EXAM 2

Neural recording

A group of techniques that allow researchers to record neural activity from either a single neuron or a population of neurons

Single-unit recording

record a single neuron using a microelectrode; you can see a clear action potential wave; has high spatial and temporal resolution

Electroencephalogram (EEG)

records neural activity from population level (thousands or millions of neurons) near the electrode; low spatial and temporal resolution

Non-invasive methods

Computerized tomography (CT), magnetic resonance imagery (MRI), diffusion tensor imaging (DTI), functional magnetic resonance imagery (fMRI)

Computerized tomography (CT scan)

gives structural info of the body part, uses x-ray to produce images of "slices" of the body, low spatial resolution, differences tissue types can be seen in CT scans

Magnetic resonance imagery (MRI)

gives strucutral info of body partys, uses external magentic fields to produce images, has higher spatial resolution

Diffusion tensor imaging (DTI)

Uses modified MRI scanner to receal bundles of myelinated axons in living human brains

Functional magnetic resonance imaging (fMRI)

gives functional info of body parts (active body parts have higher BOLD signals), measures blood oxygen level dependent signals (BOLD); provides best spatial resolution but poor temporal resolution

Rational for using fMRI

active brain regions require more blood oxygen

Endogenous

will happen even in a constant environment

• anticipates changes in the environment like temp, light, and food availability

• the body generates its own rhythm endogenously

Circadian

sleep and wake cycle

circannual

hibernation and migration signals

Suprachiasmatic nucleus (SCN)

Hypothalamic structure regulating circadian rhythms; high activity during the day, low activity during the night; necessary for generating rhythms

Lesions in the SCN caused…

hamsters to have erratic rhythms of sleep

How does the SCN control the -24 hour cycle?

single SCN neurons fire rhythmically endogenous by itself; fires action potentials for 12 hours on their own and stop for 12 hours (i.e. changes (their spiking is) on a 24 hour cycle)

3 major proteins in SCN neurons

Period, timeless, and clock

Period And Timeless

increase during the day

High p + t levels make an animal sleepy by increasing levels of clock

Clock

inhibitory with p + t

low clock = awake

high clock = sleep (reduced suprachiasmatic nucleus action potentials)

how period, timeless, and clock interact

when p + t go up, clock goes down

when clock goes up, p + t goes down

theses interactions function on a 24 hr cycle

Light sensitivity for p + t and clock

pulses of light during sleep can inhibit timeless and decrease clock.

i.e. When ur sleeping and someone turns on a light, you wake up and the cycle starts all over again

Sleep is a highly regulated and a…

behavior, we make movements while going through the stages of sleep even if we aren't aware of them they fall under behavior

Measuring sleep stages through EEG

synchronized neurons = high amplitude + low frequency

de-synchronized neurons = low amplitude + high frequency

deeper sleep = higher synchrony, more oscillation (EXCEPT for REM sleep)

Stages of sleep

awake, stage 1, stage 2, stage 3, stage 4, REM

Awake

Alpha activity- smooth, 8-12 Hz (relaxed)

Beta activity- irregular, 13-20 Hz (arousal)

Stage 1

Theta activity, 3.5-7.5 Hz activity

Stage 2

Sleep spindles- short bursts of 12-14 Hz

K complex- sudden sharp waveforms

Stage 3

Delta activity, less than 4 Hz (20%-50%)

Stage 4

Delta activity, less than 4 Hz(>50%)

High amplitude, low frequency

REM sleep

a stage of sleep characterized by rapid eye movements, a high level of brain activity, lack of muscle tonus (constant low-level activity of a body tissue), genital activity, dreams, and inhibition of motor neurons in the brain stem and spinal cord (this is why we don't act out our dreams)

Theta activity + Beta activity

Slow wave sleep

stages 3 and 4

slow waves and high amplitude (EEG synchrony)

moderate muscle tonus, slow or absent eye movements, lack of genitalia activity

REM vs slow wave

REM sleep- EEG desynchrony (rapid irregular waves), lack of muscle tonus, rapid eye movements, penile erection or vaginal secretion, draems

Slow-wave sleep- EEG synchrony (slow waves), moderate muscle tonus, slow or absent eye movements, lack of genital activity

insomnia

recurring problems in falling or staying asleep due to abnormal activity in the brain

sleep apnea

the cessation of breathing while sleeping

build up of CO2 in blood is detected by chemoreceptors in the brain which awakens the person to gasp for air and the cycle repeats

REM sleep behavior disorder

a sleep disorder in which normal REM paralysis does not occur (improper inhibition of motor neurons); instead, twitching, talking, or even kicking or punching may occur, often acting out one's dream

Narcolepsy

A sleep disorder characterized by uncontrollable sleep attacks. The sufferer may lapse directly into REM sleep, often at inopportune times.

Sleep attack

irresistible periods of sleep

Cataplexy

complete paralysis during waking (REM gone wrong)

Sleep paralysis

paralysis just prior to sleep (REM gone wrong)

Hallucinations

vivid dreams just prior to sleep (REM gone wrong)

Neural mechanisms of narcolepsy

hereditary (discovered through research on dogs bred to show symptoms)

mutation of a gene that produces orexin in the hypothalamus

7 of 9 patients with narcolepsy lack orexin in the CSF; their immune system attacks the orexin neurons

2 of 9 patients with narcolepsy may be due to a lack of orexin b receptors

Modafinil

A drug that targets orexin neurons causing an increase in secretion of norepinephrine and dopamine (arousal) to treat sleepiness

Orexin neurons

regulate a set of vital body functions, including sleep/wake states, feeding behavior, energy homeostasis, reward systems, cognition and mood

• located in the hypothalamus

• high activity during awakeness

• connected to narcolepsy

Why do we sleep theories

Recuperation- sleep repairs "damage", allows brain to rest + recover, reduces oxidative stress

Evolutionary- sleep converts energy during periods of inactivity

Memory consolidation and learning

Declarative memories (episodic)

Memories of events and memorization of facts

• slow-wave sleep (SWS) is required for declarative memory

Non-declarative memories (procedural)

memories of procedures and learning of motor function

• REM sleep is required for procedural memory

Neural mechanisms of sleep- arousal

More acetylcholine is released in the cortex during REM and awake cycle (less during slow-wave sleep)

• Acetylcholine neurons in basal forebrain + pons

Neural mechanisms of sleep- arousal promoting

Activity of noradrenergic, serotonin, histamine, and orexin neurons increase during awareness

Noradrenergic (NA) neurons

in the Locus Coerulus in the Pons

releases norepinephrine (important for awakeness)

releases norepinephrine (important for awakeness)

• amphetamines produce arousal/sleeplessness (agonists for Noradrenergic neurons; increases norepinephrine and dopamine)

Serotonin

located in the Raphe Nuclei in the Medulla + Pons

• anti-depressants can produce insomnia

Histamine

Neurons located in the tuberomammillary nucleus- hypothalamus

high activity during wake

less during SWS or REM

anti-histamines cause drowsiness

Sleep producing neurons

Located in the ventral lateral pre optic area (vlPOA) of the hypothalamus

• releases GABA (inhibitory) onto the arousal neurons to decrease activity there

• micro stimulation of vlPOA caused subjects to fall asleep in minutes

• damage to vlPOA causes insomnia in rats

• neurons in vlPOA receive inhibitory input from arousal neurons (Flip-flop concept)

Flip-flop concept

some regions promote sleep while others prompt arousal

arousal active = sleep inhibited or inactivated

sleep active = arousal inhibited or inactived

excitation = inhibition balance; reciprocal inhibition

Adenosine

Breakdown of ATP generates adenosine

Increases during waking, decreased during sleep

In VlPOA, adenosine excites neurons > causes MORE GABA to be released

Caffeine blocks adenosine

Circadian factors

SCN (suprachiasmatic Nucleus) connects INDIRECTLY with vlPOA.

SCN excites orexin neurons and inhibits vlPOA

What is stimulating neural activity?

A group of techniques that allow researchers to artificially change the neural activity of a specific brain region.

Why is stimulating neural activity important?

It allows investigation of the functions of a certain brain region by manipulating its activity.

What is electrical stimulation in neural activity?

Implanting a wire in the brain to pass electric currents, providing low spatial resolution but high temporal resolution.

What is chemical stimulation?

Implanting a cannula in the brain to inject excitatory amino acids, offering low spatial and temporal resolution.

What is optogenetics?

A method to stimulate specific types of neurons in particular brain regions that uses light, providing high spatial and temporal resolution.

What is transcranial magnetic stimulation (TMS)?

A non-invasive technique using magnetic fields to stimulate neurons, allowing for excitation or interference with brain functions.

What is behavioral genetics?

The study of the genetic basis of behavior, exploring the link between genetics and mental health issues.

What are the main methods of behavioral genetic research?

Family studies, twin studies, adoption studies, and molecular genetics.

What is the difference between monozygotic and dizygotic twins?

Monozygotic twins share 100% of their genes, while dizygotic twins share only 50%.

What do adoption studies aim to determine?

They aim to rule out environmental impacts by comparing similarities between adopted children and their biological versus adoptive parents.

What is the significance of a concordance rate in twin studies?

It measures the likelihood that both twins share a trait, indicating a genetic predisposition.

What is the role of neurotransmission in the nervous system?

It involves the release of neurotransmitters across the synaptic cleft, facilitating communication between neurons.

What are agonists and antagonists in the context of drugs?

Agonists activate receptors, while antagonists block receptors from becoming active.

How does cocaine affect neurotransmission?

It blocks dopamine transporters at the synapse, increasing dopamine levels in the synapse.

What is the action of amphetamines on neurotransmission?

They reverse dopamine transporter function at the synapse, increasing extracellular levels of monoamines.

What are some examples of amphetamines used for ADD and ADHD?

Adderall, Ritalin, and Dexedrine, which increase activity in the prefrontal cortex.

What characterizes drug addiction?

It is a biological disorder marked by compulsive drug use, loss of control, and negative emotional states when access is prevented.

What is the impact of drugs on the nervous system?

They can affect receptors, ion channels, DNA, nuclear receptors, and enzymes involved in neurotransmission.

What is the role of calcium ions (Ca2+) in neurotransmission?

They signal vesicles to release neurotransmitters by exocytosis when action potentials arrive at the axon terminal.

What is the definition of a drug according to Write & Montag (1949)?

A substance or mixture of substances found to have therapeutic value for treating human diseases.

What is the significance of the phrase 'Your genes + Your environment & lifestyle = YOU!'?

It emphasizes the interaction between genetic predispositions and environmental influences on behavior.

What does the term 'drug dependence' refer to?

It refers to the emergence of negative emotional states when access to the drug is prevented.

What is the primary function of drugs that affect the nervous system?

They modulate chemical synaptic transmission.

What determines how a drug affects brain function and behavior?

The brain circuit and type of neurotransmitter involved.

Alcohol

Potentiates GABA receptors > binds to GABA and keeps it open

Drug addiction hypothesis

Increased dopamine signals from ventral tegmental area (VTA) to nucleus accumbems (NAc) is initial common action of all addictive drugs

Long term drug abuse

Leads to reduction in activity and metabolism in the brain

Tolerance/desensitization

Brain knows when chemicals out of balance, it will adapt if getting too much. It will drop the number of receptors if too much dopamine.

physiological regulatory mechanisms

Homeostasis

System variable

Set point

Detector

Correctional mechanism

Negative feedback

Homeostasis

Process where body’s substances and characteristics are MAINTAINED at optimal level

System Variable

Variable controlled by regulatory mechanisms

Set points

Optimal value of system variable in regulatory mechanisms

Detector

Mechanisms that SIGNAL when system variable deviates from set point

Correctional mechanisms

Mechanism that is capable of CHANGING the value of the system variable

Most commonly used feedback in body

Negative feedback

Process where effect produced by an action diminishes or terminates the action (like if you drink water because of thirst, the need for water will diminish)

Heating a home example:

System variable= air temperature

Set point= temperature setting

Detector= thermostat

Correctional mechanism= the heater

Negative feedback= heat

Fluid balance

Intracellular fluid

Extracellular fluid

Intravascular fluid

Interstitial fluid

Isotonic

Intracellular fluid

Fluid contained within cells

Size of body fluid: 67%

Extracellular fluid

All body fluids outside cell

Intravascular fluid

Fluid found within blood vessels

Size of body fluid (blood plasma): 7%

Interstitial fluid

Fluid that bathed cells

Fills the space between cells of body

A type of extracellular fluid

Size of body fluid: 26%

Isotonic

Equal in osmotic pressure to the contents of a cell

Solute concentration

Hypertonic= high concentration

Hypotonic= low concentration

Isotonic= equal

First types of thirst

Osmometric thirst (osmotic): thirst produced by an INCREASE in osmotic pressure of INTERSTITIAL fluid relative to intracellular fluid

Osmoreceptors: neurons that detect changes in the solute concentration of the interstitial fluid that surrounds it

How do Osmoreceptors detect salt changes?

If salt concentration of interstitial fluid increases= water leaves cell > cell shrinks

If salt concentration of interstitial fluid decreases= water enters cell > cell swells

cell increase/ decrease in volume

True or false: Changes in cell volume triggers change in the firing rate, which signals thirst or satiety

True