Posts classified under: B

Nicholas Brecha, Ph.D.

Biography

Neurochemical and Anatomical Pathways in the Vertebrate Retina that Mediate Vision Dr. Brecha’s major research interest is concerned with understanding the functional organization of the mammalian retina by elucidating its morphology and neurochemistry. Specific investigations are focused on defining the microcircuitry of the inner retina, evaluating the neurochemical organization and regulation of both its fast (amino acid) and slow (peptide) transmitter systems, and the function of bipolar, amacrine and ganglion cell populations, which are major retinal cell types that play critical roles in the processing of visual information. Recent investigations concerned with peptide-containing cell populations are defining the cellular expression patterns of tachykinin, somatostatin, neuropeptide Y and opiate receptors, and their functional role in modulating bipolar cell responsiveness. Morphological studies have shown that peptide receptor subtypes are selectively expressed by different populations of bipolar, amacrine and ganglion cells. These observations have provided important clues to the organization of the retinal microcircuits mediating different aspects of vision, as well as the sites of action of several previously identified retinal transmitter substances. A new research direction, developed over the past three years has been focused on determining the function of peptides in the retina. The rationale of these studies is to define the cellular actions of peptides found in the retina, which we hypothesize modulate cellular responsiveness, to influence ion channels and other intercellular messenger systems. Initial studies have focused on somatostatin; our findings demonstrate that this peptide inhibits both K+ and Ca2+ ion channels in the axonal terminals of bipolar cells and photoreceptors at low concentrations. Interestingly, these cells prominently express the somatostatin receptor subtype, sst2A suggesting this action is mediated through this receptor. These investigations provide further support for a role of somatostatin in the presynaptic modulation of transmitter release from retinal cells.

Idan Blank, Ph.D.

Research and Teaching Interests:

I study how we understand language—a phenomenon that is universal across human cultures, yet unique to our species, and allows us to transmit thoughts from one mind to another. What are the component processes of comprehension? What kind of mental structures allow us to “know the meaning” of an utterance? Which distinctions in meaning do these structures make more/less salient? And what mental operations are used to manipulate them?

To understand how comprehension evolves in our minds, I study how it engages our brains: which aspects of comprehension get their own dedicated neural real estate? Which are inseparable, supported by a joint mechanism? And which rely on circuits that serve many domains beyond language? Using neuroimaging (mostly functional MRI), tools from network neuroscience, and a combination of hypothesis- and data-driven approaches, I characterize the functional regions engaged when adult native speakers understand language: their internal organization and relationship to one another (dissociable vs. tightly linked); the division of “mental labor” and the integration of information across them; and the ways they change following brain injuries.

I also use computational methods to evaluate meaning representations that are generated by algorithms trained on natural texts. I examine what knowledge—about words, their combinations, and the underlying concepts—is captured by these representations, and compare it against behavioral benchmarks. I test which features of the linguistic input are minimally required for machines to extract this knowledge.

Biography:

Idan A. Blank will join UCLA as an Assistant Professor of Psychology in July 2019. He received his PhD (2016) in Cognitive Science from MIT, working with Nancy Kanwisher and Ev Fedorenko, and continued working with Ev as a postdoctoral associate at the McGovern Institute for Brain Research. Prior to that, he studied mathematics, psychology, and theatre arts in the Lautman Interdisciplinary Program at Tel-Aviv University, where he received his MA (2011) working with Galit Yovel.

Idan Blank’s Curriculum Vitae

Representative Publications:

Mineroff, Z.*, Blank, I.A.*, Mahowald, K., & Fedorenko, E. (2018) A robust dissociation among the language, multiple demand, and default mode networks: evidence from inter-region correlations in effect size. Neuropsychologia, 119, 501-511. DOI: 10.1016/j.neuropsychologia.2018.09.011

Blank, I.A., Kiran, S., & Fedorenko, E. (2017). Can neuroimaging help aphasia researchers? Addressing generalizability, variability, and interpretability. Cognitive Neuropsychology, 34(6), 377-393. DOI: 10.1080/02643294.2017.1402756

Blank, I.A. & Fedorenko, E. (2017) Domain-general brain regions do not track linguistic input as closely as language-selective regions. Journal of Neuroscience, 37(41), 9999–10011. DOI: 10.1523/JNEUROSCI.3642-16.2017

Blank, I., Balewski, Z., Mahowald, K. & Fedorenko, E. (2016). Syntactic processing is distributed across the language system. Neuroimage, 127, 307-323. DOI: 10.1016/j.neuroimage.2015.11.069

Blank, I., Kanwisher, N. & Fedorenko, E. (2014). A functional dissociation between language and multiple demand regions revealed in patterns of BOLD fluctuations. Journal of Neurophysiology, 112(5): 1105-1118. DOI: 10.1152/jn.00884.2013

Grand, G.*, Blank, I.A.*, Pereira, F., & Fedorenko, E. (submitted) Semantic projection: recovering human knowledge of multiple, distinct object features from word-embeddings. arXiv:1802.01241