Cognitive Neuroscience Ritchey Exam 1

Willis (1650)

Willis (1650)

Noticed that brain damage caused changes in behavior - "Neurology"

Phrenology

Gal (1810) Aspects of oneself was represented based on shape of the skull --> Psuedoscience

Distributed views of brain function

- Cognitive functions are supported by distributed sets of neurons across the brain

- Impairments are proportional to total damage

Localizationist view

- Cog functions are supported by specific localized areas of the brain

- Impairments are proportional to damage to a specific region

Distributed views theories/papers

Aggregate field theory and Flourens (1824)

Localizationist view theories/papers

Functional mapping of the aphasias, Broca (1860) and Wernicke (1876)

Two Philosophical Approaches

Rationalism (Descartes, mind-body 1644)

Empiricism (Locke, tabula rasa 1697)

Experimental Approaches (late 1800s)

RT differences (Donders, 1869)

Forgetting Curve (Ebbinghaus, 1885) (Associationism)

Three Behaviorist and their Beliefs (early 1900s)

Thorndike: law of effect

Watson: mental activity cannot be observed

Skinner: operant conditioning, reward and punishment

Central Nervous System

Brain + Spinal Cord

Peripheral Nervous System

Nerves & nerve cell ganglia —> autonomic & somatic nervous systems

Nucleus

Relatively compact arrangement of nerve cell bodies and their connections

Grey matter

Neurons arranged in layers form a sheet of tissue

Most the outer region of the brain

White matter

Axons and glial cells form tracts inter-connecting the brain

Much of the inner part of the brain

Cerebral Cortex

the outer layer of your brain's surface, located on top of the cerebrum

Sylvian fissure

Divides Frontal and Temporal Lobes

Central Sulcus

Divides Frontal and Parietal Lobe

Corpus Chalosm

Divides Right and Left hemisphere

Sensory Cortices

brain regions specialized for processing sensory information, such as vision, hearing, touch, taste, and smell

Association Cortices

regions of the brain that integrate information from different sensory modalities or sensory and motor regions. Unlike sensory cortices, they are not dedicated to processing just one type of information but are involved in more complex tasks such as perception, memory, attention, and decision-making

Visual Cortex

Located in the back of the occipital lobe (Area 17 or V1)

Frontal Cortex

Divided into Medial prefrontal cortex(also includes ACC) and motor cortex

4 Major divisions of the Brainstem

Pons, Midbrain, Medulla, and Spinal Cord

Cingulate Gyrus

Wraps around corpus callosum like a belt

Component of the limbic system, it is involved in processing emotions and behavior regulation. It also helps to regulate autonomic motor function

What are the three major subcortical areas and their function

Hippocampus - memory

Basal Ganglia - controls body’s voluntary movements

Amygdala - Emotional memory

Subtraction method

Compare tasks or task conditions that differ by only one cognitive process

i.e., Experimental —> Make a decision about a word on the screen

Baseline —> press button when word appears on the screen

Spatial and Temporal Resolution of Methods (Show 8)

Three major degenerative causes neurological damage

Alzheimer’s, Parkinson’s, Huntington’s

The lesion approach

Location of lesions + neuropsychological testing

Some limitations of the lesion approach

• Other changes might be correlated with brain damage

• Damage to one region might lead to dysfunction in other connected regions

• Need really good control conditions to isolate process

Examples of Pharmacological manipulations

L-DOPA, Haloperidol —> altering amount of dopamine and testing reward based learning

Transcranial Magnetic Stimulation

Magnetic field generator to induce electrical currents through the scalp & skull

• Currents stimulate action potentials —> firing disrupts responses in that area

• Can target small areas of cortex, but only cortical regions and only one region at a time

Online vs. Offline TMS

Online —> TMS performed during the task

Offline —> TMS given before the task

Transcranial Direct Current Stimulation

Low-level currents, electricity, depolarization of anode site

Affects bigger area, does not necessarily drive action action potentials

Electroencephalography(EEG)

• Oldest cognitive neuroscience method

• Detect electrical current from pyramidal cells in cortex measured with electrodes on the scalp

• Electrical signals could be from anywhere in the head not just underneath (volume conduction)

Magnetoencephalography(MEG)

Similar to EEG but measures currents from a magnetic field; magnetic fields are less distorted by the skull

Event-Related potentials

Averaging of scalp potentials time-locked to the stimulus; Get the cognitive signal out of the noise

Electrocortogram (ECoG)

Excellent temporal resolution and spatial resolution

• limited to testing surgical patients who volunteer their time

• little control over electrode location

• Electrodes sit directly on the brain

Magnetic Resonance Imaging(MRI)

Uses magnetic fields to detect hydrogen atoms in the brain, can scan the brain slice-by-slice

Diffusion Tensor Imaging (DTI)

Use directional information to identify probable axons tracts - “tractography”

Measures the diffusion of water molecules in the brain

What is a voxel?

3-D Pixel in brain image as they all have four dimensions

Blocked-Design Trial

Similar stimuli are grouped together

• lower temporal resolution

• focused on sustained period

• Overall activation patterns during task blocks

• e.g. Block 1: Happy Faces (10 faces)

• Rest (10 seconds)

• Block 2: Sad Faces (10 faces)

• Rest (10 seconds)

• Block 3: Neutral Faces (10 faces)

• Rest (10 seconds)

Event-related Trial

Random ordering of stimuli or determined by the subject; better temporal resolution

• Face 1: Happy

• Face 2: Sad

• Face 3: Neutral

• Face 4: Happy

• Face 5: Sad

• Face 6: Neutral

• (This continues for a total of 30 faces, with a mix of emotional expressions)

Sensation

Early processing of stimulus in environment

Perception

Formation and experience of the mental representation of the stimulus

Pathways Sensation and Perception

Receptor cells —> nerve pathways —> brainstem —> thalamus —> primary sensory cortex and secondary sensory cortex

Coding Principles

Receptor cells - limited range and tuned to info in the receptive field

Acuity - how well we can distinguish two stimuli

Adaptation -adjusting to the sensitivity of the sensory system to the current environment

Rods (photoreceptors)

• rhodopsin

• sensitive to low light

• deplete quickly

• distributed throughout

• no color sennsitivity

Cones (photoreceptor)

• Photopsin

• require more intense light

• replenish quickly

• most in fovea

• color sensitivity(RGB)

Pathway of Visual System

Receptive Field

Region of space in which a stimulus will
trigger a response in a particular neuron
○ Ordered continuously
○ Arranged in an ordered way

Retinotopy

Ordered mapping of the visual field onto visual areas (retinal projection)

An example of topographical organization within the brain

Topographical Organization

The ordered mapping of the external world to its representation in the brain

• Nearby neurons represent similar aspects of the world

• Retinotopy, tonotopy, somatotopy

Ocular dominance and orientation selectivity

Pathway of the Auditory system

Two aspects of Sound Localization

Interaural time - difference in timing between ears

Differences in intensity between ears

Olfaction and Stimuli

Sensed Stimuli: Odorant

Perception: Smell

Gustation and Stimuli

Sensed Stimuli: Tastant

Perception: Taste

Gustatory Transduction Pathway

Taste receptor cells → Vagus cranial nerve → Thalamus → Cortex

Somatosensory in S1

McGurk Effect

Hearing different audio based off what your eyes see them pronouncing

Where does multisensory integration occur?

Premotor cortex, inferior prefrontal cortex, posteriors superior temporal sulcus

What is machine learning?

An algorithm that learns to make predictions; given a new set of data, similar to other data is has seen before, what will be the outcome?

Multi-Voxel Pattern Analysis

Apperceptive Agnosia

Difficulty with object constancy (e.g. unsual views)

Associative Agnosia

Difficulty linking perception to the object’s identity/function

Integrative Agnosia

Difficulty integrating parts into a whole

Evidence for category specificity

• Agnosia’s for specific categories

• Brain areas for specific categories (e.g FFA, Lateral occipital cortex(objects))

Evidence against Category specificity

• Category membership is correlated with certain characteristics(properties)

• Representations may be organized around object properties

Two Hypothesis about the organization of semantic knowledge

Ungerleider and Mishkin (1982)

Double dissociations discovered the What(ventral) pathway and the Where(dorsal) pathway. Both stem from V1

• Monkeys were tasked with what(non match to sample) or where(close to sample) related tasks

• Lesions to ventral and dorsal areas of the brain showed double dissociation

Difference between the Two What and Where pathways

Temporal Lobe Neurons(What)

• Foveal focus, selectivity for complex features, especially in anterior regions(

• Center of vision field and more details

Parietal Lobe Neurons(Where)

• Foveal and peripheral, less selective

• Entire visual field

Optic Ataxia( Balint’s Syndrome)

a condition that causes difficulty with visually guided arm movements, such as reaching for objects

• Can you tell you what an object is but cannot reach for it

Dissociating ventral & dorsal pathways through visual agnosia and optic ataxia

Sound perception pathways(Analogous to visual)

• Anterior auditory regions —> sounds identification

• Posterior auditory regions —> sound localization

The Buckner study pushed the fMRI field forward by introducing a new way to look at brain activity. What was their innovation?

Single-trial(event-related) designs can be used for fMRI research, no longer limited to blocked designs

What are the advantages to being able to look at fMRI data in this way? (Buckner 1996)

Now able to mix trials of different conditions, sorted by behavioral performance and can see changes in brain activity with much better temporal resolution

You should be able to interpret a plot of fMRI data (activity on y-axis, time on x-axis) similar to those presented in the Buckner article and in the Methods lecture slides. (Buckner 1996)

How does this study relate to the idea that sensation and perception reflect two different aspects of sensory processing? (Haynes 2005)

• The Haynes (2005) study illustrates that sensation and perception are distinct processes, as the brain's primary visual cortex (V1) can detect and encode sensory stimuli even when the stimuli are not consciously perceived(masked or subliminal)

• This demonstrates that sensation (the detection of stimuli) can occur without perception (conscious awareness), highlighting the brain's ability to process sensory information unconsciously

Is activity in the primary visual cortex sufficient to drive conscious awareness of visual information? (Haynes 2005)

• Based on the results of the Haynes (2005) study, activity in the primary visual cortex (V1) is not sufficient to drive conscious awareness of visual information.

• While V1 encodes detailed sensory information (such as the orientation of invisible stimuli), this activity alone does not lead to conscious perception, suggesting that additional processing in higher-order brain regions beyond V1 is required for conscious awareness.

What is the advantage of studying multivariate patterns of brain activity across voxels, compared to looking at the magnitude of responses in individual voxels or areas? (Haynes and Haxby)

• Easier to detect distributed, fine-grained patterns of activation that can reveal how information is encoded across the brain, which may be missed by examining the magnitude of activity in individual voxels

• Provides greater sensitivity to subtle differences and enables the decoding of complex information from broader brain regions, offering deeper insights into representational content and neural processing.

Did Haxby et al. find evidence for the distributed view or for a modular view (i.e., domain specificity)? Briefly describe the main finding that supported their conclusions.

• They showed that overlapping, distributed patterns of activity in the ventral temporal cortex represent different object categories, such as faces, houses, and tools.

• Even though certain regions like the fusiform face area (FFA) and parahippocampal place area (PPA) showed category-specific peaks, the broader patterns of activity across the entire region contained information about various categories.

• This finding indicated that object categories are represented by distributed neural patterns, not confined to specialized, isolated regions.

Did Pitcher et al. find evidence for the distributed view or for a modular view (i.e., domain specificity)? Briefly describe the main finding that supported their conclusions

• provided evidence for both a modular role of the FFA (between the rLO, rEBA, and rOFA) in face recognition and a distributed processing approach, indicating that while the FFA is specialized for faces, it can also encode information about other object categories

• This suggests a more nuanced understanding of visual processing, where certain regions are specialized but still participate in broader, overlapping networks.

What were the three areas examined in the Pitcher study, and how did they relate to the three stimulus categories?

Right Occipital Face Area (rOFA) → Faces

Right Lateral Occipital Face Area (rLO) → Objects

Right Extrastriate body area (rEBA) →Bodies

What is a double dissociation? (Also covered in lecture) What is an example of a double dissociation in this paper? (Pitcher 2009)

• Examining two functions and two lesions or impairments and the differences to them

• Lesion to Location X

  • Impairment of function A but preserve B

• Lesion to Location Y

  • Impairment of function B but Preserve A

They had three double dissociations in the Pitcher example. For experiment 1 they lesioned the the rOFA and found impairments for face but not lesions of rLO. And they found the oppsite resutls for object discrimination over the rLO

Combining Haxby & Pitcher: Why did Pitcher et al. use TMS to test their hypothesis, rather than fMRI or EEG? Why did Haxby et al. use fMRI to test their hypothesis?

• Pitcher was the first of its kind to use TMS to examine the difference between modular and distributed view and allowed for a more casual approach than TMS

• Haxby used fMRI

Dissociation between perception linked to awareness and perception linked to action

Explicit Matching task vs Action Task

• Patients with visual agnosia had trouble visually orienting the piece of paper to fit the slot but had no trouble when told to just insert the paper

Sympathetic Nervous System

Norepinephrine based; fight or flight response system

Parasympathetic Nervous System

Acetylcholine based; rest and digest system

Cognitive Psychology

Understanding how the brain represents and manipulates objects or ideas; identifying mental operations that are required to perform tasks

Single-cell recordings

• record from individual neurons and correlate increases and decreases in activity to behavior or stimulation

Primary somatosensory cortex (S1)

Contains homunculus of the body; more sensitive = larger areas of cortex

Optic Nerve

formed from the axons of the ganglion cells; they cross of from visual fields

Retinotopic Maps

Visual cortex is made up many distinct regions defined by their distinct maps; funcitonal differences e.g. V4 = color and V5 = motion processing

What region is critical for recognition of an object’s shape?

Lateral Occipital Cortex