Intro Mind And Brain (psych 251) Topic 1 - Foundation- Neurons

IPSPs are inhibitory post synaptic potentials that result in hyperpolarizations and cause the membrane potential to return to its steady state. It is important to differentiate them from excitatory post synaptic potentials, synaptic transmission-induced membrane potential changes, and axon potential in the synaptic cleft that lead to different effects on the membrane potential.

EPSPs are excitatory postsynaptic potentials that lead to depolarization, potentially triggering an action potential. They are not inhibitory or preventive of action potentials.

An action potential (spike) is characterized by rapid depolarization and repolarization, occurring at the threshold potential of 55mV. It follows the all-or-none principle with a constant amplitude (100mV above resting) and a constant timecourse of 1ms. Additionally, there is a refractory period of 5ms after which another action potential can be generated.

Voltage gated Na+ and K+ channels are crucial for the generation and conduction of action potentials in neurons. While Na+ channels depolarize the cell by allowing Na+ ions in, K+ channels help in repolarizing the cell by allowing K+ ions out. Ca2+ channels, Ligand gated channels, and Mechanical gated channels serve different purposes and are not directly involved in generating action potentials in neurons.

At threshold, the voltage gated Na+ channels open, allowing the influx of positive Na+ ions into the cell. This initiates depolarization and leads to the generation of an action potential.

During depolarization, the cell's membrane potential becomes more positive as more voltage gated Na+ channels open, allowing an influx of Na+ ions. This results in an increase in depolarization and is necessary for generating action potentials.

After the action potential reaches its peak, voltage gated K+ channels open causing K+ ions to flow out of the cell, leading to the decline in membrane potential. This process is crucial for repolarization of the cell membrane.

During hyperpolarization, the cell's membrane potential becomes more negative than the resting membrane potential due to the efflux of K+ ions. This causes voltage gated Na+ channels to close and voltage gated K+ channels to remain open, making it difficult for another action potential to be generated immediately, known as the absolute refractory period.

The relative refractory period occurs due to the difficulty in generating an action potential caused by the closure of voltage-gated K+ channels when the membrane is hyperpolarized.

The Hodgkin-Huxley Model is a specific mathematical model developed to explain the generation and propagation of action potentials in neurons, and its significance was recognized with a Nobel Prize in Physiology or Medicine in 1963.

Electrical conductance is characterized by being passive, relatively fast, exponentially attenuating, and only traveling short distances before losing strength.

Saltatory conduction is a specialized form of conduction in myelinated neurons that enables rapid transmission of electrical signals by 'jumping' between Nodes of Ranvier.

Propagation speed can vary significantly depending on the medium and conditions. The correct answer covers the range of slowest to fastest speeds typically encountered in various propagation scenarios.

The speed of propagation in neurons depends on factors such as the axon diameter, myelination, and temperature. These factors impact the efficiency and speed at which signals are transmitted along nerve cells, ultimately affecting the overall speed of propagation.

Neural coding is primarily facilitated by the rate, duration, and timing of action potentials, rather than the physical characteristics like size, color, or shape of the neuron.

The Neuron Doctrine, proposed by Santiago Ramon y Cajal in 1888, states that the nervous system is made up of individual, separate cells called neurons. This was a revolutionary idea at the time and laid the foundation for our current understanding of how the brain works.

The correct answer of approximately 100 billion neurons in the human brain is based on current scientific estimates. While the number of connections between neurons (synapses) is indeed very high, the other three incorrect answers provided do not reflect the accurate count of neurons in the human brain.

Bipolar cells of the retina are specialized neurons that play a crucial role in transmitting visual information from photoreceptor cells to ganglion cells in the retina. They have a unique structure with processes extending to different layers of the retina, allowing them to integrate and relay signals effectively.

Ganglion cells of the dorsal root are pseudounipolar neurons with a unique structure that allows for the transmission of sensory information from the peripheral nerves to the central nervous system.

Pyramidal cells of the hippocampus are characterized by their unique structure, which includes a triangular cell body, single long axon, multiple dendrites, and an apical dendrite. The incorrect answers provided do not accurately describe the structure of a pyramidal cell of the hippocampus.

Purkinje cells are unique neurons found in the cerebellum with a distinct flask-shaped cell body and multiple dendrites, making them crucial for motor coordination and control.

In the context of neuroscience, PSP stands for Post synaptic potential and refers to the changes in the membrane potential of the postsynaptic neuron following the activation of neurotransmitter receptors. These changes can either be excitatory, leading to depolarization and increased likelihood of an action potential, or inhibitory, leading to hyperpolarization and decreased likelihood of an action potential.

The correct types of connections between neurons are axoaxonic, axo dendritic, and axo-somatic synapses. Dendrodendritic and somatosomatic synapses are not commonly recognized types of connections between neurons. Axoaxonic dendrites is not a valid term and does not describe a specific type of connection.

A neuron is similar to a battery in the sense that it has a difference in electrical potential between the outside and inside, just like a battery has positive and negative terminals that create a potential difference.