Lecture 3 Flashcards
What are most neurons in the VTA? What are the main areas for the human reward system?
Around 50% of the neurons in the ventral tegmental Area are dopaminergic, this VTA projects to a number of regions including the nucleus accumbens and prefrontal cortex. The human reward system (VTA and nucleus accumbens) is activated by a wide range of reinforcers.
Why is the reward system of the brain important?
The reward system is activated to ensure we engage in behaviours which ensure survival of your genes e.g eating, drinking, copulating.
How are complex behaviours caused by neurons? What is the simplest example?
Operation of networks of neurons produces complex behaviour. The simplest of these networks is the reflex (A simple automatic response to a stimulus, it is stereotyped, subconscious and unlearned e.g eyeblink or swallowing).
What is the name of the neurons which command muscles?
Alpha motor neurons.
What is a monosynaptic stretch reflex and what is a good example of its use?
A monosynaptic stretch reflex involves two neurons with one synapse. A sensory stretch receptor is in the muscle and sends the information to the spinal cord where a single synapse waits which joins on to the motor neuron, this will then trigger the muscle. These reflexes help to maintain posture.
What is an inhibitory synapse and excitatory synapse
Excitatory connections produce a graded potential which makes the cell more likely to fire an action potential. Inhibitory connections produce a graded potential which makes the cell less likely to fire an action potential.
What is a polysynaptic reflex and how is it useful?
We have muscles on both sides of joints, one is a flexor and one is an extensor, when one is acting the other is inhibited. This is regulated via polysynaptic reflexes in which the sensory neuron sends a signal to the spinal cord which then synapses with an alpha motor neuron and an interneuron, the inter neuron sends a signal to the other alpha motor neuron to inhibit it and allow for smooth movement.
What does a withdrawal reflex involve?
In a withdrawal reflex the sensory neuron sends a signal via an interneuron in the spinal cord to the motor neuron and also sends a signal up towards the brain to let you know about the pain, this is because the pain takes longer to reach the brain and therefore helps us react to harmful stimuli faster than we can consciously register it.
Why are some reflexes tested for in events of possible brain damage?
Grasping and suckling are both reflexes held in babies which are inhibited by a maturing/mature brain but can be disinhibited by damage which prevents conscious control.
How are experiences and memories stored in the brain?
Experiences are stored as patterns of activity in networks of neurons. Memories are stored by strengthening the synapses used for that experience. A cue can then conjure up the memory.
