Neural Basis of Behavior

What is presynaptic inhibition?

Action of an axoaxonic synapse at a synaptic terminal that decreases the neurotransmitter released by presynaptic membrane

What is presynaptic facilitation?

Action of an axoaxonic synapse at a synaptic terminal that increases the neurotransmitter released by presynaptic membrane

What is an action potential?

An action potential is electrical impulse that travels down the axon triggering the release of neurotransmitters.

What is glutamate?

An amino acid neurotransmitter best known for its role in excitatory signaling pathways in the brain. Works closely with NMBA and AMPA receptors

What is GABA?

An amino acid neurotransmitter that's known as the principal inhibitory neurotransmitter in the brain. Alcohol is an example of a GABA inhibitory agonist.

Who is Paul Broca?

A French neuropsychologist who discovered that the left frontal lobe was more responsible for language, what he called "articulate language".

What is methamphetamine?

A drug that alters the release of dopamine into the striatum. Chronic use leads to decreased numbers of dopaminergic synaptic endings, as well as lower dopamine levels in the brain

What is a neural circuit?

A neural circuit is a collaborative interaction of neurons and other brain cells that function together to produce behavioral and physiological responses.

What is dopamine?

A neurochemical that is involved in reward and motor systems

Why are neurons not electrically neutral at rest?

A neuron is not electrically neutral because its negative resting potential leaves it prepared to fire strongly and rapidly in response to a stimulus. Responding to environmental challenges is critical to survival, so neurons must be ready to respond quickly to a stimulus when needed.

What is a neuron's membrane potential?

A neuron's membrane potential is the difference in charge inside vs. outside of a cell.

What is a neuron's usual resting membrane potential?

A neuron's usual resting membrane potential is -50 to -80 millivolts which can be attributed to the unequal distribution of ions which results in an overall negative polarity.

What is thrombospondin?

A protein released by astrocytes that facilitates synaptogenesis (the creation of synapses) most notably during fetal brain development and following injury

What is progesterone?

A reproductive hormone that shows promise in being able to facilitate the remyelination of axons affected by demyelinating diseases such as multiple sclerosis.

Who is Franz Joseph Gall?

A scientist who hypothesized that certain brain structures were associated with certain functions or mental faculties. He sought a correlation between brain size and specific abilities.

What is a synapse?

A synapse is a minuscule gap between neurons that functions as the site of communication between two neurons.

What are monoamines?

A type of neurotransmitter containing a single amine group. They include catecholamines (a group composed of dopamine), norepinephrine, and epinephrine. Also include indolamines, represented by the neurotransmitter serotonin.

What are the six steps of synaptic transmission?

1. Action potential reaches presynaptic terminal. 2. Presynaptic terminal depolarizes, opening voltage-gated Ca+2 channels 3. Influx of Ca+2 causes vesicles to travel to presynaptic membrane. 4. Exocytosis: vesicles release neurotransmitters into synaptic cleft. 5. Neurotransmitter binds to receptor in postsynaptic membrane. 6. Channels in postsynaptic membrane open, permitting the movement of positive or negative ions, depolarizing (EPSP) or hyperpolarizing (IPSP) the postsynaptic cell

What are the three phases of neural transmission?

1. Dendrites receive message (input) 2. Message travels to cell body 3. New message is put out by axon (output)

What are the two ways neurotransmitters terminate its activation in the postsynaptic receptors?

1. Enzymatic deactivation - the neurotransmitter is broken down by enzymes 2. Reuptake - the neurotransmitter is transported back to the presynaptic neuron and repackaged for reuse

What are the three types of dendritic spines?

1. Thin spines 2. Stubby spines 3. Mushroom spines

What did Aristotle think about the brain in reference to controlling behavior?

Aristotle thought there was good scientific evidence to show that the brain doesn't control scientific behavior. Ex. Although you cut off a chicken's head, it still moves.

What is biological psychology?

Biological psychology merges relevant information from the fields of biology, neuroscience, and psychology to reveal how the brain produces behavior.

Describe electrical synapses

Characterized by the alignment of two neurons so that specific channels known as connexons align perfectly to form a gap junction where electrical currents can be exchanged between the two cells

What are ligand-gated channels?

Chemicals that bind to other chemicals are known as ligands, and the channels involved in this process are therefore known as ligand-gated channels.

What is conduction velocity?

Conduction velocity is the speed of an action potential, which is positively correlated with axon diameter.

What is context?

Context is the circumstances surrounding an event and the unique interactions that exist among behavior, the brain and one's external and internal environment. "

What is depolarization?

Depolarization refers to a state when the inside of the membrane becomes less negative than the resting potential.

What is an agonist?

Drug that mimics or enhances the effects of specific neurotransmitters

What is temporal summation?

Enables the subthreshold changes to build on themselves, or summate, to action potential threshold

What is early evidence that the brain does control behavior?

Galen was an early Roman gladiator physician who noticed that gladiators who sustained head wounds weren't the same afterward. Phineas Gage experienced a destroyed frontal lobe after a railroad accident, and was said to have not been the same after.

Who is Nissl?

German biochemist that thought to use dyes or stains on a microscope section of the brain. Through his stain it was determined there were two sizes of brain cells - big brain cells known as neurons, and little brain cells known as glia

What is hyperpolarization?

Hyperpolarization refers to a state where the potential across the membrane is more negative than the resting potential.

What is localization of brain function?

Localization of brain function essentially refers to what areas of the brain are associated with what specific functions.

What is an antagonist?

Neurochemicals that block or decrease the effects of specific neurotransmitters

What are mirror neurons?

Neurons that activate mimicking the mirrored action of another person. Key roles in empathy, speech perception, imitation, and other behaviors typically impaired in individuals with Autism Spectrum Disorder.

What are peptide neurotransmitters?

Neurotransmitters composed of 3-40 amino acids. Examples include: endorphins, oxytocin, and vasopressin

Norepinephrine and epinephrine

Norepinephrine and epinephrine play similar roles in times of acute stress, but epinephrine is secreted from the adrenal gland and plays role in the PNS rather than the CNS.

What is the importance of past and future events on brain function?

Past events are often used to illustrate the 'use it or lose it" concept. Increased grey matter gained from neural exercise will diminish if such stimulation doesn't increase. Knowledge of impending events modify behavior.

What are proximal causes?

Proximal causes are short-term causes of behavior, such as hormonal secretions or an unexpectedly loud noise. Questions about proximal causes are usually framed as "how"

What are the enriched environment studies and what were its results?

Rats in enriched environments showed increased physical activity and social interactions. They had thicker cortexes and more connection among cells in the nervous system. Provides evidence that the brain responds to the external environment. Rats living in rat park didn't turn to drugs as much, since they had alternative forms of stimulation.

What are ionotropic receptors?

Receptors that alter the membrane potential immediately on binding to neurotransmitters. Neurotransmitters binding to ionotropic receptors directly open the ion channels.

What is saltatory conduction?

Saltatory conduction is the propagation of action potentials along myelinated axons from one node of Ranvier to the next node, increasing the conduction velocity of action potentials.

Describe the orientation of sodium and potassium ions within a neurons resting membrane

Sodium ions are more concentrated outside of a neuron than inside, and this is why within the concentration gradient sodium ions are drawn into the cell. Potassium ions are more concentrated inside the cell than outside, and this is why within the concentration gradient potassium ions attempt to push their way out the cell.

What are von Economo neurons and where are they located?

Sometimes called spindle cells, von Economo neurons are neurons that are suspected of being involved in an individual's ability to make quick, intuitive assessment of complex situations. They are located in the anterior cingulate cortical area and the fronto-insular cortical area of the brain.

What are the three types of synaptic arrangements?

Synaptic arrangements are characterized depending on the area of the postsynaptic neuron contacted by the presynaptic neuron. 1. Axodendritic synapse 2. Axosomatic synapse 3. Axoaxonic synapase

What does the Iowa Gambling Task suggest about brain function?

The Iowa Gambling task suggests that in certain situations, the brain is taking in information and making decisions faster than our conscious awareness can process.

What is the all or none law?

The all or none law states that every firing of a particular neuron produces an impulse of the same strength. As long as the membrane potential reaches the threshold value, an action potential will occur. If the membrane potential does not reach the threshold value, no action potential is triggered.

What is the spike initiation zone?

The area in the neuron where the action potential is initiated.

Describe the cell membrane of an axon

The cell membrane of an axon is composed of a phospholipid bilayer that has two main components - hydrophilic heads and hydrophobic tails. It also features ion channels made from proteins that are specific to certain ions or charged molecules. Most of these ion channels are gated ion channels, meaning they open and close based in the environmental conditions around the membrane.

What is the concentration gradient determined by?

The concentration gradient is determined by the varying distribution of ions inside and outside of the axon.

What is the electrical gradient?

The gradient at which different ions move relative to their charge (positive repels positive)

What happens when an action potential is triggered.

The membrane potential that must be reached to trigger an action potential is known as a threshold and it typically around -55 millivolts. When threshold is achieved and action potential is set in motion, a rapid depolarization of the inside of the cell begins and is achieved by opening ion channels to allow large numbers of sodium ions to enter the cell.

What is the function of the G protein?

The neurotransmitter binds to the receptor, the G protein binds to the effector protein, producing second messenger molecules that activate enzymes to open the channel.

What is the blood-brain barrier and why is it important?

The primary security system that restricts the entry of substances into the brain

What is synaptic commission?

The process by which a neuron communicates with another neuron or neurons across a synapse.

Describe the refractory period that follows an action potential

The refractory period can either be described as absolute or relative. During an absolute refractory period no amount of stimulation can trigger an action potential. During a relative refractory period it takes greater change in membrane potential to trigger an action potential.

What is the function of the sodium-potassium pump and how does it work?

The sodium potassium pump plays a key role in maintaining the unequal distribution of sodium ions and potassium ions across the membrane. Functions by using ATP to transport three sodium ions out of the cell for every two potassium ions brought into the cell.

What is acetylcholine?

This is a primary neurotransmitter that transmits impulses across the synaptic cleft.

What are anterograde tracers?

Tracers that are picked up by the cell body and transported to the end of the axon - tracers can be used to develop a map of the brain - can be useful in chemical neural anatomy - "Where are different things in the brain"

What are retrograde tracers?

Tracers that are picked up by the terminal and transported back to the cell body - tracers can be used to develop a map of the brain - can be useful in chemical neural anatomy - "Where are different things in the brain"

What are ultimate causes?

Ultimate causes are the long-term evolutionary causes of physical and behavioral characteristics. Questions about ultimate causes are usually frame as "why"

What are epigenetics?

Variation in life experiences and the environment can alter the expression of proteins dictated by genetic template.

Why are sodium ion channels referred to as voltage-gated ion channels?

Voltage-gated ion channels means that they open and close in response to changes in the membrane potential.

What is an excitatory postsynaptic potential (EPSP)?

When a neurotransmitter binds to a receptor, the membrane potential changes in the postsynaptic membrane, altering the flow of ions in and out of the postsynaptic membrane. If the neurotransmitter-receptor binding makes the membrane potential depolarized, it produces an excitatory postsynaptic potential (EPSP).

What is an inhibitory postsynaptic potential (IPSP) ?

When a neurotransmitter binds to a receptor, the membrane potential changes in the postsynaptic membrane, altering the flow of ions in and out of the postsynaptic membrane. If the neurotransmitter-receptor binding makes the membrane potential hyperpolarized, it produces an inhibitory postsynaptic potential (IPSP). This is a result of the membrane being more permeable to negative ions such as Cl-.

What is the insular cortex?

a brain area located in the most recently evolved cerebral cortex that is suspected of being able to facilitate the shift from involuntary to voluntary control of autonomic functions.

What is a unipolar neuron?

a neuron with one process extending from the soma that divides into axonal and dendritic segments

What is a bipolar neuron?

a neuron with two processes extending from the soma

What is the myelin sheath?

a special insulating covering that speed up a neural impulse.

How does amphetamine work?

blocks catecholamine (dopamine) reuptake but also enhances its release from the presynaptic neuron - MDMA (ecstasy) is a form of amphetamine that is known to be "messy," because it blocks more than one neurotransmitter system at once

How does cocaine work?

blocks reuptake of dopamine, norepinephrine, and serotonin in synaptic cleft causing dopamine (and other neurotransmitters) to hang around longer - acting as a stimulant

How does caffeine work?

blocks the effects of adenosine, competes for autoreceptors and therefore deters sleepiness

What are glial cells? What are the four types of glial cells?

brain cells that were previously thought to merely support neurons, but recent research shows they may actually process information in the same manner as neurons. 1. astrocytes 2. oligodendrocytes / Schwann cells 3. microglia 4. radial glia

What is a depressant?

drugs that depress arousal

What is a stimulant?

drugs that facilitate arousal

What is a neuron?

fundamental unit of the nervous system. the brain has abut 86 billion neurons

What are nodes of Ranvier?

gaps between myelin segments.

Who are Golgi and Cajal?

invented the Golgi stain, which dyes cells sporadically (the Nissl stain dyes every single cell). this allows scientists to see neurons starkly displayed against a clear background, leading to the determination that neurons have different parts.

What is glycine?

major inhibitory neurotransmitter in spinal cord

What is the Nernst equation?

model used to predict voltage based on the concentration of charges on the outside vs, the inside of the membrane: V = +/-60 Log(Ko/Ki)

What is serotonin?

monoamine neurotransmitter that affects mood regulation, sleep/wake cycles, temperature regulation, sexual activity, and aggression

What is spatial summation?

multiple synaptic inputs originating from different locations have a cumulative effect on depolarizing the neuron to the action potential threshold

What is an analgesic?

pain reliever ex. opium, heroin, morphine

What are metabotropic receptors?

receptors that are generally slower to respond to neurotransmitter release because they work via intracellular molecules called second messengers to cause changes in the postsynaptic neuron. Neurotransmitters binding to metabotropic receptors activate a series of events that indirectly open the ion channels.

Who is Gazzinga?

scientist who developed the idea to transect the corpus callosum, thereby corralling seizures in epilepsy patients by not allowing the hemispheres to communicate.

Who is John Flynn?

scientist who studied the effect of direct stimulation to the hypothalamus using electrodes and cats . Found that depending on location cats became ferocious and aggressive (affective/emotional attack) and at another location the cats stalked quietly in a predatory manner (quiet/biting attack). key takeaway: all of this behavior mirrored real, organized, and natural behavior which suggests that different areas of the brain control different behaviors.

Who is Wilder Penfield?

scientist who worked with epilepsy patients and thought that getting rid of the focus of the seizure would cause the seizures to cease.

What are astrocytes? What are four of their functions?

shaped like a star, they are the most abundant type of glial cell. functions: to fill in space between neurons, transport essential nutrients from brain blood vessels to neurons, maintain a constant chemical environment, and the regulation of cerebral blood flow. Additionally, they monitor and control levels of ions such as K+ ions in the extracellular space. astrocytoma: type of brain tumor

What are microglial cells?

smaller glial cells that act as the brain's first responders. functions: protects brain from invaders, clean up dead cells and cellular debris, monitor environment of nervous system. sometimes they emit toxins against the brain's resident cells instead of invader cells, causing them to be suspected in neurodegenerative diseases.

What is the axon hillock?

the entrance gate of the axon, which is where info goes after being received by the dendrites.

What is phrenology?

the mapping of mental characteristics to bumps on the skull. Many concepts of phrenology debunked due to lack of empirical evidence.

What are radial glia?

this type of glia acts as guide posts for young neurons, since the brain begins as a fluid filled tube.

What are dendrites?

tree branch-like extensions from the soma, or cell body, that establish connections with other neurons. dendritic spines are small protrusions through the dendritic processes or branches that increase surface area, which allows for greater opportunity to receive information from other parts of the nervous system.

Who are Fritsch and Hitzig?

two scientists who experimented with the brain and electricity. They stimulated portions of dogs' brain and recorded what happened. In the back of the brain it seemed like nothing was happening, but actually the dog was seeing explosions of light. In the front of the brain seemingly nothing happened. In the midsection of the brain the opposite side muscles would twitch depending on where was stimulated. key takeaway: suggest brain controls a key aspect of behavior - muscular movement

Who are Hodgkins and Huxley?

two scientists who hypothesized that the transfer of info in the brain was correlated with electrical impulses - models are important because they give people ways to support or refute ideas, and allows people to look at things in a different way than they're perhaps used to.

Who are Henry Dale and Otto Loewi?

two scientists who suspected that natural chemical substances such as acetylcholine might be transported across the synapse. experimented with frog hearts. stimulated the vagus nerve of a donor heart in special solution, then transported that solution to a second heart which then slowed down as a result of the neurotransmitters produced

What are oligodendrocytes?

type of glial cell that make up the myelin sheath that encapsulates neurons located in the brain and spinal cord. lack of oligodendrocytes to create myelin sheath can lead to neurodegenerative diseases such as multiple sclerosis

What are Schwann cells?

type of glial cell that make up the myelin sheath that encapsulates neurons located outside the brain and spinal cord.

Who are Robert Batholow and Mary Rafferty?

woman with developmental defect that left brain exposed. Experimented by stimulating brain and finding that movement was exhibited on contralateral side. key takeaway: suggests we can study mice, dogs, and other animals and learn about humans. Also electricity can be used to study brain function