lec 25.spatial cogn 2 (4)
TRANSCRIPT
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What brain areas are important for visuallandmark control of
Head Direction & Place Cell activity?
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What brain areas are important for visual landmark control
of Head Direction & Place Cell activity?
General view for processing visual information:
Dorsal streamimportant for processing spatial information - Parietalcortex
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What brain areas are important for visual landmark control
of Head Direction & Place Cell activity?
General view for processing visual information:
Dorsal stream important for processing spatial information - Parietalcortex
Ventral stream important for processing object recognition - Inferiortemporal cortex
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What brain areas are important for visual landmark control
of Head Direction & Place Cell activity?
General view for processing visual information:
Dorsal stream important for processing spatial information - Parietalcortex
Ventral stream important for processing object recognition - Inferiortemporal cortex
Visual Tectal PathwayVisual Attention
To test which pathways are important, we conducted 90
landmark rotation experiments on HD cells in animals with
lesions of various brain areas.
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Head Direction cell responses to 90cue cardrotations
Amount of ShiftFrequency Distributionfor Shift Amounts
Control
90
270
0180
Arrow representsthe mean vector
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GenerativeCircuit
PoS
EntorhinalCortex
Hippocampus
ADN
LMN
Subcortical Areas: Dorsal Tegmental Nuc. & Supragenual Nuc.
Head Direction Signal
Generative Circuit
PoS: PostsubiculumADN: Anterodorsal ThalamusLMN: Lateral Mammillary Nuc.
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PoS: Postsubiculum
ADN: Anterodorsal ThalamusLMN: Lateral Mammillary Nuc.
GenerativeCircuit
PoS
EntorhinalCortex
Hippocampus
ADN
LMN
Subcortical Areas
Head Direction Signal
Generative Circuit
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Control
Hippocampuslesion
Limbic Pathway
None
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VisualCortex
Parietal
Retspl
PoS
EntorhinalCortex
Hippocampus
Visual Streams for Processing Landmark Information:
Dorsal Stream
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VisualCortex
Parietal
Retspl
PoS
EntorhinalCortex
Hippocampus
Visual Streams for Processing Landmark Information:
Dorsal Stream
ADN
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90
270
0180
Parietal Cortexlesion
Dorsal Stream Pathway
RetrosplenialCortex lesion
90
270
0180
Control
Hippocampuslesion
Limbic Pathway
Mild-Moderate
None
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VisualCortex
Parietal
Retspl
PoS
EntorhinalCortex
Hippocampus
Visual Streams for Processing Landmark Information:
Ventral Stream
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VisualCortex
Parietal
Retspl
PoS
EntorhinalCortex
Hippocampus
Visual Streams for Processing Landmark Information:
Ventral Stream
ADN
D l S P h V l S P hC l
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Entorhinal Cortexlesion
90
270
0180
Parietal Cortexlesion
Dorsal Stream Pathway Ventral Stream Pathway
RetrosplenialCortex lesion
90
270
0180
Control
Hippocampuslesion
Limbic Pathway
None
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VisualCortex
Parietal
PoS
LDN
Tectal Stream
EntorhinalCortex
Hippocampus
Visual Streams for Processing Landmark Information:
Tectal Streamvia
LDN: Lateral DorsalThalamus
Superior ColliculusPulvinar
SuperiorColliculus
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VisualCortex
Parietal
PoS
LDN
EntorhinalCortex
Hippocampus
Visual Streams for Processing Landmark Information:
Tectal Streamvia
LDN: Lateral DorsalThalamus
Superior ColliculusPulvinar
Tectal Stream
SuperiorColliculus
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VisualCortex
Parietal
PoS
LDN
Tectal Stream
EntorhinalCortex
Hippocampus
Visual Streams for Processing Landmark Information:
Direct Projection:
Visual CortexPoS
Postsubiculum
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VisualCortex
Parietal
PoS
LDN
Tectal Stream
EntorhinalCortex
Hippocampus
Visual Streams for Processing Landmark Information:
ADN
LMN
Direct Projection:
Visual CortexPoS
Postsubiculum
Dorsal Stream Pathway Ventral Stream PathwayControl Postsubiculum
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Entorhinal Cortexlesion
90
270
0180
Parietal Cortexlesion
LMN Recording
90
270
0180
Dorsal Stream Pathway Ventral Stream Pathway
RetrosplenialCortex lesion
90
270
0180
Control
Hippocampuslesion
Limbic Pathway
Lateral DorsalThalamus lesion
TectalPathway
ADN Recording
PostsubiculumLesions
Hippocampal PlaceCell Recording
Place field absent
Severe
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VisualCortex
Parietal
PoS
LDN
Tectal Stream
EntorhinalCortex
Hippocampus
Visual Streams for Processing Landmark Information:
Direct Projection:
Visual CortexPoS
Postsubiculum
ADN
LMN
Dorsal Stream Pathway Ventral Stream Pathway PostsubiculumControl
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Entorhinal Cortexlesion
90
270
0180
Parietal Cortexlesion
Hippocampal PlaceCell Recording
LMN Recording
90
270
0180
Place field absent
Dorsal Stream Pathway Ventral Stream Pathway
RetrosplenialCortex lesion
90
270
0180
Anterior DorsalThalamus lesion
Place cell recording
ADN Recording
PostsubiculumLesions
Control
Hippocampuslesion
Limbic Pathway
Lateral DorsalThalamus lesion
TectalPathway
None
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Visual
Cortex
Parietal
Retspl
PoS
LDN
Tectal Stream
EntorhinalCortex
Hippocampus
ADN
LMN
Subcortical AreasGenerative
Circuit
So, what canwe conclude ?
SuperiorColliculus
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Visual
Cortex
Parietal
Retspl
PoS
LDN
Tectal Stream
EntorhinalCortex
Hippocampus
ADN
LMN
Subcortical AreasGenerative
Circuit
SuperiorColliculus
So, what canwe conclude ?
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Visual
Cortex
Parietal
Retspl
PoS
LDN
Tectal Stream
EntorhinalCortex
Hippocampus
ADN
LMN
Subcortical AreasGenerative
Circuit
SuperiorColliculus
So, what canwe conclude ?
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Visual
Cortex
Parietal
Retspl
PoS
LDN
Tectal Stream
EntorhinalCortex
Hippocampus
ADN
LMN
Subcortical AreasGenerative
Circuit
SuperiorColliculus
So, what canwe conclude ?
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Visual
Cortex
Parietal
Retspl
PoS
LDN
Tectal Stream
EntorhinalCortex
Hippocampus
ADN
LMN
Subcortical AreasGenerative
Circuit
Landmark control inADN and LMNoccurs because ofthe feedback loopfrom PoSLMNand ADN.
Conclusion: Forprocessing visuallandmark information:the direct pathwayfrom Visual Areas
17, 18 --> PoS iscritical.
SuperiorColliculus
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Imaging Expts and the Identification of a Brain Area Involved in
the Recognition of Places
Parahippocampal Place Area (PPA)Epstein & Kanwisher
But Studies with Humans might suggest otherwise..
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Scenes activate the PPA
Results demonstrating that the PPAresponds selectively to scenes. a.Examples of intact and scrambled
versions of the four different types ofstimuli (top), and the average per centsignal change for each stimulus typein the PPA averaged overall subjects(bottom). The difference betweenintact and scrambled versions of eachpicture is a measure of the responsein the PPA to each stimulus typepartially unconfounded from theresponse to its low-level visualfeatures. Half of the scenes wereoutdoor scenes of the MIT campus,and half were indoor scenes ofunfamiliar locations. b.The timecourse of the percent change in MR
signal intensity in the PPA over theperiod of the scan. Per cent signalchange was calculated individually foreach subject using that subjectsfixation activation as baseline and thenaveraging across subjects (black dotindicates fixation epochs). i, intact; s,scrambled; S, scenes; F, faces; O,objects; H, houses.
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Anatomical location of the PPAa,A single slice from each of the nine subjects inexperiment 1 showing the PPA; functional datafrom this experiment is overlaid on a high-
resolution T1-weighted anatomical image of thesame slice. Right hemisphere appears on the left.Significance levels reflect the results of aKolmogorov-Smirnov test comparing the MRsignal intensity during viewing of intact scenes tosignal intensity during viewing of intact objectsand faces. Note that the location of the PPA(indicated with yellow arrows) is strikinglyconsistent across subjects. The activated regionwas larger in the right hemisphere than the lefthemisphere. Significant activation was also foundin the anterior calcarine sulcus, but because of theproximity of this region to retinotopic cortex, thisactivation is not discussed here. b,Two adjacentslices form a single subject demonstrating that the
PPA (yellow arrows) does not overlap with theposterior part of the hippocampus (green arrows).Posterior slices appears on the left. Talairachcoordinates of the PPA activation for this subjectare -6, 18, -39 and -6, -34, 30 (S-I, M-L, A-P).
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FR OSLM LS ERActivation of PPA to Landmarks
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Head direction Cells in 3D
HD cells fire as a function of head direction in thehorizontal plane.
But how is the horizontal reference frame defined?
How do HD cells respond
during vertical plane or
inverted (upside-down)
locomotion?
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HD cell responses in the Vertical Plane
Generallynormaldirectional
responses on walls.
Cells contain directional tuningcurve relative to the roomreference frame.
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South Wall
WestWall
EastWall
North Wall
0
90
180
270
0
90
180
270
xy 0
90
180
270
0
90
180
270
0
90
180
270
Floor
Animal defines its horizontal reference frame as the plane it happens to be
locomoting in. Thus, it rotates [translates] its plane of locomotion by 90
as it moves into the vertical plane and defines this new surface as its
horizontal reference frame.
South Wall
WestWall
EastWall
North Wall
Floor
Room Reference Frame
UpDown
Direction of Cell Firing Along Walls
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But, what about inverted orientation?
To testit is easier to go Space-bound
Why does this matter?
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Array of Disorientation Problems & Illusions in Space
Astronauts are frequently disoriented when working in space
(0-g) and often experience several types of illusions, including:
Visual Reorientation Illusion (VRIs)Inversion IllusionExtra Vehicular Activity (EVA) acrophobiaSpace Motion Sickness
Resulting in problems: Flipping switches in wrong direction Emergency egress Otolith reinterpretation upon return to gravitational
environment
Visual Reorientation Illusions (VRIs)
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All-of-a-sudden perception of feelinginverted (upside-down).
Surface nearest your feet seems like afloor. Surfaces parallel to body seemlike walls.
The orientation of your own bodyorthat of a person you look at
redefines down.
Probability of illusion depends onvisual vertical cues, visual attentionand your familiarity with the interior.
Occurs spontaneously, but can becognitively initiated and reversed(e.g., simply closing eyes).
Incidence is almost universal.
Susceptibility persists for months.
Visual Reorientation Illusions (VRIs)
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Nexus Cube
VRIs are similar to looking at a Nexus cube, where you perception flipsback-and-forth between seeing the blocks either open towards you oraway from you.
Similarly, VRIs can come and go very quickly, where your perception ofwhat is down can flip back-and-forth quickly.
0 G I i Ill i
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Less common: < 25% of crewexperience it.
Paradoxical sensation of beingcontinuouslygravitationally upsidedown, even when visually upright inthe cabin.
Persists with eyes closed.
Fluid shift, visceral elevation, andotolith unloading likely contribute.
Temporarily reversible withproprioceptive or visual cues.
Uncommon after flight day 2.
0-G Inversion Illusions
E V hi l A i i EVA H i h V i
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Viewing Earth beneath your own feetduring EVA can trigger sudden senseof height vertigo, fear of falling, andenhanced awareness of orbital motion.
The natural compulsion to hang oncan sometimes be disabling.
Turning away from Earth and putting
spacecraft belowinstead of Earth
can resolve problem.
Extra-Vehicular Activity - EVA Height Vertigo
Th Ill i L d t S M ti Si k
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Examples
Seeing an inverted crewmemberfloating nearby.
Viewing the Earth in an unexpecteddirection.
These Illusions Lead to Space Motion Sickness
Akin to motion sickness in car or boat.
Perceived self orientation change isnot accompanied by normal confirmingsemicircular canal or gravity-receptorcues.
Multiple VRIs can cause motion sickness.A single VRI can trigger vomiting in aperson already sick.
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P bl f ti i S
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Problems from time in Space
Loss of muscle mass
Reduction of quick headturns due toOtolith Reinterpretation
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Accelerationvector
GravityvectorAlignedalonglongitudinalbodyaxis
Otolith Reinterpretation
Compensates by Steeringplane downwards
Perceived gravity vector aligned along body axis;feels like you are tilted upwards
Normal Upon acceleratingduring take-off
Interpretation of gravity vector involving gravity + accelerative forces
Example: Pilot taking off from an aircraft carrier with high accelerative forces exerted on him.
Adaptation to a 0-g environment and then return to Earth.
When in 0-g, astronauts learn to reinterpret otolith signal as only encoding linear movement
(compared to on Earth where it encodes the combination of gravity and linear movement).
However, upon return to Earth, for the first couple of days astronauts interpret any change in
otolith signal as only linear movement. Thus, a slight tilt of the head (which changes the gravity
vector on the otolith) is interpreted as a linear acceleration in the horizontal plane, and the
subject perceives that they are rapidly moving across the floor.
Spatial Disorientation Diffi lt i d t mi i g /d
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Spatial Disorientation - Difficulty in determining up/down:
Astronauts are just as likely to work upside-down as right-side up.
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HD cell firing in 0 g with parabolic flights
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HD cell firing in 0-g with parabolic flights
NASA KC-135 aircraft
40 parabolas; each parabola ~20 sec 0-g.
Rats monitored in 4 x 2 x 2 ft. rectangular cage with wire mesh on threesurfaces - floor, wall, ceiling.
Directional heading was hand-scored from video tapes off-line andcompared to cell activity.
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Humans canexperience
VRIs during theseexercises, too.
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HD cell tuning curves in 0-g conditions
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HD cell responses when upside-down on ceiling on Earth
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p p g
Si il t ll li bi fi di HD ll
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Similar to our wall-climbing findings, HD cells
treated the walls as though they were an extension
of the floor.
Cell fires duringclimb up.
Cell fires duringclimb down.
Preferreddirectionof cell.
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Running in the reverse direction, the cell is silent
on both walls.
Cell fires duringclimb up.
Cell fires duringclimb down.
Preferreddirectionof cell.
Cell is silentduring ciimb up.
Cell is silent duringciimb down.
For most cells: Loss of directional tuning on
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For most cells: Loss of directional tuning onceiling, with increased background firing rate
Cell 1 Cell 2
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Performance in the Inverted Hole Board Escape Task
Es
capeLatency(sec)
Training day
0
5
10
15
20
25
30
0 5 10
1 Start Point
1SP 2SPNumbero
fSessions
toCr
iterion
0
4
8
12
16
Criterion CenterProbe
Laten
cy(sec)
0
10
20
30
Regulartrials
Blindfolded-to-apparatus
trials
Latency(sec)
0
10
20
30
SurroundCurtainProbe
Criterion
Laten
cy(sec)
0
10
20
30
1 Start Point
2 Start Points
EscapeLatency(sec)
Training day
0
5
10
15
20
25
30
5 10 15 20 25
4 Start Points
30
Blindfold prevents seeing surrounding visual cues on way to apparatus.
Curtain prevents seeing surrounding visual cues while on apparatus.
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Conclusions from Behavioral Task:
When task was simple (1 or 2 start points) animals could
use a directional (or beacon) strategy move toward a
particular landmark.
But when task was difficult (4 start points) animals
needed a more flexible representation of their
environment.
They needed a flexible cognitive map-like spatial strategy.
It is possible that normalHD activity is required for
generation and use of a cognitive map.
Record HD cells in the
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Valerio, Clark et al. (2010) Neurobiol Learning & Memory
+
X= Familiar Release Point 1
X= Familiar Release Point 2+ = Center Release Pointx
x
Escape hole
eco d ce s t e
Inverted Hole Board Escape Task
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Familiar
Tests
2 Start
Points .
N
S
W E
NCenter
Tests
180
S
W E
.
N
S
W E
180
S
W E
N
Sample PathsTrajectories
What are Head Direction Cells doing in this Task?
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2nd Session on Floor:Upright
Session on Floor:
Upright
Head Direction
FiringRate
Rats trained from two locations
NW
SW
Thus, rats were accurately performing the simple version of the inverted
spatial task - despite the absence of a HD signal.
NW Inverted TrialCorrect
Inverted Trial: CenterError
SW Inverted TrialCorrect
I n v e r t e d T r i a l s
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Conclusions about HD Responses in 3-D
HD cells show normal activity in the vertical plane, but not when the
animal is upside-down.
When inverted, the otolith signal to the brain is quite different and may
account for the loss of directional firing.
The absence of directional activity may bring about spatial disorientationand its accompanying problems when in 0-g.
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