Right Brain and Left Brain Share Duties On "As Needed" Basis

Fluid communication and coordination between the left and right hemispheres of the cerebral cortex (colloquially referred to as “left brain-right brain”) plays a fundamental role in optimizing cognition and episodic memory function across a human lifespan, according to a new study from Duke University. This paper, “Frequency-Specific Neuromodulation of Local and Distant Connectivity in Aging and Episodic Memory Function,” was published online September 8 in the journal Human Brain Mapping.

For this study, Simon Davis

and colleagues at Duke used a neuromodulating device called “transcranial magnetic stimulation" (TMS) to temporarily alter normal brain activity in either the left or right prefrontal cortex of healthy older adults as each person performed a memory task. When TMS is applied to a specific localized brain region it temporarily inhibits the targeted area from functioning at full capacity.

Notably, as the researchers suppressed brain activity in a specific region of the left hemisphere they observed that communication activity with the exact same corresponding region in the right hemisphere skyrocketed, and vice versa. This suggests that the left and right hemisphere recruited similar brain regions in the opposite hemisphere for compensatory assistance to successfully complete an episodic memory task. The Duke neuroscientists believe this finding implies that “communication between the hemispheres is a deliberate process that occurs on an ‘as needed’ basis.”

The researchers also found that stronger white matter pathways between bilateral regions of the left and right cerebral hemispheres marked more robust structural neuroplasticity. Your brain's white matter is a complex labyrinth of myelin-covered axons that connect billions of neurons and carry signals between various brain regions. White matter integrity enables the brain to streamline its functional connectivity and work more efficiently. 

Over the past decade, neuroscientists have been using advanced brain imaging "connectomics" techniques to identify and map the elaborate web of white matter that links gray matter (neural brain volume) throughout the entire human brain—including both hemispheres of the cerebrum (Latin for "brain") and both hemispheres of the cerebellum (Latin for “little brain”).

Interestingly, in 2016, researchers at Stanford University led by Manish Saggar reported that suppressing the executive-control centers of the cerebrum—and temporarily allowing the cerebellum to be the “controller"—increased spontaneous innovative solutions or "Aha!" moments. This paper “Changes in Brain Activation Associated with Spontaneous Improvisation and Figural Creativity After Design-Thinking-Based Training: A Longitudinal fMRI Study,” was published in the journal Cerebral Cortex.