Term
| What is the definition of attention? |
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Definition
| Selection of some portion of sensory input for higher processing? |
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Term
| What are the 3 main aspects of attention? |
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Definition
spatial orienting to sensory stimuli
Selection of objects in the visual scene
Maintenance of an alert state |
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Term
| Describe Posner's spatial cuing task. What did it tell us about overt and covert attention? |
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Definition
Subjects are told to fixate and then given a valid/invalid cue in the periphery. A target then appears, and reaction time is measured to find it. It can dissociate eye movements from attentional shifts
Valid spatial cues are processed quicker than invalid cues with covert attention. |
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Term
| In the Posner task, what effect does a delay between the cue and the target have on the recation time? |
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Definition
Valid cues get quicker the longer delay
invalid cues get slower, but peak and get quicker the longer the delay |
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Term
| What are some the regions involved in spatial attention? |
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Definition
Superior colliculus
Pulvinar
Basal Ganglia
Superior Parietal cortex
Prefrontal cortex |
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Term
| How do we know the superior colliculus is involved in spatial orientation to stimuli? |
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Definition
Microstimulation of superior colliculus has the same effect of pre-cuing with a visual stimulus -> improved sensitivity
saccades and attention are related.
inactivation of part of the SC increased reaction times in the contralateral field -> can't shift attention well when lesioned |
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Term
| How do we know that the pulvinar is involved in orienting attention to objects? |
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Definition
Connections with SC (lateral and inferior pulvinar)
Connections with Parietal cortex (dorsomedial), response enhancement when attending to visual stimulus -> Covert attention
Long reaction time to invalid cues when lesioned. |
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Term
| What are basal ganglia roles in attention? |
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Definition
sensory, attentional, and memory modulation
Inhibitory activity when a stimulus is selected for a saccade
Lesions produce contralateral neglect. |
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Term
| What do Neurons in the posterior parietal cortex do when attending to a stimulus? |
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Definition
| Increase firing rate, response enhancement whether an eye task or a manual task. |
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Term
| What deficits do parietal lesions cause in monkeys? |
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Definition
can't attend to spatial cues, contralateral deficits under all conditions.
Really can't disengage attention |
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Term
| What does Parietal cortex damage in humans cause? |
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Definition
Visuospatial neglect: can't select appropriate parts of a sensory representation
Affects objects in the contralesional visual field
Difficulty disengaging
Poor extinction
Right hemisphere lesions are more troublesome |
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Term
| What is extinction as pertaining to attention? |
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Definition
The ability to orient to the appropriate stimuli, and not competing stimui
Patients with parietal lesions have difficulty with extinction tasks. |
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Term
| What do the frontal eye fields do with regards to attention? |
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Definition
Contain a visual map of space (orient to appropriate objects, movement fields)
Disctractor stimuli (sub-threshold) can improve sensitivity to contrast. |
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Term
| How do we select objects in a visual search task? |
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Definition
Simple features are in parallel (they pop out)
Combining features (color +orientation) is processed serially (color then orientation, for example)
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Term
| What areas are associated with deficits in visual search tasks? |
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Definition
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Term
| What effects does attention have on V4 and IT neurons? |
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Definition
Enhances responses for prefered stimuli, weakened responses for non-preferred stimuli
Increased sensitivity to contrast |
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Term
| What is the neural basis for competing stimuli? |
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Definition
When unattendant, stimuli that produce specific firing rates can average out
When attending, paying attention to specific stimuli will produces the specific firing rate associated with that stimulus, even if there are competing stimuli in the cell's receptive field |
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Term
| How does attention affect MT and MST? |
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Definition
Attending to preferred responses enhances the cells response, attending to non-preferred responses reduces the cells response
Increases selectivity for attended features |
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Term
| How are IT responses affected by selecting objects in a scene? |
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Definition
| Very task dependent. Some have color preferences, degree of difficulty demands. |
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Term
| How do frontal eye fields drive increased behavior in V4 when attending to an object? |
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Definition
| According to a top-down modulation theory of sensory responses, There are retinotopic and visuotopic connections between FEF and V4. Visual responses in V4 can be enhanced after stimulating relative spots in FEF (amplified by corresponding eyemovement commands) |
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Term
| What is the neurotransmitter associated with maintaining an alert state (not caffeine)? What is the structre associated with maintaining the alert state? |
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Definition
norepinephrine
Locus Coeruleus |
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Term
| What is some evidence that norepinephrine + locus coeruleus is involved with alertness? |
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Definition
Increases responses of cortical neurons (increase glu and gaba evoked responses)
Locus Coeruleus activity varies with behavioral state (shifts of attention, Tonic Activity increased during irrelevant behaviors)
Locus Coeruleus has norepinephrine producing cells
Locus Coeruleus has inputs to parietal cortex, pulvinar, SC |
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Term
| What eye behavior correlates well with locus coeruleus activity? |
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Definition
| Pupil diamater constriction/dilation |
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