title: The effects of focal epileptic activity on regional sensory-evoked neurovascular coupling and postictal modulation of bilateral sensory processing.
abstract: While it is known that cortical sensory dysfunction may occur in focal neocortical epilepsy, it is unknown whether sensory-evoked neurovascular coupling is also disrupted during epileptiform activity. Addressing this open question may help to elucidate both the effects of focal neocortical epilepsy on sensory responses and the neurovascular characteristics of epileptogenic regions in sensory cortex. We therefore examined bilateral sensory-evoked neurovascular responses before, during, and after 4-aminopyridine (4-AP, 15 mmol/L, 1 μL) induced focal neocortical seizures in right vibrissal cortex of the rat. Stimulation consisted of electrical pulse trains (16 seconds, 5 Hz, 1.2 mA) presented to the mystacial pad. Consequent current-source density neural responses and epileptic activity in both cortices and across laminae were recorded via two 16-channel microelectrodes bilaterally implanted in vibrissal cortices. Concurrent two-dimensional optical imaging spectroscopy was used to produce spatiotemporal maps of total, oxy-, and deoxy-hemoglobin concentration. Compared with control, sensory-evoked neurovascular coupling was altered during ictal activity, but conserved postictally in both ipsilateral and contralateral vibrissal cortices, despite neurovascular responses being significantly reduced in the former, and enhanced in the latter. Our results provide insights into sensory-evoked neurovascular dynamics and coupling in epilepsy, and may have implications for the localization of epileptogenic foci and neighboring eloquent cortex.
authors.affiliation: 1] Department of Psychology, University of Sheffield, Sheffield, UK [2] Department of Neurological Surgery, Brain and Spine Center, Brain and Mind Research Institute, Weill Cornell Medical College, New York Presbyterian Hospital, New York, New York, USA.
authors.forename: Sam
authors.initials: S
authors.lastname: Harris
authors.forename: Michael
authors.initials: M
authors.lastname: Bruyns-Haylett
authors.forename: Aneurin
authors.initials: A
authors.lastname: Kennerley
authors.forename: Luke
authors.initials: L
authors.lastname: Boorman
authors.forename: Paul G
authors.initials: PG
authors.lastname: Overton
authors.forename: Hongtao
authors.initials: H
authors.lastname: Ma
authors.forename: Mingrui
authors.initials: M
authors.lastname: Zhao
authors.forename: Theodore H
authors.initials: TH
authors.lastname: Schwartz
authors.forename: Jason
authors.initials: J
authors.lastname: Berwick
mesh_terms: D000818:Animals; D020937:Epilepsy, Partial, Sensory / Q000503:physiopathology*; D005073:Evoked Potentials, Somatosensory / Q000502:physiology*; D005260:Female; D007839:Functional Laterality; D006439:Hemodynamics / Q000502:physiology*; D006454:Hemoglobins / Q000032:analysis; D008839:Microelectrodes; D019579:Neocortex / Q000098:blood supply / Q000503:physiopathology; D009434:Neural Pathways / Q000503:physiopathology*; D061848:Optical Imaging; D010100:Oxygen / Q000097:blood; D010812:Physical Stimulation; D051381:Rats; D011919:Rats, Inbred Strains; D013003:Somatosensory Cortex / Q000503:physiopathology*; D014738:Vibrissae / Q000502:physiology
chemical_list: D006454:Hemoglobins; D010100:Oxygen