The anti-saccade (AS) task is a way of measuring how well the

frontal lobe The frontal lobe is the largest of the four major lobes of the brain in mammals, and is located at the front of each cerebral hemisphere (in front of the parietal lobe and the temporal lobe). It is parted from the parietal lobe by a Sulcus (neur ...

of the brain can control the reflexive

saccade In vision science, a saccade ( ; ; ) is a quick, simultaneous movement of both Eye movement (sensory), eyes between two or more phases of focal points in the same direction. In contrast, in Smooth pursuit, smooth-pursuit movements, the eyes mov ...

, or eye movement. Saccadic eye movement is primarily controlled by the

frontal cortex The frontal lobe is the largest of the four major lobes of the brain in mammals, and is located at the front of each cerebral hemisphere (in front of the parietal lobe and the temporal lobe). It is parted from the parietal lobe by a groove betw ...

Use

Research in pathophysiology

Saccadic eye movements and anti-saccadic eye movements are carried out by similar regions of the brain: the frontal eye field (FEF), the

supplementary motor area The supplementary motor area (SMA) is a part of the motor cortex of primates that contributes to the control of movement. It is located on the midline surface of the hemisphere just in front of (anterior to) the primary motor cortex leg representa ...

(SMA), the

thalamus The thalamus (: thalami; from Greek language, Greek Wikt:θάλαμος, θάλαμος, "chamber") is a large mass of gray matter on the lateral wall of the third ventricle forming the wikt:dorsal, dorsal part of the diencephalon (a division of ...

and

putamen The putamen (; from Latin, meaning "nutshell") is a subcortical nucleus (neuroanatomy), nucleus with a rounded structure, in the basal ganglia nuclear group. It is located at the base of the forebrain and above the midbrain. The putamen and c ...

. Anti-saccades involve two important cognitive functions: the ability to form an intention and the ability to inhibit a reflexive response. It was therefore thought that the

dorsolateral prefrontal cortex The dorsolateral prefrontal cortex (DLPFC or DL-PFC) is an area in the prefrontal cortex of the primate brain. It is one of the most recently derived parts of the human brain. It undergoes a prolonged period of maturation which lasts into adulthoo ...

played a greater role in anti-saccadic movements. This theory was disproved by O’Driscoll et al. in a study that used

positron emission tomography Positron emission tomography (PET) is a functional imaging technique that uses radioactive substances known as radiotracers to visualize and measure changes in metabolic processes, and in other physiological activities including blood flow, r ...

to analyze brain activity during anti-saccadic movement. The study showed that the DLPFC was equally activated in both saccadic and anti-saccadic movements. Anti-saccades required increased activation of the FEF, SMA and

. Currently, the anti-saccade task is currently used as a relatively crude or basic assessment of frontal lobe function in patients with neurological or psychiatric disorders. The task has high sensitivity, meaning that it is good at detecting frontal lobe dysfunction. However, its specificity is low, meaning that it can also be positive in patients without frontal lobe dysfunction. Of note, children and adults over the age of 70 will physiologically have an increased rate of error on the anti-saccade task.

Psychological research

Modified versions of the task, often termed as ''emotional antisaccade task'', have been used in psychological and psychophysiological research to investigate the interaction between visual attention and the processing of emotions. Emotion drives attention: people are usually biased to direct eye movements towards emotional rather than neutral and dull stimuli. The emotional version of the antisaccade task uses emotional stimuli (photographs or conditioned stimuli) as visual targets, requiring participants to look in the opposite direction. Performance in the task is a measure for attentional biases in healthy participants and various disorders such as mood disorders, addiction and social anxiety.

Procedure

To perform the anti-saccade task, an individual is asked to fixate on a motionless target (such as a small dot). A stimulus is then presented to one side of the target. The individual is asked to make a

in the direction away from the stimulus. For example, if a stimulus is presented to the left of the motionless target, the patient should look toward the right. Failure to inhibit a reflexive

is considered an error. Neurologic disorders affecting both the

or the

basal ganglia The basal ganglia (BG) or basal nuclei are a group of subcortical Nucleus (neuroanatomy), nuclei found in the brains of vertebrates. In humans and other primates, differences exist, primarily in the division of the globus pallidus into externa ...

have shown impaired performance on the anti-saccade task. These include

schizophrenia Schizophrenia () is a mental disorder characterized variously by hallucinations (typically, Auditory hallucination#Schizophrenia, hearing voices), delusions, thought disorder, disorganized thinking and behavior, and Reduced affect display, f ...

Huntington's disease Huntington's disease (HD), also known as Huntington's chorea, is an incurable neurodegenerative disease that is mostly Genetic disorder#Autosomal dominant, inherited. It typically presents as a triad of progressive psychiatric, cognitive, and ...

Parkinson's disease Parkinson's disease (PD), or simply Parkinson's, is a neurodegenerative disease primarily of the central nervous system, affecting both motor system, motor and non-motor systems. Symptoms typically develop gradually and non-motor issues become ...

, and progressive supranuclear palsy. Additionally, disseminated brain disease such as

Alzheimer's disease Alzheimer's disease (AD) is a neurodegenerative disease and the cause of 60–70% of cases of dementia. The most common early symptom is difficulty in remembering recent events. As the disease advances, symptoms can include problems wit ...

or AIDS dementia also have an increased number of errors.

History

The anti-saccade test was initially described in 1978 by Peter Hallet when he was a faculty member at the Department of Physiology of the University of Toronto. Many other researchers have used this task, including Guitton et al. and Pierrot-Deseilligny et al. In a well-known study by Guitton et al. (1985), patients with

epilepsy Epilepsy is a group of Non-communicable disease, non-communicable Neurological disorder, neurological disorders characterized by a tendency for recurrent, unprovoked Seizure, seizures. A seizure is a sudden burst of abnormal electrical activit ...

who had undergone therapeutic removal of their

were administered the anti-saccade task. Their performance was compared to healthy controls and patients who had undergone therapeutic removal of their temporal lobes. Results from Guitton’s studies showed that only patients with

lesions performed abnormally on the AS task. In contrast, studies by Pierrot-Deseilligny et al. correlated high error rates of AS to specific lesions in the

(DLPFC). In this study, patients with unilateral infarctions of the posterior parietal lobe were compared against infarctions in 3 frontal regions: the

frontal eye fields The frontal eye fields (FEF) are a region located in the frontal cortex, more specifically in Brodmann area 8 or BA8, of the primate brain. In humans, it can be more accurately said to lie in a region around the intersection of the middle frontal ...

(FEF), and the DLPFC. Only patients with infarctions of the DLPFC showed statistically significant error rates.

References

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