lecture 13 - map consolidation and human cognitive enhancement

Question 1

CONSTRAINT SATISFACTION

Answer 1

Localization discrepancy is mediated by position sense. To
resolve the discrepancy, is position sense distorted

Question 2

TO WHAT DEGREE IS THE RUBBER HAND
INCORPORATED INTO THE BODY SCHEMA?

Answer 2

Ehrsson et al., 2007 induced the
rubber hand illusion while in an
MRI scanner
* “Occasionally made brisk
stabbing movements with a
sharp needle toward the rubber
hand”
* Subjects reported feelings of
both ownership of the
rubber hand, and anxiety when
it was threatened.

Question 3

….HOW DO MAPS ‘KNOW’ TO STAY
LOCKED INTO A PARTICULAR PATTERN?

Question 4

‘GOOD’ PLASTICITY: example

Answer 4

REPRESENTATION OF FINGERS IN
THE SOMATOSENSORY CORTEX OF
STRINGED INSTRUMENT MUSICIANS

Elbert et al., Science, 1995
‘GOOD’ PLASTICITY:
REPRESENTATION OF FINGERS IN
THE SOMATOSENSORY CORTEX OF
STRINGED INSTRUMENT MUSICIANS

a representation of those fingers within the primary somatosensory system that seems to correlate with the amount of time people are practising therefore undoubtedly assists in the skill at the instrument

Question 5

‘BAD PLASTICITY’ IN
PATHOLOGIES..
Bleton et al (2011)
dystonia

Answer 5

overtrained movement leads to a pathological representation of the hand that is no longer useful

Question 6

‘CONSOLIDATION’ I

Answer 6

changes in maps = abstract memory not one that is autobiographical or semantic

looking at implicit memory, procedural, non-declarative = abstract
* Mechanisms that act to STABILISE and ENHANCE
memories over time
* ‘Memories’ do not have to be DECLARATIVE: NON-
DECLARATIVE/PROCEDURAL/IMPLICIT memory.
* The changes to cortical map structure are therefore a kind
of ‘MEMORY’

when talking about this in terms of autobiographical stuff there will be some sort of sensory info coming in that will be put into some sort of short term buffer through some process of rehearsal, you can keep it in the short term buffer but also go through some process of consolidation and pass it into long term memory and you can also get it back from there

short term buffer = short term map representation the rehearsal may be some continual pattern of stimulation coming in for it and then some process turns it into a longer term map structure that is not as easy to change passed on short exposures to sensory info

diagram in notes

Question 7

‘CONSOLIDATION’ II

Answer 7

• ‘Consolidation’ requires a SIGNAL – to ensure changes in
  the map that are of of VALUE /BEHAVIOURAL
  SIGNIFICANCE/ RELEVANCE survive.
• One system whose role in this process has been studied is
  the BASAL FOREBRAIN -> CORTICAL PROJECTION
  system. - a very diffuse projection system , subcortical coming from a number of distinct nuclei

basal forebrain made up of a small number of neurons deep within the brain but can signal to vast amounts of the brain, also can’t only effect receptors in its area aswell due to neurotransmitters

Question 7

‘CONSOLIDATION’
III

Answer 7

Within the basal forebrain is the
Nucleus Basalis of Meynert (NBM).
* Neurons within the NBM use
acetylcholine (Ach) as their
neurotransmitter.
* The projection from the NBM is the
MAJOR SOURCE OF
CHOLINERGIC (neurons using
Ach) INNERVATION to the
CORTEX.
* ACh is both a neurotransmitter AND a
NEUROMODULATOR – a substance
that can regulate the activity/firing of
larger groups of neurons.
* COULD THIS BE THE SIGNAL?

Question 8

LINKING THE NBM AND ACH TO
MAP PLASTICITY

Answer 8

• Lesion Studies = early studies
  talking about lesioning certain parts of the brain and seeing what happens after they are taken out
• Juliano, Ma, Eslin (1991)
• REMOVE NBM, cortex is ‘STARVED’ of
  Cholinergic input.
• PREVENTS MAP EXPANSION AFTER
  DIGIT AMPUTATION

NBM INTACT
NBM
REMOVED
NO ACH
PROJECTION
TO MAP

everything in the Map stays in their zones

Question 9

..BACK TO ’THE MERZ

Answer 9

• AUDITORY cortex plasticity this time (Kilgard and Merzenich,
  1998), in primary auditory cortex (A1).
• SO not a map of the body (SOMATOTOPY) but a map of sound
  FREQUENCY (TONOTOPY

auditory space = a map of frequency this is tonotopy

can do similar experiments and use rodents as have similar cortex for auditory

the experiment was mapping A1 to begin with you give them various tones and you record it from A1 using a electrode so we get an order tonopy from low to High frequencies that span the map
each colour in image represents the area within the that best responds to that given frequency

rats can hear a lot higher than we can hear
we can hear from about 20 to 20kHz

once you have a stable map you try and mess with it

Question 10

EXPERIMENTAL DESIGN Kilgard and Merzenich, 1998

Answer 10

1 - Naïve’ Rat A1 Organisation
2 - rat brain stimulation and a sound
3 - Tone+ NBM Stimulation Rat A1 Organisation

wanted to pair stimulation in the NBM with a sound simulatneously and then looked at what happened to the rats organisation

Question 11

NBM STIMULATION+ TONE RESULTS
IN MAP REORGANISATION

Answer 11

graphs in notes

in the normal rat A1 there is a nice progression between the different frequencies

after they have paired a 9kHz tone with the NBM cholinergic signal (trying to work out does it signal something to do with value or behavioural relevance - it appears to as there is a massive reorganisation around 9kHz- there is a massive over representation of 9kHz

Question 12

CHOLINERGIC INPUT MODULATES
THE WAY THAT CORTICAL
NEURONS RESPOND TO SENSORY
STIMULI

Answer 12

image in notes

if you only have a little bit of basal forebrain input and your mapping that region you get a little bit of activity not a lot, once you have active stuff in there you have a lot of activation, particularly in spatial areas related to the tone and that seems to somehow drive this map reorganisation

not ethological

Question 13

NBM+MAP PLASTICITY IN
NATURALISTIC LEARNING

Answer 13

• Kilgard and Merzenich linked map plasticity, NBM activity
  and plasticity, but there was no real LEARNING – this was
  a PASSIVE paradigm (the rats performed no TASK)
• We would like to link MAP CHANGES, FOREBRAIN(NBM)
  ACTIVITY, and CHANGES IN PERFORMANCE on an
  actual task. - if not we may have a epi phenomena = a change in the map thats occurred but we have no idea what it means
• Connor and colleagues (2003) lesioned ONLY cholinergic
  forebrain(NBM) neurons projecting to the cortex using a
  targeted immunotoxin that ‘recognised’ these neurons.
• MORE SPECIFIC than either the Juliano et al lesions (takes
  the whole NBM) or the Kilgard and Merzenich stimulations
  (primarily activating cholinergic neurons, but NO REAL
  WAY OF TESTING THIS….

Question 14

NBM+MAP PLASTICITY IN
NATURALISTIC LEARNING

Answer 14

• Behaviourally, NBM lesion group had
  LOWER ACCURACY and TOOK
  LONGER TO ACQUIRE the reaching
  task skill.
• Used mapping to look at MOTOR
  CORTEX in both groups of rats after
  training
• The cortical area that elicited forepaw
  movement was increased by 30% in sham
  lesioned rats compared to untrained rats. - training increases the motor map
• In contrast, the forepaw area of NBM
  lesioned rats actually decreased by 22%. - the area has got smaller

One of the first studies to directly link impairments in learning with disruption of
cortical plasticity after a forebrain lesion
due to Ach in this case but other signals and neurotransmitters must also do this job

Question 14

NBM+MAP PLASTICITY IN
NATURALISTIC LEARNING - motor topic map

Answer 14

which is the representation of the muscles and movements within a space
* Connor and colleagues (2003) trained rats to retrieve sugar
pellets through a small slit using a single forepaw.
* One group NBM lesioned, one group ‘sham’ lesioned
(similar surgical experience but no immunotoxin) = pretty good control as have the handling, the stress, the injection and recovery just without the immunotoxin

involves motor learning

reach training
training induced motor map expansion + high accuracy reaching

reach training with NBM lesion
lack of motor map expansion + low accuracy reaching
as no cholinergic input

Question 15

ACH IS CERTAINLY
IMPORTANT…

Answer 15

Multiple studies link the NBM and ACh to changes (or not
after lesioning) to cortical map structure.
* Sensory input from the environment may signal HOW to
learn (synchronous input demonstrates things are
‘happening together’ outside, and so maybe should be
linked in how they’re stored ‘inside’ (the map structure).
* But ACh may be the signal that determines WHAT to learn
* The release provides a ‘window’ where stimuli that
arrive during that time are deemed ’more important…’ - and may be able to change the Map in that period

Question 16

…BUT IT’S NOT THE ONLY GAME IN TOWN

Answer 16

….ARE THERE QUICKER WAYS TO IMPROVE
WITHOUT RELYING ON TRAINING AND
CONSOLIDATION? cognitive enhancers

Question 17

THE DAWN OF COGNITIVE ENHANCEMENT

Answer 17

examples in notes
modafinil + Ritalin - were designed for particular pathologies but are now used extensively for off prescription things - both seem to have effects in neurotypicals

Ritalin increase concentration but doesn’t disrupt sleep patterns

modafinil removes the need for sleep to improve clarity

need to be looked at more in neurotypcials as are drugs of abuse

the effects of them are rather limited, have to go through blood Brain barrier, they have side effects and your using them for purposes that they are not exactly designed for, so they are going to be very variable in neurotypicals

for neurotypicals a better way if we want to get in and influence the brain given that the brain is electrochemical is to dump the chemical and just go straight to the electric

Question 18

use direct electrical Brain stimulation to noninvasively modulate brain function

Answer 18

one day in the future woman prescribe electrical stimulation in a similar way to drugs

Question 19

ZAPPING THE BRAIN:
A HISTORY

Answer 19

Scribonius Largus
– 43-48 AD (torpedo fish)
– On the scalp for headache

• Galen, 131-410 AD
• Ibn-Sidah, 11th century
  – Electric catfish
• Studied by Walsh, 1773
  – Begins electrophysiology
  – Followed up by
• Galvani
• Volta
  G + V came up with modern theories of electromagnetism

Question 20

…AND THE NEXT GENERATION
Giovanni Aldini, Galvani’s Nephew, 19th Century

Answer 20

applied galvanism/shock to 27yr old farmers head who had been suffering from major depression/ melanchonic madness in 1801 - appeared to cure him at least in the short term

he also put voltage through dead bodies and made the muscles jerk

first historical example you can non-invasively trace a neuropsychiatric pathology through non-invasive scalp stimulation with direct current

but the idea of how you do it had to wait for the idea of functional localisation in the brain

Question 21

FRITSCH AND HITZIG, 1870

Answer 21

First to discover that electrical
stimulation of the cortex can
produce movements.
* Exposed surface of dog’s brain
to electrical stimulation, noted
where this produced
movement.
* Don’t try this at home? They
did…
Δ, twitching of neck muscles; +, abduction of foreleg; †, flexion of foreleg; #,
movement of foreleg; diamond,facial twitching

also found if you reverse the polarity of the current you get opposite movements

Question 22

SUMMARY OF EARLY
STIMULATION WORK

Answer 22

• Direct current can be
  applied to the body and
  brain. Aided in
  development of doctrine
  of functional localisation.
• After Fritsch and Hitzig, it
  was appreciated that
  application of a positive
  d-c stimulus to the surface
  of the cortex had a
  stimulating effect, while a
  negative current inhibited
  it.
• Aldini’s work was first to
  suggest that direct
  current applied to the
  scalp could modulate
  human brain function – in
  this case, depression.
• Largely forgotten after
  the rise of ECT –
  electroconvulsive
  therapy

Question 22

BASIC FEATURES OF TRANSCRANIAL ELECTRICAL STIMULATION (TES)

Answer 22

* Equipment: surface electrodes, constant current stimulator (battery source). * Stimulator: 0-4mA, usually 1- 2mA used . * Electrodes: Size varies (5- 50cm2), usually soaked in conductor (saline) * ‘tES’ - the umbrella term. ‘tDCS’ – one particular stimulation paradigm (using direct current) 2mA about 1/500 amount used by a 100W light bulb diagram in notes quite a basic machine with some electrodes that are stuck on the head what has changed is our understanding of how the brain works rather than how direct current influences it

Question 23

META-ANALYSES (HORVATH ET AL., 2014/15)

Answer 23

-Of the 59 analyses undertaken, transcranial Direct Current Stimulation (tDCS) was not found to generate a significant effect on any. * ‘Taken together, the evidence does not support the assertion that a single- session of tDCS has a reliable effect on cognitive tasks in healthy adult populations.’ * Main finding to take away from their papers – changes in MEP (motor evoked potentials, a way to evaluate motor cortex) amplitude after motor cortex stimulation seem to be the most reliable finding in the tES literature - still useful for recovery after stroke

Question 24

META-ANALYSES (HORVATH ET AL., 2015/16)

Answer 24

* BUT….this was a slightly unusual meta- analysis. * The authors decided to only include results that had at least one published independent replication attempt. * One hundred and seventy-six articles were excluded as a result. * A re-analysis including these papers would be extremely useful…

Question 25

SO WHY ARE TES’ EFFECTS SO VARIABLE?

Answer 25

Differences in cortical anatomy between participants Differences between electrode positioning between participants State- dependent effects of cortical activity between participants tES is SIMPLE; yet the BRAIN is complex…

Question 26

"Experimental Social Psychology" by Kurt Lewin, published in the Proceedings of the National Academy of Sciences (PNAS

Answer 26

Summary: 1. Scientific Approach to Social Phenomena: Lewin argues for the application of scientific methods—especially experimentation—to study complex social problems. He emphasizes the need to move beyond descriptive or purely theoretical approaches to more empirical, data-driven analyses. 2. Field Theory: He introduces and elaborates on field theory, which views behavior (B) as a function of the person (P) and their environment (E), formally expressed as: B = f(P, E) This approach highlights the importance of understanding individuals in the context of their environment or “life space.” 3. Importance of Group Dynamics: Lewin underscores the relevance of group dynamics, proposing that social groups are systems whose behavior cannot be reduced to the behavior of individuals alone. Group behavior must be studied in terms of the whole group's structure and processes. 4. Action Research: He advocates for action research, a method of simultaneously studying and trying to solve real-world social problems. Lewin describes how this approach is useful in areas like leadership training, reducing prejudice, and organizational change. 5. Experimental Design and Ethics: The article also touches on challenges in experimental design for social studies, particularly ethical concerns, complexity in controlling variables, and difficulties in replicating real-world conditions in the lab. 6. Practical Applications: Lewin illustrates how experimental social psychology can be applied to solve pressing societal issues—such as promoting democratic leadership styles, improving productivity, and addressing intergroup conflict. Impact: Lewin’s article is foundational, advocating a rigorous, scientific, and practical approach to understanding social behavior. His concepts—especially field theory, group dynamics, and action research—remain influential in psychology, education, organizational development, and beyond

Question 27

* Kilgard and Merzenich Cortical Map Reorganization Enabled by Nucleus Basalis Activity

Answer 27

Little is known about the mechanisms that allow the cortex to selectively improve the neural representations of behaviorally important stimuli while ignoring irrelevant stimuli. Diffuse neuromodulatory systems may facilitate cortical plasticity by acting as teachers to mark important stimuli. This study demonstrates that episodic electrical stimulation of the nucleus basalis, paired with an auditory stimulus, results in a massive progressive reorganization of the primary auditory cortex in the adult rat. Receptive field sizes can be narrowed, broadened, or left unaltered depending on specific parameters of the acoustic stimulus paired with nucleus basalis activation. This differential plasticity parallels the receptive field remodeling that results from different types of behavioral training. This result suggests that input characteristics may be able to drive appropriate alterations of receptive fields independently of explicit knowledge of the task. These findings also suggest that the basal forebrain plays an active instructional role in representational plasticity

Question 28

"Neural Correlates of a Perceptual Decision in the Parietal Cortex (LIP) of the Rhesus Monkey" by Shadlen and Newsome, published in Neuron (2001).

Answer 28

Summary Objective: The study investigates how neurons in the lateral intraparietal area (LIP) of the rhesus monkey encode information related to perceptual decision-making, specifically when interpreting noisy motion stimuli. Background: Perceptual decisions are those based on sensory evidence (e.g., deciding the direction of motion). The LIP area is known to be involved in eye movements and attention. The authors explore whether LIP neurons also reflect the evolving decision process, not just the sensory input or motor output. Methods: Rhesus monkeys performed a motion direction discrimination task using a random-dot kinematogram. Monkeys viewed a screen with moving dots and were trained to indicate the direction of motion by making a saccadic eye movement to a target. Researchers recorded from single neurons in the LIP during task performance. Key Findings: LIP neurons show gradually increasing activity during the decision period, particularly when the motion stimulus favors the neuron's preferred saccadic direction. This activity accumulates evidence over time, consistent with a drift-diffusion model of decision-making. The rate of activity increase correlates with the strength of the motion signal (motion coherence) and the decision time. The LIP activity appears to represent an internal decision variable, not just sensory input or planned movement. Conclusions: Neurons in the LIP integrate sensory evidence over time to contribute to perceptual decision-making. This supports a model in which decision-related neural activity builds up until a threshold is reached, triggering a behavioral response (e.g., an eye movement).

Question 29

The article "Neural correlates of perceptual decision in parietal cortex" by Shadlen and Newsome investigates how neurons in the lateral intraparietal area (LIP) of the monkey brain contribute to perceptual decision-making

Answer 29

The authors studied monkeys performing a direction discrimination task with moving dot patterns and found that LIP neurons reflect both the sensory evidence and the evolving decision. Key findings include: LIP neuron activity gradually increases or decreases depending on the strength and direction of motion, suggesting these neurons accumulate evidence over time—a process akin to evidence integration in decision-making models. The neuronal firing rate correlates with both the monkey's choice and the confidence in that choice. The results support the idea that perceptual decisions emerge from the temporal integration of noisy sensory evidence, and LIP serves as a critical site for this computation. Overall, this study links neurophysiological data with computational models of decision-making, providing insights into how abstract cognitive processes are implemented in the brain

Question 30

Evidence that transcranial direct current stimulation (tDCS) generates little-to-no reliable neurophysiologic effect beyond MEP amplitude modulation in healthy human subjects: A systematic review horvath et al 2015

Answer 30

Abstract Background: Transcranial direct current stimulation (tDCS) is a form of neuromodulation that is increasingly being utilized to examine and modify a number of cognitive and behavioral measures. The theoretical mechanisms by which tDCS generates these changes are predicated upon a rather large neurophysiological literature. However, a robust systematic review of this neurophysiological data has not yet been undertaken. Methods: tDCS data in healthy adults (18-50) from every neurophysiological outcome measure reported by at least two different research groups in the literature was collected. When possible, data was pooled and quantitatively analyzed to assess significance. When pooling was not possible, data was qualitatively compared to assess reliability. Results: Of the 30 neurophysiological outcome measures reported by at least two different research groups, tDCS was found to have a reliable effect on only one: MEP amplitude. Interestingly, the magnitude of this effect has been significantly decreasing over the last 14 years. Conclusion: Our systematic review does not support the idea that tDCS has a reliable neurophysiological effect beyond MEP amplitude modulation - though important limitations of this review (and conclusion) are discussed. This work raises questions concerning the mechanistic foundations and general efficacy of this device - the implications of which extend to the steadily increasing tDCS psychological literature. Keywords: Electroencephalography (EEG); Event related potential (ERP); Functional magnetic resonance imaging (fMRI); Neurophysiology; Systematic review; Transcranial direct current stimulation (tDCS); Transcranial magnetic stimulation (TMS)

Question 31

Early Views on Brain and Behavior

Answer 31

Ancient beliefs: Heart was seen as the center of thought/emotion (e.g., Egyptians, Aristotle). Hippocrates & Galen: Argued the brain is responsible for thought and senses. Galen: Dissected animal brains; showed sensory nerves connect to brain, not heart.

Question 32

Descartes & Reflexes

Answer 32

Proposed mind-body dualism: mind is separate but interacts with body via pineal gland. Believed in reflexes: automatic responses to stimuli (e.g., pulling away from heat). Used hydraulic models (inspired by garden statues) to explain movement. Wrong about fluids in nerves, but introduced testable mechanistic models.

Question 33

Galvani's Discovery

Answer 33

Showed electricity, not fluid, activates nerves/muscles. Sparked the study of electrophysiology and neural communication.

Question 34

Johannes Müller

Answer 34

Introduced doctrine of specific nerve energies: same electrical signal interpreted differently depending on the brain area (e.g., optic vs. auditory nerves). Promoted experimentation over passive observation.

Question 35

Experimental Ablation

Answer 35

Pierre Flourens: Removed animal brain parts to study function loss (e.g., movement, reflexes). Paul Broca: Linked speech loss to damage in left frontal cortex (now "Broca’s area"). Showed localization of brain function, though many processes (like speech) involve multiple regions.

Question 36

Fritsch & Hitzig

Answer 36

Stimulated dog’s motor cortex; observed muscle movements on the opposite body side. Identified primary motor cortex and its role in voluntary movement.

Question 37

Helmholtz

Answer 37

Measured nerve conduction speed (~90 ft/sec), slower than expected. Proved nerve signals are biological, not purely electrical like wires. Contributed to theories of vision, hearing, and energy conservation.

Question 38

Modern Advances

Answer 38

Inventions include: Amplifiers for electrical signals Neurochemical techniques (analyzing brain chemicals) Histological tools (viewing brain cells and structures)