Transcript Slide 1

925-3
Frontotemporal Dementia
Eye Movements
This patient with frontotemporal dementia
(FTD) has a complete paralysis of
horizontal saccadic eye movements when
he is asked to look left on command, or to
fixate on a target held on the left.
He is unable to look at his own hand when
held on the left side.
He has no saccadic intrusions.
Neuroimaging
Figure 1: Axial
NECT scan shows
striking frontal
atrophy with
relative
preservation of the
parietal gyri.
Neuroimaging
Figure 2: Sagittal
T1-weighted MR
shows the
disproportionate
enlargement of
the frontal sulci.
Neuroimaging
Figure 3: Coronal
FLAIR scan shows
the frontal gyri are
extremely atrophic
and “knife-like.” Note
increased signal
intensity in the
affected gyri and
underlying white
matter
Effects of Unilateral Lesions of the
Frontal Eye Fields (FEF)
Bilateral increase in reaction time of
saccades made to visual targets in
“overlap” task to remembered target
locations and imaged targets during the
“antisaccade” task.
Hypometria of saccades made to visual or
remembered targets located contralateral
to the side of the lesion.
Effects of Unilateral Lesions of the
Frontal Eye Fields (FEF)
Reduced ability to make saccades in
anticipation of predictable stepping
movement of a target, when the target
moves away from the side of the lesion.
Impaired ability to inhibit inappropriate
saccades to a novel visual stimulus.
Impairment of smooth pursuit and
optokinetic following of targets moving
towards the side of the lesion.
Effects of Lesions of the
Supplementary Eye Field (SEF)
Memory-guided saccades become
inaccurate if gaze shifts during the
memory period.
Impaired ability to make a remembered
sequence of saccades to an array of
visible targets (especially with left-sided
lesions).
Impaired ability to reverse saccade
direction from an established pattern of
response
Effects of Lesions of Dorsolateral
Prefrontal Cortex (DLPC)
Pharmacological blockade of D1
dopamine receptors causes inaccuracy of
saccades made to remembered target
locations lying contralateral to the side of
injection
Patients with lesions affecting this area
show defects of predictive saccades,
memory-guided saccades and
antisaccades
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