Neuroscience: Levels, Neurons, Glia, and Nervous System Structure

What is the reductionist approach in neuroscience?

It breaks systems down into smaller parts to understand them.

What are the different levels of analysis in neuroscience research?

Molecular, Cellular, Systems, Behavioral, and Cognitive.

What does the molecular level of analysis study?

It studies the smallest building blocks of the brain, such as genes and neurotransmitters.

What is the focus of the cellular level of analysis?

It examines how individual brain cells (neurons and glia) work and communicate.

What does the systems level of analysis examine?

It looks at how different parts of the brain and nervous system work together to control functions.

What is the behavioral level of analysis concerned with?

It focuses on how brain activity influences behaviors, habits, and decision-making.

What does the cognitive level of analysis explore?

It investigates higher-order mental processes like thinking, memory, learning, and problem-solving.

Why is animal research important in neuroscience?

It helps examine processes relevant to human understanding and has led to advancements in various medical fields.

What are the two main divisions of the nervous system?

The central nervous system (CNS) and the peripheral nervous system (PNS).

What is the role of dendrites in a neuron?

They receive information from other cells. They are primary input structure

What is usually but not always insulated with Myelin?

Axon- Conduction takes place here

What is the function of synaptic vesicles?

They store neurotransmitters that are released into the synaptic cleft.

What is the difference between 'efferent' and 'afferent' neurons?

'Efferent' neurons carry signals away from the CNS, while 'afferent' neurons carry signals towards the CNS.

shape classifications

multipolar, bipolar, monopolar, interneurons

What role do microglial cells play?

1. Resident immune cells → remove debris from from dead/ regenerating neuron (break it up) w/t viruses/ viruses, they wrap themselves around the neuron/degrade it/release other immune markers

2. Synaptic pruning

3. Clearing apoptic (dead) nuerons

4. Interact with multiple CnS cell types in health and disease

What do oligodendrocytes and Schwann cells do?

Both produce myelin; oligodendrocytes in the CNS and Schwann cells in the PNS.

What does the somatic nervous system control?

Nerves that interconnect the CNS with major muscles and sensory systems.

What is the function of the dorsal root of a spinal nerve?

Carries sensory (afferent) information from the body to the spinal cord.

What does the ventral root of a spinal nerve carry?

Carries motor (efferent) information from the spinal cord to the muscles.

What is the autonomic nervous system responsible for?

Controls glands and internal organs, including the sympathetic and parasympathetic responses.

Ventricles

allow fluid to run through brain tissues

5 major ventricles

Spinal canal→ with spine

Fourth ventricle→ seits near crebellum

Cerebral aqueduct

Third ventricl

Lateral ventricle → you can only see it from certain P.O.V.

What is the function of the basal ganglia?

Involved in motor control, motivation, and reward. other functions like procedural learning (driving), voluntary movements, habit learning, conditioning emotions, decision making (feeling based)

What is the ventricular system?

A series of chambers filled with cerebrospinal fluid (CSF) that cushions the brain. Brings nutrients and chemicals to the brain

Take waste away from the brain

What is the primary function of the precentral gyrus?

Important for motor control.

What does the postcentral gyrus do?

Important for touch and sensory perception.

What is the role of the thalamus?

Acts as a sensory relay region for the cerebral cortex.

temporal lobe

primary auditory cortex

parietal lobe

Somatic sensory areas touch, temptation, limb position

frontal cortex

Primary Motor Cortex (movement)

Somatic sensory (feeling)

cerebral cortex

is divided into 6 individual layers. Each layer has a different pattern

Layer 1→ Almost no cells

Layer 2 &3→ mostly local circuit neurons

Layer 4→ mostly neurons that receive thalamic input

*receives thalamic input, Thaylmus is a sensory relay region (see, touch, hear) → goes through eyes→ sent to thyalmus to the cortex

Layer 5 and 6→ mostly output and projection neurons

What is the significance of acetylcholine in the autonomic nervous system?

It is the neurotransmitter released by the parasympathetic nervous system.

What are the main components of the Basal Ganglia?

Striatum (Dorsal: Caudate Nucleus, Putamen; Ventral: Nucleus Accumbens), Pallidum.

What is the role of the Limbic System?

It includes structures important for emotion and learning/memory.

What is the function of the Amygdala?

Emotional regulation (fear/anxiety) and perception of odor.

What is the primary role of the Hippocampus?

Learning and memory; one of the two regions where neurogenesis occurs.

What does the Cingulate Gyrus regulate?

Attention and emotional responses.

What is the function of the Olfactory Bulb?

It is responsible for the sense of smell.

What is the primary function of neurons?

To take in, integrate, and transmit information.

Where is the action potential initiated in a neuron?

At the axon hillock.

What is the primary output structure of a neuron?

Axon terminals.

What do Axon terminals do?

release neurotransmitters, sending signals to other cells

What is a synapse?

The junction where information is transmitted from one neuron to another.

Flow of information in nuerons

dendrite, soma(cell body), axon hillock, axon, axon terminal

What does the Synaptic Cleft do

gap separates, pre-synaptic/post-synaptic

The Communication between neurons is

electrochemical, an electrical signal is sent down in the axon, which lads to the release of chemicals (neurotransmitters from the presynaptic mebrane, bind to the postsynaptic membrane

How do We classify Neurons?

size shape and function

What are the main types of glial cells?

Astrocytes, oligodendrocytes, microglia, and ependymal cells.

What is the function of the myelin sheath?

It insulates the axon and speeds up the conduction of action potentials.

What is the role of interneurons?

recieve input and send info to other neurons. They only form connections with other nuerons. They take input from motor and send sensory info) They connect other neurons and process information within the CNS.

What are the characteristics of multipolar neurons?

They have one axon and many dendrites; they are the most common type of neuron.

What is the function of motor neurons?

They send information from the spinal cord to muscles.

How do sensory neurons function?

They receive signals from receptor cells and transmit them to the CNS.

What are glial cells?

Glial is greek for glue, Cells in the nervous system that support and protect neurons. they are responsible for motor defeiciets in parkinsons and related to control in apetite.

4 main types of glial cells

oligodendrocytes, schwann cells, microglia, astrocytes

What is the primary function of astrocytes?

1. Regulate synapse formation, elimination and function (secrete) (2 neurons cannot talk to each other w/o astrocytes they do such by secrete chemicals combined with blood vessels to form barrier

2. Metabolic support, regulating circuit function

3. Connections with nodes of ranvier

4. Interact with other glia

What is myelin?

A fatty substance that insulates axons and speeds up action potential conduction.

What are the Nodes of Ranvier?

Gaps between myelin sheaths where the axon is exposed.

What are the two main parts of the nervous system?

Central Nervous System (CNS) and Peripheral Nervous System (PNS).

What is the Central Nervous System

Brain and Spinal Cord

What is the Peripheal Nervous System

Somatic and Autonomic Nervous System

How many cranial and spinal nerve pairs are there?

12 pairs of cranial nerves and 31 pairs of spinal nerves.

What does the sympathetic nervous system do?

Prepares the body for 'fight or flight' responses. Increased heart rate and blood pressure

Relazes airways (more O2)

Inhibits salivation digestion

What is the function of the parasympathetic nervous system?

Promotes 'rest and digest' activities.

Exits the brain at the base of the spinal cord

Slows heart rate

Stimulates digestion

Constricts airways

Acetylcholine is the chemical being released

Define medial in anatomical terms.

Towards the middle or central line.

What does lateral mean?

Towards the sides of the body.

What is the role of the cerebral cortex?

The outermost layer of the brain involved in higher brain functions.

Gyri and sulci

the ridges and valleys of the cerebral cortex

What are the four lobes of the brain?

Frontal, parietal, temporal, and occipital lobes.

What is contralateral control?

The concept that the right side of the brain controls the left side of the body and vice versa.

What are the three ways to slice the brain?

Sagittal, horizontal, and coronal.

Frontal lobe

primary motor cortex, complex cognitive processes, language, attention/planning, strategizing

occipital lobe

primary visual areas

What is cerebral spinal fluid

Cushion brain provides, nutrients for the brain to function/takes away waste

Where is the Thalamus located and what is its function?

Located in the middle of the brain; it is a sensory relay system except for smell.

What are the main functions of the Hypothalamus?

Homeostasis, temperature regulation, thirst, hunger, sex, and aggression; controls the pituitary gland--> controls the hormones

What is the role of the Cerebellum?

Crucial for motor coordination and control.

What structures make up the Brain Stem?

The pons and the medulla.

Brain Stem

relays information from the cerebrum and cerebellum to the spinal cord and regulates vital functions such as breathing, consciousness, and body temperature

Pons

Contains a variety of sensory and motor-related nuclei important for relating those types of messages to or from the brain

What functions does the Medulla control?

Essential bodily processes like respiration, heart rate, and blood pressure.

What is the function of the Spinal Cord?

Relays sensory information into the brain and motor movement out of the brain.

What are the two parts of the Midbrain?

Tectum and Tegmentum.

tectum

Superior colliculi→ visual processing

Inferior colliculi→ auditory processing

What is the function of the Substantia Nigra?

Major input to the motor components of the basal ganglia.

What does the Ventral Tegmental Area provide input to?

Motivation/reward components of the basal ganglia.

What is the role of the Corpus Callosum?

Connects the two hemispheres of the brain.

How does the Human Brain differ from Mammals

Difference in size

Sulfri gyri allows more neurons to be in a certain amount of space

Pre-frontal cortex in human whilst a lot→ we have the largest relative to size

A lot of regions conserved by evolution, i.e cerebellum, brain stem

resting neuron

polarized

Ions

electrically charged molecules

anions

negatively charged ions

Cations

positively charged ions

a cell membrane is a

Lipid Bilayer, a layer containing ion channels embedded in the liquid molecules

ion channels

are proteins that span the membrane and allow ions to pass

Gates' response to a voltage change

Gated Ion channels

Voltage-gated ion channels open and close based on voltage change.

selective permeability

The cell membrane allows some substances to pass through and others not

resting membrane potential

A neuron at rest is not actively sending a signal; it maintains a stable electrical charge difference across its cell membrane, known as the resting membrane potential

What happens during resting membrane Potential

This state involves a separation of charged particles, making the inside of the neuron negative relative to the outside, with a higher concentration of potassium ions inside and a higher concentration of sodium ions outside

The inside of the cell is more negative than the outside, and the majority of the RP is -65

What is the resting membrane potential in a typical neuron?

Ranges from -50 to -80 mV, typically around -65 mV.

Difussion

causes ions to flow from areas of high to low concentration, along their concentration gradient (the process of particles, which are solutes, moving through a solution or gas from an area of higher number of particles to an area of lower number of particles)