Division of labor Parietal: Where are things relative to me? (ego) - - PDF document

3/3/17 1

1

PPA: what is this? RSC: Where am I and which direction am I facing? Hippocampus: (allo) Where are other places? Parietal: Where are things relative to me? (ego)

Division of labor

3/3/17 2

Neural Navigation I:

constructing a cognitive map of space

• 1. Intelligent navigation: getting from here

to there

• 2. A place hierarchy in the brain
• 3. Functions of the hippocampus
• A. Representing space and spatial

memory

• B. Memory consolidation

4

3/3/17 3

Place cells recorded in human hippocampus!

5

Boundary cell

6

3/3/17 4

Boundary Vector Cell model of the sensory input to place cells

7 8

Parietal “Window” Hippocampus: Memories

• f

where things are Parahippocampal Place Area Boundary Cells

Egocentric sensory à Allocentric abstract representation of space

3/3/17 5

Neural Navigation I:

constructing a cognitive map of space

• 1. Intelligent navigation: getting from here to

there

• 2. A place hierarchy in the brain
• 3. Functions of the hippocampus
• A. Representing space and spatial memory
• B. Memory consolidation

The medial temporal lobe and anterograde amnesia

H.M.: surgical removal

• f 8 cm of medial

temporal lobe, including cortex, amygdala, and anterior 2/3s of the hippocampus

3/3/17 6

H.M. Control

12

3/3/17 7

What did we learn from H.M.?

• Medial temporal cortex

and hippocampus may be involved in consolidation

• Declarative memory

depends on medial temporal cortex but procedural memory does not

Henry Molaison RIP

Memory consolidation

“A poorly defined set of processes which take an initial, unstable memory representation and convert it into a form that is both more stable and more effective.”

Stickgold 2007

14

3/3/17 8

Neural Navigation II:

constructing a cognitive map of space

• 1. Sleep, hippocampal replay,

and preplay

• 2. Beyond space: cognitive map
• f everything

Consolidate by replay?

16

3/3/17 9

Replay in rat hippocampus during SWS NREM AWAKE

17

Human maze task Peigneux 04 18

3/3/17 10

SWS replay in human hippocampus predicts improvement

19

Sleep Conclusion

• Replay of place cell firing sequences

during sleep (both REM and NREM, and while awake and “daydreaming”) may help consolidate memories about paths the rat took while awake

• And may also simulate previously

unexplored possible paths…

20

3/3/17 11

Neural Navigation II:

constructing a cognitive map of space

• 1. Sleep, hippocampal replay,

and preplay

• 2. Beyond space: cognitive map
• f everything
• Represent space and spatial memory
• Episodic memory consolidation (by replay?)

Functions of the hippocampus

22

3/3/17 12

23 24

3/3/17 13

TRAINING CONTEXTUAL TEST CUED TEST

• Animal is placed in novel context
• Hears a tone
• Receives foot shock
• Animal is returned to same context
• Test for freezing behavior
• DEPENDS ON HIPPOCAMUS
• Animal is placed in modified context
• Hears a tone
• Test for freezing behavior

Fear Conditioning

25 26

3/3/17 14

Corneal Air Puff Elicits Eyeblink Response Corneal Air Puff Given with Tone Tone Given Alone Elicits Eyeblink Response

Eye-Blink Conditioning in Rabbits

27

Time Time

CS CS US US “Delay” Conditioning: tone and puff

• verlap in time

“Trace” Conditioning: no overlap

Two Types of Classical Conditioning

28

TONE AIRPUFF

3/3/17 15

Trace eyeblink conditioning depends on the hippocampus

29

% trials with eyeblinks in response to the tone

30

3/3/17 16

31 32

3/3/17 17

Hippocampus: Beyond space

• Episodic memory may use a similar

hippocampal system as navigation, and may consolidate by replay

• Multisensory associations/contextual

memories depend on hippocampus

• Hippocampal time cells encode time like

place cells encode space

• Maybe it contains a cognitive map of when

and where everything is, to be used for planning…