User:Atcovi/Spring2024/Psyc 410 Human Cognition/Ch. 2

Cognitive neuroscience is the study of the neural mechanisms of cognition and behavior. Focused on brain mechanisms and their roles. Clinical problems/behavior disorders are linked to brain disorders.

(end of lecture has really good information on other psychology disciplines)

Quizlet: https://quizlet.com/875759717/chapter-2-human-cognition-flash-cards/?new

2.1  The Neural Basis of Cognition

 * Dualism - Mind is non-material, separate from brain & body. Body is material. Mind and body interact with each other. Non-scientific and we can't assess the mind as it is non-material. Can't form a hypothesis of non-material as it doesn't follow the laws of science & we don't get evidence for this.
 * Peter being a reckless driver vs. having an epileptic fit. Both are the same, both have the same results, yet the latter is better than the former. Charles Whitman is an example as well. Where is the blame assigned at?
 * Materialism - Brain gives rise to the mind. Mind is the function of the brain. Science --> natural world. If we understand the brain, we understand the mind.

Neuroethicists
Consider implications of cognitive neuroscience on ethical issues. What do we do with the person that committed harm?


 * Abused children who grow up to be criminals had their brains changed when they were younger.

2.2 The Basics of Brain Structure and Function
Neuroscience idea of functional specialization: the brain has different parts that serve different functions. Different brain areas serve different perceptual/cognitive skills.

Brain Structure
Why?


 * 1) Figuring out how the brain works & the physiology of the brain.
 * 2) How do we build our cognitive information processing models? These processing models in the brain can be separate/parallel.
 * 3) How do different processings in the brain communicate with one another?
 * 4) --> Build a information-processing model of the flow of information.

Examples


 * Fusiform gyrus/face area - Region of brain that is active when we are recognizing faces (damaged fusiform gyrus --> we can't recognize faces [ PAG]). Recombines info we see and reorganize in a way we can recognize. Other cues can make up for this (voice, for example).
 * Parahippocampal place area near the hippocampus (important for long-term memory).

PPA graphic for PHPA: pictures are stimuli shown, red areas are specifically-localized increased blood flow/neural firing (since the entire brain is active, control tasks were implemented to localize brain area). Are these places new or not?

From an information-processing approach: everything is the same, the processing of stimuli, re-call components, behavioral-planning process (yes/no button), the decision-making EXCEPT for the stimuli material (places or not?). The nonsense lego picture is the control, the location pictures are the IV.

EBA: Processing what are body parts and what are not body parts. Independent variable pictures: arm, entire body, stick figure. Control conditions: smily face (faces are processed in different region of the brain), random messed up stick figure. Important for field of brain surgery.

What to remember? Brain is NOT 100% separate. These are separate parts of a whole system, all working together so we can make good decisions, plans, and judgements. Specialized systems, but the brain is an entire system that allows us to be creative in our daily lives.

Neurons and Gilal Cells
Basic unit of nervous system: neuron. Our dreams/memories/thoughts/beliefs/skills/ideas are due to the firing of billions of neurons. Neurons keep us ALIVE!!!

Why? Understanding how neurons work is important to understanding human cognition.

Function: Transmit information. Stimulated by an outward environment (rods and cones in our retina, dye reacts to lights), neurons fire! A neuron firing activates another neuron/inhibit another neuron from firing. Is it excitatory or inhibatory?

Neural transmission occurs when an input to the soma/dendrites is above a certain threshold, soma will generate action potential (electrical signal that moves down an axon) that opens up channels in the axon, where ions will move from one part of the cell membrane to another, generating an electrical current.
 * Neurons recieve input through dendrites.
 * Make decisions through molecular interactions in the soma.
 * Can send along info to other neurons through SUPER LONG axons.

The current goes down the ion ducts in the axon and nerve signals cover our nerve system in a fast manner.

When the electric current reaches the end of the axon, it causes the cell to open up channels in the cell membrane and releases neurotransmitters in the synapse. They bind to the synapse of the next neuron. THIS is what transmits the signals between neurons.

Rate of firing: how many action potentials are firing per second? The more action potentials that are firing, the more neurotransmitters that are being released into the synapse.

The Importance of the Synapse
Synpase is the important part, this is where the communications between neurons CAN change (increased surface area on cell membrane, more pores --> increased axon terminal release of neurotransmitters). Neuroplasticity takes place in the synpases! They are plastic, in that their strength can change with learning and experience.


 * Learning changes the probability of neural transmission from one neuron to another.
 * Changes in synapse strength is a foundation of memory formation.

Dendrites can produce more receptors.

Gilal cells give structural and functional support for neurons (support cells). Holds dendrites and axons in place.

Diagram Labels

Reset?
 * Pre-synaptic neuron - Firing/sending signal
 * Post synpatic neuron - Recieves signal, is the pre-synaptic neuron for the next neuron.
 * Dendrites - Recieving portion of the neuron, hold the receptacles where neurotransmitters attach to, kickstarting an action potential by sending a msg to the cell body to get the AP going.
 * Axon - Series of ducts and pumps take ions [atom with an extra electron] (+/-) out and create a positive charge and negative charge on each side of the cell membrane. An AP fires, pores/ducts open up, allows them to move across the gradient, creating an electrical current. Current reaches axon terminal, which triggers the release of neurotransmitters into the synaptic gap.

When neurons fire, they have to take all the ions that got transferred back and forth over the axon when the action potential was fired. They pump the - ions back out and + ions back in to regain polarity between the cell membranes. Gets the neuron ready again! Uses 20% of your daily calories.

More synaptic vessels there are in the pre-syn. neuron, the more efficient at releasing the NT in the synapse, faster flow of info between neurons.

2.2 - The Basics of Brain Structure and Function
The CNS [central nervous system] sends messages throughout the body to hit the neurons across the body, including sensory receptors via receptors on our hands/retina/tongue/nose. They fire based on the intensity of the stimulus at hand [hah, get it?].

Outgoing neurons, such as motor neurons, exist as well. They communicate from the brain/spinal cord to the rest of the body, such as ''hey! we need to pump more blood!'' They also control speech and eye movements. Most neurons are in the brain and the spinal cord. These neurons form networks in order to perform cognitive functions, such as language, reasoning, perception, learning, and movement. They do information processing.

Brain is divided into left and right hemispheres.


 * Left: process sensory/motor information for the right side. Language function is higher here.
 * Right: process sensory/motor information for the left side. Visuospatial tasks is higher here.

Your retina is split for each retina, which the left visual fields for your eyes are going to the right side of the brain - vice versa exists.

There are specific information-processing functions localized in certain parts of the brain.

Corpus Callosum
Corpus callosum connects the hemispheres together. These are massive groups of axons. For example, split-brain patients have the corpus callosum severed, or removed.

An epileptic seizure are caused by your neurons ALL firing at the same time.

Split Brain Patients

 * Used to severe the corpus callosum in order to control epilepsy, this reduces the spread of uncontrolled electrical activity. These patients seem to have no problem in their perceptual and cognitive functions. Dangerous regardless and is not done as often, thanks to advancements.
 * Symmetry in brain = symmetry in body. Lack of symmetry for cognitive functions = processing efficiency problems.

Through an evolutonary perspective, it may have been advantageous to get one part of the brain (left) to process language learning whilst the other part of the brain can deal with visual tasks. We want parallel processing, essentially mult-tasking in cognitive functions and tasks, vs. serial processing.

Cerebral Cortex
[[File:The Cerebral Cortex and Visual Stimulation.pdf|thumb|Cerebral cortex. The grooves are sulci (singular + suicus), whilst the bumps are gyri (singular + gyrus).

The sulci and gyrus add surface area (more regions/density of neurons to pack in a smaller volume) to our brains. ]] The cerebral cortex is the thin, folded layers of neuron that covers the brain. Fully pink stuff.

Majority of cell bodies for neurons are located here. Axons and dendrites make up the rest of the brain.

Each hemisphere can be divided into the following four lobes:


 * 1) Occipital lobe - Mainly for visual perception (retina-processing)/spatial/object-identification/mental imagery. Perception goes here first, then to other lobes.
 * 2) Temporal lobe - complex perception, memory (semantic memory: category/conceptual information), perception part of object identification is, language, taste & smell. Oh that's Larry! (occipital --> temporal).
 * 3) Frontal lobe - thinking, planning, decision-making. Central executive process: processes that control attention, maintain goals, plan. Provides neural signals/activation to other parts of the brain in order to maintain necessary info that is active. Important for athletes fighting through difficult times. Pre-frontal cortex exists HERE!
 * 4) Parietal lobe - mainly for visuospatial functions (like spacial locations). Our senses come into this part of the brain. Our hands and feets have more attachment to our parietal lobe vs. our lower back, since motor abilities are high in the former than the latter. Good in us understanding the MOVEMENTS of other people.

Parts of the brain where different senses are filtered in, those parts of the brain are important in cognitive processing, we need this info when we make informational-processing models.

2.3 - Neuroscience Methods
Some of the neuroscience methods/brain imaging methods that we will go through throughout the semester. We use neuroscience research to localize certain brain functions and figure out where certain processes take place. Different research methods are needed for different research questions. They differ in spatial resolution (figuring out the specifics), they have the ability to pinpoint where exactly neural activity is taking place. Single-cell recording can take place. Down to .001 mm for accuracy. Too precise sometimes, as it focuses on one cell instead of a large network of cells.

The EEG is a set of electrical recordings that take place outside of the brain, goes through cerebral spinal fluid in your head/skin.

The EEG is less invasive and ask questions regarding electrical activity (good timing), but it doesn't give us the specifity that small electrodes inside the brain can give.

fMRI is good for spatial resolution.

They differ in temporal resolution (when = time), or the ability to pinpoint WHEN neural activity takes place. Extremely fast for neuron firing. Good for answering between theories on sequence of events.

Tracking blood flow is another way, but it is slower (good for neural activity for an extended period of time). Electrodes in the brain (electrodes recording, high spatial resolution vs. EEG are widely varying levels of invasiveness.

MRIs (magnetic image resonance) are not invasiveness, but an MRI machine is still sort of uncomfortable. An EEG isn't all good either, its slimy and you have to stay HELLA still.

Behavioral Impacts of Brain Damage

 * Case studies - damage can be caused naturally by stroke/illness or unnaturally from trauma/surgery/car accident. Allows us to study more about the brain (where do different types of cognitive processes occur in the brain?). These case studies gives us basic knowledge of the brain, how they work, and works on improving our basic cognitive theories, but it also helps diagnosises (caution during brain surgery, therapy needed for after the brain surgery).
 * Overlap brain injuries in correlation to overlap in brain functions - Not specific, multiple parts of brain damaged. Look at the maximal area of overlap = look for clues to figure out what part of brain is responsible for deficit and function (correlational, sample sizes). For example, all patients have overlap in a certain area and share a common cognitive deficit = clue for localized brain function, guide our future research.BrocasAreaSmall.png

Functional Specialization For Language

 * Broca's area, in the left frontal lobe, controls motor aspects of language. Damage to this area caused patients to not produce coherent sentences/words. Despite, being broken in producing, they comprehended just fine. This is known as a disassociation, evidence that language comprehension and production are NOT a single process, but they occur in a parallel way.
 * Wernicke's area, in the left temporal lobe, controls the understanding of language. Wernicke's area could not understand language whatsoever.
 * Both areas support materialism over dualism. Specific areas of the brain being damaged = loss/less effective cognitive functions.
 * Because of these findings, we are able to figure out that people produce/understand language in the left hemisphere.



Different Ways of Brain Damage

 * Stroke - Interruption of blood flow to the brain, resulting in oxygen deprivation of the neurons.
 * Car accidents - Wide variety of brain injuries, good for research though.
 * Chronic head injuries/concussions cause brain damage. For example, NFL players damage their pre-frontal cortex. MRIs have showed that college football players (NFL) have 16% less volume of the hippocampus than college students who did NOT play football, whilst college football players with a concussion had 25% less functioning of their hippocampi.

Functional Specialization
Neuropsychology helps to identify functional specialization.


 * Fusiform gyrus for racial recognition. Damage to this region will make it harder for you to recognize people based on their facial appearance! They can see the individual facial features, but they have trouble re-integrating them in their unique ways to recognize one, unique individual. They may not recognize someone, me for example, after shaving their long beard.
 * Localization of function dictates how much tissue may be removed due to removing tumors.

Neuroscience Methods (#2)

 * Electrophysiology = study of direct electrical activity of neurons measured by inserted electrodes in the axons. Electrodes can pick up activity of groups of neurons, and single-neuron activity can be calculated.

Single-cell recordings directly measure the activity of a single cell.

Action potentials are all-or-none, not strong or weak. Its the firing rates that differ and they signify change in neuronal function. Electrodes can help us determine what stimuli neurons respond to best. Hubel and Wiesel won the Nobel Prize for determining changes in the firing rate of neurons in the primary visual cortex in response to different visual stimuli.

Through study of onset stimulation, brain cells are pretty selective for the stimuli they respond to. Some will respond more intensley to other stimuli than others (for example, the fusiform gyrus responds strongly to face stimuli, but not un-organized faces). An example of an intracranial recordings are electrocorticographies (ECoGs). These are used to localize the origin of a seizure occuring. These are helpful since they guide surgeons to remove the smallest amount of brain tissue as possible. Good spatial resolution, but not as good as single-cell recordings.

These ECoGs revealed highly selective face neurons and other selective neurons for non-face objects/words were found in the visual cortex.

ECoGs, pros and cons

+ = we get the sensitive neural activity of the brain

- = invasive Electroencephalography (EEG) was shown above, its a less invasive recording of neural activity using scalp electrodes - though less spatial resolution (getting entire temporal lobe rather than a small region of it, but is good at figuring out lobes), less strong neural activity, data from neurons + cranial nerves when you shut your eyes. Very cheap as well!


 * Average activity of billions of neurons
 * Can look at different states of consciousness and sleep (brain waves).
 * Can see large oscillating waves in epileptics. Start with this technique!

Event-related potential (ERG) is where we zone in on an increased onset of firing which leads to a - charge (overall) in a region of a brain. We can measure the onset of the negative polarity wave in the brain. If we are doing an ERG on the fusiform face area (EEG component N170), we'd do:

The last technique we will review is a Functional Magnetic Resonance Imaging (fMRI). The BOLD, or blood oxygen-level-dependent signal increases with more brain activity. Neurons use more oxygen when they are active, whilst the BOLD signal can be plotted on the structural image to show where brain activity is changing.
 * sensors all over the skull
 * we'd zone in on the temporal lobe
 * look for the increase of negative polarity, we will try and time it to see when there is activity in that region of the brain.


 * Puts you inside a strong electromagnet, makes anything magnetic resonate at a certain frequency --> we can measure the increased magnetic units per some volume inside a 3D space.
 * Great for spatial resolution as we can use capillaries, veins, arteries, to create a 3D space. In real-time as well, but is not as good as electrodes or EEGs in terms of temporal resolution - its real-time, but does take time!

Usually done through a big electronic machine, pretty expensive though.


 * Provides detailed views of internal structures and noninvasive measures of brain activity.
 * MRI measures differences in magnetic properties of different tissues to provide detailed structural information.

What's so useful about an fMRI?


 * 1) Helps clinicians predict deficits with brain damage.
 * 2) Identifies regions of interest (ROIs) for future testing
 * 3) Showed face areas of individuals with autism show less activity in response to faces than do the face areas of control individuals.

An Issue with All these techniques...


 * They are all correlation techniques - just because they are brain activity in a region, doesn't automatically mean that region of the brain is necessary for the task/perception (for example, your brain could be remembering similar/other stimuli, thereby activating regions of your brain). It gives us inference, but it doesn't give us a definite statement. Brain stimulation methods stimulate/disrupt activity to study causation of perceptual or cognitive function. In order to do so, we need to manipulate the neural firing going on in a certain region & then show we are unable to move forward.

Brain Stimulation


 * 1) Transcranial [outside the cranium] magnetic stimulation [magnet, TMS] - Take a strong electromagnet, positioned over brain, magnet turns on --> use the magnet to knock all the extra electrons on the ions surrounding the nerve cells. When the ion channels open up, theres not enough electrons for the action potential to fire ---> INHIBIT NEURAL STIMULATION, REMOVES FEUL FOR ACTION POTENTIAL [IONS]. We can make the causual connection through this. Used to help with drug-resistant depression.
 * 2) Transcranial direct current stimulation (tDCS) - Opposite of magnetic stimulation, here, we are trying to increase neural activity and increase performance. Can use in motor-learning regions of the brain to assist motor learning. This is a new research.