Behavioral Neuroscience

What is behavioral neuroscience?

Study of the neural bases of psychological processes and behavior.

What is neuroscience?

The scientific study of the nervous system.

Why should we study the brain and the nervous system?

To better understand who and what we are, improve the quality of life of people affected by neural diseases, and to create AI machines

What body parts were thought to control emotions during antiquity?

The heart and the guts, NOT the brain, Aristotle brain was a cooling mechanism (hot air rises and is dissipated in the brain)

Who is Galen

He linked that damage to the head in gladiators would show in a change in behavior (movement, emotional personality changes, etc)

What examples “justify” the ancient view of the heart/gut having control over emotions during antiquity?

You feel butterflies in the stomach, someone is a “kindhearted” person

Who first discovered the link between electricity and muscle movement?

Luigi Galvani

How did Luigi Galvani discover the link between electricity and muscle movement?

When electric currents were passed through the leg of a dead frog, it would twitch

What classic literature was inspired by Galvani’s theory about electricity and muscle movement?

Frankenstein

How did Descartes help discover a thermal theory of spinal reflex?

He came up with the Bell-Rope Mechanisms, where fire agitates the skin, pulls a threat into a nerve to the brain, and fluid rushes into the nerve to inflate the muscle. First stimulus-response model.

How did people believe that muscles were moved hydraulically?

Nerve fibers start in the brain and extend to the muscles and the brain acts on the muscles to move them.

Why is Da Vinci important when talking about models of the mind?

He drew models of the ventricles, the most visible part of the brain.

What is dualism?

The mind and body are made up of two different “substances,” a nonphysical mind and physical brain that communicate with each other.

What evidence is used against the dualist theory of a nonphysical mind?

Drugs affect behavior by acting on the brain, coffee binds on receptors to affect our behavior/makes us less sleepy, so does coffee damages to the brain affects behavior, brain development issues impaired cognition.

How did Phineas Gage advance neuroscientific discoveries?

Helped discover functional localization. A lesion in the brain changed specific behavior, not all behavior, thus different brain regions have different functions.

What is phrenology?

Different parts of the brain have different functions, but the mapping was incorrect. They thought the brain was like a muscle and strengthening a skill was reflected in the size of that part of the brain.

Describe some brain functions according to the modern view of functional localization.

Primary visual cortex - vision

Top of brain - motor execution

Frontal lobe - high level thinking

What are the most common metaphors about the brain?

-Hydraulic mechanism

-Thoughts are like the tiny mechanical movements of a clock

-Brain has electrical circuits and wires like a telephone switchboard

-Brain is like a computer

How is the brain like a computer?

Processes inputs and outputs, BUT we have many competing factors that try to influence behavior.

How is the brain like the federal government?

Each person in congress has a different motivation/goal. They are somewhat connected but may interpret things differently. We cannot control EVERYTHING voluntarily. For example, we can try to hold our breath, but eventually our body will breath.

Why is it important to keep an evolutionary perspective of neuroscience in mind?

Anatomical organization is well-conserved across species and can explain how our brains developed.

What is an example of an evolutionary explanation in cats?

Cats hair stands up to scare away predators, we get goosebumps.

What is an example of an evolutionary explanation in humans?

Our visual system did not evolve to figure out specific shade variations, we evolved to figure out the perspective/foreground and background.

What are the levels of organization

Unit 1 - Cellular and Molecular Neuroscience

Unit 2 - Circuits Neuroscience

Unit 3 - Systems Neuroscience

Why do we have a nervous system?

Many organisms don’t have a nervous system. The earliest animals, jellyfish, developed a nervous system to control their own movement (moving through water) instead of passively floating around the ocean.

How did neurons evolve from jellyfish?

When animals evolved from the sea to the land, they kept some of the ocean to keep the nervous system working.

What are the components of the meninges?

The brain and spinal cord are wrapped in three layers of protective membrane called meninges:

-Dura Mater (thick outer layer)

-Arachnoid (spongy middle layer)

-Pia Mater (thin inner layer)

What liquid is found around the nervous system?

Cerebrospinal fluid (CSF)

Where does cerebrospinal fluid come from?

Manufactured by an organ called the choroid plexus, which resides in hollow tubes

What is meningitis?

An condition when the meninges become inflamed and can lead to infections of the nervous system. Interferes with the correct chemical composition of the brain.

What are the two major subdivisions of the nervous system?

-Central Nervous System (CNS, brain/spinal cord)

-Peripheral Nervous System (PNS, all neurons outside of bone)

What is circuit-level analysis of neural computations?

Looks at how neurons interconnected to form circuits that perform specific functions.

What are “populations” of cells?

Neurons come in many shapes/sizes and the patterns of axonal and dendritic arbors/branches exhibit many diverse shapes (like trees).

Why are some neurons classified with the suffix -ergic?

They are named after the neurotransmitter they release.

Examples:

-Glutamatergic cells release glutamate

-GABAergic cells release GABA

-Cholinergic cells release acetylcholine

-Dopaminergic cells release dopamine

-Serotonergic cells release serotonin

-Adrenergic cells release adrenaline

-Histaminergic cells release histamine

How are cells classified by their axonal targets?

Populations are determined by their efferent connections, or where they send their axons to make synapses. These include interneurons and projection/principal neurons. W

What are interneurons?

Neurons that are only connected to local/close-by cells and send short-range connections

What are principal/projection neurons?

Neurons that send long efferent projections (synapses) to distant brain regions. WH

What is single-unit recording?

Measures spike activity of a single cell to figure out its function

What are head-direction cells?

An internal compass cell that is activated when an organisms head is pointed in a certain direction

What types of cells is the nervous system made of?

Neurons and glial cells

What are neurons?

Cells that generate fast electrical impulses called action potentials.

What is the soma?

The soma is the cell body containing the nucleus where dendrites extend from.

What are the dendrites?

Branches that receive signals from other neurons

What is the axon?

A long branched cable that sends electrical signals and where electrical signals pass through

What are the axon terminals?

Neurotransmitters are released from the axon terminal onto target cells

What are synapses?

A chemical junction where neurons connect with one another

What is a presynaptic neuron and a postsynaptic neuron?

The cell that releases the neurotransmitter is presynaptic and the cell that receives the signal is postsynaptic. Every cell is pre/postsynaptic.

How are neurotransmitters released?

A presynaptic cell fires an action potential that causes the release of neurotransmitters, which bind to neurotransmitter receptors on the dendrites of the postsynaptic cell. Can release onto thousands of different postsynaptic cells.

What is the molecular level of analysis?

A look at the ion channels of a neuron.

What are the 8 levels of analysis in neuroscience?

-Social Level

-Organ level

-Neural systems level

-Brain region level

-Circuit level

-Cellular level

-Synaptic level

-Molecular level

Explain the 8 levels of analysis in neuroscience.

• Social level: Examines interpersonal interactions and social behavior between multiple organisms.

• Organ level: Looks at the whole brain and body system as a unified organ.

• Neural systems level: Investigates large-scale networks and pathways of connected brain regions.

• Brain region level: Focuses on distinct anatomical structures and nuclei within the brain (such as the hippocampus or amygdala).

• Circuit level: Analyzes local microcircuits and small ensembles of interacting neurons.

• Cellular level: Studies the structure, function, and electrical properties of individual neurons and glial cells.

• Synaptic level: Explores communication points between cells, including neurotransmitter release and receptor activity.

• Molecular level: Inspects the baseline chemical and genetic factors, such as ion channels, second messengers, and DNA expression.

What does the brain actually look like?

No space between neurons, a lot of overlap, like a pasta dish! Meatballs are the cell bodies, noodles are dendrites

What are glial cells?

They have supportive actions for the brain

What are oligodendrocytes?

In the CNS, create myelin sheath around axon where action potential travels.

What is the myelin sheath?

Fatty layer of insulation around the axon, isolate the electricity

Why are there gaps in the myelin sheath (type of glial cells)?

Nodes of Ranvier create gaps where the axon is exposed

What are Schwann Cells (type of glial cells)?

Same as oligodendrocytes, but in the PNS (nerves found outside of the brain)

What are microglia (type of glial cells)?

In the CNS, remove waste as a part of our immune response. First responders of the brain.

What are astrocytes (type of glial cells)?

Star-shaped glial cells, mediate transfer of chemicals from blood vessels to the brain or other neurons

What is the input zone of a neuron?

Cells have many dendrites which receive information/input from other cells to excite/inhibit

What is the integration zone?

Region where inputs are combined and transformed. If excited enough, they release an action potential

What is the conduction zone?

A single axon leads away from the cell body and transmits the electrical impulse

What is the output zone?

Axon terminals at the end of the axon where activity is communicated to other cells

What are key characteristics of a larger neuron?

More complex inputs/outputs, cover greater distances, and convey information more rapidly

What are the 3 types of neurons?

Multipolar neurons (most common), bipolar neurons, and unipolar neurons

What are multipolar neurons?

Many dendrites and one axon

What are bipolar neurons?

One axon, one dendrite

What is an unipolar neurons?

A single extension that branches in two directions, forming a receptive pole and an output zone

What are the 3 functions for neurons?

Motor neurons, sensory neurons, and interneurons

What are motor neurons?

Stimulate or contract muscles/glandsW

What are sensory neurons?

Respond to environmental stimuli like light, odor or touch

What are interneurons

Neurons that send input to other nearby neurons, supporting local computationsW

What are synapses?

A chemical junction between two neurons allowing them to communicate

What are the 5 components of a synapse?

Presynaptic membrane, synaptic cleft, postsynaptic membrane, synaptic vesicles, and receptors

What is the presynaptic membrane?

Edge of axon terminal of the presynaptic neuron

What is the synaptic cleft?

A gap that separates the membranes of presynaptic neuron and the dendrite of postsynaptic neuron. Axon terminals have a lot of mitochondria to provide chemical energy.

What is the postsynaptic membrane?

The edge of the dendrite or cell body of the postsynaptic neuron.

What are synaptic vesicles?

Small spheres that contain a neurotransmitter, a specialized chemical substance. Neurotransmitters are released in response to the electrical activity in the axon.

What are receptors?

Specialized proteins that the neurotransmitter binds to

What are branch arborization patterns?

Facilitate contacts

What are dendritic spines?

Studded on the dendrites and increase surface area, where axon terminals makes a synapse on postsynaptic cell.

Describe neural plasticity of dendrites.

Allows number and structure to be rapidly altered by experience. Very dynamic.

What is the axon hillock?

A cone shaped area of the cell body that gives rise to the axon. Where axon potential is triggered and then conducted.

What are the primary subdivisions of the peripheral nervous system (PNS)?

Cranial and spinal nerves and autonomic nervous system

What is the somatic nervous system?

Cranial and spinal nerves which control muscle movements and carry sensory information to the CNS

What are the 3 major subdivisions of the autonomic nervous system?

Sympathetic nervous system, parasympathetic nervous system, and enteric nervous system

What are the main functions of the sympathetic and parasympathetic nervous system

Autonomic ganglia are located outside the CNS. Preganglionic neurons run from the CNS to autonomic ganglia and postganglionic neurons run from the autonomic ganglia to targets in the body. Preganglionic neurons originate in the lumbar and extend to other body parts.

What are the functions of the sympathetic nervous system?

Prepare the body for quick action like intense fight orw flight. Inhibit sleep, stopping digestion, pumping more blood, more light filters into the eyes, accelerates heart rate

What do postganglionic sympathetic neurons produce?

Norepinephrine/noradrenaline to accelerate activity

What is the function of the parasympathetic nervous system?

Opposite to sympathetic activity - slowing activity. Uses acetylcholine. Sometimes they have complimentary functions.

What are the cells that produce acetylcholine called?

Cholinergicw

What is the role of the enteric nervous system?

A local network of neurons that governs the function of the gut. Produces acetylcholine and serotonin.

What are the 3 most common ways to section the brain?

Horizontal plane, sagittal plane, and the coronal plane

What are the 3 versions of anatomical orientation?

-Medial-lateral: middle side

-Dorsal ventral: back belly

-Anterior-posterior: head tail

What does afferent and efferent mean?

-Afferent: carries information into a region of interest

-Efferent: carries information away from a region

How can the brain be divided into 3 major divisions?

-Spinal Cord: controls hard-wired behavior like reflexes

-Frontal cortex: complex behaviors and high-level thinking

Describe the two types of the brain surface.

-Gyrus: Ridged/raised portion of the brain surface

-Sulcus: Furrow/valleys of the brain surface

What is the function of the forebrain?

Most anterior and prominent part of the brain and consists of two cerebral hemispheres. Outer portion is the cerebral cortex and the thalamus and hypothalamus.

What does the cerebral cortex do?

Receives sensory information and controls motor movement from the opposite side of the body.

What are the two parts of the cerebral cortex?

Two hemispheres joined by the corpus callosum. Joined by the corpus callosum.