Article

Molecular Neurobiology

, Volume 33, Issue 3, pp 181-197

Neurovascular coupling and oximetry during epileptic events

  • Minah SuhAffiliated withDepartment of Neurological Surgery, Weill Cornell Medical College, New York Presbyterian Hospital Email author 
  • , Hongtao MaAffiliated withDepartment of Neurological Surgery, Weill Cornell Medical College, New York Presbyterian Hospital
  • , Mingrui ZhaoAffiliated withDepartment of Neurological Surgery, Weill Cornell Medical College, New York Presbyterian Hospital
  • , Saadat SharifAffiliated withDepartment of Neurological Surgery, Weill Cornell Medical College, New York Presbyterian Hospital
  • , Theodore H. SchwartzAffiliated withDepartment of Neurological Surgery, Weill Cornell Medical College, New York Presbyterian Hospital

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Abstract

Epilepsy is an abnormal brain state in which a large population of neurons is synchronously active, causing an enormous increase in metabolic demand. Recent investigations using high-resolution imaging techniques, such as optical recording of intrinsic signals and voltagesensitive dyes, as well as measurements with oxygen-sensitive electrodes have elucidated the spatiotemporal relationship between neuronal activity, cerebral blood volume, and oximetry in vivo. A focal decrease in tissue oxygenation and a focal increase in deoxygenated hemoglobin occurs following both interictal and ictal events. This “epileptic dip” in oxygenation can persist for the duration of an ictal event, suggesting that cerebral blood flow is inadequate to meet metabolic demand. A rapid focal increase in cerebral blood flow and cerebral blood volume also accompanies epileptic events; however, this increase in perfusion soon (>2 s) spreads to a larger area of the cortex than the excitatory change in membrane potential. Investigations in humans during neurosurgical operations have confirmed the laboratory data derived from animal studies. These data not only have clinical implications for the interpretation of noninvasive imaging studies such as positron emission tomography, single-photon emission tomography, and functional magnetic resonance imaging but also provide a mechanism for the cognitive decline in patients with chronic epilepsy.

Index Entries

Epilepsy ictal interictal intrinsic signal optical imaging voltage-sensitive dye oxygen-sensitive electrodes neurovascular coupling oximetry initial dip BOLD rat seizure human