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Hippocampal novelty signals dynamically predict goal-relevant VTA activation

Poster No:

776 

Submission Type:

Abstract Submission 

Authors:

Blake Elliott1, Vishnu Murty2

Institutions:

1Temple University, PHILADELPHIA, PA, 2Temple University, Philadelphia, PA

First Author:

Blake Elliott, Ph.D.  
Temple University
PHILADELPHIA, PA

Co-Author:

Vishnu Murty, Ph.D.  
Temple University
Philadelphia, PA

Introduction:

Novelty is an important learning signal that is known to invigorate goal-oriented behavior via engagement of the mesolimbic dopamine (DA) system. Structurally, an afferent circuit with the hippocampus (HPC) is crucial for regulating sustained signaling of VTA DA neurons (Lisman & Grace, 2005). Specifically, animal research shows that HPC novelty signals lead to increased sustained mesolimbic engagement, which in turn magnifies phasic VTA responses to goal-relevant targets. However, the extent of these interactions during active human behavior remains unclear.

Methods:

We employed a novel analysis of fMRI data from human subjects (n=91) performing a target-detection task intermixed with familiar and novel pictures. Hierarchical linear regressions examined goal-relevant VTA activation and HPC-VTA regulation during novelty.

Results:

We found that activation to novel events in the HPC dynamically predicted subsequent goal-relevant activation in the VTA (β= 0.042, p<0.05). Notably, as predicted by animal models, this relationship did not hold true for striatal novelty signals (β= 0.017, p=0.25).

Conclusions:

These findings support models of goal-oriented behavior in which HPC regulatory systems in response to novelty invigorate VTA responsivity. Future work will integrate how prefrontal responses may interact with VTA-HPC circuitry to result in diminished goal-oriented behavior.

Emotion, Motivation and Social Neuroscience:

Reward and Punishment 1

Modeling and Analysis Methods:

Activation (eg. BOLD task-fMRI) 2

Keywords:

Dopamine
FUNCTIONAL MRI
Other - Hippocampus

1|2Indicates the priority used for review

Provide references using author date format

Lisman, J. E. (2005). The hippocampal-VTA loop: controlling the entry of information into long-term memory. Neuron, 46(5), 703-713.