NROC64H3 Chapter Notes - Chapter 21: Receptive Field, Gaba Receptor Antagonist, Robert Desimone

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25 Jan 2013
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Chapter 21: Attention
Introduction
o Attention: state of selectively processing simultaneous sources of information
There is interactions between modalities
Has to do with preferential processing of sensory information
ADHD: inattention, hyperactivity and impulsiveness
5-10% of all school aged children worldwide
Some continue to show symptoms as adults
Cause: unknown
Smaller prefrontal cortex and basal ganglia
Hereditary
Non genetic factors: brain damage, pre mature birth.
D4 and D2 dopamine receptor gene and dopamine transporter gene
Ritalin: mild central nervous system stimulant, increases dopamine effect
Cortical activity affected by attention
Behavioural Consequences of Attention
o We place object on fovea
o Can pay attention to something on retina outside fovea
Enhanced Detection
o Experiment: cue stimulus at fixation point, half trials small target flashed left or right after delay
period
Cue: plus sign (equally likely target left or right), arrow (4x more likely it would appear on
side arrow points to)
Had valid and invalid cues with arrows (valid 4x more likely than unlikely)
There was a covert switch in attention without moving the eyes that made valid cues more
detected than neutral and invalid cues less detected than neutral
Less sensitive to side opposite of attention
Faster Reaction Times
o Experiment 2: told to push button when they perceive a stimulus at either location
Same arrows or plus
Invalid greater reaction time than neutral and valid had a smaller reaction time than neutral
20-30 msec difference
o Attention can alter speed of visual processing
Neglect Syndrome as an Attentional Disorder
o Neglect syndrome: ignore objects, people and sometimes themselves to one side of center gaze
o Less common after left hemisphere damage
o Best studied after damage to the right side (neglect left side); right has to do with spatial sense
o Often also show denial
o Draw wrong, point wrong,
o Lesions in posterior parietal cortex in right hemisphere
also after prefrontal cortex, cingulate cortex and others
Posterior parietal: involved in attending to objects at different positions in extrapersonal
space
Neglect: hard to capture attention on neglected side or disengage attention from
neglected side
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