lec 25.spatial cogn 2 (4)

8/10/2019 Lec 25.Spatial Cogn 2 (4)

1/68

What brain areas are important for visuallandmark control of

Head Direction & Place Cell activity?


2/68

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


3/68




Dorsal stream important for processing spatial information - Parietalcortex

Ventral stream important for processing object recognition - Inferiortemporal cortex


4/68




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.


5/68

Head Direction cell responses to 90cue cardrotations

Amount of ShiftFrequency Distributionfor Shift Amounts

Control

90

270

0180

Arrow representsthe mean vector


6/68

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.


7/68

PoS: Postsubiculum

ADN: Anterodorsal ThalamusLMN: Lateral Mammillary Nuc.

GenerativeCircuit

PoS

EntorhinalCortex

Hippocampus

ADN

LMN

Subcortical Areas

Head Direction Signal

Generative Circuit


8/68

Control

Hippocampuslesion

Limbic Pathway

None


9/68

VisualCortex

Parietal

Retspl

PoS

EntorhinalCortex

Hippocampus

Visual Streams for Processing Landmark Information:

Dorsal Stream


10/68

VisualCortex

Parietal

Retspl

PoS

EntorhinalCortex

Hippocampus


Dorsal Stream

ADN


11/68

90

270

0180

Parietal Cortexlesion

Dorsal Stream Pathway

RetrosplenialCortex lesion

90

270

0180

Control

Hippocampuslesion

Limbic Pathway

Mild-Moderate

None


12/68

VisualCortex

Parietal

Retspl

PoS

EntorhinalCortex

Hippocampus


Ventral Stream


13/68

VisualCortex

Parietal

Retspl

PoS

EntorhinalCortex

Hippocampus


Ventral Stream

ADN

D l S P h V l S P hC l


14/68

Entorhinal Cortexlesion

90

270

0180


Dorsal Stream Pathway Ventral Stream Pathway


90

270

0180

Control

Hippocampuslesion

Limbic Pathway

None


15/68

VisualCortex

Parietal

PoS

LDN

Tectal Stream

EntorhinalCortex

Hippocampus


Tectal Streamvia

LDN: Lateral DorsalThalamus

Superior ColliculusPulvinar

SuperiorColliculus


16/68

VisualCortex

Parietal

PoS

LDN

EntorhinalCortex

Hippocampus


Tectal Streamvia

LDN: Lateral DorsalThalamus

Superior ColliculusPulvinar

Tectal Stream

SuperiorColliculus


17/68


18/68

VisualCortex

Parietal

PoS

LDN

Tectal Stream

EntorhinalCortex

Hippocampus


Direct Projection:

Visual CortexPoS

Postsubiculum


19/68

VisualCortex

Parietal

PoS

LDN

Tectal Stream

EntorhinalCortex

Hippocampus


ADN

LMN

Direct Projection:

Visual CortexPoS

Postsubiculum

Dorsal Stream Pathway Ventral Stream PathwayControl Postsubiculum


20/68


90

270

0180


LMN Recording

90

270

0180



90

270

0180

Control

Hippocampuslesion

Limbic Pathway

Lateral DorsalThalamus lesion

TectalPathway

ADN Recording

PostsubiculumLesions

Hippocampal PlaceCell Recording

Place field absent

Severe


21/68

VisualCortex

Parietal

PoS

LDN

Tectal Stream

EntorhinalCortex

Hippocampus


Direct Projection:

Visual CortexPoS

Postsubiculum

ADN

LMN

Dorsal Stream Pathway Ventral Stream Pathway PostsubiculumControl


22/68


90

270

0180


Hippocampal PlaceCell Recording

LMN Recording

90

270

0180

Place field absent



90

270

0180

Anterior DorsalThalamus lesion

Place cell recording

ADN Recording

PostsubiculumLesions

Control

Hippocampuslesion

Limbic Pathway

Lateral DorsalThalamus lesion

TectalPathway

None


23/68

Visual

Cortex

Parietal

Retspl

PoS

LDN

Tectal Stream

EntorhinalCortex

Hippocampus

ADN

LMN

Subcortical AreasGenerative

Circuit

So, what canwe conclude ?

SuperiorColliculus


24/68

Visual

Cortex

Parietal

Retspl

PoS

LDN

Tectal Stream

EntorhinalCortex

Hippocampus

ADN

LMN


Circuit

SuperiorColliculus



25/68


26/68

Visual

Cortex

Parietal

Retspl

PoS

LDN

Tectal Stream

EntorhinalCortex

Hippocampus

ADN

LMN


Circuit

SuperiorColliculus



27/68

Visual

Cortex

Parietal

Retspl

PoS

LDN

Tectal Stream

EntorhinalCortex

Hippocampus

ADN

LMN


Circuit

SuperiorColliculus



28/68

Visual

Cortex

Parietal

Retspl

PoS

LDN

Tectal Stream

EntorhinalCortex

Hippocampus

ADN

LMN


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


29/68

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..


30/68

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.


31/68

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).


32/68

FR OSLM LS ERActivation of PPA to Landmarks


33/68


34/68

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?


35/68

HD cell responses in the Vertical Plane

Generallynormaldirectional

responses on walls.

Cells contain directional tuningcurve relative to the roomreference frame.


36/68

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


37/68

But, what about inverted orientation?

To testit is easier to go Space-bound

Why does this matter?


38/68

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)


39/68

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)


40/68

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


41/68

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


42/68

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


43/68

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.


44/68

P bl f ti i S


45/68

Problems from time in Space

Loss of muscle mass

Reduction of quick headturns due toOtolith Reinterpretation


46/68

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


47/68

Spatial Disorientation - Difficulty in determining up/down:

Astronauts are just as likely to work upside-down as right-side up.


48/68

HD cell firing in 0 g with parabolic flights


49/68

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.


50/68


51/68


52/68


53/68

Humans canexperience

VRIs during theseexercises, too.


54/68

HD cell tuning curves in 0-g conditions


55/68

HD cell responses when upside-down on ceiling on Earth


56/68

p p g

Si il t ll li bi fi di HD ll


57/68

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.


58/68

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


59/68

For most cells: Loss of directional tuning onceiling, with increased background firing rate

Cell 1 Cell 2


60/68


61/68

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.


62/68

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


63/68

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


64/68

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?


65/68

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


66/68


67/68

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.


68/68

lec 25.spatial cogn 2 (4)

Documents