Module 13.2 Flashcards
What did Wilder Penfield conclude from his brain stimulation experiments? What re some problems with his conclusion?
He concluded that each neuron stores a particular memory. The problem with his conclusion is that brain stimulation rarely elicited a memory of a specific event and it almost never elicited memories of doing anything-just seeing and hearing.
Describe G.A. Horridge’s experiments with headless cockroaches.
He cut the connections between a cockroach’s head and the rest of its body. The he help the cockroach so that its legs dangled just above the surface of water. An electrical circuit was arranged, so that the roach’s leg received a shock whenever it touched the water. Each experimental roach was paired with a control roach that got a shock whenever it touched the water. Each experimental roach was paired with a control roach that got a leg shock whenever the first roach did. Only the experimental roach had control over the shock. Roaches in the experimental group increased a
response of tucking the leg under the body to avoid shocks and roaches in the control group did not. The response of the experimental group classifies as learning.
Describe the experiments with planaria and rats that seemed to transfer learning from one individual to another via RNA or protein.
A planaria was classically conditioned to respond to light, then another planaria ate that planaria. The second planaria then learned the response faster than planeria generally do. A rat was trained to approach a clicking sound for food, then their brain was ground up and RNA was extracted from it. The RNA was injected into another rat, who learned to approach the clicking sound faster than rats in the control goup did
What is a Hebbian Synapse?
A synapse that increases in effectiveness because of simultaneous activity in the presynaptic and postsynaptic neurons.
How is a Hebbian synapse related to classical conditioning?
pairing the activity of a weaker CS axon with a stronger UCS axon produces an action potential and in the process strengthens the response of the cells to the CS axon. On later trials, it will produce a bigger depolarization of the postsynaptic cell, which we can regard as a conditioned response
Why do scientists study for Aplysia?
Because its neurons are large and easy to study and their neurons are identical between individuals, so different researchers can examine the same thing.
What mechanism accounts for habituation in Aplysia?
A change in the synapse between the sensory neuron and the motor neuron
How is sensitization produced experimentally in Aplysia?
by electric shock
Describe the cellular events that explain sensitization in Aplysia. How does a decrease in potassium outflow increase neurotransmitter release?
Shock causes an interneuron to release serotonin at the sensory neuron’s synapses. Causes a prolonged action potential. So, more NT is released to the motor neuron.
How does long-term sensitization differ from the short-term variety?
Repeating the cellular process of sensitization causes the sensory neuron to synthesize new proteins that produce long term sensitizations
How is long-term potentiation produced? How long does it last? In what brain area was it first discovered?
One or more axons connected to a dendrite bombard it with a brief but rapid series of stimuli and this burst of intense stimulation makes some of the synapses more responsive to new input of the same type for minutes, days, or weeks It was first discovered in the hippocampus.
What is meant by cooperativity?
the tendency for nearly simultaneous stimulation by two or more axons to produce long-term potentiation much more effectively than stimulation by just one
What is meant by associativity?
the tendency for pairing a week input with a stronger input to enhance the later effectiveness of the weaker input
What is meant by specificity?
when highly active synapses become strengthened but less active synapses do not
What is Long Term Depression (LTD)?
Prolonged decrease in response at a synapse where the axons have been less active than certain other axons afferent to that neuron
