Sen Cheng

Publications (14) View all

• Article: Identification of two forebrain structures that mediate execution of memorized sequences in the pigeon.

  Sascha Helduser, Sen Cheng, Onur Güntürkün
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  ABSTRACT: The execution of action sequences is the basis of most behavior. However, little is known about the neural foundation of visuomotor sequence execution in birds, although pigeons are a classic model animal to study sequence learning and production. Recently, we identified two structures in the pigeon brain, the nidopallium intermedium medialis pars laterale (NIML) and the nidopallium caudolaterale (NCL), that are involved in the execution of a serial reaction time task (SRTT). In the SRTT sequence execution is always cue guided. Thus, the previous study could not unambiguously clarify if NCL and NIML contribute to a memory-based execution of sequential behavior. In addition, a possibly differential role of these two structures could not be identified. Therefore, the present study was conducted to further elucidate the role of NCL and NIML for sequence execution in a task where pigeons performed a memorized four item sequence. Transient inactivation of each NIML and NCL severely impaired sequence execution. Results confirm and extend our previous findings. NIML and NCL seem to store sequence information in parallel. However, results support the hypothesis that NCL in contrast to NIML is especially required for sequence initiation.
  Journal of Neurophysiology 12/2012; · 3.32 Impact Factor
• Article: Constraints on the synchronization of entorhinal cortex stellate cells

  Patrick Crotty, Eric Lasker, Sen Cheng
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  ABSTRACT: Synchronized oscillations of large numbers of central neurons are believed to be important for a wide variety of cognitive functions, including long-term memory recall and spatial navigation. It is therefore plausible that evolution has optimized the biophysical properties of central neurons in some way for synchronized oscillations to occur. Here, we use computational models to investigate the relationships between the presumably genetically determined parameters of stellate cells in layer II of the entorhinal cortex and the ability of coupled populations of these cells to synchronize their intrinsic oscillations: in particular, we calculate the time it takes circuits of two or three cells with initially randomly distributed phases to synchronize their oscillations to within one action potential width, and the metabolic energy they consume in doing so. For recurrent circuit topologies, we find that parameters giving low intrinsic firing frequencies close to those actually observed are strongly advantageous for both synchronization time and metabolic energy consumption.
  Physical Review E 01/2012; 86(1):011908. · 2.26 Impact Factor
• Article: The structure of networks that produce the transformation from grid cells to place cells.

  Sen Cheng, Loren M Frank
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  ABSTRACT: Since grid cells were discovered in the medial entorhinal cortex, several models have been proposed for the transformation from periodic grids to the punctate place fields of hippocampal place cells. These prior studies have each focused primarily on a particular model structure. By contrast, the goal of this study is to understand the general nature of the solutions that generate the grids-to-places transformation, and to exploit this insight to solve problems that were previously unsolved. First, we derive a family of feedforward networks that generate the grids-to-places transformations. These networks have in common an inverse relationship between the synaptic weights and a grid property that we call the normalized offset. Second, we analyze the solutions of prior models in terms of this novel measure and found to our surprise that almost all prior models yield solutions that can be described by this family of networks. The one exception is a model that is unrealistically sensitive to noise. Third,
  Neuroscience 09/2011; 197:293-306. · 3.38 Impact Factor
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  Article: Reactivation, replay and preplay: How it might all fit together

  Laure Buhry, Amir Hossein Azizi, Sen Cheng
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  ABSTRACT: Sequential neural activity that occur during “offline” states, such as sleep or awake resting, are correlated with sequences recorded during preceeding exploration phases. This so-called reactiva- tion, or replay has been observed in a number of different brain regions such as the striatum, pre- frontal cortex, primary visual cortex and, most prominently, the hippocampus. Reactivation largely co-occurs with hippocampal sharp-waves/ ripples, brief high-frequency bursts in the local field po- tential. Here we review the mounting evidence for the hypothesis that reactivation is the the neural mechanism for memory consolidation during sleep. This evidence includes the properties of the neu- ral activity during reactivation, correlations between ripple rate and subsequent memory perfomance in animals and humans, and ripple interruption studies in animals. At the same time, recent studies suggest that offline sequential activity, especially in the waking state, might not be simple repetitions of previous
  Neural Plasticity 01/2011; 2011:203462-203462. · 2.00 Impact Factor
• Article: New experiences enhance coordinated neural activity in the hippocampus.

  Sen Cheng, Loren M Frank
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  ABSTRACT: The acquisition of new memories for places and events requires synaptic plasticity in the hippocampus, and plasticity depends on temporal coordination among neurons. Spatial activity in the hippocampus is relatively disorganized during the initial exploration of a novel environment, however, and it is unclear how neural activity during the initial stages of learning drives synaptic plasticity. Here we show that pairs of CA1 cells that represent overlapping novel locations are initially more coactive and more precisely coordinated than are cells representing overlapping familiar locations. This increased coordination occurs specifically during brief, high-frequency events (HFEs) in the local field potential that are similar to ripples and is not associated with better coordination of place-specific neural activity outside of HFEs. As novel locations become more familiar, correlations between cell pairs decrease. Thus, hippocampal neural activity during learning has a unique structure that is well suited to induce synaptic plasticity and to allow for rapid storage of new memories.
  Neuron 02/2008; 57(2):303-13. · 14.74 Impact Factor