Lecture 13 - Map Consolidation & Human Cognitive Enhancement Flashcards
(28 cards)
What is constraint satisfaction in the context of sensory integration?
It refers to how the brain resolves conflicting sensory input (e.g., tactile vs visual) to maintain a coherent sense of body ownership and positioning, such as in the rubber hand illusion
What was the key finding from Ehrsson et al. (2007) on the rubber hand illusion?
Participants reported both ownership of the rubber hand and anxiety when it was threatened, indicating incorporation into the body schema
What is meant by ‘map consolidation’?
It refers to processes that stabilise and enhance memory representations (including sensory/motor maps), converting short-term representations into long-term structures
What type of memory do map changes reflect?
Non-declarative (procedural/implicit) memory
What role does rehearsal or training play in map consolidation?
It helps maintain short-term representations, which through consolidation, can be transformed into long-term structural changes
What signal is required for map consolidation?
A signal indicating behavioural significance or value, often mediated by cholinergic input from the basal forebrain, particularly the Nucleus Basalis of Meynert (NBM)
What neurotransmitter does the NBM primarily use?
Acetylcholine (ACh), which acts as both a neurotransmitter and neuromodulator
What happens to map plasticity after NBM lesion? (Juliano et al., 1991)
Removal of the NBM prevents cortical map expansion after sensory changes (e.g., digit amputation), suggesting ACh is necessary for map plasticity
What did Kilgard and Merzenich (1998) show with tone pairing and NBM stimulation?
Pairing tones with NBM stimulation reorganised the tonotopic map in auditory cortex, demonstrating cholinergic modulation of cortical responses
How did Connor et al. (2003) test map plasticity and learning in a naturalistic task?
- They lesioned cholinergic neurons from the NBM and trained rats on a forepaw-reaching task
- Lesioned rats showed poorer accuracy and reduced cortical map expansion
What were the key outcomes in Connor et al.’s 2003 study?
- Sham-lesioned rats had 30% motor cortex expansion
- NBM-lesioned rats showed 22% reduction
- Behaviourally, the lesioned rats learned more slowly and less accurately
What do these findings suggest about ACh?
- ACh is crucial for learning-induced cortical plasticity
- It acts as a gating signal to mark relevant inputs for consolidation
What might ACh determine versus sensory input?
ACh may determine WHAT to learn, while sensory input may suggest HOW to learn (e.g., synchronicity)
What are neuroenhancers and how are they trending in use?
- Neuroenhancers are drugs used to improve cognition
- Use is generally highest among younger adults and for non-medical enhancement
Give the negative cognitive effects of certain neuroenhancers in healthy individuals, and name the studies
- Donepezil: Impaired working memory (Beglinger)
- Methylphenidate: Increased distractibility (Clark), anxiety (Gobbi), disrupted attention (Rogers), overestimation of performance (Bray)
- Modafinil: Increased anxiety/aggression (Randall), negative affect (Tanja), overestimation (Baranski)
What is transcranial electrical stimulation (TES)?
- A non-invasive method of brain stimulation using electrodes and low current (1-2mA)
- tDCS is one type that uses direct current
What historical precedents exist for brain stimulation?
- Torpedo/electric fish used for headaches (43 AD)
- Aldini’s galvanic treatment of depression (1801)
- Fritsch & Hitzig (1870) electrically stimulated the dog cortex to induce movement
What contributions did Aldini make to neurostimulation?
Applied electric curents to his own and patients’ heads, reported strong cognitive and physical responses, contributing to early theories of electrical brain modulation
What did Fritsch and Hitzig discover?
Electrical stimulation of specific brain aeas can produce specific bodily movements, laying the groundwork for functional localisation
What are key features of TES equipment and usage?
Uses constant current (0-4mA), electrodes soaked insaline (5-50 cm^2), typically applies 2mA (about 1/500 of a 100W bulb)
Summary: What underlies map plasticity and learning?
- Interaction between sensory input
- Neuromodulatory signals (like ACh from the NBM)
- Behaviourally significant training or task performance
Which neurotransmitter is primarily linked to cortical map consolidation
Acetylcholine (ACh)
What brain structure provides cholinergic input to the cortex?
Nucleus Basalis of Meynert (NBM)
What study linked map changes, NBM activity, and tone-paired stimulation?
Kilgard & Merzenich, 1998
