Attention Pt. 2

Question 1

EEG’s and Attention

Answer 1

• When many neurons work together
  on a task, the EEG appears
  somewhat synchronized
• Averaging the EEGs during several
  repeated trials give the event-
  related potential (ERP), also called
  evoked potential

Question 2

Auditory Attention and ERP

Answer 2

• About 110-150 ms after the onset of
  a sound stimulus, two large waves
  appear in the ERP
  
  • An initial positive-going wave, PI
  • Immediately followed by a larger
    negative-going wave, N1
• This auditory N1 effect is
  strengthened for selectively
  attended stimuli

Question 3

ERP’s: Effects of Attention to Visual

Answer 3

• The visual P1 effect is the
  the appearance of an enhanced,
  a positive wave of the ERP that
  occurs when the stimuli is a valid
  cue, but not when it is invalid
• The P1 effect is evident in visual
  tasks using spatial temperature
  (where is the target?), but not other
  features, such as color or more
  complex properties of late-selection
  tasks
• Exogenous visual attention
  augments processing of visual
  attention augments processing of
  visual stimuli as endogenous
  attention does but only in short-
  latency trails
• As the delay between sensory cues
  and targets lengthen, P1
  enhancement is reduced and
  eventually becomes inverted
  
  • Inhibition of return

Question 4

fMRI Attention Research

Answer 4

• “Sustained attention tasks” confirm
  that attention enhances neural
  activity in brain regions important
  for processing a particular stimulus
• fMRI shows greater activity in
  anatomical regions that correspond
  to the target of attention, and brain
  activity shifts when the target of
  attention changes.

Question 5

Attention Directly Affects Neurons

Answer 5

• When attention is placed on a
  preferred stimulus within a cell’s
  receptive field - neurons fire actively
• When attention is shifted to an
  ineffective field - neurons fire less,
  even though the exciting stimulus is
  still within the receptive field

Question 6

A Network of Brain Shifts

Answer 6

• Whether voluntary (top-down) or
  reflexive (bottom-up), attention
  strongly affects neural processing in
  the brain, augmenting
  electrophysiological activity
• While sources of attention are quite
  different, the consequences are
  comparable

Question 7

Subcortical Structures Involved in Attention

Answer 7

Pulvinar:
- Involved in visual processing,
orienting, shifting attention, and
filtering of stimuli
Superior Colliculus:
- Guides movement of eyes toward
objects of attention
Lateral Intraparietal Area (LTP)
- Crucial for endogenous attention in
monkeys
Frontal Eye Field (FEF)
- Directs gaze according to cognitive
goals rather than characteristics of
stimuli
Dorsal Frontoparietall:
- Several cortical areas are important in generating or directing attention
Right Temporoparietal Network:
- Temporoparietal junction, steers
attention toward novel or
unexpected stimuli

Question 8

The Right Temporoparietal System & Reflexive

Answer 8

• ER-fMRI studies show a spike in
  activity if a relevant stimulus
  suddenly appears in an unexpected
  location

Question 9

Ventral TPJ System

Answer 9

• Acts like an alerting signal or “circuit
  breaker”, overriding our current
  attentional priority if something new
  and unexpected happens
• Receives input directly from the
  visual cortex
• Strong connections with ventral
  frontal cortex (VFC)
  
  • Involved in working memory
  • VFC may analyze novelty by
    composing stimuli over short
    periods