Lawrence Cohen, PhD

  • Professor of Cellular And Molecular Physiology
  • Principal Scientist, Korea Institute of Science and Technology

Research Interests: Neuroscience; Olfactory processing; and Imaging brain activity

My laboratory pioneered the development and use of optical methods for following, on a large scale, rapid electrical events that underlie brain activity and changes in ion concentration in biological systems. Some contemporary imaging methods of modern neurobiology and cardiac physiology are founded on these developments.

Research interests
Neurosciences
Research summary

One reason the brain is difficult to study is that many individual neurons or brain areas are active at once; conventional techniques allow one to monitor only one or a few neurons or locations at a time. We have worked on two optical methods for measuring brain activity; both utilize voltage-sensitive or Calcium-sensitive dyes and a fast camera with frame rates of 1 kHz or a 2-photon microscope. In the first variation, we use the dyes and a 2-photon microscope to follow the spike activity of individual neurons, and in favorable preparations about 500 individual neurons can be monitored simultaneously. We hope that monitoring many neurons simultaneously will improve our understanding about how nervous systems are organized to generate behaviors. In the second variation, each pixel in the recording receives light from a large number of neurons and processes (e.g. from an area of cortex 20 um x 20 um) and thus each signal represents the average of a population of neurons. There are several interesting aspects of vertebrate brain function where populations are involved.

Specialized Terms: Brain; Central Nervous System; Neurons; Vertebrate Physiology; Olfaction; Olfactory Bulb; Protein Sensors of Voltage and Calcium

Extensive research description

One active area is the development of fluorescent protein sensors of membrane potential. At present the voltage signals are just large enough to be useful in monitoring activity in invertebrate and mammalian nervous systems. We hope to find sensors that are both faster and have larger signals.



A second area is understanding the role of the mammalian olfactory bulb in olfactory processing. We have started comparing the input (from the nose) and the output (carried by mitral/tufted cells) to determine the olfactory transformation carried out by the bulb. We also want to know what the interneurons do to carry out this transformation.

Education
  • PhD, Columbia University, 1965
Publications
  • Storace DA, Braubach OR, Jin L, Cohen LB, Sung U. Monitoring brain activity with protein voltage and calcium sensors. Scientific Reports 2015, 5:10212.
  • Homma R, Kovalchuk Y, Konnerth A, Cohen LB, Garaschuk O. In vivo functional properties of juxtaglomerular neurons in the mouse olfactory bulb. Frontiers In Neural Circuits 2013, 7:23.
  • Jin L, Han Z, Platisa J, Wooltorton JR, Cohen LB, Pieribone VA. Single action potentials and subthreshold electrical events imaged in neurons with a fluorescent protein voltage probe. Neuron 2012, 75:779-85.
  • Lam YW, Cohen LB, Zochowski MR. Odorant specificity of three oscillations and the DC signal in the turtle olfactory bulb. The European Journal Of Neuroscience 2003, 17:436-46.
  • Homma R, Cohen LB, Kosmidis EK, Youngentob SL. Perceptual stability during dramatic changes in olfactory bulb activation maps and dramatic declines in activation amplitudes. The European Journal Of Neuroscience 2009, 29:1027-34.
  • Wachowiak M, Cohen LB. Representation of odorants by receptor neuron input to the mouse olfactory bulb. Neuron 2001, 32:723-35.