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Full-Text Articles in Life Sciences
Spatial Representation In Postrhinal Cortex, Patrick Lachance
Spatial Representation In Postrhinal Cortex, Patrick Lachance
Dartmouth College Ph.D Dissertations
Animals rely on a variety of internal and external cues to orient themselves when navigating their environments and determining their current spatial context. Information regarding these cues enters the brain from the navigator’s first-person perspective. Information of this type is considered to be egocentric, or self-centered. However, decades of behavioral, electrophysiological, and imaging research suggest that the brain contains a rich collection of spatial representations that are unrestricted by the animal’s first-person perspective, and instead are defined relative to the surrounding environment. These representations are considered allocentric, or world-centered. Despite an abundance of promising modeling work, the specific mechanisms by …
Axonal Activity In Vivo: Technical Considerations And Implications For The Exploration Of Neural Circuits In Freely Moving Animals, Jeremy M. Barry
Axonal Activity In Vivo: Technical Considerations And Implications For The Exploration Of Neural Circuits In Freely Moving Animals, Jeremy M. Barry
Dartmouth Scholarship
While extracellular somatic action potentials from freely moving rats have been well characterized, axonal activity has not. We have recently reported extracellular tetrode recordings of short duration waveforms (SDWs) with an average peak-trough duration less than 172μs. These waveforms have significantly shorter duration than somatic action potentials and tend to be triphasic. The present review discusses further data that suggests SDWs are representative of axonal activity, how this characterization allows for more accurate classification of somatic activity and could serve as a means of exploring signal integration in neural circuits. The review also discusses how axons may function as more …
Short Duration Waveforms Recorded Extracellularly From Freely Moving Rats Are Representative Of Axonal Activity, Ashlee A. Robbins, Steven E. Fox, Gregory L. Holmes, Rod C. Scott, Jeremy M. Barry
Short Duration Waveforms Recorded Extracellularly From Freely Moving Rats Are Representative Of Axonal Activity, Ashlee A. Robbins, Steven E. Fox, Gregory L. Holmes, Rod C. Scott, Jeremy M. Barry
Dartmouth Scholarship
While extracellular somatic action potentials from freely moving rats have been well characterized, axonal activity has not. We report direct extracellular tetrode recordings of putative axons whose principal feature is a short duration waveform (SDW) with an average peak-trough length less than 179 μs. While SDW recordings using tetrodes have previously been treated as questionable or classified as cells, we hypothesize that they are representative of axonal activity. These waveforms have significantly shorter duration than somatic action potentials, are triphasic and are therefore similar to classic descriptions of microelectrode recordings in white matter and of in vitro action potential propagation …
Vestibular And Attractor Network Basis Of The Head Direction Cell Signal In Subcortical Circuits, Benjamin J. Clark, Jeffrey S. Taube
Vestibular And Attractor Network Basis Of The Head Direction Cell Signal In Subcortical Circuits, Benjamin J. Clark, Jeffrey S. Taube
Dartmouth Scholarship
Accurate navigation depends on a network of neural systems that encode the moment-to-moment changes in an animal's directional orientation and location in space. Within this navigation system are head direction (HD) cells, which fire persistently when an animal's head is pointed in a particular direction (Sharp et al., 2001a; Taube, 2007). HD cells are widely thought to underlie an animal's sense of spatial orientation, and research over the last 25+ years has revealed that this robust spatial signal is widely distributed across subcortical and cortical limbic areas. The purpose of the present review is to summarize some of …