Download 1. What different types of attention exist? Name and describe at least

1. What different types of attention exist? Name and describe at least four types of attention.
Exogenous or bottom-up attention: type of attention associated with sensory stimuli “popping out”
of the background withouth cognitive input, e.g., a flash of light in the darkness, a loud sound in
quietness, a warm spot in a cold environment etc.
Endogenous / selective / top-down attention: attention deliberately directed by the brain to serve a
behavioral goal, e.g., focusing of auditory attention to a specific speaker in at a social event.
Sustained attention: attention devoted to a specific task for a prolonged period of time.
Alternating attention: attention alternating between several tasks over time, e.g., reading a circuit
schematic and building it.
Divided attention: attention used to perform multiple tasks at the same time, e.g., checking e-mails
at a lecture : )
2. What are the causes, symptoms, and treatments of attention-deficit/hyperactivity disorder?
ADHD is commonly associated with symptoms such as inattention, hyperactivity and
impulsiveness. The causes for ADHD are poorly understood. MRI-studies however suggest that the
condition is associated with smaller-than-usual sized brain structures associated with regulation and
planning of behavior such as the prefrontal cortex and basal ganglia. Similarly, the condition is
associated with abnormalities in the genes related to the function of dopaminergic neurons.
Heredity plays a significant role in ADHD. Children of parents with ADHD are more likely to
develop the condition themselves. Likewise, the probability of a child developing ADHD is
significantly increased if the child's identical twin has the condition. Nongenetic factors such as
brain injury and premature birth may also be involved.
Currently ADHD is typically treated with behavioral therapy and psychostimulant drugs such as
ritalin. Ritalin is a mild CNS stimulant with inhibitory effects on dopamine transporters.
3. Which brain areas might be related to attention? How?
The brain areas involved in attention compose the so called frontoparietal attention network. The
associated brain areas include: the prefrontal cortex, basal ganglia, pulvinar, parietal cortex and
superior colliculi as well as areas FEF, LIP, MT, IT, V1, V2, V3 and V4. A large amount of the
evidence for the involvement of these brain regions in attention has been acquired through brain
imaging, psychophysical studies and combinations thereof performed on human subjects. Further
evidence has been gained from invasive studies performed on other primates such as the macaque
monkey. The involvement of some of these brain regions in attention is described briefly below.
The pulvinar nucleus of the thalamus contains neurons that respond more strongly to a stimulus in
the receptive field than in the case where attention is directed somewhere else. Furthermore, the
pulvinar has mutual connections with several cisual cortical areas in the occipital, parietal and
temporal lobes, allowing it to modulate cortical activity in a wide range of brain regions. In studies
performed on monkeys, it has been found out that when attention is drawn to a pulvinar receptive
field, the synchronicity of neural activity between the pulvinar and areas V4 and IT increases. This
suggests that the pulvinar regulates information flow in visual cortex.
FEF stands for frontal eye fields. Area FEF refers to a cortical area in the frontal lobe with direct
connections between numerous brain areas associated with attention (V2,V3,V4, MT, parietal
cortex). Neurons in FEF have small areas in the visual field known as motor fields. If neurons in the
FEF are stimulated, the eyes make a saccade to the motor field corresponding to the stimulated
neurons. Experimental evidence suggests that FEF is a part of system for directing attention and
enhancing visual performance in a location-specific manner. It is possible that FEF activity
indicating the location of a potential to-be-performed saccade is fed back to the connected cortical
areas, thus enhancing the neural activity in these brain regions.
The lateral intraparietal cortex, also known as area LIP, is thought to be responsible for constructing
a so called priority map of vistual stimuli. A priority map is a map of locations where attention
should be directed based on stimulus salience and cognitive input. A related concept is the salience
map; this maps the exogenous attention features of a stimulus scenario. A priority map can be
through of as a salience map with added top-down / endogenous effects.
4. How would you study the brain areas involved in directing selective attention in humans?
A common way to study brain functions in humans is to combine psychophysical studies with brain
imaging techniques. This approach is attractive as it is a non-invasive and relatively safe way to
perform experiments. An example of such an approach is the experiment performed by Steven
Petersen at Washington University. In the experiment, an image was flashed on a computer display
for half a second followed by another image after a delay period. The images were composed of
individual units with various variable features e.g., size, shape and color. The psychophysical task
of the participant was to indicate whether or not the two images were the same or not. The
experimenters attempted to separate the effects of selective and divided attention by devising two
similar experiments. In the selective attention task subjects had to pay attention to a selected feature
of the stimulus elements, e.g., size or shape and indicate whether this feature was different in the
later image. Conversely, in the divided attention experiment subjects were asked to monitor changes
in more than one stimulus feature, for example size and attention. The subjects brainactivity was
recorded with a PET scanner during the psychophysical task. The differences in the brain activity
regions between the two experiments indicate how brain activity differs between selective and
divided attention. It would be interesting to apply similar methods to study brain activity in
decoding spatial cues in auditory signals.