When we observe the environment, our eyes make a great number of movements to capture each and every detail and movement that make it up. Our brain then composes a harmonious image of everything around us, including moving objects and people.

Our eyesight works like a video camera that takes thousands of frames of what is around it, while our brain projects the “film” in our mind. However, what happens when this function is altered? In these cases, acinetopsy appears, a disorder in which the person has difficulty perceiving movement.

What is acinetopsy?

Acinetopsy, also known under the terms akinetopsy or movement blindness , consists of a disorder of neurological nature and affecting the sense of sight. Specifically, acinetopsy causes, in those who suffer from it, an inability to perceive movement through sight.

This condition, first described around 1991 by the British neurologist Semir Zeki, makes the affected person unable to perceive movement . The patient cannot see the movement of his own body, like that of other people or objects.

However, acinetopsy is not an all-or-nothing condition. The condition can be of varying degrees of severity. From the mildest, in which the person perceives the movement as if it were a sequence of images or a film in which the frames are in slow motion, to the most severe, in which the patient experiences a total inability to perceive the movement.

In this disorder, the person can only perceive other subjects, objects or himself in a particular place and suddenly in another. Or at most, he perceives a kind of blurred trail behind the moving object.

Although all other sensory functions and abilities remain intact, people with acinetopsy also have their visomotor abilities disturbed . Since they do not perceive their own movements well, tasks such as walking and moving, or reaching for objects can be really complicated.

Types of acinetopsy and symptoms

As mentioned above, acinetopsy can occur in varying degrees of condition. These degrees constitute the different typologies of this disorder, which vary both in the severity of the symptoms and in the level of blindness it causes in the person.

There are two different types of acinetopsy . They are as follows.

1. Fine or discrete acinetopsy

This first type of acinetopsy, known as fine or discreet, is the one with the least severe symptoms and therefore the least disabling for the person. Although equally, people who suffer from it report experiencing enormous discomfort.

In light acinetopsy, the person perceives the movement as if he or she were visualizing a reel in which the frames pass at a much slower speed . Another example would be a multiple-exposure photograph, in which the person can perceive the trail of movement of both objects and people, including the patient himself.

At the moment, it is not known what abnormality in the functioning of the organism causes this disorder. However, experts point to the idea that abnormal functioning in the mechanisms that allow us to maintain visual stability in eye movements may cause this type of acinetopsy.

2. Macroscopic acinetopsy

Also known as gross acinetopsy, this type of movement blindness is extremely rare and of very low incidence among the population.

In contrast to fine acinetopsy, in macroscopy the person is completely unable to perceive movement in its entirety. This means that the person can only see a static world in which for a moment the object or person is in one place and at the same time in a different one.

The few people who suffer from it, tend to suffer from numerous problems in carrying out their daily tasks normally . Daily activities such as holding a conversation are highly complicated since the patient is unable to perceive changes in the movement of facial expressions. Likewise, daily routines, such as crossing the street, become very dangerous, since it is not possible to perceive the movement of cars.

In order to compensate for these difficulties, people with acinetopsy train their hearing. In this way, they can, for example, use their sense of hearing to calculate the distance to moving objects.

What are the causes?

The origin of acinetopsy is found to be abnormal function or interruption of activity in the area of the cortex that is located in the central zone of the temporal lobe .
Structural alterations in this area of the brain can transform the processes of understanding sensory information. In the case of this strange disorder, it is the processes that deal with visual information that are compromised.

There are several reasons why this brain region may be affected. From brain injuries, to the consumption of certain antidepressants or hallucinogens, or some diseases such as Alzheimer’s disease.

1. Brain injuries

One of the causes of this disorder may be a lesion caused in the posterior zone of the visual cortex , although it is really complicated, since a lesion of this type is likely to generate many more sensory deficits.

2. Antidepressant medication

Very high doses of some antidepressants can cause visual problems such as acinetopsy. However, this tends to go away when treatment is stopped or the dose is readjusted.

3. Hallucinogenic substances

Regular or recurrent use of certain hallucinogenic substances can cause sensory disturbances of all kinds , including the less severe version of acinetopsy, fine acinetopsy.

4. Migraine aura

The aura is a visual phenomenon that accompanies migraine headaches. It tends to appear moments before the onset of pain and is manifested by visual symptoms such as spatial spots, flashes or fine acinetopsy.

5. Alzheimer’s disease

Although not very common, acinetopsy, present in varying degrees, may accompany the memory impairments of Alzheimer’s patients.

Is there a treatment?

At the moment, there are no pre-established guidelines for the treatment of acinetopsy. In cases where acinetopsy is caused by the administration of psychotropic drugs, discontinuing their use should eliminate the symptoms of this disorder.

Nevertheless, brain surgery, although risky, is an option to try to eliminate acinetopsy in those cases where a brain lesion is underlying.