W9 - Clinical Neuroscience, Navigational Systems Flashcards
(46 cards)
1
Q
Why is studying navigation in aging important? (4)
A
- Global aging population, currently 1.1 billion people over 60 years, by 2050 will have 2 billion people over 60 years
- Navigation is critical for one’s sense of independence, autonomy and social participation
- New findings suggest navigational deficits might be a reliable sign of cognitive decline, sometimes before memory loss, especially in neurodegenerative disorders
- Deficits go beyond memory — affect self-motion processing, strategy switching, spatial coding
2
Q
What was the case of Kent Cochrane?
A
- Brain damage to the temporal lobe in a motorcycle accident
- LTM intact = Can recall long term memories of the self, what year he was born, and intact semantic memory, factual information,
- Anterior-grade amnesia =inability to form new memories after the motorcycle accident, before accident memories are intact
- STM impaired = Unsure of what year it is, present information is damaged, less ability to form new memories
* Self-knowledge was impaired,
* procedural information was retained (couldn’t remember having a flat tire, but can accurately describe how to change a flat tire)
H
3
Q
Anterograde vs. retrograde amnesia?
A
Anterograde amnesia is the inability to form new memories AFTER a specific event or injury, LTM INTACT
- Retrograde amnesia is the inability to recall past memories, STM INTACT
4
Q
What type of memory does the hippocampus process?
A
episodic but NOT semantic or procedural memory
5
Q
What claims does Tulvin make about episodic memory?
A
- “Recalling “What, where, when” of the episode, what happened, where it happened and when it happened for any autobiographical memory
- Autonoetic consciousness = mental time travel - going back in time in your mind to relieve the actual episode
- Assumption is that mental time travel is uniquely human, if you can recall it, it is assumed
Limitation = there is no explicit capturing of episodic memory
6
Q
What 2 examples of memories are semantic and NOT episodic according to Tulvin?
What doesn’t involve ‘autonoetic consciousness’
A
- Binge drinking, can’t remember the memory: so the memory based on others description and photographs of memory is NOT episodic, but semantic, as there is no personal ‘mental time travel’ back to reliving that memory
- Memories from early life: memories are based of others recollections, photographs, is an AUTOBIOGRAPHICAL MEMORY, but NOT an episodic memory
7
Q
What 5 things do we use to navigate?
A
- Self-motion cues (using distance and direction)
- Environmental cues (using landmarks and boundaries)
- Ecocentric view = self centered
- Allocentric view = world centered
- Cognitive maps
8
Q
What brain regions and cells are involved in the navigational system in the brain?
A
- Hippocampus
- Entorhinal cortex
- retrosplenial cortex
Specialised cells include
- Place cells (encodes location)
- Grid cells (encodes distance)
- Head direction cells (encodes orientation)
Network
Formation of cognitive maps
9
Q
Grid cells are primarily located in which brain area?
A
Entorhinal cortex
10
Q
Place cells are primarily located in which brain area?
A
Hippocampus
11
Q
What occurs in the place cell experiments with rats?
A
- A place cell recorded as a rat explores a square open field environment.
- This cell has a place field towards the top side of the enclosure.
- More often than not when the rat visits this location the cell fires, which is indicated by the popping sounds in the EEG
- Sometimes the cell fires when the rat is outside the place field location, but often this is followed by the rat moving there.
- These brief events are possibly examples of replay or other prospective activity associated with decision making.
12
Q
In aging, what stays intact and what becomes impaired in navigation?
A
- Static spatial perception is preserved
- Self-motion perception, path-integration accuracy and place and grid cell stability becomes impaired
13
Q
What 2 strategies do older adults make to compensate for declining navigation?
A
- Older adults prefer ECOCENTRIC (habit based strategies) over ALLOCENTRIC (map based strategies) in navigation
- Older adults find it more difficult to SWITCHING between egocentric and allocentric strategies, especially when adapting to new environments
14
Q
Previous diagnostic tools: What are 2 limitations of episodic memory as a diagnostic tool for preclinical AD?
A
- As healthy aging is associated with general declines in memory, it’s hard to identify which individuals are at risk of AD in the preclinical stage (where no cognitive deficits are yet apparent) purely using episodic memory tests
- Other types of dementia, eg., frontotemporal, show similar types of memory impairments that are caused by DIFFERENT brain changes/pathologies
15
Q
What is the new potential diagnostic tool for preclinical AD and why?
A
- Spatial memory and navigation
- Spatial disorientation is thought to be an early symptom in Alzheimer’s disease, and might precede other symptoms of memory loss
16
Q
What are the 4 advantages of using navigational tests as potential for early detection of AD?
A
- Spatial navigation tests can show HIGHER SPECIFICITY in differentiating Alzheimer’s from frontotemporal dementia compared to traditional episodic tests
- Brain regions supporting spatial navigation are impacted EARLIER on in AD disease progression than episodic memory
- Measures of spatial performance in animal studies generalise easier to human clinical trials than episodic memory, (harder to operationalise a definition of episodic in animals)
- Navigation-based tasks can be adapted across different cultural & linguistic backgrounds
17
Q
What were the 3 main findings in Coughlan et al., 2018 regarding neural changes in AD progression?
A
- In preclinical AD (normal cognition) = changes to neuron and metabolic processes, reduced connectivity in hippocampus, precuneus, PPC, RSC
- In prodromal AD (mild cognitive impairment) = neural loss in precuneus and hippocampus subregions
- In early AD (moderate cognitive impairment) = further neuronal changes in hippocampus, PHC, thalamic nuclei, amygdala and prefrontal cortex
18
Q
What does the Sea Hero Quest VR
aim to do and what are its advantages?
A
- a virtual reality game to help scientists to fight dementia
- Measures spatial navigation, sense of direction in game performance, how good they are at estimating where they’ve come from
- Can track gender differences in navigation and changes in aging
- Help to more specifically diagnose spatial navigational problems in dementia patients
19
Q
What 2 specific aspects of the hippocampus are associated with navigation and spatial memory in London taxi drivers?
A
- Increased gray matter in the posterior hippocampus (I - P)
- Decreased gray matter in the anterior hippocampus (D - A)
20
Q
Q: How does hippocampal volume relate to taxi driving experience?
A
- A: Posterior hippocampal volume increases with years of experience, but this is not observed before training or in those who fail to qualify.
21
Q
What is “The Knowledge”? and how do trainees begin learning The Knowledge?
A
- Extensive memorization of over 26,000 streets and thousands of landmarks in a 6-mile radius of central London required for licensing as a London taxi driver.
Through a structured set of 320 “Blue Book” origin–destination runs, divided into 20 lists of 16 runs each, focusing on main roads.
22
Q
What 4 tools and methods are used during training?
A
- A: Map study (e.g., cottoning-up),
- quarter-mile radius exploration,
- memory techniques (mnemonics, method of loci)
- physical route practice on scooters.
23
Q
What is the “cottoning-up” method?
A
- A: Drawing or imagining a straight line between origin and destination to plan the most direct route, identifying 50% and 75% markers for subgoal planning.
24
Q
: How do taxi drivers plan routes compared to the general population?
A
A: They rely on a mental cognitive map using allocentric strategies and subgoal planning, rather than habitual or GPS-based navigation
25
What is the role of subgoal planning in navigation for taxi drivers?
A: Subgoals (like 50% markers) help break down complex routes into manageable parts, aiding efficient mental route planning.
26
How does map-based learning contribute to taxi drivers’ cognitive maps?
A: Studying maps supports allocentric spatial representations and helps avoid geographic misconceptions (e.g., misalignments due to river bends).
27
How does aging affect spatial navigation?
A: Aging leads to deficits in navigation, particularly with using allocentric strategies and integrating self-motion cues.
28
What are egocentric and allocentric navigation strategies?
A: Egocentric strategies rely on the body’s position relative to the environment (e.g., “turn right at the shop”), while allocentric strategies involve map-like spatial representations, independent of one's current location.
29
What kinds of cues are important for navigation, and how do they change with age?
1. A: Navigation relies on self-motion cues
- vestibular
- proprioceptive
-visual flow)
2. environmental cues (landmarks, boundaries)
Aging affects the accuracy of self-motion processing due to sensory degradation.
30
Q: How does vestibular degradation in old age affect navigation?
A: It impairs self-motion perception and reduces the accuracy of positional computations, contributing to difficulties in path integration.
31
What age-related changes occur in hippocampal place cells?
A: Aged animals show less stable and slower-forming place fields;
sometimes they retrieve the wrong spatial map in familiar environments.
32
How is long-term potentiation (LTP) affected in aging hippocampi?
A: Aging is linked to
1. reduced LTP
2.faster decay of LTP
2. increased susceptibility to long-term depression (LTD)
contributing to memory deficits.
33
Q: How does pattern separation and completion change in aging?
in pyramidal neurons are the major principal cell types of the hippocampus proper, CA1 and CA3
1. CA1 may show too much pattern separation (new maps for familiar places)
2. Aged CA3 shows excessive pattern completion (retrieving the wrong map for distinct environments
34
What neurotransmitter systems contribute to age-related memory decline?
1. Aging affects cholinergic, dopaminergic, serotonergic, glutamatergic systems, altering synaptic plasticity in the hippocampus
35
What happens to spatial memory consolidation with aging?
1. Aging disrupts hippocampal replay sequences, impairs consolidation during sleep, and may affect waking reactivation.
36
How is sequence learning impacted in older adults?
1. A: Older adults have trouble binding direction to landmarks and recalling sequences, likely due to impaired hippocampal plasticity.
37
What is the role of medial prefrontal cortex (mPFC) in aging-related navigational deficits?
A: Age-related changes in mPFC, including reduced NMDA receptor function, impair spatial working memory and navigation goal tracking.
38
Do older adults retain the ability to perceive static spatial relationships?
A: Yes, they accurately perceive distances and positions of static objects, both egocentrically and allocentrically.
39
Q: Can older adults still recognize landmarks effectively?
A: Yes, their ability to recognize and recall landmarks encountered along a route is generally preserved.
40
How does aging affect self-motion perception?
A: It becomes less accurate due to vestibular decline, reduced visual flow processing, and increased neural noise.
41
What areas are speed cells in?
Speed cells are in the hippocampus and medial entorhinal cortex
42
Are older adults impaired in path integration tasks?
A: Yes, they underestimate distances and angles, and have difficulty returning to starting locations after movement.
43
Distance and direction to boundaries are signaled by border cells are found in....
the entorhinal cortex, subiculum, pre- and parasubiculum
44
What changes occur in hippocampal place cell function with age?
Place cells in older adults are less stable, take longer to stabilize, and may encode incorrect environments.
45
How is pattern separation and completion affected in aging?
1. A: CA3 shows excessive pattern completion (confusing similar locations),
2. CA1 may over-separate familiar places.
46
How does aging affect sequence learning in navigation?
1. A: They have difficulty remembering the order in which landmarks were encountered and linking them to directions.
