The regions of the brain responsible for gustatory hallucination in this case are the insula and the superior bank of the sylvian fissure. General somatic sensations
General somatic sensations of a hallucinatory nature are experienced when an individual feels that their body is being mutilated, i.e. twisted, torn, or disemboweled. Other reported cases are invasion by animals in the persons internal organs, such as snakes in the stomach or frogs in the rectum. The general feeling that ones flesh is decomposing is also classified under this type of this hallucination. Multimodal
A hallucination involving sensory modalities is called multimodal, analogous to unimodal hallucinations which have only one sensory modality. The multiple sensory modalities can occur at the same time (simultaneously) or with a delay (serial), be related or unrelated to each other, and be consistent with reality (congruent) or not (incongruent). For example, a person talking in a hallucination would be congruent with reality, but a cat talking would not be. Multimodal hallucinations are correlated to poorer mental health outcomes, and are often experienced as feeling more real. Cause
Hallucinations can be caused by a number of factors. Hypnagogic hallucination
These hallucinations occur just before falling asleep and affect a high proportion of the population: in one survey 37% of the respondents experienced them twice a week. The hallucinations can last from seconds to minutes; all the while, the subject usually remains aware of the true nature of the images. These may be associated with narcolepsy. Hypnagogic hallucinations are sometimes associated with brainstem abnormalities, but this is rare.
However, abstaining from hallucinogenic drugs, stimulant drugs, managing stress levels, living healthily, and getting plenty of sleep can help reduce the prevalence of hallucinations. In all cases of hallucinations, medical attention should be sought out and informed of ones specific symptoms. Meta-analyses show that cognitive behavioral therapy and metacognitive training can also reduce the severity of hallucinations. Epidemiology
Prevalence of hallucinations varies depending on underlying medical conditions, which sensory modalities are affected, age and culture. As of 2022, auditory hallucinations are the most well studied and most common sensory modality of hallucinations, with an estimated lifetime prevalence of 9.6%. Children and adolescents have been found to experience similar rates (12.7% and 12.4% respectively) which occur mostly during late childhood and adolescence. This is compared with adults and those over 60 (with rates of 5.8% and 4.8% respectively). For those with schizophrenia, the lifetime prevalence of hallucinations is 80% and the estimated prevalence of visual hallucinations is 27%, compared to 79% for auditory hallucinations. A 2019 study suggested 16.2% of adults with hearing impairment experience hallucinations, with prevalence rising to 24% in the most hearing impaired group.A risk factor for multimodal hallucinations is prior experience of unimodal hallucinations. In 90% cases of psychosis, a visual hallucination occurs in combination with another sensory modality, most often being auditory or somatic.