Visual snow (VS) is a distressing, life-impacting condition with unrelenting and persistent disturbing visual phenomena. Disease onset is usually around age 20 and is characterized by continuous perception of innumerable flickering dots (like a 'broken television'). The disease is often accompanied by comorbidities such as migraine, tinnitus, depression and anxiety.

Neuronally, VS patients show cerebral hypermetabolism, resulting in altered neuronal excitability, as well as increased grey matter volume in parts of the visual cortex.

For this pilot study, the investigators aim to recruit VS patients. In a double-blind, randomized and placebo-controlled longitudinal experiment, the investigators will use real-time functional magnetic resonance imaging (rtfMRI) neurofeedback to teach patients to downregulate activity in different regions of the visual cortex.

The investigators hypothesize that neurofeedback will allow patients to learn to downregulate their abnormal visual cortex activity. Moreover, the investigators predict that a stronger downregulation of activity from the lingual gyrus will correlate with a more pronounced decrease in VS symptoms.

Currently, there is no pharmacological or non-pharmacological treatment available that significantly reduces the high disease burden produced by VS. Thus, there is an unmet need for an appropriate intervention to treat patients with VS. In this study, the investigators will:

1. Test if rtfMRI-based neurofeedback could serve as therapeutic option for patients with VS.

   Here, the investigators will examine correlations of neurofeedback regulation success with clinical scores 3 after neurofeedback

2. Examine brain function and structure in patients with VS

Primary and secondary endpoint/outcome(s)

• Primary outcome variable: VS symptom severity before and after rtfMRI, using standardized clinical assessment.
• Secondary outcome variables: fMRI and structural MRI, clinical questionnaires (visual function, anxiety, depression, tinnitus, and migraine), parameters from psychophysical data (assessed before and after neurofeedback).
• Linear Mixed model analysis will be performed (using clinical and imaging data) to estimate the impact of rtfMRI on clinical progression and brain function/structure.

Inclusion Criteria:

• Patients with VS (≥ 18 to ≤ 60 years), which can read and sign the informed consent form.
• Male and female
• Healthy controls (≥ 18 to ≤ 60 years), which can read and sign the informed consent form.

Exclusion Criteria:

• MR exclusion criteria (patients only): metallic items in the body (i.e. eye splinter, MR incompatible implants), pacemaker, claustrophobia).
• pregnant participants
• participants suffering from a degenerative disorder of the Central Nervous System, such as Stroke, Multiple Sclerosis, Parkinson's Disease, Alzheimer's Disease and Huntington's Disease and with major psychiatric disorders such as schizophrenia, depression, or anxiety disorder requiring pharmacological treatment (psycho-pharmaca).

The datasets presented in this study are not readily available because due to Swiss law, the researchers must assess whether the use of the data and coded datasets are within the primary scope of the informed consent. Subject level data is only available upon request and after the researchers have reviewed the purpose of the inquiry. Requests to access the datasets should be directed to Dr. Lars Michels, lars.michels@usz.ch.

Double Blind