Part 5: The Neurological Basis of Behavior

What are the 3 interactions adaptive behavior relies on?

The environment, nervous system, and the remainder of the body

What are the two parts of the nervous system, what do they consist of?

CNS (central nervous system), consisting of the brain and spinal cord in vertebrates and the brain and nerve cord in invertebrates.

PNS (peripheral nervous system), consisting of all aspects of the nervous system other that the CNS. Can be divided into a Sensory Division and a Motor Division.

What are the basic parts of the neuron, and what do they do?

Cell Body/Perikaryon contains basic organelles of animal cell, located in the CNS or in ganglia in PNS.

Dendrites are branching extensions of the cell. More numerous of two types of neurites.

Axons are typically singular extensions of the cell, distributive in nature, most animals axon has insulating coating of

Myelin, insulating coating of axons. Allows faster transmission of information, produced by glial cells.

What are the 3 classes of neurons, what do they do?

Sensory/Afferent Neurons respond to stimuli and send sensory information to CNS

Motor/Efferent Neurons carry motor information from the CNS to effector organs such as muscles and glands.

Interneurons process sensory input and determine the appropriate motor response.

What are the terms for message of a neuron?

Impulse or an Action Potential.

What is an action potential? How do they work?

The message of a neuron, an electrochemical signal conducted along the length of an axon due to uneven exchange of sodium and potassium cations.

They work “all-or-none” and the number of and firing rate of neurons involved causes variation in intensity of stimuli. Must rest between firing.

Where do neurons exchange information with other cells, and what is this space?

A synapse, or a synaptic cleft, is the space between the two communicating cells, typically a presynaptic axon and a postsynaptic dendrite.

What are the two types of synaptic events? What are the signals called in the more common of the two events?

Chemical Synapse, where the electrical impulse causes chemicals to be released that will cross the cleft and propagate an impulse in the postsynaptic neuron. These chemical signals are neurotransmitters.

Electrical Synapse, the electrical impulse simply jumps the synaptic cleft. Less common.

How has natural selection affected an animal’s efficiency in processing important stimuli?

Over evolutionary time, a species will become more sensitive to stimuli specific to its environment and to its fitness.

Why are many of our special sense organs paired?

To allow for localization of the source of a stimulus. Paired nostrils, eyes, ears, etc.

Explain the cricket and bat case study.

Crickets will drop out of air when hearing bat’s echolocating calls. This is a negative phonotaxis tropism. The cricket does this in an extremely short time frame. Unlike moths, cricket ear has a lot of complex receptors, with high sensitivity to echolocating calls. The AN2 auditory interneuron exhibits rapid responses, while another interneuron carries information about cricket song. The interneuron that gets excited by sounds at the bat range is INT-1. Brain is also necessary for this response, headless won’t carry out negative phonotaxis.

What does true learning require? How does this happen? What does it involve?

Formation of a memory, which forms through the strengthening of synapses in the brain. Can involve changes in production of neurotransmitters at synapse, changes in number of receptors on postsynaptic cell membrane, changes in number of synapses that a neuron will have, or growth of new neurons (only happens in memory center)

What are the three types of memories, what separates them? What can develop the later of them?

Short term memories can be retrieved for minutes, hours, or a day after learning.

Intermediate term memories can be retrieved for one or more days after learning. Can develop from short term memories that have been strengthened.

Long Term Memories can be retrieved for weeks, months, or even years after exposure to the learning experience. Can develop from intermediate term memories that have been strengthened.

What is Nonassociative Learning?

A change of the behavior of an animal due to an experience from specific kinds of stimuli.

What are the 3 different forms of nonassociative learning?

Habituation when stimulus is repeatedly presented to a test and there is a progressive decrease in response to that stimulus.

Sensitization is increase of a response due to presentation of novel, maybe noxious, stimulus.

Dishabituation is when the animal is presented to another novel stimulus and a partial or complete restoration of a habituated response occurs

Explain the Sea Hare case study.

Sea Hare is very easy to study learning in as it only has 20,000 neurons and are large easy to work with. Did habituation, sensitization, and dishabituation on them. Fewer synaptic vesicles are recruited and less neurotransmitter released. In sensitization, amount of neurotransmitter released is increased increasing the rate of firing motor neuron.

What are the four processes for the changes in synaptic connections involved in the formation of memory? Explain a bit about each

Long Term Potentiation (LTP) is stable and long lasting response to an action potential by receiving neuron caused by rapidly repeated strong stimulation

Long Term Depression (LTD) is a lasting decrease in the responsiveness of the postsynaptic neurons after sensory neurons have received a slow repetition of stimuli.

Synaptic Remodeling is the refinement of synaptic connections that occur during memory formation through development of new synapses and eradication of less used synapses.

Neurogenesis is creation of new neurons.

Go more into detail on the difference between LTP and LTD

LTP (Long Term Potentiation) strengthens the connections between adjacent neurons, is the molecular mechanism underlying storage and acquisition of memories, is long-lasting enhancement in signal transmission between two neurons, underlies synaptic plasticity.

LTD (Long Term Depression) is mechanism that weakens effectiveness of a synapse, decreasing magnitude of a response by postsynaptic cells. Activity dependent reduction in efficacy of neuronal synapses for hours or longer. Considered opposite of LTP. Can occur in hippocampus of mammals, and may be important for clearing old memory trace allowing new memories to form.

Explain the Zebra Finch case study

Young male zebra finches learns his song in two phases, memorization and practice. Can rapidly memorize the song of an adult tutor but may need to practice singing as many as 100,000 times in a 45 day period. This process of listening then singing is a traditional practice in humans. Brain region needed for motor control of a song also has an essential role in helping auditory learning of the tutor song.

What is SBN and who proposed the idea?

Social Behavior Networks, proposed by Sarah Newman. Each region form the network and each plays a role in a number of social behaviors. Mapped out in mammals but also seems to exist in other vertebrates.

What does motor response involve?

Motor (or efferent) information traveling from the CNS to an effector organ causing response to stimulus. Motor neurons receive an impulse from interneurons of the CNS. Each response could be considered to be part of a neural circuit.

What are the primary 3 ways neural circuits can control and coordinate a motor response?

Sensory Reflex - sensory neurons can initiate an activity in motor neurons. Can be direct synaptic interface between sensory and motor neuron although those are rare. Typically will involve interneurons.

Central Pattern Generator (CPG) - a neuron or neural network that produce rhythmic patterned motor outputs without requiring sensory feedback. Outputs resembling normal rhythmic motor pattern production even in isolation from motor and sensory feedback. Requires two or more processes that interact and as a result, system repeatedly returns to its starting condition. Breathing, rhythm generation, etc..

Motor Command - sending out of an impulse from CNS to effector organ based on sensory input. Can impart varying degrees of flexibility to the system of motor control. Interneurons from brain initiate and modulate activity in a CPG.