Transcript Eye Movement Control by the Cerebral Cortex Charles Pierrot

Eye Movement Control by
the Cerebral Cortex
Charles Pierrot-Deseilligny
Dan Milea
René M. Müri
Eun H. Kim
February 21, 2008
Outline
• Purpose
• Introduction
• Frontal Lobe
• Parietal Lobe
• Cingulate cortex
• Summary
• Conclusion
Purpose
http://www.cosmosmagazine.com/node/637
To better understand the eye
movement control by the cerebral
cortex using recent techniques
such as transcranial magnetic
stimulation and functional
magnetic resonance imaging.
Why study eye movement?
“It gives new meaning to the distinction between 'quantitative' and
'qualitative' techniques for evaluating brain-behavior
relationships.”
William B. Barr, Chief of Neuropsychology, Comprehensive Epilepsy Center,
New York University School of Medicine
Quantify relatively complex neuropsychological processes
1. attention
2. spatial memory
3. motivation
4. decisional processes
Introduction
• Classic Methods
– Lesion
– Electrical Stimulation
• Two recent methods to study eye
movement
– Transcranial magnetic stimulation
– Functional magnetic resonance imaging
New Methods vs. Old Methods
www.psych.mcgill.ca/.../Techniques.htm
Transcranial Magnetic
Stimulation
• Temporarily disrupts the functioning of
a specific region of the brain.
– Magnetic field is applied to a subject’s head which
crosses the scalp and skull
– Electric current from Magnetic field disrupts the
neural activity
– Inactivation lasts <1 sec
intra.ninds.nih.gov/Lab.asp?Org_ID=104
• Advantage: increased temporal resolution
Functional Magnetic
Resonance Imaging
• Non-invasive method
• MRI scanner exploits the natural magnetic
properties present in our bodies to obtain
image of blood flow in the brain.
• Advantage: increased spatial resolution
flickr.com/photos/macronin47/85007177/
http://www.hku.hk/cogsci/media/neuro/1-imaging.jpg
Control of Human Eye
Movement in Cerebral
Cortex
• Frontal Lobe
• Parietal Lobe
• Cingulate Cortex
http://www.gpc.edu/~bbrown/psyc1501/brain/lobes2.jpg
Frontal Lobe
• Three main areas involved in eye
movement control
– Frontal Eye Field (FEF) [BA 8]
– Supplementary Eye Field (SEF)
– Dorsolateral prefrontal cortex
(DLPFC)[BA9 and BA46]
Frontal Eye Field
• Controls Pursuit Eye Movements (PEMs)
– Smooth tracking of an object
• Preparation and triggering of Intentional saccades
–
–
–
–
Visually guided saccades
Predictive saccades
Memory guided saccades
Antisaccades
FEF and PEMs
• Control two type of PEMs
• Ipsilateral PEMs (main control)
• contralateral PEMs (superficial)
• Controls optokinetic nystagmus
• Involuntary eye movement to foveate a moving
target to maintain the perception of self-motion
– In the monkey, FEF neurons controlling PEMs are
also involved in vergence. However, no literature
shows vergence FEF activation in humans.
FEF and Saccades
• Antisaccades: intentional saccades to a target
located in the opposite direction.
• Two different Mechanisms
– 1. Inhibition of an unwanted reflexive misdirected
saccade
• PEF triggers towards the target. DLPFC inhibits and
the error between the PEF and DLPFC reflect the
inhibition function
– 2.Simultaneous triggering of an intentional correct
antisaccade, made in the direction opposite to the
target by FEF
Supplementary Eye
Field (SMA)
• SEF: connected with FEF, the DLPFC, the anterior
cigulate cortex and posterior parietal cortex
• Location: Medial surface of the superior frontal gyrus, in
the upper part of the paracentral sulcus.
• Function: involved in motor programmes comprising of
saccade with a body movement or successive
saccades.
Supplementary Eye
Field Cont.
• TMS and fMRI studies show that
pre-SEF is involved in motor
learning
• SEF is involved in the execution of
motor sequence.
Dorsolateral Prefrontal
Cortex
• Involved in
– saccade inhibition
– short-term spatial memory
• TMS support that DLPFC is exerted during
delay period when spatial memory is involved.
• fMRI show activity up to 24 second.
– decisional processes
• lesion studies show that percentage of
predictive saccades decreased significantly.
Parietal Lobe
• Posterior Parietal Cortex
• Involved in the control of saccades and attention
• Parietal Eye Field
– Corresponds to lateral intraparietal area
– Involved in control of saccades and attentional
processes.
– Projects to both FEF and the superior colliculus
• Parieto-FEF projection: visual fixation
• Parieto-superior colliculus projection: saccadic
involvement
Cingulate Cortex
• Divided into the anterior cingulate
cortex (ACC) [BA 24] and the
posterior cingulate cortex (PCC)
[BA 23].
Cingulate Cortex
• ACC: involved in intentional saccade control
• Cingulate Eye Field: located between BA 23
and 24, prepare all the frontal ocular motor
areas involved in intentional saccade control
to act in the forthcoming motor behaviour.
• PCC: reflexive saccade control (?)
– fMRI study shows that the PCC is active during
reflexive saccades.
– Activation during PEM
Summary
Conclusion
• Recent data have summarized some of
the cortical pathways and mechanisms
involved in saccade control.
• TMS and fMRI are currently used to
understand new information and
interpret cortical control of eye
movements in humans.
Reference
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http://www.neuropsychologyarena.com/books/The-Quantified-ProcessApproach-to-Neuropsychological-Assessment
www.psych.mcgill.ca/.../Techniques.htm
Intra.ninds.nih.gov/Lab.asp?Org_ID=104
http://fourier.eng.hmc.edu/e180/handouts/figures/brainbrodmannareas.gif
www.schoppik.com/data/articles/jneurosci2006.html
http://www.gpc.edu/~bbrown/psyc1501/brain/lobes2.jpg
Questions?
www.schoppik.com/data/articles/jneurosci2006.html