Attentional Processes

Question 1

phenomena associated with selective attention

Answer 1

• Change Blindness
  
  • Ex. Continuity errors in movie
• Inattentional Blindness
  
  • Simons and Chabris (1999) Gorilla Experiment

Question 2

behavioral consequences of attention

Answer 2

• Visual attention and Foveation
  
  • But attention can also be directed without foveation
  • Timing of eye movements (200 ms) vs. attentional shifts (50 ms)
• Shifting attention paradigm (Posner et al. 1980)
  
  • Cues enhanced visual processing
  • Detection (valid > invalid)
  • Faster reaction times to valid cues

Question 3

spatial attention summary

Answer 3

• Attention can occur independent of gaze
• Spotlight model of attention
• Location of attention is mapped retinotopically in the same way that actual visual space is mapped according to spatial location

Question 4

three neural networks subserving attentional processes

Answer 4

1. The Orienting Network
2. The Arousal Network
3. The Executive Network

Question 5

the orienting network overview

Answer 5

• Frontal Eye Fields (FEF)
• Superior colliculus
• Posterior Parietal Cortex
  
  • Integration of visual and somatosensory information
  • Damage: impairs ability to disengage attention from present focus, difficulty shifting to a target contralateral to a location

Question 6

Frontal Eye Field (FEF)

Answer 6

• Attention and Eye Movements
  
  • Frontal Eye Fields (FEF) are instrumental in directing attention to areas of interest for eye movements
• Stimulation of neurons in FEF leads to sharpening of attention within motor field, and inhibition of surrounding areas
• Works much like lateral inhibition in the visual system

Question 7

Superior Colliculus

Answer 7

Superficial layers project to V1 and PPC

Question 8

Posterior Parietal Cortex (PPC)

Answer 8

• PPC (posterior parietal cortex) neurons fire when attending to novel objects in receptive field
• Greater firing when attention precedes saccade to location of object
• No increase in firing when saccade is away from target
• Greater firing also when attending to object followed by passive response (release of lever to fading stimulus)

Question 9

the arousal network

Answer 9

1. Ascending reticular activating system (ARAS) of brain stem
   
   • Projection to cortex via thalamus, hypothalamus and other limbic structures
2. Arousal processes
   
   • Tonic Arousal
     
     • Diurnal alterations e.g. sleep/wakefulness (raphe nuclei)
     • Also influenced by suprachiasmic nucleus, which receives input from optic nerve, and influences circadian rhythm
   • Phasic Arousal
     
     • Sensory input to Ascending Reticular Activating System (ARAS) can lead to change in arousal level
     • Can lead to activation of hypothalamus – pituitary secretions– fight or flight response
       
       • ​Catecholamines and acetycholine

Question 10

neurotransmitters in ascending reticular activating system

Answer 10

• Catecholamines
  
  • Norepinephrine: Wide cortical projection from locus coeruleus, which receives input from cingulate cortex, activates attentional network associated with posterior parietal (& secondarily prefrontal)
  • Dopamine: Projection from ventral tegmental area of substantia nigra through medial forebrain bundle to striatal-frontal areas, posterior parietal and several limbic structures
• Acetylcholine: Receptors
  
  • Nicotonic: from basal nuclei; influence alertness through wide cortical projection
  • Muscarinic: from Pontomesencephalic complex; influence memory processes through projection to hippocampus

Question 11

the executive network

Answer 11

• Selection of information relevant to achievement of goals leading to coherence of behavior; inhibition of irrelevant inputs
• Anterior cingulate cortex
• Connections with:
  
  • DLPFC (dorso-lateral prefrontal cortex à working memory)
  • Posterior Parietal Lobe (attention)
• ACC implicated in
  
  • executive functions and
  • resolving conflicting information (Stroop task)

Question 12

Unilateral Neglect: Neurological substrate and clinical signs

Answer 12

• Hemispatial Neglect
  
  • Side Inattention
• Left hemiplegia:
  
  • Usually associated with RH
  • inferior parietal damage (with or without hemianopia) leading to contralateral (left) attentional hemineglect (or spatial neglect)
• Neglect has also been found following frontal damage (rare)
• Neglect can be shown in motor behavior or any perceptual modality (visual, auditory, tactile) and commonly involves a combination of deficits
  
  • Self Portrait of Anton Raderscheidt
    
    • recovery from stroke over course of several months