What Does the Right Inferior Frontal Gyrus Do?

The right inferior frontal gyrus, abbreviated as rIFG, is a region in the frontal lobe of the brain. It is part of the larger prefrontal cortex and is involved in a variety of higher-level cognitive functions. This area helps regulate thoughts and actions, and its role in managing cognitive processes is integral to many everyday behaviors.

Locating the Right Inferior Frontal Gyrus

The right inferior frontal gyrus is situated in the lower portion of the frontal lobe in the right cerebral hemisphere. It is bordered by distinct anatomical landmarks, lying below the inferior frontal sulcus and above the lateral sulcus, also known as the Sylvian fissure. This location places it in a position to communicate with various other brain regions.

The gyrus is composed of three distinct subregions, arranged from front to back: the pars orbitalis, the pars triangularis, and the pars opercularis. The pars orbitalis is the most forward section, the pars triangularis is the middle, triangular-shaped section, and the pars opercularis is at the rear. This segmented anatomy allows for functional specialization within the broader gyrus.

The rIFG’s Role in Cognitive Control

The right inferior frontal gyrus is recognized for its contribution to cognitive control, particularly response inhibition. This function allows an individual to cancel or suppress a planned action that is no longer appropriate. An example is stopping suddenly when a traffic light turns red or resisting the urge to eat an unhealthy snack. This ability to apply a “brake” on motor responses is often studied using tasks where participants must withhold a response under specific conditions.

Beyond stopping actions, the rIFG is also involved in the broader network for attentional control. This includes the ability to reorient attention to unexpected but relevant events in the environment. Research suggests that the rIFG doesn’t just act as an inhibitor but also helps detect important cues that require a change in behavior. This function is integral for flexibly shifting attention between different tasks or stimuli.

The rIFG does not work in isolation. It is part of a larger network that includes the pre-supplementary motor area (pre-SMA) and the subthalamic nucleus. This network collectively monitors behavior and adjusts actions based on goals and external feedback. Communication between these areas is a primary mechanism through which inhibitory control is implemented.

Language Processing and the rIFG

While the left hemisphere is more traditionally associated with language, the right inferior frontal gyrus makes distinct contributions to the emotional and contextual aspects of speech. One of its primary roles is processing prosody, which refers to the rhythm, stress, and intonation of speech. These elements convey emotional tone and pragmatic meaning, such as detecting sarcasm or understanding a speaker’s emotional state.

The rIFG’s involvement extends to semantic processing, which relates to the meaning of words and sentences. While the left IFG is heavily involved in core language tasks, the right IFG plays a complementary role. It becomes particularly active when understanding non-literal language, such as metaphors or irony, where the intended meaning differs from the literal interpretation.

The rIFG’s inhibitory function also applies to language, helping suppress irrelevant verbal responses or meanings to focus on the most appropriate interpretation. Both the right and left inferior frontal gyri are involved in processing emotional language. This indicates a bilateral network for understanding the full spectrum of verbal communication.

Impact of rIFG Dysfunction

When the right inferior frontal gyrus is damaged or functions atypically, it can lead to difficulties in behavior and cognition. Dysfunction in this area is implicated in Attention-Deficit/Hyperactivity Disorder (ADHD), particularly in relation to symptoms of impulsivity and inattention. Studies show that individuals with ADHD may exhibit reduced activation in the rIFG during tasks that require response inhibition.

Difficulties with inhibitory control associated with the rIFG are also observed in Obsessive-Compulsive Disorder (OCD). In OCD, individuals struggle to inhibit intrusive thoughts and suppress repetitive, compulsive behaviors. Research suggests that altered function in the rIFG and its associated neural circuits contributes to these symptoms.

Acquired brain injuries, such as from a stroke or traumatic brain injury (TBI) affecting the rIFG, can result in a range of deficits. These can include impaired response inhibition, leading to socially inappropriate behavior, and difficulties with attentional control. Damage to this area can also impair the ability to understand and interpret prosody, causing individuals to misinterpret the emotional tone of speech and affecting social interactions.