Environment Shape Change
Objective: Test how head-direction cell firing properties respond to changes in environmental geometry by recording neural activity as rats move freely in different shaped enclosures
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
Baseline recording in cylinder with cue card
Record head-direction cell activity from postsubicular neurons as rats move freely in the 76-cm diameter gray cylinder with white card cue present
Note: White card occupies 100 degrees of arc and serves as major orienting spatial cue
View evidence from paper
“Head-direction cells were recorded from rats as they moved freely in a 76-cm-diameter gray cylinder. A white card, occupying 100 degrees of arc, was taped to the inside wall”
Rotate cue card
Rotate the white card cue and record changes in head-direction cell preferred firing direction
Note: Observe rotation of preferred firing direction relative to card rotation
View evidence from paper
“Rotation of the cue card produced near-equal rotation in the preferred firing direction of head-direction cells, with minimal changes in peak firing rate”
Remove cue card
Remove the white card from the cylinder and record head-direction cell activity
Note: Monitor for changes in preferred direction and firing characteristics
View evidence from paper
“Card removal had no effect on peak firing rate or range of firing, but in 8/13 cells the preferred direction rotated by at least 24 degrees”
Change environment to rectangular enclosure
Transfer rat to rectangular enclosure and record head-direction cell firing properties
Note: Measure preferred firing direction rotation and changes in peak firing rate and directional firing range
View evidence from paper
“changing the shape of the environment to a rectangular or square enclosure caused the preferred firing direction to rotate by at least 48 degrees for 8/10 cells in the rectangle”
Change environment to square enclosure
Transfer rat to square enclosure and record head-direction cell firing properties
Note: Measure preferred firing direction rotation and changes in peak firing rate and directional firing range
View evidence from paper
“changing the shape of the environment to a rectangular or square enclosure caused the preferred firing direction to rotate by at least 48 degrees for 8/10 cells in the rectangle and 3/8 cells in the square”
Hand holding manipulation
Hand hold animals and move them around the cylinder while recording head-direction cell activity
Note: Assess effects on preferred direction, firing range, and maximal firing rate
View evidence from paper
“Hand holding the animals and moving them around the cylinder had no effect on the preferred direction or firing range of the cell, but decreased the maximal firing rate in 7/9 cells”
Simultaneous dual-cell recording
On selected occasions, record from two head-direction cells simultaneously during environmental manipulations
Note: Compare rotation of preferred firing direction between simultaneously recorded cells
View evidence from paper
“On 2 occasions, 2 head-direction cells were recorded simultaneously. The rotation of the preferred firing direction for one cell was the same as the rotation of the preferred direction for the second cell”