Attention: Neural Substrates & Measurement

Voluntary attention:

attention shifts that come from within according to our interests and goals

• Top-down attentional processing, controlled by higher-level, conscious processes

Reflexive attention

involuntary reorientation toward a sudden or important event

• Bottom-up attentional processing, controlled by lower-order sensory inputs rather than by voluntary, conscious processes

Attention

Attention can alter the activity of individual neurons:

• Enhance or suppress responses

• Narrow the range of stimuli that neurons respond to

• Shift the range of stimuli that neurons will respond to

Subcortical structures that are important for attention:

• In the midbrain:

• The superior colliculus are involved in processing visual information

• Helps guide eye movement towards object of attention

• The thalamus:

• General function → “switchboard”

• Involved in visual processing, orienting and shifting attention, and attentional filtering of stimuli

At the level of the cortex:

• Two networks work together to control attention:

• Dorsal frontoparietal system >

• Frontal and parietal cortex

• Right temporoparietal system ^>

• Temporal and parietal cortex of the right cerebral hemisphere

• Lateralized

Dorsal frontoparietal system → cognitive control of voluntary attention

• Top-down control of attention

Intraparietal sulcus (IPS)

encodes salience (priority)

• Highly active when focusing attention on a stimulus

• Important for shifting attention to different stimuli in your environment

Frontal eye field (FEF)

helps establish gaze in accordance with cognitive goals

• Closely connected to the superior colliculus

Reflexive Attention

Temporoparietal system → reflexive shifts of attention

• Bottom-up control of attention

Temporoparietal junction (TPJ)

directs attention to novel or unexpected stimuli

• Increases activity in response to stimuli at unexpected locations

• Receives input directly from the visual cortex

• Also connected to areas in the frontal cortex involved in working memory

True or False

Networks that control voluntary and reflexive attention need to work together

True

Voluntary control of attention involves a processing stream that travels dorsally

Frontal cortex → IPS

Reflexive attention involves a processing stream that travels ventrally

Visual cortex → TPJ

Connections between the temporoparietal junction and intraparietal sulcus allow the networks to interact

Novel stimuli can “interrupt” and reorganize attentional priorities

Hemispatial neglect – neurological condition in which an individual fails to attend to (disregards) one side of the environment or body

• Neglect is contralateral to site of damage

• Frequently results from a stroke or traumatic brain injury

• Damage usually overlaps with the attention network

• Sensory systems may be intact

Measures of Attention

Self-report (or other report) measures can be used to assess attention

Neurocognitive tasks are frequently used to measure attention

• Administered via computer or paper

• Different tasks/tests may be used to measure different types of attention

• Some tasks may tap into (or are attributed to) multiple cognitive functions

Divided attention

attending to two or more sources of information at the same time, so that two or more tasks can be performed at the same time

Sustained attention:

attentional focus on a task for an extended length of time