Week 11-12 Biopsych

What is the main role of spatial navigation?

To determine where we are located in the world and support movement through the environment

What does spatial navigation support besides movement?

Episodic memory, prediction, and future planning

What is a cognitive map?

A mental representation of spatial relationships in the environment

Who proposed the idea of cognitive maps?

Edward Tolman in the 1940s

What evidence supported Tolman’s cognitive map theory?

Rats could rapidly switch to alternative paths when routes were blocked

What are place cells?

Hippocampal neurons that fire at specific spatial locations

Who discovered place cells?

O’Keefe and Dostrovsky in 1971

Where are place cells located?

Hippocampus

What do grid cells do?

Fire in a hexagonal lattice pattern across the environment

Where are grid cells located?

Medial entorhinal cortex

What do head direction cells encode?

The direction the head is facing

What do border/boundary cells encode?

Distance from environmental boundaries in specific directions

Who discovered grid cells?

Moser and Moser in 2005

What is the Papez circuit associated with?

Memory and navigation

Why is translating rodent navigation research to humans difficult?

Humans have more complex visual systems and navigation involves broader memory processes

Why are fMRI studies of navigation difficult?

Participants must remain stationary in scanners

What tasks are commonly used in human navigation fMRI studies?

Virtual navigation, imagined navigation, and spatial memory recall

What is the parahippocampal place area (PPA)?

A brain region specialised for scene perception

Who identified the PPA?

Russell Epstein and Nancy Kanwisher

Where is the PPA located?

Along the parahippocampal gyrus and collateral sulcus

What type of stimuli strongly activate the PPA?

Scenes such as landscapes, rooms, and buildings

Does the PPA respond strongly to faces or objects?

No

What aspect of scenes does the PPA encode?

Global spatial layout and geometry

How does removing background versus objects affect PPA activity?

Removing background reduces activity but removing objects does not

How does the PPA respond to scrambled scenes?

Response is reduced compared to intact realistic scenes

What happens after damage to the PPA?

Patients can see objects but lose the overall scene organisation

What is distance coding in the hippocampus?

Hippocampal activity reflects subjective spatial distance between landmarks

What did Morgan et al. (2011) investigate?

fMRI adaptation and distance coding in the hippocampus

What happens to hippocampal responses when landmarks are close together?

Responses become more similar

Why are hippocampal responses compared to border/boundary cells?

Because activity scales with spatial distance relationships

What did recordings from epilepsy patients reveal about human navigation?

Humans have place-responsive cells similar to rodents

Where are place-responsive cells most prevalent in humans?

Hippocampus

What is allocentric heading?

Representing direction independent of viewpoint

Which region is associated with allocentric heading?

Retrosplenial complex

What brain region changes with navigational expertise?

Hippocampus

What causes cortical blindness?

Damage to primary visual cortex (V1)

What is homonymous hemianopia?

Loss of vision in the same half of the visual field in both eyes

What is blindsight?

Above-chance visual performance without conscious awareness

What abilities can remain intact in blindsight?

Motion detection, localisation, orientation discrimination, and pupillary reflexes

Who conducted important blindsight research?

Weiskrantz

Which structures support unconscious visual processing in blindsight?

Superior colliculus and pulvinar nucleus

What is change blindness?

Failure to detect changes in a visual scene

What is inattentional blindness?

Failure to notice unexpected stimuli due to attention limits

Why are we consciously aware of only part of the visual world?

Neural, metabolic, and computational limitations

How did William James define attention?

Focalisation and concentration of consciousness on selected information

What are key aspects of attention?

Selectivity, vigilance, switching, and capacity limitation

What is covert selective attention?

Directing attention without moving the eyes

Who studied covert attention?

Hermann von Helmholtz

How does spatial attention affect processing speed?

Valid attentional cues improve reaction time

Which brain region shows attentional modulation?

Parietal cortex

How does attention affect visual cortex processing?

It enhances neural responses to attended stimuli

Who was patient HM?

Henry Molaison, a famous amnesia patient

Why did HM undergo surgery?

To treat severe temporal lobe epilepsy

What brain tissue was removed in HM’s surgery?

Bilateral mesial temporal lobe tissue

What major deficit occurred after HM’s surgery?

Severe anterograde amnesia

What is anterograde amnesia?

Impaired formation of new memories after injury

What is retrograde amnesia?

Loss of memories formed before injury

What abilities remained intact in HM?

Personality, intelligence, short-term memory, and procedural learning

What could HM not do after surgery?

Form new long-term declarative memories

Could HM learn new motor skills?

Yes

What task demonstrated preserved procedural memory in HM?

Mirror drawing

What is declarative memory?

Conscious memory for facts and events

What is procedural memory?

Memory for skills and actions

What did HM reveal about memory systems?

Declarative and procedural memory are separate systems

What role does the hippocampus play in memory?

Formation and consolidation of new declarative memories

What structures make up the hippocampal formation?

Dentate gyrus, hippocampus, and subiculum

What is relational memory?

Memory linking unrelated pieces of information

What is Hebb’s rule?

Repeated activation strengthens connections between neurons

What is synaptic plasticity?

Changes in synaptic strength associated with learning and memory

What neurotransmitter is strongly associated with LTP?

Glutamate

What is long-term potentiation (LTP)?

A long-lasting strengthening of synaptic transmission

How can LTP alter synapses?

By changing neurotransmitter release and receptor numbers

What is long-term depression (LTD)?

A decrease in synaptic strength after low-frequency stimulation

What is habituation?

Reduced synaptic response after repeated stimulation

What is sensitisation?

Enhanced response after a noxious stimulus

What disease is associated with temporal lobe neurodegeneration?

Alzheimer’s disease