Christos Constantinidis, Ph.D.
Associate Professor of Neurobiology & Anatomy
Ph.D., Johns Hopkins University, 1997

Research in the laboratory of Dr. Constantinidis aims to understand how neuronal activity in the cerebral cortex gives rise to cognitive functions. Experiments in recent years have focused on the posterior parietal and dorsolateral prefrontal cortex, two areas implicated in visual perception, attention, and working memory. Simultaneous neuronal recordings from multiple micro-electrodes during performance of cognitive tasks are addressing how these areas are functionally organized and how experience and learning modifies the properties of their neurons. Neuronal activity in these areas is also monitored under administration of drugs that produce cognitive effects, and at different stages of development. Computational and modeling approaches are then employed to understand the neural mechanisms that mediate complex cognitive functions such as the selective representation of an attended stimulus or its maintenance in memory.

Research in the laboratory investigates the neurophysiology of cognitive functions. Ongoing projects examine the role of dorsolateral prefrontal and posterior parietal cortex in processes such as working memory, learning, and selective attention.

Effects of Learning
Neurophysiological experiments in the laboratory are addressing how learning to perform a cognitive task affects the organization of the cerebral cortex and functional properties of individual neurons. Recordings from the prefrontal cortex of monkeys before and after training to perform a working memory task indicate that two prefrontal subdivisions, the dorsal and ventral prefrontal cortex are innately organized to represent different types of information and are activated differently by training to perform a task. Experiments monitor the spiking activity of multiple neurons, as well as local-field-potentials are allowing us to understand how experience alters the organization of the cortical networks. 

Cortical Circuit Analysis
Simultaneous cortical recordings from arrays of microelectrodes allow us to monitor the activity of multiple neurons at a time and to infer their patterns of connectivity using analytical methods such as cross-correlation and trial-to-trial (noise) correlation. Neuronal cell types (putative pyramidal neurons and interneurons) can be resolved based on the action potential waveform and discharge rate characteristics of neurons recorded. The patterns of effective connectivity between neurons and the flow of information between them can then be determined.

Computational Analysis and Modeling
Results of our neurophysiological experiments are used for computational analysis and modeling. Computer simulations can investigate the patterns of interactions between neurons and provide insight on the functions of the cortical circuits.

Specialization of Higher Cortical Areas
Virtually all cognitive functions generate activation of a large network of cortical areas. The unique roles and cooperative interactions of these areas have only recently begun to be investigated. We are currently focusing on the posterior parietal and prefrontal cortex, two interconnected brain regions, which are involved in the processing of visual, spatial information.

Experiments seek to understand how a) the physiological properties of neurons in the two areas differ during execution of a variety of cognitive tasks that involve visual attention and working memory; b) what underlying circuit specializations mediate the functional specificity of the two areas; c) what the functional implications of such circuit differences are.

Recent Publications

F. Katsuki, and C. Constantinidis. Early involvement of prefrontal cortex in visual bottom-up attention. Nature Neuroscience (2012) 15:1060-1066.  [Abstract]

E. M. Meyers, X. L. Qi, and C. Constantinidis. Incorporation of new information into prefrontal cortical activity after learning working memory tasks. Proc. Natl. Acad. Sci. USA (2012) 109:4651-4656. [Abstract]

X. L. Qi, T. Meyer, T. Stanford and C. Constantinidis. Neural correlates of a decision variable before learning to perform a Match/Nonmatch task. J. Neuroscience (2012) 32(18): 6161-6169. [Abstract].

X. Zhou, F. Katsuki, X. L. Qi, and C. Constantinidis. Neurons with inverted tuning during the delay periods of working memory tasks in the dorsal prefrontal and posterior parietal cortex. J. Neurophysiology (2012) 108:31-38. [Abstract].

F. Katsuki, and C. Constantinidis. Unique and shared roles of the posterior parietal and dorsolateral prefrontal cortex in cognitive functions. Frontiers in Integrative Neuroscience (2012) 6:17. [Article].

X. L. Qi and C. Constantinidis. Variability of prefrontal neuronal discharges before and after training in a working memory task. PLOS One (2012) in press.

X. L. Qi and C. Constantinidis. Correlated discharges in the primate prefrontal cortex before and after working memory training. European Journal of Neuroscience (2012) in press.

T. Meyer, X. L. Qi, T. Stanford and C. Constantinidis. Stimulus selectivity in dorsal and ventral prefrontal cortex after training in working memory tasks. J. Neuroscience (2011), 31:6266-6276 [Abstract]

X. L. Qi, T. Meyer, T. Stanford and C. Constantinidis. Changes in prefrontal neuronal activity after learning to perform a spatial working memory task. Cerebral Cortex (2011), 21:2722-32. [Abstract]

X. Zhou, X. L. Qi, K. Douglas, K. Palaninathan, H. S. Kang, J. J. Buccafusco, D. T. Blake, C. Constantinidis. Cholinergic modulation of working memory activity in primate prefrontal cortex. J. Neurophysiology (2011), 106:2180:8. [Abstract]

Other Selected Publications
C. Constantinidis and M. A. Steinmetz. Posterior parietal cortex automatically encodes the location of salient stimuli. J. Neuroscience (2005), 25:233-238. [Article]

X. J. Wang , J. Tegner, C. Constantinidis, P. S. Goldman-Rakic. Division of labor among distinct inhibitory neurons in a cortical microcircuit of working memory. Proc. Natl. Acad. Sci. USA (2004), 101: 1368-1373. [Abstract]

C. Constantinidis, G. V. Williams and P. S. Goldman-Rakic. A role for inhibition in shaping the temporal flow of information in prefrontal cortex. Nature Neuroscience (2002), 5:175-180. [Abstract]

C. Constantinidis, M. N. Franowicz and P. S. Goldman-Rakic. Coding specificity in cortical microcircuits: a multiple-electrode analysis of primate prefrontal cortex. J. Neuroscience (2001), 21:3646-3655. [Abstract]

C. Constantinidis, M. N. Franowicz and P. S. Goldman-Rakic. The sensory nature of mnemonic representation in the primate prefrontal cortex. Nature Neuroscience (2001), 4:311-316 [Abstract]

Reviews

F. Katsuki, and C. Constantinidis. Unique and shared roles of the posterior parietal and dorsolateral prefrontal cortex in cognitive functions. Frontiers in Integrative Neuroscience (2012) 6:17. [Article].

J.B. Rawley, C. Constantinidis. Neural correlates of learning and working memory in the primate posterior parietal cortex. Neurobiology of Learning and Memory (2009)  [Abstract]

C. Constantinidis. Posterior parietal mechanisms of visual attention. Rev. Neurosci. (2006), 17:415-427. [Abstract]

C. Constantinidis and X. J. Wang. A Neural Circuit Basis for Spatial Working Memory. Neuroscientist (2004), 10:553-565. [Abstract]

C. Constantinidis and E. Procyk. The primate working memory networks. Cognitive Affective and Behavioral Neuroscience (2004) 4:444-465. [Article]

Methods Articles
T. Meyer and C. Constantinidis. A software solution for the control of visual behavioral experimentation. J. Neuroscience Methods (2005), 142:27-34. [Abstract]

Full Publication List
[Pubmed]

Current Lab Members

Xuelian Qi, Ph.D. Postdoctoral Fellow	Fumi Katsuki, Ph.D.  Postdoctoral Fellow	Xin Zhou  Doctoral Student	Mitchell Riley Doctoral Studen
William John Doctoral Student	Bryce Lambert Undergraduate Student	Mizuki Saito Undergraduate Student	Kathini Palaninathan Lab Tech II

Lab News

• Xin was awarded the Fine Science Tools travel award for the 2012 Society for Neuroscience meeting!
• Fumi defended successfully her Ph.D. dissertation! Congratulations Dr. Katsuki!
• Bryce received a Wake Forest Research Fellowship!
• Fumi received a WFU Alumni Student Travel Award for her presentation at the IBRO World Congress in Florence, Italy!
• Xuelian was nominated for an SfN travel award by the Western North Carolina Chapter of the Society for Neuroscience!
• Fumi won the Elsevier/Vision Research Award of the Vision Sciences Society!

 Former Lab Members

• Travis Meyer, PhD (Neuroscience)
  • Recepient of Sulkin Fellowship for Outstanding Thesis
  • Present Position: Postdoctoral Fellow, Center for Neural Basis of Cognition, Univ. of Pittsburgh
• Justin Rawley, PhD (Neuroscience)  
  • Present Position: NCI postdoctoral fellow, Radiation Oncology, Wake Forest School of Medicine
• Kristy Douglas, MS (Psychology)
  • Present Position: University of Alabama, Clinical Psychology PhD Program
• Frederik Joelving, MS (Biology) 
• Steven Heffner, MD
  • Present Position: Resident, North Carolina Baptist Hospital
• Kelvin Chan, MD
  • NRSA Predoctoral Fellow
  • Present Position: Resident, Internal Medicine, University of South California
• Adam Leigh
  • Medical Student, WFU Class of 2012
    NRSA Predoctoral Fellow
• Scott Dellorso
  • Medical Student, WFU Class of 2012
    NRSA Predoctoral Fellow