NROC64H3 Chapter Notes - Chapter 21: Muscimol, Bicuculline, Gaba Receptor Antagonist

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8 Apr 2012
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Chapter 21: Attention
Intro:
Attention = state of SELECTIVELY processing simultaneous sources of info;
preferential processing of sensory info; selectively attend to some info & ignore rest
Interactions btn modalities may occur (performing attention-demanding VISUAL
task like reading; less sensitive to incoming SOUNDS)
ADHD:
Characteristics:
oInattention
oHyperactivity
oimpulsiveness
5-10% of all school children worldwide
brain structures:
oprefrontal cortex = smaller
obasal ganglia = smaller
onot sure if these differences found in children are behavioural significant;
but these structures have been implicated in regulation/planning of beh
heredity, brain injury, premature birth
genes related to fxn of DA neurons:
oD4 dopamine receptor gene
oD2 dopamine receptor gene
oDopamine transporter gene
Common treatments:
oBehavioural therapy
oRitalin (methylphenidate) = mild CNS stimulant (amphets)
Inhibits DA transporter = increases post-syn effect of DA
Decreases impulsiveness & inattention
Long-term use?
Behavioral Consequences of Attention
Shifting attention to some location on retina enhances visual processing by: enhanced
detection and faster reaction times.
Enhanced Detection
Experiment:
oDirect visual attention to diff location
oFixate on central point; say whether stimulus flashed on right, left of
fixation point or not at all
oTrial begins w/ cue at fixation point cue = + (neutral), or
oCue extinguished, variable delay period during which fixation point
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o½ trails = no further stimulus; other ½ of trials = small target circle on R or
left for 15 ms
oinitial cue at fixation point used to direct attention
if target appeared to the cued side, the cue was valid
if target appeared opposite to cued side, the cue was invalid
oresults:
when central cue is +, detected target stimulus 60% of the trials in
which one was presented
when central cue is , detected target stimulus on R 80% of trials in
which one was presented; but when central cue is , detected target
stimulus on L 50% of trials in which one was presented there
oexpectation of observer based on central cues influenced her ability to detect
subsequent targets
arrow cues caused observer to shift attention to side where arrow
pointed, EVEN THO EYES DIDN’T MOVE
covert shift of attention = easier to detect flashed targets compared
to trials where central cue was +
observer less sensitive to targets on opposite side of where cue
pointed
Conclusion: attention makes things easier to detect
Faster Reaction Times
Experiment similar as above: attention increases speed of rxn in perceptual studies
oPreceding target stimulus was cue stimulus (same as b4); in this experiment,
observer has to wait til he perceived a stimulus on either R or L and then
had to push a button ; +, or were cue stimulus which indicated if
neutral cue, or target stimulus would appear on the side of the central
stimulus cue arrow
oIf central cue was +, 250-300 ms to press button
oIf central cue was arrow that correctly indicated where target would appear,
rxn time = 20-30 ms faster
oIf central cue was arrow that incorrectly indicated where target would
appear, rxn time = 20-30 ms slower
Rxn time includes:
oTime for transduction in visual system
oTime for visual processing
oTime to make decsion
oTime to code for finger mvt
oTime to press button
But still saw reliable effect depending on which way arrow was point – directed the
person’s attention
Possible that attention can alter speed of visual processing or time taken to make
decision about pressing button
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