@article{MTMT:2717967,
	title = {Evoked effective connectivity of the human neocortex},
	url = {https://m2.mtmt.hu/api/publication/2717967},
	author = {Entz, László and Tóth, Emília and Keller, CJ and Bickel, S and Groppe, DM and Fabó, Dániel and Kozák, Lajos Rudolf and Erőss, Loránd and Ulbert, István and Mehta, AD},
	doi = {10.1002/hbm.22581},
	journal-iso = {HUM BRAIN MAPP},
	journal = {HUMAN BRAIN MAPPING},
	volume = {35},
	unique-id = {2717967},
	issn = {1065-9471},
	abstract = {The role of cortical connectivity in brain function and pathology is increasingly being recognized. While in vivo magnetic resonance imaging studies have provided important insights into anatomical and functional connectivity, these methodologies are limited in their ability to detect electrophysiological activity and the causal relationships that underlie effective connectivity. Here, we describe results of cortico-cortical evoked potential (CCEP) mapping using single pulse electrical stimulation in 25 patients undergoing seizure monitoring with subdural electrode arrays. Mapping was performed by stimulating adjacent electrode pairs and recording CCEPs from the remainder of the electrode array. CCEPs reliably revealed functional networks and showed an inverse relationship to distance between sites. Coregistration to Brodmann areas (BA) permitted group analysis. Connections were frequently directional with 43% of early responses and 50% of late responses of connections reflecting relative dominance of incoming or outgoing connections. The most consistent connections were seen as outgoing from motor cortex, BA6-BA9, somatosensory (SS) cortex, anterior cingulate cortex, and Broca's area. Network topology revealed motor, SS, and premotor cortices along with BA9 and BA10 and language areas to serve as hubs for cortical connections. BA20 and BA39 demonstrated the most consistent dominance of outdegree connections, while BA5, BA7, auditory cortex, and anterior cingulum demonstrated relatively greater indegree. This multicenter, large-scale, directional study of local and long-range cortical connectivity using direct recordings from awake, humans will aid the interpretation of noninvasive functional connectome studies. Hum Brain Mapp, 2014. (c) 2014 Wiley Periodicals, Inc.},
	year = {2014},
	eissn = {1097-0193},
	pages = {5736-5753},
	orcid-numbers = {Fabó, Dániel/0000-0001-5141-5351; Kozák, Lajos Rudolf/0000-0003-0368-3663; Erőss, Loránd/0000-0002-5796-5546; Ulbert, István/0000-0001-9941-9159}
}

@article{MTMT:1121164,
	title = {Suppressed neuronal activity and concurrent arteriolar vasoconstriction may explain negative blood oxygenation level-dependent signal.},
	url = {https://m2.mtmt.hu/api/publication/1121164},
	author = {Devor, A and Tian, P and Nishimura, N and Teng, IC and Hillman, EM and Narayanan, SN and Ulbert, István and Boas, DA and Kleinfeld, D and Dale, AM},
	doi = {10.1523/JNEUROSCI.0134-07.2007},
	journal-iso = {J NEUROSCI},
	journal = {JOURNAL OF NEUROSCIENCE},
	volume = {27},
	unique-id = {1121164},
	issn = {0270-6474},
	abstract = {Synaptic transmission initiates a cascade of signal transduction events that
		couple neuronal activity to local changes in blood flow and oxygenation. Although
		a number of vasoactive molecules and specific cell types have been implicated,
		the transformation of stimulus-induced activation of neuronal circuits to
		hemodynamic changes is still unclear. We use somatosensory stimulation and a
		suite of in vivo imaging tools to study neurovascular coupling in rat primary
		somatosensory cortex. Our stimulus evoked a central region of net neuronal
		depolarization surrounded by net hyperpolarization. Hemodynamic measurements
		revealed that predominant depolarization corresponded to an increase in
		oxygenation, whereas predominant hyperpolarization corresponded to a decrease in 
		oxygenation. On the microscopic level of single surface arterioles, the response 
		was composed of a combination of dilatory and constrictive phases. Critically,
		the relative strength of vasoconstriction covaried with the relative strength of 
		oxygenation decrease and neuronal hyperpolarization. These results suggest that a
		neuronal inhibition and concurrent arteriolar vasoconstriction correspond to a
		decrease in blood oxygenation, which would be consistent with a negative blood
		oxygenation level-dependent functional magnetic resonance imaging signal.},
	year = {2007},
	eissn = {1529-2401},
	pages = {4452-4459},
	orcid-numbers = {Ulbert, István/0000-0001-9941-9159}
}