Visual Perception, Attention & Action

Anthony J Greene2

3 Attention 1) Visual Spotlight X ♥

Anthony J Greene4 Attention 2) Visual Short Term Memory For items not presently in the perceptual stream Capacity depends upon familiarity and item complexity Delayed match to sample N-back task Interaction of Dorsolateral Frontal System and Posterior Parietal System

Anthony J Greene5 Attention 2) Visual Short Term Memory For items not presently in the perceptual stream Capacity depends upon familiarity and item complexity Delayed match to sample N-back task Interaction of Dorsolateral Frontal System and Posterior Parietal System

Anthony J Greene6 Attention 2) Visual Short Term Memory For items not presently in the perceptual stream Capacity depends upon familiarity and item complexity Delayed match to sample N-back task Interaction of Dorsolateral Frontal System and Posterior Parietal System

Anthony J Greene7 Attention 3) Hemi-field Neglect as an Atttention Disorder

Anthony J Greene8 Eye Movements 1) Smooth Pursuit Eye Movement 2) Vergence Eye Movements 3) Saccades 4) Microsaccades 5) Vestibular Eye Movements

Anthony J Greene9 1) Smooth Pursuit Eye Movement Volitional eye movements for tracking laterally moving objects Dynamic visual acuity is less than static acuity because of image slip. DUI

Anthony J Greene10 2) Vergence Eye Movements Volitional eye movements for tracking approaching or receding objects Conjugate vs. Discongugate

Anthony J Greene11 3) Saccades Volitional eye movements for gaze shift Change point of fixation Up to 6/sec. Role of motor efferents in perceptual stability Saccadic suppression

Anthony J Greene12 4) Microsaccades Nonvolitional eye movements Prevent receptor fatigue

Anthony J Greene13

Anthony J Greene14 5) Vestibular Eye Movements Nonvolitional eye movements to compensate for head motion The semicircular canals of the inner ear detect head position and motion What if vestibular information does not match visual information?

Anthony J Greene15 Balance & Posture Interaction of visual, proprioceptive and vestibular systems Depends heavily on vision Afferents from perceptual systems are processed very quickly to produce the correct efferents to the musculature

Anthony J Greene16 Dynamic Balance Running in the dark Postural Sway

Anthony J Greene17 Visual Control of Locomotion Simple Updating

Anthony J Greene18 Visual Control of Locomotion Complex Brains Allow Complex Strategies Motor learning allows strategies to become adaptive

Anthony J Greene19 Action Observation & Imitation Neurons of macaques respond to visual recognition of hand actions performed by others. Response of these cells is dependent upon the interrelation of hand and object movements. Lack of response when the object is grasped with a tool.

Motor properties of a typical F5 motor neuron: is active specifically during a particular grasping action phase (opening, closing, holding) Area F5 may be considered a storage of motor plans (“vocabulary”)

Anthony J Greene21 An F5 “mirror” neuron fires during initial observation and then similarly during action However, it only fires during initial observation if the task is to be copied Monkey grasps Monkey looks Monkey See, Monkey Do

Anthony J Greene22 F5 Neuron While Monkey Observes Grasping

Anthony J Greene23 Same Motor Neuron During Grasping

Anthony J Greene24 Experimental situation: Observation of mouth grasping vs observation of static mouth Observation of hand grasping vs observation of static hand Observation of foot pressing vs observation of static foot The human mirror system: fMRI

Anthony J Greene25 The human mirror system: fMRI OBSERVATION OF: MOUTH MOVEMENTS HAND MOVEMENTS FOOT MOVEMENTS Buccino et al. 2001, Europ. J. Neurosci.

Anthony J Greene26 MELTZOFF Imitation based on the neonate's capacity to represent visually and proprioceptively perceived information in a form common to both modalities. Observations in six newborns- one only 60 minutes old - suggest that the ability to use intermodal equivalences is innate (Meltzoff and Moore 1977)

Anthony J Greene27 Imitation Normal development –Neonates can imitate a range of facial expression (Meltzoff & Moore, 1970). Tongue protrusion Lip protrusion Mouth opening –Toddlers imitate movements that they believe to have been performed intentionally by the model (Meltzoff, 1995). Imitation deficits in autism Impairment in spontaneous imitation of action on novel objects. Impairment in instructed imitation

Anthony J Greene28 Imitation Evidence of imitation in birds. Pigeon and Quail Imitate the appendage (beak or feet) used to depress a lever. Carib grackles Imitate features of beak (closed pecking versus open prying). Imitate features of head (down vs up)