a. ______________________________________________________________
b. ______________________________________________________________
14. According to paragraph 14, what are the two factors that contribute to the neuronal
synchronization?
a. ______________________________________________
b. ______________________________________________
15. What is the writer’s conclusion?
a. The expected location of the stimuli strengthens synchronization.
b. Human brain is a passive system entirely controlled by its environment.
c. Schizophrenic patients suffer from disturbed neuronal synchronization
d. Human brain responds to incoming stimuli via neuronal synchronization
Vocabulary practice
Study the meanings of the following words
Paragraph Word
5
significant
subtitle
brain
8
influence
subtitle
conscious
10
regardless
1
intention
10
measure
2
characteristic
12
subject
2
limit
12
intentional
3
distinguish
13
experiment
4
deal with
13
compare
5
link
13
value
Fill in the missing word. Pay attention to the part of speech of the missing word.
characteristics distinguish
intentional
deal with
subjects
significant
value
influence
1. Both schools and parents need to ________________ the issue of violence of the young
generation.
2. There has been a ____________________ increase in the employment rate in this
developing city.
3. Charisma is one of the most important __________________ of a leader.
4. The child’s misbehavior was ___________________. He wanted to draw everybody’s
attention.
5. The _________________ were asked to fill out a questionnaire followed by personal
interviews.
6. It is sometimes difficult to ________________ between real diamonds and fake ones.
7. Real estate values have doubled in _______________ over the last decade.
8. Beatles still have an __________________ on many singers and musicians.
Translate
1. Parents should never compare their kids the children of others.
______________________________________________________________________
2. The match will take place regardless of the weather.
______________________________________________________________________
3. Much research is devoted to the study of the brain.
_______________________________________________________________________
4. There is a definite link between genetics and intelligence.
_______________________________________________________________________
5. The new manager declared his intention to make reforms in the company.
________________________________________________________________________
6. How can we measure one’s BMI?
________________________________________________________________________
7. The experiment focused on subjects from low-income and middle-income class.
________________________________________________________________________
8. Health-conscious people eat healthy diets and exercise regularly.
_________________________________________________________________________