Final Review

Question 1

Mechanisms for maintaining a voltage across a neuron’s membrane

Answer 1

Selective Permeability: lipid bilayer that separates the extracellular from intracellular space allows some substances to pass through, but not others

Active ion transport: specialized pumps within the lipid bilayer that pump ions in and out of the cell

Question 2

Action potentials

Answer 2

produced by voltage gated ion channels

propagated down the axon, from the soma toward the synapse

When a presynaptic neuron fires an action potential, it causes a postsynaptic potential in the postsynaptic neuron.

Question 3

Axon hillock

Answer 3

Cone shaped region where the axon emerges from the soma. Contains a high density of voltage gated channels

Question 4

EPSPs and IPSPs

Answer 4

At the Summation at the Axon Hillock, EPSPs add in mV, while IPSPs reduce

Question 5

Synapses

Answer 5

briefly translate electrical action potentials into chemical signals, then back into electrical signals.

When an AP arrives at the Synapse, it activates voltage gated calcium (Ca2+) channels, which allow calcium levels to increase in the presynaptic terminal, which causes vesicles to fuse with the membrane of the presynaptic terminal, releasing neurotransmitter into the synaptic cleft.

Question 6

Synaptic Vesicles

Answer 6

small bags filled with neurotransmitters, just waiting in the presynaptic terminal for an action potential to arrive.

Question 7

Ionotropic receptors

Answer 7

fancy ion channels. Neurotransmitter molecules bind directly onto ionotropic receptors. This causes a conformational change – the receptor changes its shape, which allows ions to pass through.

Different ionotropic receptors allow different ions to enter the postsynaptic neuron. Those that allow cations to enter are excitatory synapses and produce EPSPs. Those that allow anions to enter are inhibitory synapses and Produce IPSPs

Question 8

Metabotropic receptors

Answer 8

indirectly allow ions to enter the postsynaptic neuron. Neurotransmitter molecules bind directly onto metabotropic receptors too. But these receptors do not allow ions in. Instead, they activate G proteins (also called second messengers), that bind to ion channels from the inside, allowins ions to enter the postsynaptic neuron.

Question 9

G proteins

Answer 9

Talk to other machinery inside cell to facilitate synaptic plasticity.

Can be activated by metabotropic receptors to bind to ion channels from the inside allowing ions to enter the postsynaptic neuron.

Question 10

Drugs and Neurotransmitter Receptors

Answer 10

Neurotransmitters are endogenous, produced from within, agonists of neurotransmitter receptors.

Drugs that mimic or potentiate the actions of a transmitter are called exogenous agonists.

A partial agonist only partially activates a receptor.

Drugs that reduce the normal action of a neurotransmitter are called agonists

Question 11

Psychedelics (Hallucinogens)

Answer 11

Hallucinogens act on serotonin receptors.

LSD (acid) is a serotonin receptor agonist

Psilocybin (magic mushrooms) are agonists for serotonin receptors and bind particularly in the prefrontal cortex

MDMA (ecstasy) increases extracelullar levels of serotonin (+ dopamine and norepinephrin) in part by blocking their reuptake. This leaves more transmitter in the synaptic cleft to bind to postsynaptic receptors.

Question 12

Psychedelics (Dissociatives)

Answer 12

Dissociatives act on glutamate receptors

Ketamine: inhibits NMDA glutamate receptors by occupying the Ca2+ channel

Dextramethorphan (cough syrup) is metabolized to DXO, which is an NMDA receptor antagonist

Question 13

Sensations are routed into the brain

Answer 13

Labeled lines: Nerve fibers that carry information about each sensory modality are segregated from one another, keeping sensory information about different modalities separate until they reach the brain.

Eventually combined together in the brain in a concept called binding.

There can even be labeled lines within a particular sensory modality, for different types of tough (light, stretch, pain, etc.)

Question 14

Spatial Receptive Fields

Answer 14

Often have center-surround organization, which have three regions. They are most responsive to stimuli in the center. They are suppressed by stimuli in a ring around the center. And they are unaffected by stimuli outside the surround.

Question 15

Attention alters neural responses

Answer 15

ERPs (which are measures of neural activity) made over primary visual cortex are different when a subject views the exact same image, depending on whether or not they are attending to it.

Question 16

Motor plans

Answer 16

strive for speed and accuracy.

The speed/accuracy tradeoff is the concept that improvement in one of these goals usually comes at the cost to the other.

Question 17

Motor neurons

Answer 17

Most motor neurons synapse onto a few muscle fibers.

The fewer the fibers a motor neuron connects to, the finer the control of movement.

Motor neurons and the muscle fibers they connect to form the motor unit.

The muscle fibers that a motor neuron connect to produce a voltage, called electromyograms (EMGs)

Question 18

Motor Cortex

Answer 18

Primary motor cortex lies just anterior (in front) to the somatosensory cortex.

Like the somatosensory cortex, the motor cortex is organized (like a homunculus)

Together, motor cortex neurons form a population code of movement

Question 19

Motor Cortex Responses Measuring Experiment

Answer 19

Monkey reaches in one of several different directions while the action potentials produced by M1 neurons are recorded.

Each movement is made several times, and the action potential patterns produced by a neuron are visualized to examine the tuning of each neuron

The activity of a single neuron is not adequate for decoding movement direction

Question 20

Visualizing motor cortex neurons

Answer 20

Each M1 neuron has a best direction, which is the reach direction at which the neuron fires the most action potentials.

When arm movements are made in one direction, a population of M1 neurons are active. And a largely (but not completely) non-overlapping population of neurons are active when arm movements are made in another direction

Question 21

Patient HM

Answer 21

had his medial temporal lobe removed, including his hippocampus and surrounding cortical regions.

HM suffered rom anterograde amnesia, or the ability to form new memories. But he didn’t lose the ability to form all memories (non-declarative)

Question 22

Long Term Memory

Answer 22

Declarative: Things you know that you can tell others (hippocampus dependent)

- Episodic: remembering your first day of school (Storage in cortex) - Semantic: knowing the capital of france (Storage in cortex)

Non-Declarative: Things you know that you can show by doing (hippocampus independent)

• Skill Learning: knowing how to ride a bike (Basal ganglia, motor cortex, cerebellum)
• Priming: Being more likely to use a word you heard recently (Cortex)
  -Classical conditioning: salivating when you see your favorite food (Cerebellum)

Question 23

Short term habituation

Answer 23

occurs because the synapse connecting the sensory motor neuron becomes weaker (Gill withdrawal)

Question 24

Long term habituation

Answer 24

Occurs because some of the synapses connecting the sensory to motor neuron are pruned away (Gill Withdrawal

Question 25

Schizophrenia Positive Symptoms

Answer 25

Abnormal behavioral states that are gained. (Symptoms that are present but should not be).

Hallucinations, Delusions, Disorganized thought and speech. Bizarre behaviors

Question 26

Schizophrenia Negative symptoms

Answer 26

Abnormalities that reflect insufficient functioning. (Characteristics of the individual that are absent but should be present.

Lack of emotional expression, reduced facial expression (Flat effect), inability to experience pleasure in everyday activities (anhedonia).
Reduced conversation (alogia), Diminished ability to begin or sustain activities, social withdrawal

Question 27

Delusion

Answer 27

false belief that is strongly held in spite of contratry evidence

Question 28

Hallucination

Answer 28

realistic sensory percept that is not actually happening

Question 29

Schizophrenia Cognitive Symptoms

Answer 29

Refers to problems with processing and acting on external information.

Memory problems, poor attention span, difficulty making plans, reduced decision making capacity, poor social cognition, abnormal movement patterns

Question 30

Dopamine Hypothesis

Answer 30

Antipsychotic drugs are more effective than lobotomies

Idea that schizophrenia results from excessive levels of DA or excessive postsynaptic sensitivity to DA.

The strength with which a drug binds to the dopamine D2 receptor strongly predicts the dose of the drug necessary to relieve symptoms

Question 31

Depression

Answer 31

caused by a combination of genetic and environmental factors. (like schizo)

Stress is one of the more common environmental factors that leads to depression

Question 32

Dose Response Curve

Answer 32

Shows increasing drug dose (x axis) agains increasing strength of response being studied

The effective dose (ED50) is the dose at which the response reaches 50% of its maximum effect

The lethal dose (LD50) is defined as the dose that takes you 50% of the way to lethality

The therapeutic index is the difference between ED50 and LD50 doses

Question 33

Psychedelics

Answer 33

Hallucinogens act on serotonin receptors

LSD (acid) is a serotonin receptor agonist

Psilocybin (magic mushrooms) are agonists for serotonin receptors and bind
particularly in the prefrontal cortex

MDMA (ecstasy) increases extracellular levels of serotonin (+ dopamine and
norepinephrin) in part by blocking their reuptake. This leaves more transmitter in
the synaptic cleft to bind to postsynaptic receptors.

Dissociatives act on glutamate receptors

Ketamine (special K) inhibits NMDA glutamate receptors by occupying the Ca2+
channel

Dextramethorphan (cough syrup) is metabolized to DXO, which is an NMDA
receptor antagonist. (“robo-tripping”)