top of page

​Our research aims to uncover the neurobiological mechanisms by which the brain extracts predictive relationships from everyday experiences and leverages them to anticipate future events. In particular, we examine the neural implementation of relational learning and inference through diverse cognitive tasks in rodent models. By monitoring and manipulating the activity of brain cells, we link these cognitive processes to real-time dynamics in neural ensembles. In parallel, we use the fundamental principles of neural ensemble dynamics to probe the pathophysiological basis of cognitive impairments in mental disorders.

Neural implementation of knowledge construction and application
Project1.jpg

Decision-making relies on both present sensory input and prior knowledge. To apply past experiences, the brain must learn relational structures and flexibly generalize them to new contexts. Our research investigates how large populations of neurons in the medial prefrontal cortex and hippocampus support these processes of knowledge construction and application. By capturing millisecond-scale dynamics of neural ensembles, we aim to uncover the underlying circuit mechanisms that enable relational inference and adaptive behavior.

  1. Jarovi J, Pilkiw M, Takehara-Nishiuchi K, (2023) Prefrontal neuronal ensembles link prior knowledge with novel actions during flexible action selection. Cell Reports, 42, 113492

  2. Takehara-Nishiuchi K, (2022) Flexibility of memory for future-oriented cognition. Current Opinion in Neurobiology 76:102622.

  3. Xing B, Morrissey MD, Takehara-Nishiuchi K, (2020) Distributed representations of temporal stimulus associations across regular-firing and fast-spiking neurons in rat medial prefrontal cortex, J Neurophysiology, 123(1): 439-450. 

  4. Morrissey M, Insel N, Takehara-Nishiuchi K. (2017) Generalizable knowledge outweighs incidental details in prefrontal ensemble code over time. eLife, 6:e22177. Featured on more than 20 news websites, including Neuroscience News, ScienceDaily, and U of T Bulletin.

Neuronal dynamics supporting selective memory encoding
CNO_edited.jpg

Effectively extracting meaningful information from everyday experiences—without encoding irrelevant details—is essential for adaptive behavior and mental well-being. One mechanism guiding this selective encoding is the similarity between current and prior experiences. New information is rapidly incorporated into memory when it aligns with existing knowledge structures, such as latent patterns, categorical frameworks, or abstract rules. Our research examines the role of the medial prefrontal cortex in facilitating this accelerated encoding process, with a particular focus on its contribution to schema-based memory integration.

  1. Takehara-Nishiuchi K, Morrissey MD, Pilkiw M (2020) Prefrontal neural ensembles develop selective code for stimulus associations within minutes of novel experiences, J Neurosci, 40(43): 8355-8366.

  2. Takehara-Nishiuchi K, (2020) Prefrontal-hippocampal interaction during the encoding of new memories, Brain and Neuroscience Advances, 4: 1-10.

  3. Jarovi J, Volle J, Yu XT, Guan L, Takehara-Nishiuchi K, (2018) Prefrontal theta oscillations promote selective encoding of behaviorally relevant events, eNeuro, 5(6) e0407-18.

  4. Volle J, Yu XT, Sun H, Tanninen SE, Insel N, Takehara-Nishiuchi K. (2016) Enhancing prefrontal neuron excitability enables associative learning of temporally disparate events. Cell Reports, 15(11):2400-2410.

Function of the lateral entorhinal cortex in memory and memory disorders
5.jpg

The entorhinal cortex (EC) serves as an interface between the hippocampus and neocortex and consists of the medial and lateral areas with dissociable anatomical connectivity. We study the role of its lateral portions (LEC) in memories of event-context associations. Our focus is how disrupted LEC affects memory processing in other brain regions to gain insight into mechanisms of memory problems in elderly and Alzheimer's disease patients with the degenerated LEC.

  1. Nouriziabari, SB, Sarkar S, Tanninen SE, Dayton R, Klein RL, Takehara-Nishiuchi K. (2018) ERP-based detection of brain pathology in rat models for preclinical Alzheimer’s disease. Journal of Alzheimers Disease, 63(2): 725-740.

  2. Pilkiw M, Insel N, Cui Y, Finney C, Morrissey MD, Takehara-Nishiuchi K. (2017) Phasic and tonic neuron ensemble codes for stimulus-environment conjunctions in the lateral entorhinal cortex, eLife, 6, e28611.  

  3. Tanninen SE, Nouriziabari, SB, Morrissey MD, Bakir R, Dayton R, Klein RL, Takehara-Nishiuchi K. (2017) Entorhinal tau pathology induces a neuronal signature in preclinical stages of Alzheimer’s disease. Neurobiology of Aging, 58:151-162.

  4. Takehara-Nishiuchi K. (2014) Entorhinal cortex and consolidated memory. Neuroscice Research, 84C:27-33.

  5. Morrissey MD, Maal-Bared G, Brady S, Takehara-Nishiuchi K (2012) Functional dissociation within the entorhinal cortex for memory retrieval of an association between temporally discontinuous stimuli. Journal of Neuroscience, 32(16), 5356-5361. 

​

bottom of page