Cognitive Neuroscience Ch 2

How many neurons are in the human brain?

86 billion

How many neurons are in the cerebral cortex?

16 billion

How many neurons are in the spinal cord?

1 billion

How many neurons are in the cerebellum?

69 billion

What is the classification of neurosystems from smallest to the biggest?

Cell-Circuit-Network-System

Define Neurons

Basic signaling unit; brain cells that process information

Define Glial Cells

Cells that serve various functions besides constructing signals Ex: structural support, electrical insulation, and moderating neural activity.

Define Astrocytes

Cells responsible for dilating blood vessles, creating the blood brain barrier, and moderating neural activity.

Astrocytes overall function

synchronization of neural networks

Oligodendrocytes

myelinate axons in the brain and spinal cord (CNS)

Schwann cells

myelinate axons in the PNS

Microglial Cells

Act as immune cells in the CNS that remove debris and damaged cells

Soma (neuron)

maintains metabolic function (cell body)

Dendrite (neuron)

receive inputs from other neurons

Axon (neuron)

transmits electrical signals

Axon Terminal

(buttons) releases chemicals to communicate with other neurons

What is neuronal signaling?

When neurons receive, evaluate, and transmit information.

Where does transmission occur in the neuron?

at the synapse

What are the gaps between myelin segments called?

Node of Ranvier

Are most neurons presynaptic or postsynaptic?

Both

Where do electrical processes occur?

Within the neuron.

Where do chemical processes occur?

Between neurons

What is the resting membrane potential?

-70mV

Define the sodium-potassium pump.

a pump on the membrane where 3 sodium (Na+) ions exit and 2 potassium (K+) ions enter

What is action potential?

a rapid polarization and depolarization of a region on the neuronal membrane caused by the opening and closing of ion channels. (Think that this is when the opposite of the sodium-potassium pump works; in this scenario, K+ leaves and Na+ enters)

Where does the action potential begin and where does it travel to?

It begins at the axon hillock/ initial segment and propagates along the axon towards the axon terminal buttons.

What is the all or none law?

1 or 0 (the neuron fires with tons of strength or none)

Where are action potentials regenerated at?

Nodes of Ranvier

What is a neurons maximum firing rate?

200/sec

What is the intensity of a stimulus is coded by the neurons?

rate of firing

What is LFP?

Local field potential- local population of neurons.

What is an EEG?

Electroencephalography- large population of neurons that are mainly cortical

Membrane Potential

Difference of the electrical potential inside and outside of the cell

Depolarization

When sodium (Na+) ions enter into the cell

Repolarization

When potassium (K+) ions exit the cell

What is a neurons maximum rate of firing?

200/sec

True or false- Action potential is measured by frequency rather than amplitude

true

What is step one of synaptic transmission

1 action potential arrives at the terminal and voltage-gated Ca2+ channels open

What is step two of synaptic transmission

2. synaptic vesicles containing neurotransmitters bind to the presynaptic membrane

what is step three of synaptic transmission

3. neurotransmitters are released into the synaptic cleft by exocytosis and diffuse across the cleft

what is step four of synaptic transmission

4. neurotransmitters bind to receptor molecules on the postsynaptic membrane

Ionotrophic receptor

(AKA LIGAND-GATED); fast effects; neurotransmitter directly opens an ion channel (postsynaptic receptor)

Metabotrophic receptor-

(AKA G-Protein coupled receptor) (GPCR)- slower but longer lasting effects(postsynaptic receptor)

What are the two different postsynaptic potentials?

Excitatory postsynaptic potential (ESP) and Inhibitory postsynaptic potentials (IPSP)

What is the dopaminergic system?

Involved in reward processing and regulates brain regions involved in motor, cognitive, and motivational behaviors.

What is the norepinephrine system?

plays a role in many bodily functions such as “fight or flight” response

What is the serotonin system

It influences mood, temperature, appetite, stress, sleep, pain, and sexual behaviors

What happens to neurotransmitters in the synaptic cleft?

They are subject to inactivation or reuptake

What are autoreceptors?

they detect the amount of neurotransmitter released and inhibit further synthesis and release negative feedback.

Are electrical or chemical synapses faster

electrical are faster but less plastic

Gap Junctions

provide direct connections between the cytoplasm of one neuron and another

What can spread from one cell to another to synchronize the neurons

depolarization

meninges

thin protective membranes that surround the brain and spinal cord

Cerebrospinal Fluid (CSF)

what the brain is suspended in

Ventricles

four interconnected cavities within the brain

nucleus

a relatively compact cluster of neuronal cell bodies and their connections

Gray matter

consists primarily of neuronal cell bodies, dendrites, axons, and glial cells

White matter

consists primarily of myelinated axons and glial cells

corpus callosum

a white matter structure that connects the left and right cerebral hemispheres

Afferent neurons

enter through the dorsal roots and carry sensory information to the spinal cord

Efferent neurons

exit through the ventral roots and carry motor information from the spinal cord

dorsal root ganglia

cell bodies of sensory neurons located in clusters outside the spinal cord

Medulla

essential for life and controls vital

where is life support in the brain

in the center

Cerebellum and Pons

maintain posture balance and coordinated movements

Midbrain

involved in eye movements, auditory (inferior colliculus) and visual (superior colliculus) processing and motor control (substantial nigra, red nucleus)

Thalamus

a gateway to the cerebral cortex and most sensory modalities (except olfaction) relay through the thalamus before reaching their primary sensory cortical areas

Hypothalamus

links the nervous and endocrine systems as well as regulates homeostasis, body temperature, metabolism, hormone release, circadian rhythms, fluid balance

What structures are included in the limbic system

hippocampus, amygdala, hypothalamus, and cingulate cortex

Function of limbic system

memory, emotion, motivational states (like eating, anxiety, aggression, sex, drinking)

Basal ganglia structures

caudate nucleus, putamen, globus pallidus, subthalamic nucleus, and substantia nigra

Basal ganglia function

action selection, action gating, reward based learning, motor preparation, it ultimately integrates sensory, motor, and cognitive activities

Prefrontal cortex

EXECUTIVE FUNCTION of cognitive control as well as planning, organizing, controlling, and executing behaviors

True or false- very few neurons are generated after birth

true

synaptogenesis

the process of forming connections between neurons in the nervous system (an explosion of this happens during early brain development)

synapse elimination

pruning and fine tuning of neuronal connectivity

Neurogenesis

the division of neural stem cells that become hippocampus networks and increase neural plasticity

where does neurogenesis occur

the hippocampus (learning and olfactory system)

True or false exercise increases neurogenesis

true