PSYCH 221 Final Review

Individual differences are _____ and _____ characteristics that make people think, feel, behave in their own unique ways.

Long-lasting and biologically + environmentally shaped

What do Brain-Wide Association Studies look for the relationship between?

• Brain measures

• Behavioral or clinical traits

What is a pro and con about BWAS (Brain-Wide Association Studies)?

Pro: They are generalizable because they look at whole-brain data across many individuals

Con: The average brain metrics across people which means they can wash out meaningful details about individual differences

Explain what Precision Functional Mapping (PFM) is

It focuses on one individual at a time, collecting a large amount of high-quality data from a single person. It aims to capture the unique features of one specific person.

What is a pro and con of PFM (Precision Functional Mapping)?

Pro: It typically requires fewer people overall because it collects so much data per person

Con: It typically requires atleast 90 minutes of fMRI time per patient to get stable and reliable measurements

What is the main tension between breath (BWAS) and depth (PFM)

• PFM = deep, precise, individualized data (but small samples → limited generalizability)

• BWAS = broad, population-level data (but shallow per person → limited individual resolution)

What are resting-state networks and why are they useful to measure?

At rest, the brain shows consistent patterns of synchronized activity, which reveals systems of regions that work together. These networks show the brain’s functional organization.

What is a fixation task?

A fixation task means that participants stare at a fixed point (like a +) in order to get a resting-state fMRI.

What are functional connectivity and why are they useful?

When people are resting, some brain regions show synchronized ups and downs in their BOLD signal. To quantify this synchrony, researchers take the time series for each region and calculate the correlation.

What did Poldrack do that inspired PFM?

He scanned his own brain twice a week for 18 months. From this study, he found that his overall brain networks were mostly stable, but where slightly sensitive to daily-life factors.

What was one key finding from the Poldrack study?

He found that if he didn’t have caffeine, the connectivity between the somatosensory-motor networks and high-level visual networks became tighter.

What are 2 studies that expanded PFM after Poldrack’s initial self-study?

• Washington University - Midnight Scan Club

• Harvard - Buckner Lab

Explain the Washington University - Midnight Scan Club

A group of 10 researchers scanned themselves late a night. Each person scanned themselves 10 times.

Explain the Harvard - Buckner Lab

They recruited 4 volunteers and scanned each person 24-30 times. 

What are 3 things the Harvard and WashU groups converged on for PFM?

1. To get a stable map of a person’s networks, you need many minutes or hours of data per individual (one scan is NOT enough)

2. Brain networks differ across people, but are stable within a person

3. Each group released data, analysis pipelines, software tools, etc. to make PFM accessible to labs worldwide

What is precision medicine?

Precision medicine is an approach where treatments are tailored to the individual, rather than assuming the same treatment works equally well for everyone.

Explain the intractable depression case study?

There was a 44 year old man with severe treatment resistance depression. He tried many depression treatments that didn’t work, so an individualized brain-based approach was used. The PFM revealed major deviations (SN ~400% expansion and DMN + FP Networks ~25% smaller)

Explain how Personalized Adaptive Cortical Electro-Stimulation (PACE) works

1. Electrodes are implanted in the brain to target sites based on patient’s functional network maps

2. Stimulation parameters (frequency, intensity, timing) are customized to individual’s brain connectivity patterns to modulate dysfunctional networks and preserve normal function

What are 3 observed effects of PACE?

1. Noticeable mood and cognitive improvements within 24 hours

2. Suicidal thoughts were completely resolved after 7 weeks

3. Full remission of depression by 9 months

What are 2 significant things about using precision-targeted brain stimulation for TRD?

1. Promising: The study showed that PACE was effective even against TRD

2. Scalable: If validated, this method could guide treatments for other patients

What is the basic emotion theory?

It states that emotions are:

• Biologically innate: Emotions are hardwired

• Discrete: Each emotion is a distinct category

• Universal: Emotions appear across all cultures, with similar expressions

• Dedicated neural and physiological systems: Specific brain circuits and body systems generate each emotion

What does PFM tell us about brain development?

It tells us that brain networks supporting emotion differ in exact layout and connectivity across individuals. Even within an individual, connectivity between networks can evolve with age.

It suggests emotions are not entirely fixed and can be shaped by experience, environment, and development, interacting with innate biology.

What are 5 principles of adolescent brain development?

1. Myelination: Faster thinking and better coordination between regions

2. Cortical Thinning: Redundant connections are eliminated (synaptic pruning)

3. Hierarchal Development: Basic sensory and motor regions mature first to support development of more complex cognitive abilities

4. Plasticity: Brain can be shaped by experience

5. Nonlinear Development: Small changes in network connectivity can produce large behavioral effects

How does the adolescent brain compare to an adult brain in terms of efficiency?

The structure of a adolescent brain is less efficient and less integrated than the adult brain

What is mean diffusivity and how does it change over time?

• High MD means water moves more freely → less organized/less mature white matter

• Lower MD means water movement is restricted along axons → stronger, more myelinated connections

Decreasing MD over age = strengthening and maturation of white matter pathways

What does MD show about brain development? What idea does it support?

It shows that different parts of the brain mature at different rates, supporting the idea of hierarchical brain development.

Explain why gray matter declines?

1. During early brain development, neurons move to their proper positions in the cortex

2. In early development, the neurons form a lot of connections (more than necessary)

3. Some neurons are misconnect or not optimally used, causing the brain to prune those connections

Explain how synapse rearrangement works and what effects it could have

Pruning proceeds from caudal regions (back of brain - visual and sensory areas) to rostral areas (front of brain - prefrontal cortex). Since the prefrontal cortex develops last, it explains some adolescent behaviors.

What is plasticity?

The brain’s capacity to change and adapt in response to experience, learning, or environmental input.

What is the sensitive period?

It is a window in development when the brain is especially receptive to certain experiences or stimuli. Experiences during this time will have stronger and longer-lasting effects on neural structure and function.

What is the critical period?

It is a narrow developmental window during which specific input is essential proper development. If the brain does not receive the required experience during this time, the function may never develop properly.

What is amblyopia?

It is a vision impairment in one eye that often occurs when one eyes is misaligned or experiences blurred input during development. The result is that the brain learns to ignore input from the affected eye, leading to incomplete vision.

• If not treated early, normal vision cannot be fully restored

What is binocular deprivation?

If deprivation of sight lasts too long, it results in loss of dendritic spines and synapses in the visual cortex. If deprivation happens for too long, sight cannot be restored.

What is the imbalance model?

It explains certain adolescent behavior based on asynchronous brain development.

1. Emotion and reward system develop too early

2. Control systems lag behind

This leads to:

• Greater emotional intensity

• Impulsive decision-making

• Increased risk-taking behavior

Explain the experimental setup of the go/no-go task?

1. Participants see series of stimuli (faces showing emotions)

2. One type of face is a go target (press button whenever that face appears)

3. Another face is a no-go target (withhold pressing when that face appears)

4. Some faces were emotionally eye-catching

5. They recorded brain activity to see which regions were engaged

What 2 findings did the go/no-go task reveal?

1. Subcortical regions (amygdala, ventral striatum) respond to emotional stimuli.

2. Prefrontal regions (prefrontal cortex) are engaged during inhibition.

During adolescence, why do teenagers often experience heightened negative emotions?

During adolescence, medial prefrontal cortex (mPFC) activity is elevated, which contributes to more self-referential thinking

What is memory?

Its the ability to store and retrieve knowledge

What is learning

Its the process of acquiring new knowledge

What is neuroplasticity

Its changes in structure and function of synapses

What is amnesia?

It causes difficulty with forming or retrieving memories

What were the 2 memory impairments that patient H.M. experienced after having portions of his medial temporal lobes removed?

1. Retrograde Amnesia (Graded): He lost memories from before the surgery. (In this context, graded means older memories were in tact while memories closer to the surgery were more impaired)

2. Anterograde Amnesia: He could not form new memories after the surgery

What is the mirror-tacing task?

The person has to trace a shape while only seeing their hand through a mirror.

• It is a tricky task that requires practice

What did the mirror-tracing task reveal about patient H.M.?

He improved day after day even though he did not recognize the task. This implies that his declarative memory was impaired, but his procedural memory system was intact.

What are the 2 types of long-term memory?

• Declarative (What): Memories that you can say out loud and describe

• Procedural (How): Memories expressed through actions, skills, or behaviors

What are the 2 types of declarative memory?

1. Episodic Memory: A specific experience tied to a particular time, place, and context

2. Semantic Memory: General knowledge (facts, concepts, word meaning, etc.)

Which part of the brain is involved in declarative memory?

Hippocampus

What lobe is involved in learning and long-term storage of declarative memories?

The medial temporal lobe

What are 2 pathways that connect to the hippocampus? What can happen if they’re damaged?

• Mammillary Bodies

• Dorsomedial Thalamus

Damaging these pathways can lead to sever anterograde amnesia

Explain the delayed non-matching-to-sample (DNMS) task

1. Sample Phase: Monkey is shown an object (they touch it to get a reward)

2. Delay: Monkey waits a few seconds to minutes

3. Test Phase: Monkey is shown 2 objects (familiar object + new object)
   

To get the reward, the monkey must touch the new object

What is memory trace? Explain the process of forming new memories

A memory trace is the physical change in the brain that occurs when a memory is formed.