Reporter: 周蔚倫 2005/10/27

1. Johnson, M. H. (2002).The development of visual attention: A cognitive neuroscience perspective.In M.H.Johnson, Y. Munakata, & R. O. Gilmore (Eds.), Brain development and cognition: A reader (pp. 134-150). Blackwell Publishers. (chap 9) Reporter: 周蔚倫 2005/10/27

2. Outline • Introduction • Overt attention in early infancy • Newborn, 1,2,3 months of age • Covert attention in early infancy • Exogenously cued • Endogenously cued • Cortical control of attentional shifts and the oculomotor circuit • Conclusions and future diractions

3. Introduction • The methods for studying the relation between neural systems and cognition • Patient data • Animal data • Developmental studies • complement data from other sources

4. Multiple pathways involved in the control of eye movements and visual attention • Solid lines: parvocellular input • Dashed lines: magnocellular input Superior colliculus Brain stem

5. components of attention (Posner, 1980) (Klein et al., 1992) (triggered by stimulus, short-latency, reflexive)

6. ← • Exogenous cuing • Endogenous cuing

7. Aim • The mapping between the various neural pathways and the attentional components

8. Outline • Introduction • Overt attention in early infancy • Newborn, 1,2,3 months of age • Covert attention in early infancy • Exogenously cued • Endogenously cued • Cortical control of attentional shifts and the oculomotor circuit • Conclusions and future diractions

9. Overt attention in early infancy • Cortical-subcortical dichotomy(Bronson, 1974) • Subcortical retinocollicular pathway (newborn)  cortical pathways (2 or 3 months) • But: • Several independent cortical streams • Some perceptual abilities of infant  question the notion of “decorticate” infant • Partial cortical functioning of newborn(Johnson, 1990)

10. 4 Oculomotor pathways (Schiller, 1985) 3 • Retina  superior colliculus • V1 / MT  superior colliculus • FEFs • Substantia nigra / basal ganglia  superior colliculus 4 1 2

11. Overt attention in early infancy • The characteristics of the infant is determined by which of these pathways is functional(Johnson, 1990) • The developmental state of V1 plays a crucial role (Johnson, 1990)

12. The developmental state of V1plays a crucial role The primary visual cortex: • is the major gateway for 2, 3, 4 pathways • shows a postnatal continuation of the prenatal inside-out pattern of growth(deeper layers showing greater dendritic branching than superficial layers) • restricted pattern of inputs and outputs

13. Pathway 3 ∵inside-out pattern of growth  output from V1 to pathway 2 should be stronger than the output to pathway 3 at early stages of development Pathway 2

14. Some newborn behaviors are consistent with predominantly subcortical control(collicular control of orienting) • Saccadic pursuit tracking of moving stimuli • Non-smooth pursuit ("jerky" motions) • Lag behind the stimulus • Preferential orienting to the temporal field • Much more readily orient toward stimuli in the temporal visual field (see also adult blindsight case) • The externality effect • Do not attend to stationary pattern elements within a larger frame

15. Some cortical functioning (1) • 1 month of age • obligatory attention (disengage difficultly) • without tonic inhibition of the colliculus via the substantia nigra (pathway 4) (Johnson, 1990) • parietal function (Posner & Rothbart, 1980) • object-centered(Johnson, 1994)

16. Some cortical functioning (2) • 2 months of age • smooth visual tracking • become sensitive to nasal-visual-field stimuli and coherent motion (Aslin, 1981) • the functioning of pathway 2 (involve MT) (Johnson, 1990)

17. Some cortical functioning (3) • More than 3 months of age • eye movements predict the movement of the stululus (Haith et al., 1988) • FEF (pathway 3)

18. Outline • Introduction • Overt attention in early infancy • Newborn, 1,2,3 months of age • Covert attention in early infancy • Exogenously cued • Endogenously cued • Cortical control of attentional shifts and the oculomotor circuit • Conclusions and future diractions

19. Covert attention in early infancy (1) • Measures of overt orienting are used to study covert shifts of attention • Very short cue (infants do not make saccades)

20. Covert attention in early infancy (2) • Exogenously cued • The characteristics of covert attention in adults ** • Parietal lobe lesion  impair the covert attention (neglect case, Posner, 1988) • Rapid parietal development between 3~6 monthes(Conel, 1967) • Infant covert attention study **

21. Explanation of Infant covert attention data • Facilitation depend on the functioning of the parietal lobe (4-month infant) • Inhibition depend on the functioning of the superior colliculus (inhibition should be present from newborn) • Why 2-month infant did not show inhibition?

22. Two possibilities about the neural basis of IOR • In addition to the colliculus, IOR involves cortical structures such as the FEF (which become mature 3~4 months after birth) • Covert shift of attention require cortical structures, and thus IOR after COVERT orienting cannot be demonstrated until 3~4 months • On the other hand, IOR after OVERT orienting can be demonstrated from newborn (Valenza et al., 1992)

23. Covert attention in early infancy (3) • Endogenously cued • 4-month-old infants: • Endogenously cued shifts of attention (memory cue, Johnson et al., 1991) • Endogenous factors override the influence of exogenous cues (antisaccade task, Johnson, 1994) • Sustained attention ** (heart rate marker) • The involvement of prefrontal cortex (Funahashi et al., 1990; Jonides et al., 1993)

24. Outline • Introduction • Overt attention in early infancy • Newborn, 1,2,3 months of age • Covert attention in early infancy • Exogenously cued • Endogenously cued • Cortical control of attentional shifts and the oculomotor circuit • Conclusions and future directions

25. Cortical control of attentional shifts and the oculomotor circuit • 3 cortical regions are important: • Parietal cortex: covert shifts • FEF: endogenous control of eye movement • Prefrontal cortex: endogenous control involving delays • Oculomotor circuit: voluntary saccadesparietal, FEF, prefrontal  subcortical structures (ex., substantia nigra)  FEF

26. Summary 4 m/o Parietal lobe 4 m/o 4 m/o newborn Pathway 1:retina  SC 3 m/o Pathway 3:FEF Prefrontal cortex Frontal cortex 2 m/o Pathway 2:V1/MT  SC Prefrontal cortex 4 m/o 4 m/o Pathway 4:inhibition of SC

27. Conclusions and future directions • Neural developments are reflected in a general trend at the behavioral level: • Exogenous orienting  endogenous orienting • Developmental data complement data from other sources • 3 future directions: • Preattentive processing (e.g., “pop-out”) • Brain damage infants • Neuroimaging studies

29. invalid valid The characteristics of covert attention in adults • Posner & Cohen (1984) Facilitation Inhibition of return Stimulus Onset Asynchrony (SOA) (ms) SOA: 0, 50, 100, 200, 300, 500 ms

30. covert attention in 2 & 4 months infants • Johnson, 1993 • Only 4 months infantfacilitation & inhibition inhibition facilitation

31. The heart rate-defined method • Richards & Casey, 1991 • During sustained attention RT of shift gaze toward the distractor ↑accuracy ↓(collicular-generated saccade)