Apparatus Shape Change Study — RU Muller | ReplicateScience

ReplicateScience

Submit Paper ConductScience

Apparatus Shape Change Study — RU Muller | ReplicateScience

View Abstract

Using the techniques set out in the preceding paper (Muller et al., 1987), we investigated the response of place cells to changes in the animal's environment. The standard apparatus used was a cylinder, 76 cm in diameter, with walls 51 cm high. The interior was uniformly gray except for a white cue card that ran the full height of the wall and occupied 100 degrees of arc. The floor of the apparatus presented no obstacles to the animal's motions. Each of these major features of the apparatus was varied while the others were held constant. One set of manipulations involved the cue card. Rotating the cue card produced equal rotations of the firing fields of single cells. Changing the width of the card did not affect the size, shape, or radial position of firing fields, although sometimes the field rotated to a modest extent. Removing the cue card altogether also left the size, shape, and radial positions of firing fields unchanged, but caused fields to rotate to unpredictable angular positions. The second set of manipulations dealt with the size and shape of the apparatus wall. When the standard (small) cylinder was scaled up in diameter and height by a factor of 2, the firing fields of 36% of the cells observed in both cylinders also scaled, in the sense that the field stayed at the same angular position and at the same relative radial position. Of the cells recorded in both cylinders, 52% showed very different firing patterns in one cylinder than in the other. The remaining 12% of the cells were virtually silent in both cylinders. Similar results were obtained when individual cells were recorded in both a small and a large rectangular enclosure. By contrast, when the apparatus floor plan was changed from circular to rectangular, the firing pattern of a cell in an apparatus of one shape could not be predicted from a knowledge of the firing pattern in the other shape. The final manipulations involved placing vertical barriers into the otherwise unobstructed floor of the small cylinder. When an opaque barrier was set up to bisect a previously recorded firing field, in almost all cases the firing field was nearly abolished. This was true even though the barrier occupied only a small fraction of the firing field area. A transparent barrier was effective as the opaque barrier in attenuating firing fields. The lead base used to anchor the vertical barriers did not affect place cell firing.(ABSTRACT TRUNCATED AT 400 WORDS)

1

Establish baseline recording in standard cylinder

Record place cell firing patterns in the standard small cylinder apparatus with uniform gray interior and white cue card

Not specifiedNot specified

Note: The standard apparatus serves as baseline for all subsequent manipulations

View evidence from paper

“The standard apparatus used was a cylinder, 76 cm in diameter, with walls 51 cm high. The interior was uniformly gray except for a white cue card”

2

Manipulate cue card position

Rotate the white cue card and record resulting changes in place cell firing field positions

Not specifiedNot specified

Note: Rotating the cue card produces equal rotations of firing fields

View evidence from paper

“Rotating the cue card produced equal rotations of the firing fields of single cells”

3

Manipulate cue card width

Change the width of the white cue card while recording place cell firing patterns

Not specifiedNot specified

Note: Width changes do not affect field size, shape, or radial position, though modest rotation may occur

View evidence from paper

“Changing the width of the card did not affect the size, shape, or radial position of firing fields, although sometimes the field rotated to a modest extent”

4

Remove cue card

Completely remove the white cue card from the apparatus and record place cell firing patterns

Not specifiedNot specified

Note: Removal leaves field size, shape, and radial positions unchanged but causes unpredictable angular rotation

View evidence from paper

“Removing the cue card altogether also left the size, shape, and radial positions of firing fields unchanged, but caused fields to rotate to unpredictable angular positions”

5

Scale apparatus size - small to large cylinder

Record place cells in both small and large cylinders scaled by factor of 2 in diameter and height

Not specifiedNot specified

Note: 36% of cells show scaling of firing fields, 52% show different patterns, 12% silent in both

View evidence from paper

“When the standard (small) cylinder was scaled up in diameter and height by a factor of 2, the firing fields of 36% of the cells observed in both cylinders also scaled”

6

Scale apparatus size - rectangular enclosures

Record place cells in both small and large rectangular enclosures with scaling

Not specifiedNot specified

Note: Similar results obtained as with cylinder scaling

View evidence from paper

“Similar results were obtained when individual cells were recorded in both a small and a large rectangular enclosure”

7

Change apparatus shape - circular to rectangular

Record place cells in both circular and rectangular apparatus configurations and compare firing patterns

Not specifiedNot specified

Note: Firing patterns cannot be predicted from one shape to the other - this is the critical shape change manipulation

View evidence from paper

“When the apparatus floor plan was changed from circular to rectangular, the firing pattern of a cell in an apparatus of one shape could not be predicted from a knowledge of the firing pattern in the other shape”

8

Place opaque barrier in firing field

Set up an opaque vertical barrier to bisect a previously recorded firing field and record resulting changes

Not specifiedNot specified

Note: Barrier nearly abolishes firing field despite occupying only small fraction of field area

View evidence from paper

“When an opaque barrier was set up to bisect a previously recorded firing field, in almost all cases the firing field was nearly abolished”

9

Place transparent barrier in firing field

Set up a transparent vertical barrier to bisect a previously recorded firing field and record resulting changes

Not specifiedNot specified

Note: Transparent barrier is equally effective as opaque barrier in attenuating firing fields

View evidence from paper

“A transparent barrier was effective as the opaque barrier in attenuating firing fields”

10

Test lead base control

Verify that the lead base used to anchor barriers does not independently affect place cell firing

Not specifiedNot specified

Note: Control to ensure barrier effects are not due to anchor apparatus

View evidence from paper

“The lead base used to anchor the vertical barriers did not affect place cell firing”