lecture 7: simple neural circuits and memory Flashcards
why is dopamine studied
because of its involvement in parkinsons disease and schizophrenia, but also because of its connection to many drugs of abuse
how does dopamine relate to drugs of abuse
dopamine causes a pleasurable surge which imitates drugs such as cocaine or nicotine which cause dopamine to flood the reward pathway
dopamine
a chemical messenger in the brain that affects mood, movement and motivation
how does intracranial self stimulation work
- electrodes are placed in a certain part of the brain, connected to a stimulus which was connected to a lever that the animal could press
- it appears to produce a pleasurable effect in animals
- ICSS activates dopaminergic pathways including the nucleus accumbens and VTA
reward system
made up of VTA and nucleus accumbens and is activated by a wide range of reinforcers including food, sex, money, drugs of abuse, beauty and humour
nucleus accumbens
a small, subcortical brain structure within the ventral striatum, known for its role in reward processing, motivation and addiction
ventral tegmental area (VTA)
- a midbrain region crucial for reward processing, motivation and emotional regulation
- around 50% of the neurons in the VTA are dopaminergic
- the VTA projects to a number of regions including the nucleus accumbens and prefrontal cortex
how is complex behaviour produced
the nervous system relies on the operation of networks of neurons to produce complex behaviour
the reflex
A simple automatic response to a stimulus
- stereotyped
- subconscious
- unlearned
eg: eye blinking, swallowing
what are the commands to muscles communicated through
approx. 400,000 alpha motor neurons
monosynaptic stretch reflex
a rapid, involuntary contraction of a muscle in response to being stretched, mediated by a single synapse between a sensory neuron and a motor neuron
polysynaptic reflex
- more than one synapse involved
- can get info processing in the spinal cord, don’t always have to send it back to the brain
what is the effect of experiences which are likely to lead to memory formation
- they change the structure of the brain
- this change in structure includes a change in synaptic connectivity
- changes in synapses are, in turn, associated with better memory and learning capabilities
an increase in synaptic strength could be mediated by
- an increase in neurotransmitter release
- an increase in postsynaptic response
- an increase in synaptic connections between neurons
synaptic excitation and inhibition
excitation= increases the likelihood of a postsynaptic neuron firing
inhibition = decreases that likelihood
–> these are fundamental processes for neuronal communication and circuit function
vestibulo-oscurlar reflex
- modifiable
- a rapid involuntary reflex that stabilizes vision during movements by causing the eyes to move in the opposite direction of the head movement, ensuring a stable retinal image
