Resting-state activity in development and maintenance of normal brain function

Abstract

One of the most intriguing recent discoveries concerning brain function is that intrinsic neuronal activity manifests as spontaneous fluctuations of the blood oxygen level-dependent (BOLD) functional MRI signal. These BOLD fluctuations exhibit temporal synchrony within widely distributed brain regions known as resting-state networks. Resting-state networks are present in the waking state, during sleep, and under general anesthesia, suggesting that spontaneous neuronal activity plays a fundamental role in brain function. Despite its ubiquitous presence, the physiological role of correlated, spontaneous neuronal activity remains poorly understood. One hypothesis is that this activity is critical for the development of synaptic connections and maintenance of synaptic homeostasis. We had a unique opportunity to test this hypothesis in a 5-y-old boy with severe epileptic encephalopathy. The child developed marked neurologic dysfunction in association with a seizure disorder, resulting in a 1-y period of behavioral regression and progressive loss of developmental milestones. His EEG showed a markedly abnormal pattern of high-amplitude, disorganized slow activity with frequent generalized and multifocal epileptiform discharges. Resting-state functional connectivity MRI showed reduced BOLD fluctuations and a pervasive lack of normal connectivity. The child underwent successful corpus callosotomy surgery for treatment of drop seizures. Postoperatively, the patient's behavior returned to baseline, and he resumed development of new skills. The waking EEG revealed a normal background, and functional connectivity MRI demonstrated restoration of functional connectivity architecture. These results provide evidence that intrinsic, coherent neuronal signaling may be essential to the development and maintenance of the brain's functional organization.developmental neuroimaging | epilepsy

Abnormal cognitive network interactions in Lennox‐Gastaut syndrome: A potential mechanism of epileptic encephalopathy

“…24 Our results are consistent with fMRI data in LGS showing that cognitive network behavior may predict cognitive improvements following successful seizure control. Pizoli et al 25 performed pre-and postoperative fMRI in a child with LGS who underwent corpus callosotomy, leading to seizure remission. Following surgery, the patient showed a normalization of large-scale network interactions, including greater segregation of the DMN and DAN, accompanied by a restoration of cognitive development.…”

Multimodality MR Imaging Findings of Low-Grade Brain Edema in Hepatic Encephalopathy

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“…The degree of synchrony is thought to indicate the strength of functional connections (i.e., functional connectivity) that are organized into distinct networks of functionally related brain regions (Zhang and Raichle, 2010). These networks are hypothesized to help develop, maintain, and increase the reliability of neural responses to external stimuli (Pizoli et al, 2011;Uddin et al, 2010).…”