Selective attention III

Attention, (Fan and Posner, 2004)

• Described attention as an “organ system”

• Argued that the system had differentiated structures adapted for specific functions which are grouped with other structures into a system

Features of attention

• Involves specialist networks that maintain alertness and orient resources to relevant sensor events

• Can be fractionated into subsystems with specific cognitive functions and anatomical substrates

What are the 3 different ways to respond to attention stimuli

• Alerting

• Orienting

• Executive control (conflict)

How does imaging of subsystems differentiate (signals)

• Source signals, associated with activation of attention eg orienting

• Site signals, reflect the influence of sources on processing eg signal enhancement

Function of source and site signals

• Source, control signals that co-ordinate activity in relevant sensory cortex

• Site, enhancement of relevant response in sensory cortex

How does alerting work

• Cues in the environment may signal when but not where a relevant stimulus occurs

• Preparatory change in the individuals ability to receive, evaluate and respond to upcoming stimulus

How does orienting work

• A physical distinction between exogenous and endogenous cues

• Neuroimaging studies can compare activation in response to these exo/endogenous cues

• Temporal distinction in enhancement and inhibition of stimulus at cued locations

• Functional distinction in the component processes for valid and invalid cues

• Invalid cues require disengagement with cued locations to resample scenes

Endogenous and exogenous cues in relation to orientation

• Endogenous, associated with activation in FEF, interparietal sulcus and superior parietal lobe

• Cortical attention is also associated with endogenous orienting of attention towards spatial locations and global features

• Exogenous, associated with activation of ventral prefrontal cortex and temporal parietal junction

Testing attention

• Theoretical models and empirical studies explain the brain mechanisms associated with prioritisation of relevant over irrelevant information

• Models also provide a way to quantify individual variability in attentional control against normative data

• Useful for quantifying change in specific populations eg older adults or clinically diagnosed groups