Cognitive Neuroscience Quiz 2

Nature vs Nurture

The extent to which cognition & behavior can be attributed to genes OR environment

Genes

NOT a predetermined blueprint

Environment

Includes biological & personal, and social circumstances. Can turn genes on and off

Piaget’s definition of nature vs nurture

Development is a cyclical process of interactions between the child & environment

Genetic contribution

developing a brain that is ready to learn in certain ways

Environment contribuation

assimilating evidence via experience & developing new mechanisms from feedback obtained

Neuroconstructivism

Genetic AND environmental conditions influence brain development and cognitive development, and their INFLUENCES

Neuroconstructivism vs Piaget

Similar BUT no strict adherence to stages & an emphasis on brain-based constraints

Neural activity

changes neural architecture

and is affected by the environment & behavior

Predetermined Development

Genes → Brain structure → Brain function → Experience

Probabilistic Development

Genes ←→ Brain Structure ←→ Brain function ←→ Experience

Neurogenesis

Creation of new neurons

Synaptogenesis

Creation of new synapses

Synaptic Pruning

Elimination of some synaptic connections between neurons pre- and postnatally

What happens prenatally? 

cell division, neuroblasts, neurons moving to their destination

Cell division 

followed by differentiation into different tissues

Neuroblasts

proliferating cells in the neural tube that make up the nervous system

how neurons move to their destination

Newly formed neurons are either passively pushed or actively carried via radial glial cells

When are most neurons formed?

Prior to birth

Causes of postnatal increase in brain size

Myelination; synaptogenesis; glial cell proliferation

Synaptic density

Peaks after birth & then falls to adult levels

Where does neurogenesis still occur after birth?

Hippocampus and olfactory bulb

What is thought to increase gray matter density

Growing dendritic branches, synapses, or axon collaterals

Reducing excess synapses & efficiency

Reducing excess synapses may be related to increased efficiency in the adult brain

Plasticity

Brain changes in adults after motor skill practice

Juggling study (Draganski et al., 2004)

Before & after MRIs, juggling practice

Measurable increases in gray matter in V5 and intraparietal sulcus, temporal, & parietal regions.

• Practice can shape the macroscopic brain landscape

How do neurons in different parts of the brain develop specializations, in terms of what they connect to?

Protopmap and protocortex

Protopmap

- Regional layout is specified prenatally, with little role of experience

- Determined genetically, before thalamic input

Protocortex

- Sensory experience via the thalamus is important for determining the specialization of the cortex

- E.g., the somatosensory cortex transplanted into the visual area of a rat behaves like the visual cortex

Critical periods

• Gradually

• Period of maximal sensitivity

• Skill can still be learned, but less efficiently

• i.e., language development

Sensitive periods

A period in development when specific experiences have enhanced long-lasting effects on behavior and the brain. Optimal time for learning.

• Abrubtly

• An organism has heightened sensitivity to external stimuli that are compulsory for the development of a particular skill

• Cortical areas allocated for the particular skill will adapt and perform a different function

• i.e., full development of visual capabilities (from 8 months to 3 years)

2nd language learning and sensitive periods

No endpoint

Decreases linearly with age

No critical window

Early learners are more successful

Wartenburger et al (2003)

Compare L1 to L2

Learned later (mean 19), more activity in language-related brain regions for L2, regardless of how proficient

Learned earlier (birth), the same activity→is more efficient

More efficient in terms of brain activity if learned earlier

More of a sensitive period

What are the implications for the idea of a sensitive period for language learning

More efficient if learned early

Role of visual deprivation in one eye – what happens and at what time? Hubel & Wiesel studied with cats. What is this evidence of?

Removed at 6 mos.

Neurons in the visual cortex did not respond in the deprived eye

Vision unaffected in adult cat

Stimulation shapes the brain in a critical period

Genetically Programmed Synaptogenesis

Occurs throughout the lifespan

Explosion during early brain development

Connections are shaped by experiences

What could cause the closure of the window? Evidence?

Pre-set timetable or could be initiated by learning itself

i.e., an environmental cue

GABA explanation and study findings

Suppressing GABA production in the visual cortex of young mice deprived of visual stimulation protected them from blindness

Perineuronal Nets explanation and study

injected an enzyme that dissolves the net in the visual cortex of adult mice, opened the 2nd critical period window

Reversed effects of early visual deprivation

Blocking or removal of PNNs influences functional recovery after a variety of CNS lesions.

Role in learning & memory

Perineuronal Nets

specialized extracellular matrix structures responsible for synaptic stabilization in the adult brain.

Surround the soma & dendrites of some mammalian neuronal cell types

what do Executive Functions do

Optimize performance in situations that require coordination between a number of cognitive processes → GOAL-ORIENTATED

Supervisory EF

Not linked to one domain

Not just for language, hearing, and vision - it’s for everything

All cognition and social processing

Prefrontal cortex

like Central Executive in WM

Implicated in many types of cog control or executive decisions

EF helps regulate what

behavior according to higher-order goals or plans

can be simple goals or more complex

Executive processing

requires conscious awareness, effortful, and limited in capacity

Requires attention and EF

AKA controlled processing 

Can’t do multiple things at once

Automatic processing

fast, effortless, no attentional capacity limits

Don‘t require attention or EF

Don’t have to think about doing it

Controlled processing

can become automatic through preparation and learning

Automatic processing examples

Riding a bike (not in the beginning)

“Reading” a stop sign (cannot not read it)

Recognizing the face of someone familiar

Walking (after 8m)

Tying shoes (after learned)

Sports or instrument

Many motor skills

Simple math (2+2)

Controlled processing examples

Driving in an unfamiliar area

Writing an email

Solving complex math problems

Playing a new sport

Writing a paper

Goal-oriented Behavior

an action that is planned & produced to achieve a particular result

Habit-driven behavior

a response that is under stimulus control

- Occurs independently of reinforcement

- Inhibitory control matters here

Executive functions

Inhibition, Cognitive Flexibility, Working Memory

Inhibition

ability to suppress automatic responses or distractions

Cognitive Flexibility

the capacity to adapt to new rules or shifting demands

Working memory

ability to hold and manipulate info

Role of prefrontal cortex

Helps regulate behavior according to higher-order goals or plans

Lateral

Sides

Medial

Middle

Orbital

Front

Lateral surface

Cognitive aspects of executive functioning

Orbital and medial surfaces

Emotional/social regulation of behavior

Dysexecutive Syndrome

linked to frontal lobe injury

Perseveration

Distractablitlity

Planning difficulties

WCST errors

Perseveration

produce the same response on successive trials, even when the response is no longer appropriate

Distractability

Stroop task

Utilization behavior

Stroop task

inhibit the word to say the ink color

Utilization behavior

dependency on the prototypical use of an object without regard to use in a particular context

Hammer, nail, & picture in office

Planning

Some patients are normal on these tests, but have difficulty planning future actions

Prospective memory

memory for future events

Norman and Shallice (1986) identified five general situations requiring executive functions – know these and descriptions of tasks used to measure them.

(1) Planning or decision making

(2) Error correction or troubleshooting

(3) Where responses are not well-learned or contain novel sequences of actions

(4) Dangerous or technically difficult situations

(5) Require the overcoming of a strong habitual response or resisting temptation

Planning and decision making

Tower of London task: PFC is activated in functional imaging during the task, & damage to the PFC results in poor performance

Error Corrections and Troubleshooting

Wisconsin Card Sorting Task (WCST)

Wisconsin Card Sorting Task (WCST)

shift in strategy following an unexpected rule change

PFC damage – perseverate:

Fail to correct errors when pointed out

Novelty

FAS Test

FAS test

1 minute, all words that start with F

Left PFC damage-impaired:

Says repeats

Dangerous or technically difficult situation

Situations generally involve immediate threats to life and health:

Overcoming Habitual Response

Stroop Test

Stroop test

Name the ink color, not the word

Left PFC – patients have difficulty

Unitary Accounts

PFC is involved in “executive control.”

A single factor can account for the data

3 types of evidence/arguments in support of unitary account

Patients' performance on many tests of EF correlated with each other (Duncan et al.)

Review of imaging literature suggests hard to localize an individual EFs (Duncan & Owen, 2000)

Single-cell recording of PFC neurons show that they change their responsiveness flexibility (Miller & Cohen, 2001)

Goldman-Rakic’s Theory of Working Memory

Based mainly on primate studies (e.g. single-cell recordings)

Assumes a unitary executive (like "central executive"): PFC not divided into separate processes (based on single cell recordings)

Assumes some division into spatial processing and object-based WM

Multiple Process Accounts (Non-Unitary)

There are executive functions supported by the PFC

Distinct processes are all related to the general concept of control functions

2 pieces of evidence/arguments for Non-Unitary accounts

Evidence of functional specialization in PF

Low correlations among performance on executive tests

Functional Specialization within the Lateral Prefrontal Cortex

Multiple process accounts

Ventro-Lateral PFC

Retrieval & Maintenance of Info

Left processing in Ventro-Lateral PFC

Broca’s – semantic/linguistic info

Right processing in Ventro-Lateral PFC

visual/spatial info

Dorsolateral PFC

Suppression & Monitoring

Left Dorsolateral PFC

Suppressing inappropriate responses & selecting a response

Frith et al. (1991)

region active in "free will" (PET)

choosing which finger to move vs. being told which finger to move

TMS in the left dorsolateral PFC

disrupts random digit generation

Right Dorsolateral PFC

Monitoring info held in memory and sustained attention

When is right doraolateral PFC active (during what kinds of tasks/under what conditions)?

In conditions of uncertainty:

- tip-of-tongue states

- confidence judgments in memory (low confidence = greater activity)

Anterior PFC

Multitasking - “branching”

Active when multiple tasks need to be coordinated

Role of the Anterior Cingulate in Executive Functions

Monitoring in situations of response conflict & error detection

Monkey study for Anterior Cingulate in Executive Functions

Monkeys with lesions here don’t troubleshoot or correct after making an error (error+1 trial worse than correct+1)

fMRI shows activity greatest on error trial, but lateral PFC greatest on error+1 trial

Suggests anterior cingulate detects but doesn’t correct errors

Anterior Cingulate and Emotion Regulation

Connections to the PFC & Limbic System

Negative emotional stimuli activate a broad network

- medial prefrontal cortex (mPFC)

- anterior cingulate cortex (ACC)