A method for recording evoked local field potentials in the primate dentate gyrus in vivo.
ABSTRACT Recording evoked local field potentials (LFPs) in the hippocampus in vivo has yielded us useful information about the neural mechanisms of learning and memory. Although this technique has been used in studies of the hippocampus of rodents, lagomorphs, and felines, it has not yet been applied to the primate hippocampus. Here, we report a method for recording evoked LFPs in the hippocampus of monkeys. A stimulation electrode and a recording electrode were implanted in the perforant pathway and dentate gyrus, respectively, under the guidance of electrophysiological recording. With a low stimulus intensity just above the threshold, the potential appeared as a slow positive-wave component, which was regarded as field excitatory postsynaptic potential (putative fEPSP); as stimulation intensity increased, the fEPSP amplitude increased, followed by a sharp negative component which was regarded as putative population spike. When the coordinates of the recording or stimulation electrode were moved stepwise, we observed a systematic change in the waveforms of evoked LFPs; this change corresponded to the structural arrangement through which the electrode passed. In a test for short-term synaptic plasticity by paired-pulse stimulation, potentials evoked by the second pulse were influenced by the first one in a manner dependent on interpulse intervals. In a test for long-term synaptic plasticity by high-frequency stimulation, the slopes of the fEPSPs and the area of population spikes were increased for more than 1 h. These results indicate that the method developed in the present study is useful for testing theories of hippocampal functions in primates.
- [show abstract] [hide abstract]
ABSTRACT: This article considers the role of the hippocampus in memory function. A central thesis is that work with rats, monkeys, and humans--which has sometimes seemed to proceed independently in 3 separate literatures--is now largely in agreement about the function of the hippocampus and related structures. A biological perspective is presented, which proposes multiple memory systems with different functions and distinct anatomical organizations. The hippocampus (together with anatomically related structures) is essential for a specific kind of memory, here termed declarative memory (similar terms include explicit and relational). Declarative memory is contrasted with a heterogeneous collection of nondeclarative (implicit) memory abilities that do not require the hippocampus (skills and habits, simple conditioning, and the phenomenon of priming). The hippocampus is needed temporarily to bind together distributed sites in neocortex that together represent a whole memory.Psychological Review 05/1992; 99(2):195-231. · 9.80 Impact Factor
- Journal of Neurosurgery 01/1971; 33(6):689-707. · 3.15 Impact Factor
- [show abstract] [hide abstract]
ABSTRACT: The effects of paired and brief trains of stimuli were compared in the medial and lateral components of the perforant pathway to the rat fascia dentata, both in vivo, and in the vitro transverse hippocampal slice. In the intact preparation a sharp transition in response properties occurred at the midpoint of the medial to lateral range of input. In vitro this transition was found to correspond exactly to the transition in Timm stainability which characterizes the border of the medial and lateral termination zones in the outer 2/3 of the molecular layer. These data indicate that there are two physiologically distinct subdivisions of the perforant path. Evidence is presented that the interpathway differences are at least partly due to differential quantal contents of the EPSP under resting conditions.Brain Research 11/1980; 199(1):1-19. · 2.88 Impact Factor