Book contents
- Frontmatter
- Contents
- List of contributors
- Part I Introduction
- Part II Organization of neuronal activity in neuronal populations
- Part III Neuronal population information coding and plasticity in specific brain areas
- 7 Functional roles of theta and gamma oscillations in the association and dissociation of neuronal networks in primates and rodents
- 8 Theta rhythm and bidirectional plasticity in the hippocampus
- 9 Distributed population codes in sensory and memory representations of the neocortex
- 10 The role of neuronal populations in auditory cortex for category learning
- 11 The construction of olfactory representations
- Part IV Functional integration of different brain areas in information processing and plasticity
- Part V Disturbances of population activity as the basis of schizophrenia
- Part VI Summary, conclusion, and future targets
- Index
- References
8 - Theta rhythm and bidirectional plasticity in the hippocampus
Published online by Cambridge University Press: 14 August 2009
- Frontmatter
- Contents
- List of contributors
- Part I Introduction
- Part II Organization of neuronal activity in neuronal populations
- Part III Neuronal population information coding and plasticity in specific brain areas
- 7 Functional roles of theta and gamma oscillations in the association and dissociation of neuronal networks in primates and rodents
- 8 Theta rhythm and bidirectional plasticity in the hippocampus
- 9 Distributed population codes in sensory and memory representations of the neocortex
- 10 The role of neuronal populations in auditory cortex for category learning
- 11 The construction of olfactory representations
- Part IV Functional integration of different brain areas in information processing and plasticity
- Part V Disturbances of population activity as the basis of schizophrenia
- Part VI Summary, conclusion, and future targets
- Index
- References
Summary
Introduction
The local field potential from the hippocampus of an awake, stationary animal is filled with seemingly random low-amplitude high-frequency activity and arrhythmic high-amplitude low-frequency activity. To the untrained eye it is nearly impossible to discern any clear patterns or relationships of the signal to behavior, as the local field potential appears to be only noise. Then something striking happens, as the animal starts to move around, an extremely rhythmic high-amplitude 6–10-Hz sinusoidal waveform appears and instantly offers a window into the relationship between the hippocampal field potential and the animal's behavior. When Green and Arduini (1954) first recorded local field potentials activity from the hippocampus of behaving animals they saw this rhythmic activity (theta rhythm; 6–10-Hz high-amplitude sinusoidal activity: Buzsáki et al., 1986) and it was clear to them that theta rhythm played a significant role in hippocampal function. Theta appeared whenever the animal walked, ran, sniffed, oriented, reared, or went into rapid eye movement (REM) sleep, and theta was notably absent during consummatory behaviors (eating and drinking), grooming, and slow wave sleep.
The nature of theta's role in hippocampal processing was somewhat clarified when studies of the effect of hippocampectomy in humans and rodents were performed, and the hippocampus's central role in associative memory was suggested (Scoville and Milner, 1957; Morris et al., 1982). Since those original studies, further work has shown memory impairments in a wide range of behavioral and cognitive tasks that utilize multiple sensory modalities and behavioral responses (Eichenbaum, 2000).
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- Information Processing by Neuronal Populations , pp. 174 - 191Publisher: Cambridge University PressPrint publication year: 2008