Brain & Behavior COMPS

Classical Conditioning

A type of learning where a neutral stimulus is repeatedly paired with an unconditioned stimulus (that naturally elicits an unconditioned response) which then causes the neutral stimulus to become a conditioned stimulus causing a conditioned response.

Operant Conditioning, types of punishments and rewards

A type of learning where punishments and rewards control behavior

-positive punishment: adding a stimulus to stop a behavior from happening

negative punishment: taking away a stimulus to stop a behavior from happening

positive reward: adding a stimulus to increase frequency of behavior

negative reward: taking away a stimulus to increase the frequency of behavior

What are memories (in neuroscience)

neuronal ensembles or strengthened and weakened connections between neurons

What are neuronal ensembles

strengthened and weakened connections between neurons

Give an example for cellular mechanisms

Building new dendrites or new neurons

Give an example for molecular mechanisms

Long term potentiation

Synaptic plasticity requires both ________ and ________ mechanisms

cellular and molecular

Synaptic plasticity requires...

protein synthesis

Long-term potentiation

The prolonged increase in responsiveness of the post-synaptic neuron after high frequency stimulation of the pre-synaptic neuron. Long term excitability of neuron to specific synaptic input

Declarative memory

Explicit memory, acquisition and retrieval of facts, events and episodes

Non-declarative memory

Implicit memory, memory for skills, habits and behavior

What are the two types of memory

Declarative (explicit) and non-declarative (implicit) memory

What type of learnings is primarily involved in non-declarative memory

classical conditioning

What does the amygdala do?

Plays a role in learning, memory, and controls emotional responses, particularly fear, anxiety and aggression

What does the hippocampus do?

Plays a role in memory, particularly long-term and spatial memory

Draw a brain and mark the Hypothalamus, Cerebral Cortex, Thalamus, Pituitary Gland, Amygdala, Hippocampus

n/a

What does the pituitary gland do

secretes hormones to regulate other glands

What does the cerebral cortex do?

Higher order functions, sensory-integration, decision-making.

How does the cerebral cortex contain?

Cortical columns that differ in neuron density

What are the four zones of a neuron

input zone, integration zone, conduction zone, output zone

What are the structures at the input zone of a neuron

dendrites

what are the dendrites gathered around?

cell body

What is the structure OF the conduction zone

axon

What is the structure AROUND the conduction zone

schwann cells (wrap around) or olygodendrocytes (supply myelin to multiple cells)

What is the structure of the output zone called

axon terminal

What are the three electrical phases of an action potential

depolarization, repolarization, hyperpolarization

Describe the resting potential

Inside the cell there are more negatively charged proteins, and more positively charged potassium ions.

Outside there are more positively charged sodium (Na+) ions and more negatively charged Chloride ions (Cl-)

Sodium Potassium Pump is active. Sodium and Potassium channels are closed but the membrane has selective permeability.

What does the sodium potassium pump do?

pumps three Sodium molecules out and two potassium molecules inside the cell, therefore maintaining the different concentrations (thus negative charge inside the cell). This process requires ATP

Why is the inside of the cell negative?

Different concentrations of ions and proteins. Inside the cell there are more negatively charged proteins, and more positively charged potassium ions. Outside there are more positively charged sodium (Na+) ions and more negatively charged Chloride ions (Cl-)

The sodium potassium pump also contributes to the negative charge because there are a larger number of positively charged Na+ ions outside than positively charged K+ ions inside the sell.

Describe Depolarization

First, the threshold of excitation needs to be reached at Axon Hillock (membrane needs to be depolarized somehow, e.g a neurotransmitter causing some change that depolarizes the membrane).

Then, the voltage-gated sodium (Na+) channels open and Na+ rushes in, thus the membrane rapidly depolarizes (further). Na+/K+ pump is now closed. The charge inside reaches up to +40 mV. Voltage gated Potassium (K+) channels open (due to the now positive charge)

Describe Repolarization

Voltage gated Potassium (K+) channels open (due to the positive charge). At peak voltage, sodium channels close and go into a refractory period. K+ continues to rush out because of both diffusion AND electrostatic forces (because now the inside of the cell is positive, repelling K+), causing the membrane to hyperpolarize to around -80 mV. (Eventually potassium channels close, once full hyperpolarization occurs)

Describe the Refractatory period

Sodium and potassium channels close and the resting potential is restored by the sodium potassium pump. During this period no arriving action potential can be propagated.

Saltatory conduction (when there is a myelin sheath)

Rapid transmission of a nerve impulse along an axon, resulting from the action potential jumping from one node of Ranvier to another, skipping the myelin-sheathed regions of membrane. (results in faster propagation of action potentials)

Three type of structures of neurons

unipolar, multipolar and bipolar neurons

Unipolar neurons

Single branch that extends into two directions from one cell body and serves as both dendrite and axon. (basically only one axon)

Bipolar neuron

Single dendrite and single axon

Describe Synaptic transmission

An action potential arrives at the axon terminal causing the voltage gated Calcium channels to open. Calcium flows into the cell causing the synaptic vesicles in the pre-synaptic neuron to fuse with the membrane via exocytosis, which releases neurotransmitters into the synaptic cleft. In the post-synaptic membrane the neurotransmitters bind to receptors which then initiate action potentials

What are the two types of receptors

Metabotropic and ionotropic

What are Ionotropic receptors? How do they work

ligand-gated ion channels. They open and close with the binding of a neurotransmitter (thus allowing ions to enter the cell)

What are Metabotropic receptors? How do they work

G-protein coupled receptors (a membrane with intra and extra-cellular portions). Binding to extracellular portions activates the G-protein that inhibits or stimulates an enzyme to produce a second messenger that goes to carry out different functions (e.g change DNA or interacting with ion channels)

What are agonists? (Give examples)

Increase efficacy of a neurotransmitter. (Increase synthesis, encourage vesicle packaging, prevent reuptake, bind to receptor and activate it)

What are antagonists? (Give examples)

Decrease efficacy of a neurotransmitter (prevent synthesis, packaging, reuptake, bind to receptor and block it -indirectly or directly)

Name some common neurotransmitters

Glutamate, GABA, Acetylcholine, Dopamine, Serotonin

Describe the structure of the nervous system (main branches and subbranches)

Central Nervous System and Peripheral Nervous System. PNS consists of Autonomic and Somatic NS. Autonomic consists of Sympathetic and Parasympathetic. Somatic consists of cranial and spinal nerves.

What are nerves

bundles of axons in the peripheral nervous system

What does an electroencephalogram measure

Measures synchronous activity of neurons, "brain waves"

What is the activity displayed when you're awake

Alpha and Beta waves

When do alpha waves occur?

They're both displayed during wakeful stages but alpha waves happen when you're resting and beta waves when you're concentrated

What are alpha waves

the relatively slow brain waves of a relaxed, awake state (meditation, prayer),

What are beta waves

more intense mental activity, irregular, desynchronized, small amplitudes

What happens in Stage 1 of sleep

Transition between sleep and wakefulness, theta waves

theta waves display

greater synchrony than alpha and beta, bigger amplitudes, each wave is farther apart (more distinguishable)

What happens in Stage 2 of sleep

Sleep spindles, K-complexes (large sudden waves - brief periods of neural inhibition)

What happens in Stage 3 of sleep

high amplitude delta waves, slow, synchronized, high amplitude waves

What is REM sleep also called

emergent stage 1

What happens in REM sleep

EEG is desynchronized, people are paralyzed, theta activity and beta activity, (rapid eye movement), most dreaming occurs here

Why Do We Sleep? (Theories)

memory consolidation (repetition and thus rehearsal of information), brain rest and recuperation, development of the brain (especially in babies), immune system deterioration (+diabetes, obesity, cardiovascular diseases)

What are three important structures inside the cell?

Cytoplasm (semiliquid substance), Nucleus (contains DNA), Mitochondria (produces ATP), Microtubules

What are microtubules? What do they do?

protein filaments bundled around a hollow core, help in axoplasmic transport (e.g neurotransmitters being transferred)

During the resting potential, potassium is... In opposition, sodium ...

Potassium is at an equilibrium, electrostatic pressures and diffusion are balancing each other out. Equal numbers of K+ flowing in and out. (Chloride, too, is at an equilibrium by the way)

Sodium however is being drawn inside the cell due to diffusion and electrostatic pressures

What are postsynaptic potentials?

A neurotransmitter binds to a receptor and causes BRIEF changes in resting membrane potential, which influences the likelihood of an action potential. They are DIFFERENT from action potentials because postsynaptic can be graded (action potentials are an all or nothing event)

What are the two types of postsynaptic potentials and how are they different? What causes each of them?

Excitatory post synaptic potential (EPSP), which depolarizes the membrane (e.g through allowing Sodium (Na+) to enter) and increases the chances that the neuron will fire, and the Inhibitory post synaptic potential (IPSP), which hyperpolarizes the membrane (e.g through allowing Potassium to exit or Chloride to enter) allowing and decreases the chance that the neuron will fire.

Why are post-synaptic potentials brief?

Neurotransmitters are quickly removed from the receptor, e.g through reuptake (e.g a protein that pumps it back) or enzymatic degradation (enzymes in the synapse that break the molecule down)

What causes a postsynaptic neuron to fire (or not)

Spatial summation: EPSPs and IPSPs are both present (come from different neurons) - are there more presynaptic neurons with EPSPs or more with IPSPs?

Does the EPSP/IPSP arrive closer or farther away from the Axon Hillock?

Temporal summation: The one that is more "frequent" (thus building off each other) "wins"

Is the threshold of excitation reached at the Axon Hillock or not? If yes, an action potential is triggered.

What are two types of (ant)agonists. How are they different?

direct and indirect. Direct binding is competitive binding = it binds to the same site the neurotransmitter would. Indirect binding is non-competitive binding, binds to a different site and thus inhibits or facilitates neurotransmitter action

Glutamate

The most common neurotransmitter in the brain. Excitatory. All receptors are ionotropic.

GABA

THE inhibitory neurotransmitter. It keeps the other neurons from firing uncontrollably. Benzodiazepines are indirect agonists and Alcohol is an agonist.

Acetylcholine

Neurotransmitter involved in muscle contraction, learning and memory. (Nicotine is an agonist, Botox is an antagonist)

Dopamine

Involved in movement (parkinson's), reward, short-term memory, planning (Cocaine blocks reuptake)

Norepinephrine

Involved in attention, mood, vigilance (arousal of the sympathetic nervous system)

Serotonine

Involved in mood, eating, sleep, pain, impulse control

Myelencephalon Function

Medulla. Controls involuntary functions: heart rate, breathing, vomiting , sneezing, digestion, swallowing. Carries signals between the brain and the rest of the body.

Reticular Formation Function

Sleep attention, movement, muscle tone, cardiac, circulatory and respiratory reflexes

Cerebellum

Voluntary, Coordinated sensorimotor activities (movement -> enables us to walk smoothly) receives visual, auditory, vestibular (balance), somatosensory and muscle input

Pons

Communicates between cerebral cortex and cerebellum. Contains parts of reticular formation.

Thalamus

Sensory-relay station. Contains relay nuclei (groups of neurons). Receives signals from sensory receptors and project them to cerebrum/cortex. Involves in selective attention.

Hypothalamus

Controls autonomic nervous system, endocrine system via pituitary glands, feeding, fleeing, fighting, fornicating, hunger, eating, mating behavior, homeostasis, circadian regulation

Amygdala

Learning, memory, emotional responses (fear, anxiety, aggression)

Hippocampus

Memory, learning,

Limbic system

amygdala and hippocampus

Metencephalon

Pons and cerebellum

Mesencephalon

Periaquaductal grey (pain), substantia nigra (sensorimotor), ventral tegmental area (reward)

What brain regions are involved in operant conditioning

Sensory Association Cortex has a direct and indirect connection to the Motor Cortex. The direct/transcortical connection is taken for declarative memories and when we're in the process of learning a movement and it's slow and awkward. The indirect connection is taken for automatic and routine behavior and involves the basal ganglia which is responsible for motor control. The Ventral Tegmental Area and Nucleus Accumbens also play a role since they are the reward pathway (dopamine) they connect to basal ganglia.