Impairment of intradimensional shift in an attentional set-shifting task in rats with chronic bilateral common carotid artery occlusion

• Rat received bilateral common carotid artery occlusion (BCCAo).
• Testing attentional function of BCCAo rats using an attentional set-shifting task.
• Impairment of intradimensional shift in the attentional task in BCCAo rats.
• Alterations of GABAergic neurons in the anterior cingulate cortex in BCCAo rats.
• Attentional impairment and dysfunction of ACC in the animal model for VaD.

Studies of rats with chronic bilateral common carotid artery occlusion (BCCAo), an animal model for vascular dementia (VaD), have reported hippocampus-dependent memory impairment and associated neuropathologies. Patients with VaD also experience attentional shifting dysfunction. However, animal models of VaD have not been used to study attentional function. Therefore, the present study examined attentional function in rats with BCCAo, using attentional set-shifting task (ASST) that required rats to choose a food-baited pot from 2 possible pots. ASST included 6 consecutive sessions including simple discrimination, compound discrimination, intradimensional shifting, extradimensional shifting, and reversals. The BCCAo rats were significantly slower at learning the intradimensional set-shifting task compared to control rats. Previous studies have demonstrated that the cingulate cortex and medial prefrontal cortex are critical to intradimensional and extradimensional set-shifting, respectively. Additionally, inflammatory responses and neuronal dysfunction were observed in rats with chronic BCCAo. In addition, OX-6 positive microglia significantly increased in the forceps minor white matter of BCCAo rats, and glutamate decarboxylase signals co-localized with NeuN were reduced in the anterior cingulate cortex of BCCAo rats, compared to control rats. Impaired neuronal and GABAergic neuronal integrity in the anterior cingulate cortex, damage to white matter, and attentional impairments observed in BCCAo rats suggest dysfunction of brain structures that are associated with attentional impairments observed in patients with VaD.