Posts classified under: H

Keith Holyoak, Ph.D.


Combining behavioral studies of normal cognition, computational modeling, and neuropsychological and neuroimaging studies, to understand the role of the prefrontal cortex in human thinking Keith J. Holyoak conducts research in human reasoning and problem solving. Much of his work is concerned with the role of analogy in thinking. One of the major themes of this work is the way in which analogy serves as a psychological mechanism for learning and transfer of knowledge. In his book Mental Leaps with Paul Thagard, he presents a general theory of analogical thinking that includes analysis of how the capacity to use analogy evolved in primates, how it develops in children, and how it is used to reason in domains ranging from law and politics to science. Other related reserach, in collaboration with Dan Simon, deals with complex decision-making in fields such as the law. Holyoaks research combines studies of thinking in normal adults with neuropsychological studies of how thinking in brain-damaged individuals. This work, in collaboration with Barbara Knowlton and others, is investigating the role of prefrontal cortex in complex human reasoning. In addition to experimental work, Holyoak works with John Hummel to develop computational models of human thinking based on neural-network models. These models use neural synchrony to preform dynamic variable binding, and thereby represent and maniputlate symbolic knowledge. The overall goal is to understand the neural basis for human thought.

Ronald Harper, Ph.D.


The laboratory examines neural mechanisms underlying sleep state: control of breathing, somatomotor activity, and cardiovascular action in developing and adult small animal preparations. Neural mechanisms are examined through neurophysiologic techniques which include assessment of intrinsic optical changes in neural tissue, functional magnetic resonance imaging, and chronic single neuron recording; the optical imaging and cell recording studies are often combined with microdialysis techniques to determine neurochemical mechanisms underlying cell action. We found that a substantial portion of sleep effects on normal and disordered breathing result from rostral brain influences on pontine and medullary structures, that activity over wide areas of these structures can be visualized during ventilatory and pressor challenges in freely behaving animals, and that immature development of mechanisms controlling descending rostral brain influences on breathing can place the organism at risk.

Steve Horvath, Ph.D., Sc.D.


Dr Horvath is an aging researcher and bioinformatician whose research lies at the intersection of epidemiology, chronic diseases, epigenetics, genetics, and systems biology. He developed systems biologic approaches such as weighted gene co-expression network analysis. He works on all aspects of biomarker development with a particular focus on genomic biomarkers of aging. He developed a highly accurate multi-tissue biomarker of aging known as the epigenetic clock. Salient features of the epigenetic clock include its high accuracy and its applicability to a broad spectrum of tissues and cell types. He develops and applies methods for analyzing and integrating gene expression-, DNA methylation-, microRNA, genetic marker-, and complex phenotype data. His lab members apply and develop data mining methods to study a broad spectrum of diseases, e.g. aging research, cancer, cardiovascular disease, HIV, Huntington’s disease, neurodegenerative diseases.