2C

• Neural synapse: the region that includes the axon terminals of the presynaptic neuron, the synaptic gap, and the dendrites of the postsynaptic neuron
• presynaptic neuron: the neuron that releases neurochemicals into the neural synapse
• axon terminal (also known as terminal button): the end of a neuron that releases neurochemicals into the neural synapse
• Two neurons in a neural pathway meet at the neural synapse, which is the region that includes the axon terminals of the presynaptic neuron, the synaptic gap, and the dendrites of the postsynaptic neuron
• synaptic gap: the space between the presynaptic neuron and the postsynaptic neuron
• postsynaptic neuron: the neuron that receives neurochemicals from the neural synapse
• Dendrite: a branched extension of a neuron on which receptor sites are located
• Receptor site: a protein molecule on the dendrites of a neuron that receives neurochemicals
• Neurochemical: a chemical substance that transmits neural information within the nervous system
• Synaptic transmission: the chemical conveyance of neural information between two neurons across a neural synapse
• neural synapse

  A) presynaptic

  B) postsynaptic

  C) receptor site

  D) dendrite

  E) axon terminal

  F) synaptic gap

  G) neural synapse

  
• Neurochemicals are released by the presynaptic neuron and affect the postsynaptic neuron. In this way, these chemical substances enable synaptic transmission
• NEURAL SYNAPSE STEPS

  1. Neurochemicals are produced in the axon terminals of the presynaptic neuron.
  2. Neurochemicals are released from the axon terminals of the presynaptic neuron into the synaptic gap.
  3. Neurochemicals bind to receptor sites on the dendrites of the postsynaptic neuron.
  4. Neurochemicals affect the postsynaptic neuron, either triggering or inhibiting a response
• Each neurochemical has a distinct molecular structure that corresponds to a specific receptor site. A neurochemical can only bind to the corresponding receptor site that matches its specific molecular structure.
• DIRECTION OF NEURAL TRANSMISSION

  A) electrical

  B) chemical

  C) electrical

  D) neurochemicals

  E) action potential

  
• Neurotransmitter: a chemical molecule that has an effect on one or two postsynaptic neurons
• Action potential: an electrical impulse that travels down the axon of a neuron
• Excitatory effect: when the neurotransmitter increases the likelihood of the postsynaptic neuron firing an action potential
• Glutamate: the main excitatory neurotransmitter in the nervous system
• Both inhibitory and excitatory neurotransmitters bind to their corresponding receptor sites on the dendrites of the postsynaptic neuron
• excitatory effects enhance neural transmission along neural pathways by activating postsynaptic neurons
• Glutamate has an important role in learning and memory. Specifically, the excitatory effects of glutamate form and strengthen synaptic connections between neurons that are repeatedly activated during learning. These strong synaptic connections represent memories of what has been learnt. In this way, glutamate enables synaptic plasticity
• inhibitory effect is when the neurotransmitter decreases the likelihood of the postsynaptic neuron firing an action potential.
• Inhibitory effects occur when an inhibitory neurotransmitter binds to receptor sites on the dendrites of the postsynaptic neuron. They suppress neural transmission from occurring along neural pathways by regulating the activation of postsynaptic neurons.
• GABA (gamma-aminobutyric acid) is the main inhibitory neurotransmitter in the nervous system.
• GABA has an important role in regulating postsynaptic activation in neural pathways, preventing the overexcitation of neurons.

  - GABA reduces anxiety, by inhibiting excitatory neural signals that contribute to anxiety

  - GABA has an important role in preventing seizures
• anxiety; a physiological and psychological response that involves general feelings of worry and apprehension
• Neuromodulator: a chemical molecule that has an effect on multiple postsynaptic neurons
• neuromodulators are released into multiple neural synapses and consequently affect multiple postsynaptic neurons, unlike neurotransmitters
• neuromodulators have widespread modulatory effects as they can influence large areas of brain tissue. Furthermore, the action of neuromodulators produces relatively long-lasting effects, as they modulate neural activity more slowly than neurotransmitters
• NT V NM

  A) Neurotransmission

  B) neuromodulation

  
• Neuromodulators can also modulate the effects of neurotransmitters by:

  • changing the responsiveness of the receptor sites of a particular neurotransmitter, enhancing the excitatory or inhibitory effects of neurotransmitters.

  • changing the neurotransmitter release pattern of the presynaptic neuron.
• Dopamine: a neuromodulator primarily responsible

  for voluntary motor movement, the experience of pleasure, and reward-based learning.
• Norepinephrine (noradrenaline): a neuromodulator involved in attention, memory, and stress response.
• originate from regions that produce dopamine, including:

  • the substantia nigra, which is located in the midbrain.

  • the ventral tegmental area, which is located in the midbrain
• Dopamine can have excitatory and inhibitory effects on the postsynaptic neuron. The effect dopamine has depends on the type of receptor sites present at the particular brain location.
• ROLE OF DOPAMINE:

  • Dopamine has an important role in coordinating voluntary motor movement.
  • has an important role in reward-based learning
  • Dopamine also has a role in motivation, given its role in reward-based learning
• Dopamine has an important role in coordinating voluntary motor movement. Dopamine produced in the substantia nigra transmits neural information that enables smooth, coordinated muscle movement.
• Dopamine has an important role in reward-based learning. When a person is rewarded for doing a behaviour, dopamine produced in the ventral tegmental area is released, which is associated with the experience of pleasure.
• Dopamine also has a role in motivation, given its role in reward-based learning. Rewarding behaviours that trigger the release of dopamine have a pleasurable consequence for the person and are therefore more likely to be repeated.