Biology

What Causes Hallucinations?

Hallucination is a false experience involving the apparent perception of something not exist and specify abnormality in perception, it seems very real or true but actually, it is created by your mind. This false perception can occur in any of the five sensory modalities. So, this false perception (hallucinations) essentially is seeing, hearing, tasting, feeling, or smelling something that is not there.

Image result for hallucinations

This false perception is not considered for by the people’s religious or cultural background. Some people experiencing hallucinations may be aware that the perceptions are false, whereas others may truly believe that what they are seeing, hearing, tasting, feeling, or smelling is real.

We know from fMRI (Functional magnetic resonance imaging) studies that these hallucinations activate the same brain areas as sight, areas that are not activated by imagination. Many other hallucinations, including smells, sights, and sounds, also involve the same brain areas as real sensory experiences.

Because of this, the cerebral cortex is thought to play a part in hallucinations. This thin layer of grey matter covers the entire cerebrum, with different areas processing information from each of our senses.

But even in people with completely unimpaired senses, the brain constructs the world we perceive from incomplete information. For instance, our eyes have blind spots where the optic nerve blocks part of the retina. When the visual cortex processes light into coherent images, it fills in these blind spots with information from the surrounding area.

When the visual cortex is deprived of input from the eyes, even temporarily, the brain still tries to create a coherent picture, but the limits of its abilities become a lot more obvious. The full-blown hallucinations of Charles Bonnet Syndrome are one example. Because Charles Bonnet Syndrome only occurs in people who had normal vision and then lost their sight, not those who were born blind.

Scientists think the brain uses remembered images to compensate for the lack of new visual input. And the same is true for other senses. People with hearing loss often hallucinate music or voices, sometimes as elaborate as the cacophony of an entire marching band.

In addition to sensory deprivation, recreational and therapeutic drugs, conditions like epilepsy and narcolepsy, and psychiatric disorders like schizophrenia, are a few of the many known causes of hallucinations.

Some of the most notorious hallucinations are associated with drugs like LSD and psilocybin. Their hallmark effects include the sensation that dry objects are wet and that surfaces are breathing.

At higher doses, the visual world can appear to melt, dissolve into swirls, or burst into fractal-like patterns. Evidence suggests these drugs also act on the cerebral cortex. But while visual impairment typically only causes visual hallucinations, and hearing loss auditory ones, substances like LSD cause perceptual disturbances across all the senses. That’s likely because they activate receptors in a broad range of brain areas, including the cortical regions for all the senses. LSD and psilocybin both function like serotonin in the brain, binding directly to one type of serotonin receptor in particular.

While serotonin’s role in the brain is complex and poorly understood, it likely plays an important part in integrating information from the eyes, nose, ears, and other sensory organs. So one theory is that LSD and psilocybin cause hallucinations by disrupting the signaling involved in sensory integration.

Hallucinations associated with schizophrenia may share a similar mechanism with those caused by LSD and psilocybin. Patients with schizophrenia often have elevated levels of serotonin in the brain. And antipsychotic drugs relieve symptoms of schizophrenia by blocking the same serotonin receptors LSD and psilocybin bind to.

Hallucinatory experiences are much more closely tied to ordinary perception than we once thought. And by studying hallucinations, we stand to learn a great deal about how our brains construct the world we see, hear, smell, and touch.

A short movie on Hallucinations: H A L L U C IN A T I O N.

  • Visual Hallucinations

It includes seeing things that aren’t there. This hallucination may be of objects, visual patterns, people, or lights, etc. 

  • Olfactory hallucinations

It involves your sense of smell. You might experience the smell of an unpleasant odor or your body smells bad when it doesn’t. This hallucination can also include scents you find enjoyable.

  • Gustatory hallucinations

It involves your sense of taste. These tastes are often strange or unpleasant. Gustatory hallucinations (often with a metallic taste) are a relatively common symptom for people with epilepsy.

  • Auditory hallucinations

It is the most common type of hallucinations. You might hear someone speaking to you or telling you to do certain things. The sounds may be angry, soft or neutral. 

  • Tactile hallucinations

It includes the feeling of touch or movement in your body. You might feel the imagined touch of someone’s hands on your body or some insects crawling in your body.

  • Temporary hallucinations

Temporary hallucinations are not chronic. They may occur if a relationship has just ended or if someone dear to you has just passed away. You might hear the person’s voice for a moment or briefly see his or her image. This type of hallucination typically disappears as the pain of your loss fades.

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