Critical flicker frequency

Smith, J.M. and Misiak, H., Critical Flicker Frequency (CFF) and psychotropic drugs in normal human subjects — a review, Psychopharmacology, 47, 175, 1976. 

Sensory tests measure ability to differentiate between objects varying along a stimulus dimension, such as auditory or visual intensity or frequency, or light flicker rate. The critical flicker frequency test is a commonly used type of sensory test. 

Ogle CW, Turner P, Markomihelakis H. The effects of high doses of oxprenolol and of propranolol on pursuit rotor performance, reaction time and critical flicker frequency. Psychopharmacologia 1976 46(3) 295-9. 

Kircheis, G., Wettstein, M., Timmermann, L., Schnitzler, A., Haussinger, D. Critical flicker frequency for quantification of low-grade hepatic encephalopathy. Hepatology 2002 35 357—366... 

In a placebo-controlled, randomized, double-blind, three-fold crossover clinical study, 12 healthy volunteers were evaluated for the effects of a single dose of kava extract equivalent to 120 mg kavalactones and 10 mg diazepam. Measurements were taken directly before, and two and six hours post ingestion. The washout period before crossover was seven days. After kava administration, a non-significant increase compared to placebo was noted in the quantitative EEG in the delta/theta intensity in the occipital and frontal areas, as well as a reduction of the alpha-wave relative intensity (P < 0.05). An increase in beta activity typically found with benzodiazepines was not observed with kava. The placebo group witnessed a decline in the relative intensity of the slow delta- and theta-waves and an increase in the alpha-waves (P < 0.001). Maximal effects of diazepam were usually observed two hours after application, as opposed to the kava extract where the effects had not decreased even after six hours. The critical flicker frequency in the psychophysiological tests was found to be lower under the influence of kava extract and diazepam compared to placebo (P < 0.05). In contrast, significant increases in performance in the Pauli Test after the administration of kava extract were noted which were not present with the placebo or diazepam (P < 0.05) (Gessner and Cnota, 1994). 

A double-blind, crossover study in 13 healthy subjects given 10 to 30 mg of mianserin twice daily for 8 days, with and without alcohol 1 g/kg, found that their performance in a number of psychomotor tests (choice reaction, coordination, critical flicker frequency) were impaired both by mianserin alone and by concurrent use with alcohol. The subjects were aware of feeling drowsy, muzzy, and less able to carry out the tests. These results confirm the findings of other studies. ... 

Recently the critical flicker frequency test (Kircheis et al., 2002 Romero-Gomez et al., 2007) has been recommended for the diagnosis of minimal HE. With this tool, the threshold frequencies at which light pulses are perceived as fused or... 

Romero-Gomez, M., Cordoba, J., Jover, R., Del Olmo, J.A., Ramirez, M., Rey, R., de Madariti, E., MontoUu, C., Nunez, D., Ravia, M., Company, L., Rodrigo, J.M., Felipo, V. 2007. Value of the critical flicker frequency in patients with minimal hepatic encephalopathy. Hepatology 45(4) 879-885... 

Phenalkvlamine Derivatives - An examination of the recent clinical experiences with fenfluramine (l) indicates it to be an effective anorexi-genic agent without cardiovascular and stimulant effects.9>10 Its failure, at therapeutic doses, to influence the "critical flicker frequency" correlates well with the clinical observation of lack of central stimulation. A sedative component is suggested since slowing of cortical waves and abolishment of cortical after-discharge were observed in cats. ... 

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