Lecture Notes

Empirical: use observation to gather knowledge about the world

Monty Hall Problem:

• AKA 3 Prisoners Problem

• Like 3 doors in Let’s Make a Deal gameshow

  • One door has a car, other two have goats

• Basically says that if you pick a door, and a different door is revealed to be lose, you have a higher chance of winning when you switch

  • Good explanation on the lecture slides that I ain’t typing here

Ockman’s Razor

• says that the simplest explanation is the best

• Explains that simple theories are more testable

Scientific Method

1. Create hypothesis

   • Specify problem, definitions, variables, and how to quantify data

2. Test hypothesis

   • Experimental and quantifiable data

   • Experiment must be replicable

3. Form Theory

   • What you think is happening after the experiment

4. Replicate, try again

   • Try different populations, data, and experiment

Measures

• Validity: correct measure?

• Reliability: consistent results?

• Power: can we detect effect

Types of Data

Descriptive Data

• Central Tendency - measures where most of the scores fall

  • Mean, median, mode

• Variability - measures how scores differ

  • Range, standard deviation

Correlational Data

• $\Delta$ variable → $\Delta$ other variable

• R coefficient

• Limitations of correlation data

  1. The “third-variable” problem (confounding)

     • ex: eating more ice cream correlates with sunburn

       • in reality its because the sun is out and you get hot and that’s why you eat more ice cream

     • “100% of people who breathe, die”

9/5/24 - M2: Research Methods contd.

Experimental Design

• Independent variable - data you control

• Dependent variable - data that’s measured

Choosing a sample

• Case study: single individual

• Random sample: every member of a population has an equal chance of being represented in the sample

• Generalizability is important

• Control group: group that doesn’t get the experiment

  • kinda like the baseline to compare experimental with

• Experimental group: group that gets experiment

Case of Phineas Gage

• Some guy that was detonating Earth for mining

• During detonation a railroad iron rod (big af) shot through his face, specifically via the upper jaw, passing back of the left eye, through the top of his head.

• Still alive and even walked up a flight of stairs

• The rod impacted the Benevolence and Veneration regions of the brain; impacted his personality (more wild behavior, impulsive, etc)

• Died later when impairments returned (seizures, etc).

• Frontal injury = some disruption of personality for a limited time

Controlled Lesions

Hermann Munk (1884)

• Experimented in the Occipital cortex of dogs

• Seelenblindheit: psychic blindness

• Navigation working, but object recognition was impaired

Mishkin & Underlieder (1980’s)

• Found 2 seperate pathways for vision and location

• Tested on Macque monkeys

9/9/24 - M2 Research Methods cont.

Direct Brain Stimulation

• Done by Wilder Penfield in 1950s

• Instead of damaging brain for research, stimulating is harmless

  • asked people how they felt during stimulation

He found map of body in parental cortex

• somatosensory cortex

• stimulating different areas of somatosensory cortex → feel vibrations etc in different parts of body

• 
  

  

Neurophysiology

• Single neuron recordings

  • Lettvin et al. (1959): What the frog’s eye tells the frog’s brain

    • I think the most cited paper in science or smth like that

    • Recorded data from single cells in frog eye retinas

    • Eyes responded to small moving spots of light

  • Hubel and Wiesel (1962): cat eye’s brain cells

    • recorded cell reaction in cat occipital cortex

    • cells responded to oriented lines

    • neurons make a ton of popping noise when looking at lines (think of Geiger counter going crazy near radiation)

Neuroanatomy

• Staining and tracer dyes

  • traces how information is passed from one brain region to another based on metabolism in brain

  • like contrast staining in MRI

  • showed functions of diff brain regions (e.g. orientation-specific cells in visual cortex, like the cells responded to lines from cat study above)

  • showed structure of neurons (e.g. visual structure)

Neuroimaging

1. CT - Computed Tomography

   • Uses X-rays

   • Achieves tomographic images (slices of sections of brain)

   • Slices are 2D; multiple slices → 3D

   • High resolution

2. EEG - Electroencephalogram

   • Electrodes on scalp surface detect electrical current

   • literally measure electrical current in areas of head as a result of brain activity

   • Directly measures neural activity

   • great for sleep studies and seizure observations

3. MEG - Magnetoencephalography

   • same signal as EEG but instead observing magnetic fields produced by electrical currents

   • directly measures neural activity

   • same clinical/experimental applications as EEG

   • very expensive, but lot easier to setup than EEG cap

4. PET - Positron Emission Tomography

   • inject radioactive isotope tracer carried by glucose to brain

     • less radioactive exposure than when you go on a plane

   • track neural activity via tracer

   • Indirect measure of neural activity

   • expansive and invasive (bc inject in skin)

   • excellent spatial resolution, not so much temporally

5. MRI - Magnetic Resonance Imaging

   • Giant magnet that pulses tissue with an electromagnetic pulse

   • measures differences in tissue magnetization

   • basically takes a pic of how cells react to being “knocked over” by magnets

   • awesome spatial resolution

9/13/24 - M2: Cognition and Brain Overview

Nervous system

• maintains contact with the outside world

• regulation of inside world

• 2 nervous systems

• Central Nervous System

  • consists of Brain, Spinal card etc

  • Split in 5 sections

    1. Cervical

    2. Thoracic

    3. Lumbar

    4. Sacral

    5. Coccygeal

  • handles automatic reflexes

• Peripheral Nervous System

• Connects central NS to organs and muscles

• basically controls everything that isn’t brain or spinal cord

• Somatic Nervous System - Sub system that controls muscles

  • Afferent nerves bring info in

  • Efferent nerves take info out

  • no other divisions for this system

• Autonomic Nervous System - Subsystem that controls stuff we don’t think about

• breathing, heart beating, glands, muscles, etc

• happens automatically

• its why we don’t have to worry about breathing or beating our heart

• Sympathetic Nervous System - subsystem of Autonomic NS for fight or flight

  • Fight, fly, freeze

  • Dilating pupils, sweating, increased heart rates, and dry mouth result from Sympathetic NS triggering during stressful/nervous situations.

• Parasympathetic Nervous System - subsystem of Autonomic NS for calmness when body is not doing anything

  • Homeostasis

    • lowered heartrate, decreased stress, etc

Neurons

• Basic info

  • Building blocks of central nervous system (CNS)

  • we have ~100 billion neurons & 1 quadrillion synapses

  • ~600 miles of neurons in our body

  • we have as many neurons as there are stars in the milky way

  • rate of neuron growth during fetal development in utero =

• Discovering neurons

  • Golgi Staining: Camillo Golgi

    • Silver nitrate turned nerve cells dark black for viewing

  • Santiago Ramon y Cajal: discovered gaps between neurons

    • shared Nobel Prize with Golgi

• Neuron Structure

• Like a regular body cell, but with more specific functions

• Information processing from receptors called Dendrites

• Axon - Information transmission

  • Lengths: 1mm to 1m

  • longest axon is sciatic nerve

• Dendrite - Information reception and relay

• Myelin - protected and speeded information transmission

• Fatty material composed of glial cells

• Insulates axon

• Stores energy

• speeds up information transmission

9/16/24 - Missed lecture 💀

9/18/24 - M3 Zaps

• Reflection set due date → All ZAPS grades recorded on Canvas

• Reflection sets aren’t pledged → collaboration allowed

  • but you can’t copy answers word for word

• Pooling material from all lectures in one response is not expected

  • instead dr. OH expects everyone to have their own interpretations of the lectures

• Reflection will have <15 short answer questions

now onto actual lecture

left and right brained people dont exist

• left side of the brain → controls left side of the body

  • and left visual field → left side of both eyes

• right side of the brain → controls right side of the body

  • and right visual field → right side of both eyes

Lateralization of function

• when different mental functions tend to belong in left or right side of brain

• examples:

  • speech comprehension → left side

  • speech production → left side

  • language (grammar, vocab) → left side

  • 
    

  • visual semantics (object recognition) → right side

  • face processing → right side

  • language (patterns, rhyme, etc)→ right side

Corpus callosum

• connects left and right hemispheres of the brain

  • cutting the corpus callosum does not actually impact brain that much

  • ex: guy in video had frequent seizures (2-3 times a day)

    • scientists cut corpus callosum because it would prevent “electrical storm” that causes seizures from starting

    • it worked

    • actually the guy was able to control left and right side of the body easily and independently

      • ex: he could draw circle and square with respective hands easily

    • “its like 2 different people doing the same thing in 1 body”

anatomy of brain

• Frontal lobe - Memory and Motor

  • Speech, motor cortex

• Parietal lobe - Sensory and Spatial

  • Speech, taste, reading, etc.

• Occipital lobe - vision

• Temporal lobe - language, memory, auditory

  • Smell, auditory association area, hearing

    

Directions and planes

• Lateral view - side view from outside

• Medial view - view as if cut through middle

• Anteror - front side

• posterior - back side

• dorsal - top side (superior)

• ventral - bottom side (inferior)

Views for neuroimaging

• Saggital - view slice of brain basically

  • 3d scan is a bunch of these slices

  • angle of slice doesn’t matter

• Coronal (Frontal) - slice from front of face

• transverse - slice from bottom side

• 
  

  

• Cerebral cortex - outer layer of brain

Subcortical structures - inner part of brain

• Thalamus → sensory relay center

• Hypothalamus → basic and essential body needs (heartbeats, breathing, organ function etc).

• Hippocampus → memory and learning (super important)

• Amygdala → emotion, super primitive

• Olfactory bulb → smell

Attempt ZAPS before Friday (9/20/24)

9/23/24 - Sensation and perception

• Purpose of perception is survival

Basics of sensation

• 5 senses

• Vision is the most important sense

• Phantom limb phenomenon

  • when painful sensations originate from where an amputated limb is

• Vision

  • Cornea - light refraction

  • Pupil - lets light in

  • Iris - dilates the pupil; eye color

  • Lens - change shape to change focal structure

    

  • Retina

    • Rods - sensitive to light intensity = better in low light, better with motion

      • Brightness?

    • Cones - sensitive to light wavelength = color vision, high acuity

      • Color!

    • Fovea - center of visual field, highest concentrations of cones

    • Optic disc - blind spot

      • this is because there’s a hole in retina where optic nerves come from

    • Photoreceptors don’t see color, they sense light

    • There’s no such thing as color, our brains just interpret color.

• optic chiasm - visual field info decussates to contralateral hemisphere

  • left visual field goes to right brain

  • right visual field goes to left brain

• LGN - relay center in the thalamus

  • bunch of nuclei in the thalamus that are responsible for vision and other senses (except smell)

  • LGN sends to the primary visual cortex (V1)

9/25/24 - Pathways for other senses

Dorsal and Ventral Routes

• What happens after visual cortex?

  • Dorsal - where and how; parietal association areas

  • Ventral - what; temporal lobe

Sound

Functional Utility

• Location: binaural cues carry info about where you are and where things are.

  • we have bad echolocation, but blind people can actually echolocate because they much better sense of sound

  • basically because the visual cortex isn’t at work in blind people, so the brain reassigns that brainpower towards sound cortex

• Identification

• Efficiency: travels fairly well in air

Touch

Functional Utility

• Somatosensation - feeling on your skin

• Proprioception - when you can still know where you and some objects around you are when you cant see

  • ex: when you get soap in your eyes in the shower and still know where the other stuff is

• Nociception and pain perception - help you survive, we percept pain individually

Taste

Functional Utility

• helps prevent eating things that will kill you

• Bumps (papillae) contain taste buds.

• taste buds house taste receptor cells.

• all areas of tongue taste the same uniformly

Smell

Functional Utility

• Helps us survive — smell fire

• social behaviors

• Olfactory bulb transmits info to olfactory cortex. Axons also project to:

  • Medial temporal lobe (hippocampus and adjacent areas): memory

  • Amygdala: emotion

• Smell is a huge memory trigger for humans bc of how closely linked hippocampus is with the olfactory

From sensation to perception

Sensation → transduction → perception

9/27/24 - Missed Lecture

9/30/24 - Cancelled Lecture

10/2/24 - Perception

• Bottom-up — what we actually perceieve

• Top-down — how our brain processes stimuli?

• Unconscious inference — filling in the blanks

• Necker cube with holes in slides example.

• We see things not as they are, but as we are