Source Paper
Comparison of spatial firing characteristics of units in dorsal and ventral hippocampus of the rat
MW Jung, SI Wiener, BL McNaughton
Journal of Neuroscience • 1994
View Abstract
The septal and temporal poles of the hippocampus differ markedly in their anatomical and neurochemical organization. Although it is well established that the internal representation of space is a fundamental function of hippocampal neurons, most of what is known about spatial coding in the hippocampus of freely moving animals has come from recordings from the dorsal one-third (largely for technical convenience). The present study therefore compared the spatial selectivity of CA1 neurons in the dorsal and ventral hippocampi of rats during performance of a food reinforced, random search task in a square chamber containing simple visual landmarks. Neural activity was recorded in the dorsal and ventral hippocampi of opposite hemispheres in the same rats, in many cases simultaneously. As in dorsal hippocampus, ventral CA1 units could be classified as “complex spike” (pyramidal) cells or “theta” interneurons. Both dorsal and ventral theta cells fired at relatively high rates and with low spatial selectivity in the apparatus. Of the population of complex spike cells in the ventral hippocampus, a significantly smaller number had “place fields” than in the dorsal hippocampus, and the average spatial selectivity was of significantly lower resolution than that found among dorsal hippocampal complex spike cells. Thus, a septotemporal difference of spatial selectivity was found in the CA1 field of the rat hippocampus, complementing many other anatomical and neuropharmacological studies. A number of possible functional interpretations can be suggested from these results, including a computational advantage of representing space at different scales or a preeminence of essentially nonspatial information processing in the ventral hippocampus.
Random Search Task in Open Field
Objective: Compare spatial firing characteristics of CA1 neurons in dorsal and ventral hippocampus during a food-reinforced random search task to assess spatial selectivity differences between hippocampal regions
Gather these items before starting the experiment. Check off items as you prepare.
Equipment3
Materials1
Not specified • Not specified • Not specified • Not specified
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Protocol Steps
Surgical preparation and electrode implantation
Implant recording electrodes in dorsal and ventral hippocampi of opposite hemispheres in rats
Note: Electrodes positioned to allow simultaneous recording from both regions in many cases
View evidence from paper
“Neural activity was recorded in the dorsal and ventral hippocampi of opposite hemispheres in the same rats, in many cases simultaneously”
Behavioral task setup
Place rat in square chamber containing simple visual landmarks for spatial reference during random search task
Note: Chamber contains visual landmarks to provide spatial cues
View evidence from paper
“random search task in a square chamber containing simple visual landmarks”
Food-reinforced random search task
Rat performs random search task in chamber with food reinforcement as reward
Note: Task is food-reinforced to motivate search behavior
View evidence from paper
“food reinforced, random search task in a square chamber containing simple visual landmarks”
Neural recording during task
Record neural activity from CA1 neurons in dorsal and ventral hippocampi while rat performs random search task
Note: Simultaneous recording from opposite hemispheres in many cases
View evidence from paper
“Neural activity was recorded in the dorsal and ventral hippocampi of opposite hemispheres in the same rats, in many cases simultaneously”