Cog Sci Test 1 Brain and Functions

Sagittal plane

left and right hemispheres (up the middle)

Transverse plane

cross-sectional (across the middle)

Brain development order

Brain development begins early in gestation, with the formation of a singular

neural tube that differentiates into various brain structures.

By three weeks of gestation, the brain is primarily a tube that will develop into the

hindbrain, midbrain, and forebrain.

The brainstem, part of the hindbrain, is one of the first structures to become

functional, supporting essential life functions at birth.

The Skull and Fontanels: human skull is soft at birth, allowing for growth and

expansion of the brain, which is critical during early development.

Papez Circuit

found that emotional regulation and memory are related to one

another, limbic system, alzheimers’s

Amygdala

associated with emotional regulation, specifically aggressive behavior

Charles Whittman Case

went on a shooting rampage, killed his mom, gf, 14 people,

and himself, they found a tumor in his brain in his autopsy

Septum

regulates fear

Frontal lobe

decision making

Occipital lobe

visual processing

What are the two key markers of the brain structure

central and lateral sulcus

The brain is protected by 3 membranes known as meninges

dura mater, arachnoid mater, and pia mater

The dura mater

outermost layer, providing a tough protective barrier

The arachnoid mater

resembles a spider web, facilitating blood flow to

the brain.

The pia mater

innermost layer, closely adhering to the brain's surface

and providing additional cushioning.

Hindbrain

survival and life support/is what develops first (responsible for basic

life support functions, such as breathing and heart rate, and includes structures

like the brainstem, newborns can't regulate their temperature which is why they

get swaddled)

RAS, cerebellum, pons, medulla

RAS

Arousal and keeping the brain awake

(maintaining wakefulness), habituation (filters out irrlevant stimuli and

prevents sensory overload)

Cerebellum

“little brain” coordinates body movements and balance

(responsible for body position and movement), is susceptible to

“temporary” damage, such as alcohol (hard to walk in a straight line)

Pons

latin for “bridge” connects different parts of the brain, upper part

controls waking, lower controls sleep, if you inject anesthesia into a cat’s

upper pons-> cat is asleep

Medulla

physical connection between spinal cord and brain, controls

heart rate, blood pressure, and respiration (area postrema responsible for

sneezing, coughing, and vomiting)

Midbrain

plays a role in sensory processing and motor control (the relay station

for sensory info), especially helpful for visual and auditory processing

structure relatively reserved across different species->

fundamental role in survival and basic functions (reptillian

brain/evolutionary apsects of the brain)

Brainstem

hindbrain and midbrain together

Forebrain structure and function

involved in higher cognitive functions, including decision-making and

emotional regulation (relay station for different kinds of information)

Thalamus, hypothalamus, limbic system, hippocampus, septum, amygdala, cerebral cortex

Thalamus

switchboard for sensory info (acts as a relay station for all

senses except for smell and is vital for coherent perception of the

environment), Synesthesia (stimulating one sense involuntarily triggers a

simultaneous autonomic and involuntary experience in another sense

(seeing colors when you hear music or speciifc tastes with certain words),

includes specific nuclei for sensory modalities

Hypothalamus

“under” the thalamus, if you eat too little or too much,

influences the the pituitary gland which releases hormones that affect

odily function, if you are cold /hot, if you are thirsty, trying to maintain

homeostasis

Limibic system

involved in emotional regulation, motivation, and memory

and links them to phsiological responses( Olfactory information: does not

go through your thalamus and goes straight to your limbic system (this is

why strong memories and emotional responses are related to certain

smells)

Critical for dangerous information like spoiled food or gas leaks

Hippocampus

memory and learning (long term memory), Henry

Molaison (underwent a surgical procedure to remove his

hippocampus to alleviate severe epilepsy, resulting in anterograde

amnesia-> no new memories)

Septum

reward and reinforcement behaviors (contributing to

motivation), also plays a role in regulating fear, helps to explain

anxiety disorders (lesions in septum can lead to a lack of fear)

Amygdala

processing emotions, particularly fear, pleasure, and

aggression/its regulation

Alzheimer's disease demonstrate the connection between

memory loss and emotional disturbances, affecting

patients' interactions and emotional responses.

Case studies show that patients may confuse

names or identities, highlighting the emotional

impact of memory loss on relationships.

The amygdala's role in emotional memory suggests that

emotional experiences can enhance memory retention,

making them more vivid and easier to recall.

Cerebral Cortex

Outer layer of the forebrain (thin layer of tissues

containing 100 billion neurons which result in 100 trillion synaptic

connections), responsible for higher cognitive functions, including

reasoning, problem-solving, planning and reasoning, and complex

behaviors (most advanced and complex behavior that makes us human

as it allow sus to think), and has two hemispheres

Main lobes of the cortex

frontal parietal occipital temporal

Frontal lobe of cortex

higher cognitive functions such as decision making

and problem solving, motor activity, social behavior, and

emotional regulation, includes primary motor complex

which is responsible for planning and executing voluntary

movements.

Includes prefrontal cortex: most advanced part of

the brain, responsible for complex cognitive

behavior, working memory, decision-making, and

social interactions. It does not fully develop until the

mid-twenties, which has implications for adolescent

behavior and decision-making.

Broca's Aphasia: Individuals (damage to the brocas

area in the frontal lobe) have difficulty producing

speech but can understand language, leading to

halting and effortful speech.

Frontal Lobe Syndrome: Symptoms may include

slowed thought processes, loss of spontaneity, and

difficulty in shifting strategies or behaviors. Patients

may exhibit perseveration, where they continue a

behavior despite changing circumstances.

Wisconsin Card Sorting Test: a

neuropsychological assessment used to

evaluate cognitive flexibility and

problem-solving abilities. Participants must

sort cards based on changing rules, which

tests their ability to adapt to new

information. Participants initially sort cards

by color, but the sorting rule changes

unexpectedly, requiring them to adapt their

strategy. This test is significant in

diagnosing frontal lobe dysfunction and

understanding executive function

impairments.

Parietal lobe of cortex

processing bodily perception and sensory

information related to touch, pain, pressure, and

temperature, includes primary somatosensory cortex which

is responsible for processing sensory information from the

body

Agraphia: damage to the left parietal lobe can result

in the inability to write

Damage to the right parietal lobe is associated with

visual-spatial abilities and drawing (False Steam

Test)

Temporal lobe of cortex

auditory processing (located near the

ears;linking sound perception to spatial awareness) and

memory

Wernicke’s aphasia: Patients can produce speech

(and hear it) but it is often nonsensical and they

struggle to comprehend spoken language (damage

to left temporal lobe)

Right temporal lobe damage: affects the

interpretation of non-language auditory stimuli,

such as music and environmental sounds

Occipital lobe of the cortex

visual processing/perception, located towards

the back of the head, damage to this area can lead to

temporary vision loss, often associated with trauma or

alcohol consumption, known as 'being blind drunk'

Agnosia: condition characterized by the inability to

process visual information can result from occipital

cortex damage

Visual Object Agnosia: Individuals cannot

recognize objects as wholes, only as parts. A

famous case is 'The Man Who Mistook His Wife for

a Hat'

Prosopagnosia: A specific type of agnosia where

individuals cannot recognize human faces but can

recognize animal faces.

Motion Agnosia: Difficulty perceiving motion, akin to

viewing a series of still images without connection,

affecting the perception of movement.

Surface of the cortex appearance

The surface of the cortex features gyri (ridges) and sulci (deep

grooves), which increase its surface area and enhance its

processing capabilities/allow more neurons to fit.

The central sulcus separates the frontal and parietal lobes, while

the lateral sulcus separates the temporal lobe from the frontal and

parietal lobes.

Two hemisperes of cerebral cortex (same structure but different

function-> structural redundancy allows for compensation if one

hemisphere is damaged) connected by corpus callosum (200

million nerves in corpus callosum), contralaterality = “opposite

side” where left hemisphere controls the right sode of body and vice versa, does have some ipsalateral (same side) control as

well,

“split brain patient”: bad for coordination and multitasking, but

a last resort for seizures

Lateralization

specialization of the left

and right hemispheres for different cognitive tasks

Parallel processing

ability of both hemispheres to work

together and enable multitasking

Left vs right hemisphere

language, analytical tasks

visual-spatial information, creativity, and

analytical tasks

Neuroanatomy

study of the structure of the nervous system, particularly the brain

Major brain structures: cerebral cortex, cerebellum, and brainstem

The hommunculus

representation of the body within the brain, illustrating the

relationship between body parts and their representation in the primary motor and

somatosensory cortices

Different body parts have varying levels of sensitivity based on the density of

sensory receptors; for example, fingers are more sensitive than the back.

The homunculus illustrates that body parts with more sensory receptors have

larger representations in the somatosensory cortex.

Damage to specific areas of the motor cortex can lead to paralysis or loss of

sensation in corresponding body parts.

Brodmans area

a system of numbered regions in the human cerebral cortex that

were defined by German neuroanatomist Korbinian Brodmann in 1909

Neurons

fundamental units of the brain, with approximately 100 billion neurons and 100

trillion synapses in the human brain

Sensory neurons: transmit messages from the body to the CNS

Motor neurons: action messages from CNS to muscles and glands

Interneurons: how motor and sensory neurons communicate

Neuronal structure

dendrites → soma → axon, facilitating communication between

(neuronsnformation flows in one direction)

Soma: (cell body which contains the nucleus, essential for cell division

and functions as the 'brain' of the neuron.

Dendrites: receive incoming signals and delivers to soma

Axon: transmits signals away from the soma/send messages to other

neurons

Synapse

is the gap between axon of sending neuron and dendrites of receiving neuron

where communication occurs

Information is transmitted chemically across the synapse via neurotransmitters

Connectivity between neurons, rather than the sheer number of neurons, is now

understood to be more important for cognitive function and intelligence

Brain cells regenerate

Neuroplasticity: allows for the formation of new connections, which is vital for

learning and memory.

The ratio of interneurons to sensory and motor neurons is approximately 5000:1,

highlighting their importance in processing information.

Pre and post synaptic neurons

The presynaptic neuron releases neurotransmitters(electrochemical nature) that

bind to receptors on the postsynaptic neuron. This process transforms the

electrical action potential into a chemical signal, allowing for communication

between neurons. The 'lock and key' mechanism describes how specific

neurotransmitters fit into their corresponding receptors, ensuring precise

signaling.

Action potential

Action potentials are electrical impulses that travel down the axon (when a

stimulus is strong enough) to where the neurotransmitter release occurs. This

electrical-to-chemical conversion is vital for neuronal communication

The resting potential of a neuron is approximately -70 millivolts, and

depolarization occurs when the neuron is activated.

Sodium-potassium pumps play a critical role in maintaining the resting potential

and propagating action potentials.

Neurotransmitters

Each neurotransmitter has a specific chemical structure that determines its

function and interaction with receptors

Over 40 have been identified, we will focus on 3

Dopamine, acetylcholine, seritonin

Acetylcholine

Learning and memory

Endogenously in the brain and is crucial for activating cholinergic receptor

sites, facilitating communication between neurons.

A deficiency in acetylcholine is linked to Alzheimer's disease, highlighting

its importance in maintaining cognitive health.

Certain foods can enhance acetylcholine production, including omega-3

fatty acids and cruciferous vegetables like broccoli. However, the

effectiveness of dietary changes is limited by the BBB, which restricts the

amount of acetylcholine that can reach the brain. A significant intake of

these foods would be required to make a meaningful impact, which is

impractical due to fiber content.

Alzheimer's disease is characterized by a decrease in acetylcholine

levels, leading to cognitive decline. The presence of amyloid plaques and

neurofibrillary tangles in the brain correlates with reduced acetylcholine

and cognitive impairment. Maintaining homeostasis of acetylcholine is

crucial; both excess and deficiency can lead to neurological issues

Dopamine

Movement, attention, and memory

The balance of dopamine is critical; too much can lead to psychosis, while

too little is associated with conditions like Parkinson's disease.

Parkinson's disease results from a deficiency of dopamine, leading to

motor symptoms like tremors and rigidity. The film 'Awakenings' illustrates

the effects of dopamine restoration through L-DOPA treatment, allowing

patients to regain movement after years of paralysis.

Tolerance to dopamine medications can develop, requiring higher doses

for the same effect, which can lead to side effects such as psychosis.

Drugs that increase dopamine activity can lead to addiction and other

behavioral issues, as they exploit the brain's reward pathways.

Serotonin

arousal, sleep, mood, appetite, sensitivity to pain

Low levels of serotonin are linked to depression, leading to the

development of SSRIs (Selective Serotonin Reuptake Inhibitors) like

Prozac, which help increase serotonin availability in the synapse.

SSRIs work by inhibiting the reuptake of serotonin, allowing for more

effective use of existing serotonin rather than simply increasing its

production.

Endo and exogenous substances

Endogenous neurotransmitters

produced by the body and play essential roles in

regulating behavior and cognition.

Exogenous Substances/Neurotransmitters

exogenous substances, such as drugs, can influence neurotransmitter

systems and alter behavior

Blood brain barrier

selectively allows certain molecules to pass, protecting

the brain from harmful substances. Only small, lipid-soluble molecules can cross

the blood-brain barrier, which is crucial for maintaining brain health. Selective

permeability barrier that protects the brain from harmful substances while

allowing essential nutrients to pass through

Pharmacological tolerance

Tolerance refers to the body's adaptation to a drug, requiring increased dosages

to achieve the same effect. This phenomenon is particularly evident with

medications like L-dopa, which can lead to adverse effects such as

schizophrenia-like symptoms.

The dynamic nature of the body makes it challenging to control drug effects, as

the body continuously adapts to the presence of substances.

Case studies show that patients may require escalating doses over time, leading

to a cycle of increased medication to manage side effects, exemplifying the

complexity of treatment regimens.

Polypharmacy: the concurrent use of multiple medications, often seen in older

adults who may take numerous drugs for various health issues, leading to

potential drug interactions and complications.

Animal studies in neuropsych

Animal studies, such as those involving vervet monkeys, provide insights into

cognitive performance and the effects of drugs on behavior.

The object retrieval task demonstrates how animals can learn to inhibit behaviors

based on environmental cues, showcasing attentional control.

Research by Jess Redmond and colleagues in 1997 utilized pharmacological

mechanisms to study attention in animals, highlighting the importance of

controlled experimental designs.

Animals exhibit attentional control, which allows them to inhibit certain behaviors

based on past experiences and environmental cues. For example, baboons learn

to avoid attempting to grab food when barriers are present, demonstrating their

ability to inhibit impulsive actions.

Monkeys administered PCP (phencyclidine) twice daily for 14 days displayed a

significant inability to inhibit their behavior when presented with food behind

barriers. This behavior mimics symptoms of schizophrenia, highlighting the drug's

impact on cognitive control and impulsivity. Control groups receiving saline

injections showed normal inhibitory behavior, emphasizing the role of PCP in

altering cognitive functions. To restore normal behavior in PCP-treated monkeys,

researchers explored methods to lower dopamine levels chemically. The

administration of pain pauses was effective in returning the monkeys' inhibitory

control to baseline levels, demonstrating the potential for pharmacological

interventions in behavioral studies.

Experimental techniques in neuroscience

Techniques such as lesion studies and single-cell recording are essential for

understanding brain function and the effects of drugs on behavior.

Lesion studies involve damaging specific brain areas to observe changes in

behavior, providing insights into the roles of different brain regions. Researchers

often wait for patients with specific injuries to study their cognitive functions,

particularly in planning and decision-making tasks. Lesion studies provide

insights into brain function but can be complicated by individual variability and

ethical concerns.

Variability in lesions: Not all brain injuries are the same, leading to

challenges in drawing consistent conclusions from lesion studies.

Depth of lesions: Some injuries may affect deeper brain structures,

complicating the interpretation of results.

Task design: Clinical tasks used to measure cognitive functions may be

artificial and not reflective of real-world scenarios, potentially skewing

results.

Single-cell recording allows researchers to map neuronal responses to stimuli,

contributing to our understanding of sensory processing and cognitive functions

Post-mortem studies: provide limited insights into behavioral changes, as many

conditions can only be diagnosed after death. For example, Alzheimer's disease

can only be confirmed through autopsy, limiting the ability to study living patients

with dementia. Postmortem studies are often ineffective for understanding

behavior due to the lack of real-time data.

ERPs or event related potentials

measures the electrical activity of the brain in

response to stimuli, providing insights into cognitive processes in real-time. Setup

involves multiple electrodes placed on the scalp, allowing for high temporal

resolution (4-6 milliseconds). ERP has poor spatial resolution due to the

interference of skin and skull, making it difficult to pinpoint specific brain areas

involved in cognitive tasks. However advantages are that it is cost-effective

compared to other imaging techniques, with a relatively low setup cost of around

$100,000. ERP is a non-invasive technique that measures electrical activity in the

brain through electrodes placed on the scalp. Up to 256 electrodes can be used,

enhancing the spatial resolution of the data collected.

Electrical patterns of the brain time-locked to some event

Best temporal solution, but poor spatial

PETs or position emission tomography

radiological tag/tracer attached to glucose

to measure active parts of the brain/allowing visualization of active brain regions

during cognitive tasks.The resulting images show areas of increased blood flow,

indicated by warmer colors (orange, red) compared to cooler colors (blue) for

less active areas (Measuring brain activity through blood flow and metabolic

changes). PET is particularly useful for studying metabolic processes in the brain

and can help identify abnormalities in brain function. The technique provides a

more comprehensive view of brain activity compared to ERP, but involves

exposure to radiation. Limitations include lower temporal resolution compared to

ERP, making it less effective for capturing rapid cognitive processes. Regional

cerebral blood flow (rCBF) is a key concept, indicating that active brain regions

receive increased blood flow/ radioactive tags (e.g., Oxygen-15, Nitrogen-13) are

attached to glucose, highlighting active brain regions during cognitive tasks.

Temporal resolution is poor (40-60 seconds), making it less effective for tracking

rapid cognitive changes. Disadvantage: high cost, small sample size, and

radiation. The study by Baker, Rogers, Frith, Nolan, Kodiak, and Robbins

investigates planning behavior using PET. Six right-handed male participants

were involved, highlighting the issue of small sample sizes in neuroimaging

research. The Tower of London task is used to assess planning abilities, where

participants must move pieces to achieve a goal position. Tower of London task

to assess planning behavior, contrasting it with a control task of moving colored

balls randomly. Dwell time or response latency is a critical measure, indicating

how long it takes participants to plan their responses before executing them.

Poor temporal, nicer spatial resolution.

fMRI or functional magnetic resonance imaging

measures oxygen consumption

in active parts of the brain by differentiating between oxy- & deoxyhemoglobi.

measuring brain activity through regional cerebral blood flow and metabolic

changes. fMRI measures brain activity by detecting changes in blood

oxygenation levels, providing insights into metabolic activity. The BOLD (Blood

Oxygen Level Dependent) signal is the primary measure used in fMRI, reflecting

regional blood flow changes associated with neural activity. The technique is

non-invasive and does not involve radiation, making it safer for repeated use in

studies. fMRI measures brain activity by detecting changes in blood oxygenation

levels, providing insights into regional cerebral blood flow. Unlike PET, fMRI does

not involve radiation, making it a safer alternative for participants. Temporal

resolution is still limited (4-6 seconds), but it offers high spatial resolution and

detailed 3D images of brain structures.Provides clearer images of brain activity

compared to PET, allowing for better localization of cognitive functions.

Non-invasive and does not involve the use of radioactive materials, reducing

ethical concerns. Neuroimaging techniques, such as fMRI, can pose risks,

especially in strong magnetic fields, which can affect metal implants or piercings.

Historical anecdotes highlight the dangers of magnetic fields, such as the

potential for wheelchairs to be pulled away or credit cards to be erased.

Best spatial resolution, 3D image

Subtraction methods

The use of subtraction methods is critical to isolate cognitive signals from

background noise in both ERP and metabolic imaging. The challenge lies in

ensuring that control tasks used for subtraction do not inadvertently remove

relevant cognitive signals, leading to type II errors.

The phrase 'throwing the baby out with the bathwater' illustrates the risk of losing

important data during the subtraction process.