Brain and Behavior Exam

Which of the following can be done WITHOUT the involvement of the cortex?

Release of hormones to prevent dehydration

The best term to describe the part of the spinal cord that is closest to a person's back is

Dorsal

Which of the following is a correct match between cortical lobe & function?

occipital lobe & vision

The thalamus is part of the

diencephalon

The cranial nerves are different from the spinal nerves in that

 

only the cranial nerves carry information for all five senses

Which of the following is NOT part of the brain?

Spinal cord

The sympathetic and parasympathetic divisions of the autonomic nervous system BOTH

have an effect on cardiac muscle

Which part of the brain is especially important for long-range planning, keeping inhibitions in check, and following the rules of society?

Prefrontal Cortex

Which of the following is NOT true about the hypothalamus and brainstem?

they allow you to find an object in your environment and pick it up

Damage to the hypothalamus is UNLIKELY to affect which of the following?

auditory perception

Which of the following is NOT part of the limbic system?

Midbrain

The membrane potential of a particular location along an axon

Changes over time

During an action potential, an individual potassium ion might

move from the inside of the cell's axon to the outside

Why does potassium leave a neuron during an action potential?

because it is positively charged, and the inside of the cell is positive at the time when it leaves, and also because it flows down its concentration gradient (with high potassium inside the cell and low potassium outside)

What useful function does myelin perform?

increasing the velocity of action potentials

Which of the following is NOT a function carried out by astrocytes?

Wrapping axons in myelin

During an action potential, potassium channels open because

the cell's membrane potential has become more positive

Which of the following is UNLIKELY to be affected by multiple sclerosis?

spinal nerves

Dilation of the pupils can be caused by activation of the

Sympathetic nervous system

Which of the following is NOT true about the sympathetic nervous system?

It promotes rest and digestion

Which cortical lobe is important for making decisions, controlling movements, and allowing proper social behavior?

frontal

Cocaine enhances dopamine action by

blocking reuptake of dopamine

Which of the following is NOT an important factor in determining whether binding of neurotransmitter to a post-synaptic receptor will make the post-synaptic cell fire an action potential?

how much of the neurotransmitter's precursor is present

Dendrites and axons are similar in terms of

having a resting membrane potential of about -70 mV

Which of the following steps occurs the EARLIEST in synaptic transmission?

neurotransmitter is released into the synaptic cleft

The use of G-proteins by a post-synaptic neurotransmitter receptor, relative to the use of an ionotropic receptor, has the advantage of

amplifying a small signal

During an action potential, which of the following travels the farthest?

the depolarization of the cell’s membrane potential

During an action potential, potassium ions leaving an axon cause its membrane potential to

repolarize

Axons and dendrites are different in that

action potentials occur only at axons

A new neurotransmitter that has only one kind of receptor was just discovered. To determine whether the neurotransmitter is generally excitatory or inhibitory, which of the following is the most important factor to consider?

which kind of ion passes through the post-synaptic membrane after the neurotransmitter binds

The lobe of cortex that is circled can be described as having what kind of function in general?

a "what" function related to object recognition

The circled area is the

midbrain

Giving muscarine to a person would be likely to make them

salivate

At a certain moment in time a presynaptic cell starts to release fewer molecules of inhibitory neurotranmitter than normal.  As a result

the postsynaptic cell will be likely to increase its firing rate

Which of the following steps must occur between calcium entering the axon terminal and degradation of the neurotransmitter?

release of neurotransmitter into the synapse

Which of the following is NOT a real difference between ionotropic and metabotropic neurotransmitter receptors?

whether they can bind acetylcholine

Which ion is essential for allowing vesicles at the axon terminal to fuse with the cell membrane and release neurotransmitter?

calcium

What comes standard on your genuine model human brain?

• Consciousness

  • Double-edged sword; knowing the actual state of the world we live in, unlike other animals.

• Movement

  • Dexterity; having a complex brain that can send signals that allow our body to have this movement

• Object Recognition

  • Artificial neural nets can be trained to recognize objects, but then are extremely sensitive to small changes

• Language

• Basic Survival

  • E.g. baroreflex

Central Nervous System

Consists of brain and spinal cord

Peripheral Nervous System

• Contact skeletal and smooth muscle, skin, blood vessels, and visceral organs

• Somatic and autonomic components

• Axons bundled into nerves

  • Spinal for body into nerves and somatosensation

  • 12 cranial nerves for head movement and all 5 senses

• Afferent = Sensory

• Efferent = Motor

Planes in the Brain

• Horizontal plane

• Coronal Plane = Frontal or cross-section

• Sagittal plane = parasagittal

Outer part of the Brain

 controls outward-looking functions

• Conscious awareness, under voluntary control

Inner core of the brain controls

inward looking functions

• Hypothalamus + brainstem

• Unconscious, involuntary

Limbic System

• Link between cortex (conscious perception) and Hypothalamus 

  • located in between them

• Mediates emotions, memory, motivation, pleasure, reward

• Includes hippocampus, amygdala, nucleus accumbens

Prefrontal Cortex

• Inhibitory, controls behavior

• Especially large in human beings

• Involved in planning foresight control of social behavior (manners, cultural customs)

Central Nervous System

• Forebrain (prosencephalon)

  • Telencephalon

    • Cerebral Cortex

    • Basal Ganglia

  • Diencephalon

    • Thalamus

    • Hypothalamus

  • Brainstem

    • Midbrain (mesencephalon)

    • Pons

    • Medulla

  • Spinal cord

General functions of the Forebrain

• Conscious perception

• Control and planning of movement

• Homeostasis (physiology and behavior)

  • E.g., water balance

• Language

• Memory

Cerebral Cortex - Conscious Perception

• Insula not visible from the lateral surface - receives taste information

• Anterior to central sulcus - generally “motor”

• Posterior to central sulcus - generally “sensory”

  • But there are connections between them, and Both are involved in most real-world tasks

• Parietal lobe: “where/how”

• Temporal lobe: “what”

• Basal ganglia (telencephalon)

Thalamus (diencephalon)

Egg-shaped and made up of many individual nuclei

• Similar to the cortex but with a lack of conscious awareness

Hypothalamus (diencephalon)

 The general function is to maintain homeostasis

• Done by controlling:

  • Hormone release 

  • Autonomic nervous system

  • Behavior

• Individual functions controlled by individual nuclei

Brainstem (midbrain, pons, medulla)

general functions

• Sensory processing (for some of the senses)

• Control of the autonomic nervous system

• Contains the reticular formation

  • Organization of reflected

  • Regulation of sleep and waking

  • Origin of neurotransmitter systems

Peripheral nervous system

Spinal nerves and cranial nerves

Autonomiv Nervous System

• Purpose: To maintain homeostasis

  • Unconscious and involuntary

• Targets

  • Smooth muscle

  • Glands

  • Cardiac muscle

Three Divisions of Autonomic Nervous System

• Sympathetic nervous system (fight or flight)

• Parasympathetic nervous system (rest and digestion)

• Enteric nervous system (gut)

Effects of Sympathetic Activation

• “Fight or flight”, stress, excitement

• Increased heart rate

• Increased metabolic rate

• Increased blood glucose

• Dilation of pupil

Effects of Parasympathetic Activation

• Rest and digestion

• Salivation

• Increased gastric motility

• Decreased heart rate

• Constriction of pupil

The Autonomic Nervous System has both

sensory and motor components

• Sensory

  • Signals related to heart rate, digestion, etc.

• Motor

  • Control of smooth muscle

  • 2 neuron chain

• Both together

  • Autonomic reflects 

Baroreflex

keeps heart rate approximately constant

• Both sensory and motor functions are automatic

Generally opposite functions for SNS and PSNS but…

For some functions, activation of both SNS and PSNS is involved

Oligodendrocytes

• Wrap axons in the central nervous system in sheath of myelin (with gaps at Nodes of Ranvier)

Potential Problem with Oligodendrocytes

• Multiple sclerosis (MS)

  • Patches of demyelination in CNS - Causes problems with neurons communicating

  • Generally starts in optic nerve, spinal cord, or cerebellum

  • Most cases occur between ages 20 and 40

  • Symptoms often wax and wane

Reticular Formation

• Spans brainstem dorsally

• Involved in sensory-motor integration (semi-automatic movements)

Ventricles and Meninges

• The brain is cushioned by cerebrospinal fluid (CSF), which also maintains the chemical environment of neurons

CSF is contained and produced in the ventricles and constantly flows out and is regenerated (blockage of CSF flow results in hydrocephalus)

3 Meninges

• Dura mater - 2 layers that separate at places to form sinuses

• Arachnoid - weblike, adheres to dura

• Pia mater - thin, adheres to brain and surrounds blood vessel branches

Blood supply to brain

• Brain has a high demand for oxygen

• Blood-brain barrier regulates which molecules can enter the brain, except at certain places (circumventricular organs)

The Blood-Brain Barrier (BBB)

BBB can be crossed by some molecules, but not others relevant for drug administration

In general differences between functions of the inner and outer parts of the brain

However they interact with each other, and both are necessary

Parietal lobe

“Where/how”

Temporal lobe

“What”

Glial Cells

• Equal to neurons in number

• Provide support to neurons

• Several Kinds

  • Oligodendrocytes

  • Schwann cells

  • Astrocytes

  • Microglia

Schwann Cells

• Similar to oligodendrocytes, except:

  • Peripheral, not central

  • Do not cover multiple neurons with myelin

Astrocytes

• Regulate the chemical environment of neurons

• Provide neurons with nutrients

• Synchronize the firing of neurons located near each other

• Regulate blood flow in the brain and help form the blood-brain barrier

Microglia

• The immune cells of the brain

• Sensors for pathological events in the CNS (e.g. bacteria)

• Involved in repair of injured neurons

• Release cytokines (immune system molecules)

What makes neurons special?

Neurons are capable of carrying electrical signals without decrement, even over large distances

Transduction and Digital coding

Physical energy and chemical identity are transduced by the nervous system

Unmyelinated axons

Small diameter (pain sensation): 1m/sec

Myelinated Axons

large diameter (proprioception): 100m/sec (= 224 miles/hour)

The nervous system is derived from?

ectoderm

During development, the neural tube forms due to folding of the

Neural plate

After human beings are born…

synaptic pruning takes place

People are able to contract skeletal muscle and make voluntary movements due to

acetylcholine binding to nicotinic receptors

Which of the following is NOT true about CSF?

The same CSF continually recirculates, rather than any new CSF being produced

The Blood-Brain Barrier

can be crossed easily by lipid-soluble substances

The Reticular Formation

is important for semi-automatic movements like chewing

Multiple sclerosis involves a reduction in the number of

Oligodendrocytes

Rate Coding

Information is carried in their rate of firing not in their size (“All or none law”)

Neurons are surrounded by …

a cell membrane that is normally impermeable to ions

High concentration of organic anions (A-) inside cell

These concentration differences set up an electrochemical gradient, and ions are sometimes able to move through selective channels

Sodium is attracted by

a negative charge

Some sodium channels are

Voltage-gated and they open at a depolarization threshold

As sodium enters the cell

the cell becomes more positive (A depolarization)

When membrane potential is positive…

Potassium is repelled by positive charge and follows concentration gradient

When voltage gated potassium channels open and potassium leaves the cell…

the neuron goes back to a resting potential of -70mV

Refractory Period

Delay before the cell can fire another action potential

Transmission of an action potential resembles

A wave that propagates

At each location along an axon changes in membrane potential are the same size

Saltatory Conduction

Depolarization gets regenerated at Nodes of Ranvier

Timeline of an Action Potential

When the Threshold is passed (-50mV) neuron fires

1. Sodium channels open, sodium rushes in

2. Further depolarization, potassium channels open

3. Sodium channels close, potassium rushes out

4. Repolarization (membrane potential more neg.)

5. Potassium channels close, and return to resting potential

Saltatory Conduction is

Fast; depolarization gets regenerated at nodes of Ranvier (in between myelin)

The NA+/K+ pump restores the original ion concentration (requires ATP as energy)

Common Neurotransmitters

Dopamine

Norepinephrine

Serotonin

Acetylcholine

Glutamate (excitatory)

Gamma-aminobutyric acid (GABA; inhibitory)

Many neuromodulators (small peptides)

Neurotransmitters is deactivated by

enzymatic degradation and reuptake into the cells

Ex. dopamine is taken back up into the presynaptic neuron by the dopamine-active transporter

This reuptake is blocked by cocaine, so dopamine acts for longer on the post-synaptic receptors