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Visual hallucinations may be simple/non-formed visual hallucinations, or complex/formed visual hallucinations. [15] Simple visual hallucinations without structure are known as phosphenes and those with geometric structure are known as photopsias. [16] These hallucinations are caused by irritation to the primary visual cortex (Brodmann's area 17 ...
A visual hallucination is "the perception of an external visual stimulus where none exists". [33] A separate but related phenomenon is a visual illusion, which is a distortion of a real external stimulus. Visual hallucinations are classified as simple or complex:
Simple visual hallucinations are commonly characterized by shapes, photopsias, and grid-like patterns. [6] Complex visual hallucinations consist of highly detailed representations of people and objects. [6] The most common hallucination is of faces or cartoons. [7]
During an aura, "there's a spontaneous firing of neurons in this visual cortex creating very specific visual hallucinations," Broner explains. ... it goes beyond the visual cortex," Broner says ...
Peduncular hallucinosis (PH) is a rare neurological phenomenon that causes vivid visual hallucinations that typically occur in dark environments and last for several minutes. Unlike some other kinds of hallucinations, the hallucinations that patients with PH experience are very realistic, and often involve people and environments that are ...
Hallucination is defined as visual perception without external stimulation. It must be distinguished whether the individual is able to recognize that the perception is not real, also called pseudo-hallucination, or that the individual endorses it as real, also called delusion.
Pathological visual illusions usually occur throughout the visual field, suggesting global excitability or sensitivity alterations. [33] Alternatively visual hallucination is the perception of an external visual stimulus where none exists. [32] Visual hallucinations are often from focal dysfunction and are usually transient.
Closed-eye hallucinations and closed-eye visualizations (CEV) are hallucinations that occur when one's eyes are closed or when one is in a darkened room. They should not be confused with phosphenes, perceived light and shapes when pressure is applied to the eye's retina, or some other non-visual external cause stimulates the eye.