Out with the Old and in with the New: the Contribution of Prefrontal and Cerebellar Areas to Backward Inhibition

• Published in: Cerebellum (London, England) Vol. 19; no. 3; pp. 426 - 436
• Main Authors: Picazio, Silvia, Foti, Francesca, Oliveri, Massimiliano, Koch, Giacomo, Petrosini, Laura, Ferlazzo, Fabio, Sdoia, Stefano
• Format: Journal Article
• Language: English
• Published: New York Springer US 01.06.2020; Springer Nature B.V
• Subjects: Achievement tests; Adult; Biomedical and Life Sciences; Biomedicine; Cerebellum; Cerebellum - physiology; Excitability; Female; Humans; Inhibition, Psychological; Male; Neurobiology; Neurology; Neurosciences; Original Paper; Photic Stimulation - methods; Prefrontal Cortex - physiology; Presupplementary motor area; Psychomotor Performance - physiology; Reaction Time - physiology; Space Perception - physiology; Verbal Behavior - physiology; Young Adult; Task-switching; Theta burst stimulation; Executive functions; Inhibitory control; Transcranial magnetic stimulation
• ISSN: 1473-4222; 1473-4230; 1473-4230
• DOI: 10.1007/s12311-020-01115-9

The inhibitory mechanism named backward inhibition (BI) counteracts interference of previous tasks supporting task switching. For instance, if task set A is inhibited when switching to task B, then it should take longer to immediately return to task set A (as occurring in an ABA sequence), as compared to a task set that has not been just inhibited (as occurring in a CBA sequence), because extra time will be needed to overcome the inhibition of task set A. The evidenced prefrontal and cerebellar role in inhibitory control suggests their involvement even in BI. Here, for the first time, we modulated the excitability of multiple brain sites (right presupplementary motor area (pre-SMA), left and right cerebellar hemispheres) through continuous theta burst stimulation (cTBS) in a valuable sham-controlled order-balanced within-subject experimental design in healthy individuals performing two domain-selective (verbal and spatial) task-switching paradigms. Verbal BI was abolished by prefrontal or cerebellar stimulations through opposite alterations of the basal pattern: cTBS on pre-SMA increased CBA reaction times, disclosing the current prefrontal inhibition of any interfering old task. Conversely, cerebellar cTBS decreased ABA reaction times, disclosing the current cerebellar recognition of sequences in which it is necessary to overcome previously inhibited events.