Contingent negative variation

Contingent Negative Variation (CNV)

The Contingent Negative Variation (CNV) is a slow cortical potential change that occurs in the brain, typically observed using electroencephalography (EEG). It is a type of event-related potential (ERP) that reflects the brain's preparation for a motor response or cognitive task. CNV is particularly interesting in the study of attention, anticipation, and motor preparation.

History

The CNV was first described by William Grey Walter and his colleagues in the 1960s. They discovered this phenomenon while studying the brain's electrical activity in response to stimuli that required a timed motor response.

Characteristics

The CNV is characterized by a slow, negative shift in the EEG that occurs between two stimuli: the warning stimulus (S1) and the imperative stimulus (S2). The CNV begins after the presentation of S1 and reaches its peak just before S2, which typically requires a response.

Phases of CNV

The CNV can be divided into two main phases:

1. Initial CNV (iCNV): This phase occurs immediately after the warning stimulus (S1) and is thought to reflect the orienting of attention and the initial processing of the stimulus.
2. Terminal CNV (tCNV): This phase occurs closer to the imperative stimulus (S2) and is associated with motor preparation and anticipation of the response.

Neurophysiological Basis

The CNV is believed to originate from the cerebral cortex, particularly the frontal lobe and parietal lobe. It involves the activation of neural circuits related to attention, anticipation, and motor preparation. The neurotransmitter dopamine is thought to play a significant role in modulating CNV amplitude.

Clinical Significance

CNV has been studied in various clinical populations to understand its role in different neurological and psychiatric conditions. For example, alterations in CNV have been observed in patients with Parkinson's disease, schizophrenia, and attention deficit hyperactivity disorder (ADHD). These findings suggest that CNV can serve as a biomarker for certain cognitive and motor dysfunctions.

Research Applications

CNV is used in research to study:

• The mechanisms of attention and anticipation.
• The effects of pharmacological agents on cognitive and motor processes.
• The development of cognitive and motor skills in children and adolescents.

Measurement and Analysis

To measure CNV, researchers use EEG to record brain activity while participants perform tasks that involve a warning stimulus followed by an imperative stimulus. The CNV is analyzed by averaging the EEG signals across multiple trials to isolate the slow negative shift from other brain activity.

See Also

• Event-related potential
• Electroencephalography
• Motor preparation

References

• Walter, W. G., Cooper, R., Aldridge, V. J., McCallum, W. C., & Winter, A. L. (1964). Contingent Negative Variation: An Electric Sign of Sensorimotor Association and Expectancy in the Human Brain. Nature, 203, 380-384.
• Tecce, J. J. (1972). Contingent negative variation (CNV) and psychological processes in man. Psychological Bulletin, 77(2), 73-108.