Indicate (on Figure) the following structures of the neuron (myelin, axon, cell body, dendrite, synapse)

• S oma (cell body) – integrates information provided by dendrites and produce action potential

• Dendrite – target for synaptic imputes, accumulate information and provides signals to the cell body

• Axon – always only 1 for the cell body, provides signal to the next cell

• M

  Synapse ->

  yelin - is a dielectric material that forms a layer, the myelin sheath, usually around only the axon of a neuron. It is essential for the proper functioning of the nervous system. It is an outgrowth of a type of glial cell. The main purpose of a myelin layer (or sheath) is to increase the speed at which impulses propagate along the myelinated fiber. Along unmyelinated fibers, impulses move continuously as waves, but, in myelinated fibers, they hop or "propagate by salutatory (скачущий) conduction." Myelin decreases capacitance(емкостное сопротивление) and increases electrical resistance across the cell membrane (the axolemma). Thus, myelination helps prevent the electrical current from leaving the axon

• Synapse is a structure that permits a neuron (or nerve cell) to pass an electrical or chemical signal to another cell.

Indicate (on the picture) key brain regions: Lobes (occipital. Temporal…), striatum, amygdale, orbitofrontal cortex…

Dorsal

Ventral

• Gyrus – извилина

• Sulcus – борозда

Lateral – ближе к переферии мозга

Medial – ближе к центру мозга

Orbital – localysed above eyes

Functions

In frontal lobe a lot of areas concentrated on the decision making

Dorsolateral prefrontal cortex –involved into self-contol, rational decision making,

Ventro-medial prefrontal cortex is involved in

emotional learning, anticipation of the future positive and

negative consequences of the action.

Amygdala

http://bigthink.com/videos/the-amygdala-in-5-minutes

This area is responsible for potential costs estimation. It is activated when we experience fear. The amygdala (Latin, corpus amygdaloideum) is an almond-shape set of neurons located deep in the brain's medial temporal lobe. Shown to play a key role in the processing of emotions, the amygdala forms part of the limbic system.

Amygdala is also contributes to the emotional learning process. We have to learn that objects have values. We learn to associate potential costs of doing something this initially neutral stimuli. Amygdala is a critical area for this conditioning, related to painful stimuli ( animal without amygdala doesn’t create connection between sound and electrical shock in the conditioning experiment). Thalamus sends information direct to amygdala which help one to react to the threat faster.

In sum

• orbitofrontal cortex – fast learning, quickly update values

• amygdala – slow learning, lasting process of association between stimuli and cost

Experiment 1:

Rat without amygdala is not afraid of robotic cat, because the brain can’t estimate the risk, the potential cost of being close to the cat.

Experiment 2:

Participants learned that some cues are connected with potential losts or benefits. Color – reward, shape – lost. Subject have to make a choice which cue to select. OFC activity was proportional to activity of Amygdala and NA in this case. OFC compares costs and benefits of doing something, so we can apply diffusion model metaphor.

Role of amygdala:

•Processing of the ”negative” information/costs

•Conditioning processes (learning)

•Emotional memory

•Triggers vegetative reactions

Explain the following terms:

• Action potential

An action potential is a short-lasting event in which the electrical membrane potential of a cell rapidly rises and falls, following a consistent trajectory (траектория).

Action potentials in neurons are also known as "nerve impulses" or "spikes", and the temporal sequence of action potentials generated by a neuron is called its "spike train". A neuron that emits an action potential is often said to "fire. The more active a neuron is the highest frequency of AP this neuron produces.

Action potentials are most commonly initiated by excitatory postsynaptic potentials from a presynaptic neuron.^[11] Typically, neurotransmitter molecules are released by the presynaptic neuron. These neurotransmitters then bind to receptors on the postsynaptic cell. This binding opens various types of ion channels. This opening has the further effect of changing the local permeability of the cell membrane and, thus, the membrane potential. If the binding increases the voltage (depolarizes the membrane), the synapse is excitatory. If, however, the binding decreases the voltage (hyperpolarizes the membrane), it is inhibitory. Whether the voltage is increased or decreased, the change propagates passively to nearby regions of the membrane (as described by the cable equation and its refinements). Typically, the voltage stimulus decays exponentially with the distance from the synapse and with time from the binding of the neurotransmitter. Some fraction of an excitatory voltage may reach the axon hillock and may (in rare cases) depolarize the membrane enough to provoke a new action potential. More typically, the excitatory potentials from several synapses must work together at nearly the same time to provoke a new action potential. Their joint efforts can be thwarted, however, by the counteracting inhibitory postsynaptic potentials.

• Synapse – было в вопросе про устройство нервной клетки

• Firing rate – the number of action potentials (spikes) produced by neuron per second

• Grey & white matter (белое и серое вещество)

Grey matter consists of cell bodies; most of the NE studies focuses on this matter.

White matter consists of axons, thus consists of connections.