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Attention 10 Physiology of Attention.pdf

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PSYC 330
Richard Wright

10 - Physiology of Attention March-25-13 11:45 PM • There isn't one memoryor attention area! They're spread all over the brain. ○ NOT A SINGLE AREA!IT'S A WASTE OF TIME TO FINDANY. • Check out some TED talks (a clip from today willbe from TED talk) I. Overviewof Brain Structure • Built on the second lecture • [TED talk] Julia, the neuroscientist, had a stroke ○ The two hemisphereare completely separate from one another , but communicate through corpus collosum • What brainareas mediate attention? ○ Probably easierto say which areas AREN'T • Attention's critical brain areas ○ Reticular activating system (RAS) -- associated with production of neurotransmitter and arousal ○ Superior colliculus-- playsa major role in programmingof saccades (maps of current location & destination) ○ Pulvinar(regionof thamalus)-- filtering other stimuli so you can focus on attended stimulus, esp. spatial attention ○ Anterior cingulatecortex -- interference (Stroop effect) ○ Parietal cortex ○ Frontal cortex -- controls other types of processing, esp. orienting network • What havewe learned from studying the monkey brain ○ Lots of research based on studies on [macaque] monkey ○ Lots of similaritiesin temporal cortex ○ Direct cuing works on monkeys (stimulus-driven),but even faster than human (shows same pattern though) II. Subcortical Attentional Processing • Esp. the thalamus and superior colliculus • "older part of the brain" • Subcortex and involuntaryattention ○ More reflexive,less cognitive ○ Thalamus, pulvinar nucleus, superior colliculus, RAS • Chemical basisof attention ○ Looking at the effects of different neurotransmitters on attention processing ○ Still a new field ○ Dopamine -- frontal cortical processing, serves executive function  e.g.,in Parkinson there's a deficit in dopamine& break down of attentional processing ○ Serotonin -- related to depressivesymptoms,  Raphe nucleus  Associated with low arousal routine activity (high levelof serotonin) ○ Norepinephrine -- related to adrenaline, learning  Associated with alertness/arousal  Reciprocal relationshipwith serotonin in terms of arousal  Reciprocal relationshipwith serotonin in terms of arousal • Focused attention and superior colliculus activity ○ b/c it's so based on monkeys → look at their saccadic eye movements ○ Looking at eyemovements wereBIG! This was such a boom  Used micro-stimulationor singlecell recording ○ Superior colliculus activates when shifting attention, even if monkeydoesn't move eyes  Confirmedin human with PET (after it was invented) ○ [Experiment] eyes are on fixation cross and not paying attention to the light→ lower firing rates  Eyes are on fixation cross but attending to the light→ higher firing rates • Inhibitionof Return (IOR) involvessuperior colliculus ○ Damageto the superior colliculus= no IOR • ProgressiveSupranuclear palsy(PSP) affects superior colliculus ○ Parkinson likedisease ○ Alsoaffects eye movements, starting with vertical movements;not until later stages that horizontal movements degrade ○ [Experiment at those in earlierstages of PSP]P can move their attention left/right(and show IOR), but has difficultyfor top/bottom shifts (show lessIOR)  Reaction time in cued = uncued  No slope = no IOR ○ One source of evidencethat superior colliculu is important for IOR • Essar had thiaminedeficiency disrupts superior colliculus and IOR ○ IOR performance, compared to age matched P → no IOR (no slope between un/cued) ○ When treatment targets thiaminedeficiency, they fixedthis problem • Thalamusis the gatewaybetween subcortex and cortex ○ Other than smell,all sensory input must pass through thalamus ○ Nice bottleneck role (Rememberthe structural bottle neck of attentional listening?This is likea similaridea) • Pulvinar activated when P isblocking out visual information to focus on target (attentional filtering of distractors) ○ If damaged(by stroke, lesions): attentional filtering starts to break down • [will come back to this when we talk about ADD] ○ Maybe they have thalamus dysfunction~ III. Cortical Attentional Processing • Primarilythe parietal lobe • Occipital lobe -- visual processing Temporal -- more varied; associated with auditory lobe, but there's some complex visual processing (pattern, face recognition) • Parietal -- lots of attentional operations are carried out here ○ Spatial attention [more on this on another week]  Spatial neglect ○ Active no matter what kind of attention task P is doing ○ Different from monkeys' brains • Frontal -- controlling attentional processing ○ Seat of consciousness (prefrontal cortex, or thalamus? Peoplecan still function without frontal, but not without thalamus) • Visual ERPs and covert orienting ○ [Experiment] look at fixationcross, shift attention to sideof display Activation occurs in contralateral hemisphere (i.e.,right sideof fixation cross, activation in ○ Activation occurs in contralateral hemisphere (i.e.,right sideof fixation cross, activation in left hemisphere) ○ Increase in magnitudein P1 when paying attention to target → greater if they're paying attention to a stimulus than attending
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