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Eye Movements –
Target Selection & Control
READING
Schall JD (2002) The neural selection and control of saccades by frontal eye field.
Philosophical Transactions of the Royal Society of London: Series B Biological
Sciences. 357:1073-1082.
Schall JD, Boucher L. (2007) Executive control of gaze by the frontal lobes. Cogn
Affect Behav Neurosci. 7:396-412.
Brainstem Saccade Generator
Eye position
Oculomotor neuron
Tonic neuron
Medium lead burst neuron
"Where"
Omnipause neuron
"When"
100 msec
How does the brain
choose where to look?
How does the brain
control when to move?
How does the brain
correct errors?
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The function of the FEF cannot be
understood outside the context of the
network in which it is a node. That
network includes connections with
extrastriate visual areas as well as
connections with the basal ganglia and
brainstem motor structures.
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Superior colliculus
Visual input from retina and visual cortex
Neurons have receptive fields
Responses of some cells enhanced if stimulus is target
No saccade
Saccade to RF
Saccade to CON
Superior colliculus
There is map of the visual field
Superior colliculus
Deeper layers have neurons active before saccades
Innervate saccade generator circuit in brainstem
“Movement fields” are broad
Superior colliculus
Population coding of saccade direction
Saccade averaging
The superior colliculus is “controlled” by the basal ganglia
Effects of manipulation
Coordinated neural modulation
Normal
After GABA
agonist
in right SNpr
In the 19th century David Ferrier discovered that electrical
stimulation of the frontal lobe around the arcuate sulcus
evoked movements of the eyes.
He called this the
Frontal Eye Field
The frontal eye field projects to ocular motor
structures to produce movements of the eyes
and is reciprocally connected with extrastriate
visual areas.
Frontal Eye Field
Motion
Color &
Shape
Ocular
Motor
Structures
SC & FEF neurons select the target when
it can be found automatically.
Activation (sp/sec)
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Time from array (msec)
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Thompson, Hanes, Bichot, Schall (1996) Perceptual and motor processing stages
identified in the activity of macaque frontal eye field neurons during visual
search. Journal of Neurophysiology 76:4040-4055.
Gaze is guided by knowledge as well as vision
Remember the location
of the objects in the room.
Remember the ages
of the people in the room
Yarbus, A. L. 1967 Eye Movements and Vision. New York: Plenum Press.
FEF neurons also select the target when
knowledge must be combined with vision.
Target in RF
Similar distractor in RF
Dissimilar distractor in RF
Bichot, N.P. & Schall, J.D. (1999). Effects of similarity and history on neural
mechanisms of visual selection. Nature Neuroscience 2:549-554.
The time of target selection
does not specify when gaze
will shift. This means another
neural process must intervene
between target selection and
saccade initiation and that
process is of randomly
variable timing.
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The control of movement can be studied
with the countermanding (stop signal) task
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error
Frontal Eye Field
(as part of a network!)
Activation
Controls when gaze shifts
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Time from stimulus (sec)
Hanes, D.P. and J.D. Schall (1996) Neural control of voluntary movement initiation. Science 274:427-430.
Variability in saccade
preparation can account
for some of the delay
and variability of
reaction times.
Countermanding paradigm: Race model
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Activaon
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Count
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Time needed to cancel
the planned movement
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Logan, G.D. & Cowan, W.B. (1984) On the ability to inhibit thought and action: A theory of an act of control. Psychological Review
91:295-327.
Hanes DP and Schall JD (1995) Countermanding saccades in macaque.Visual Neuroscience 12:929-37`
Frontal Eye Field
(as part of a network!)
Also controls whether gaze shifts
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Activaon(Spkes/)
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Hanes, D.P., W.F. Patterson, J.D. Schall (1998) The role of frontal eye field in countermanding saccades:
Visual, movement and fixation activity. Journal of Neurophysiology 79:817-834.
Frontal eye field (as part of network!) controls gaze.
Does supplementary eye field do the same?
Some neurons in supplementary eye field &
anterior cingulate cortex signal errors
Error-related unit activity
Error-related negativity
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Stuphorn V, Taylor TL, Schall JD (2000) Performance monitoring by supplementary eye field.
Nature 408:857-860.
Ito S, Stuphorn V, Brown JW, Schall JD (2003) Performance monitoring by the anterior cingulate
cortex during saccade countermanding. Science 302:120-122.
0
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Time from EMG onset (msec)
from Gehring and Fencsik, The Journal of Neuroscience
21(23):9430-9437
Performance during countermanding varies stochastically…
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Fraction stop trials
Response time (msec)
… and adaptively
Trial Number
Emeric EE, Brown JW, Boucher L, Carpenter RH, Hanes DP, Harris R, Logan GD, Mashru RN, Paré M, Pouget P, Stuphorn V, Taylor TL, Schall JD. (2007) Influence of
history on saccade countermanding performance in humans and macaque monkeys. Vision Research 47:35-49.
The supplementary eye field can exert executive control on the
ocular motor system
Microstimulation of some sites
in SEF reduced the probability
of producing an error
Probability (Non-Canceled|SSD)
1.0
0.8
Without Stimulation
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0.4
With Stimulation
0.2
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100
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Stop Signal Delay (msec)
400
Stuphorn V, Brown, JW, Schall JD (2006) Executive control of countermanding saccades by the supplementary eye field. Nature Neuroscience 9:925-931.
500
A network for guidance and control of gaze
Interface of control
and executive systems?
SEF
Selection and
control of
eye movements
Monitor conflict
and consequences
ACC
FEF
Stimulus
Response
Consequences