Processing of Salient Emotional Stimuli as a Function of Tetrahydrocannabinol (THC) and Cannabidiol (CBD)

Attentional blink refers to a phenomenon where the detection of the second of two target stimuli that are presented in Short succession within a stream of stimuli is impaired. This is explained by an insufficient availability of attentional resources. Additionally, emotionally salient stimuli, like for example pictures with a positive or negative content, are detected more often compared to neutral pictures during this attentional blink period.

Cannabinoids are involved in the modulation of cognitive, attentional, and emotional processes. Interestingly, data from animals suggests that THC and CBD, both active ingredients in the Cannabis sativa plant, have opposing effects on brain cannabinoid (CB1) receptors. CB1 receptors modulate the expression of emotionally salient conditioned association in rats, if salience processes in humans are modulated in the same way remains unclear.

Employing a task to detect salient stimuli, Bhattacharyya et al. (2012) showed that THC seems to make non-salient standard stimuli more salient. They showed decreased activation of the right caudate and increased right prefrontal cortex stimuli during processing of salient stimuli. Importantly, this was associated with decreased response times to standard relative to oddball stimuli. Generally, THC and CBD differentially modulate brain areas associated with attentional salience processing. For example THC seems to increase prefrontal and striatal activation whereas CBD seems to decrease it.

The investigators assume that THC increases the number of correctly detected emotional stimuli during the attentional blink period, whereas CBD has no effect. Additionally, the investigators assume that pictures of the positive category are detected with higher accuracy than negative ones under the influence of THC.