Reward and MOtivation Flashcards
Why do act the way we do?
Behaviorism: we only know our actions, we will never fully understand “why”
All boils down to the answer: “because my brain told me to”
We make decisions based on prediction, reward, outcome
…and what motivates us
3 aspects underlying reward-related behaviors
Learning and memory -- Based on sensory and emotional experience Motivation (wanting) -- Based on internal states Pleasure (liking) -- Based on experiencing a reward
Hebbian learning:
“Neurons that fire together, wire together”
When an axon of cell A is near enough to excite a cell B and repeatedly or persistently takes part in firing it, some growth process or metabolic change takes place in one or both cells such that A’s efficiency, as one of the cells firing B, is increased.
The aplysia told us that Hebb was right
Shock the tail plus the light skin touch major response. Remove the tail stimulus– > still a strong response.
Multiple shocks lead to long-term potentiation
what is the neural correlate to Hebbian learning ?
long-term potentiation
What 2 things contribute to learning and memory?
Both Long-term Potentiation (LTP) and Depression (LTD) Contribute to Learning and Memory
Physical Determinants of Plasticity:
Increasing dendritic spines to increase synapses
On every spine there are a ton of different receptors that can be expressed. These spines can form in a matter of hours. The more potentiation– the more spines. This increases the volume of a part of the hippocampus
Hippocampal Neurogenesis
The other place where adult neurogenesis can happen is the Sub Granular Zone of the hippocampus. BrdU (yellow) says a neuron has undergone mitosis. SCX is a young neuron. Green NeuN is an adult neuron.
Stress/ cortisol inhibits this process!
Circuits for Motor Learning in the Cerebellum interact with
Hippocampal Circuits for Navigation
Certain cells in the Hippocampus code for “Place” by firing whenever they are in a particular area or spatial context
Long-Term Depression Between the Parallel Fibers and Purkinje Cells are thought to Underlie Motor Learning in the Cerebellum
The basic cerebellar circuitry is defined by
GABA and glutamate
The circuit allows for the comparison of ongoing movement and sensory feedback derived from it
The cerebellum measures expectation vs. outcome
LTD Underlies Extinction of Memories, Controlled by 3-Structure Circuit
Limbic cortex integrates hippocampal and amygdalar inputs
Hippocampus contributes context info to other associations
Amygdala acquires emotion-laden memories, especially associated with fear
The Amygdala has Bi-Directional Connections with Brainstem, Limbic and Cortical Structures
2 Pathways :
Stria Terminalis
Amygdalofugal Tract
Amygdala is collection of nuclei
2 pathways
1 involves basolateral nucleus to central nucleus indirect
- This is slow response
- Fear association that isn’t immediate
1 involves visceral responses, direct
- This is a fast response
- Think “what happens when I see a snake”
Many types of memory, many circuits responsible
Long term memory
Declarative: episodic, semantic –> medial temoral lobe, diencephalon
nondeclarative memory: procedural memory, skills habits –> basal ganglia
priming–> neocortex
simple classical conditioning–> amygdala, cerebellum
habituation, sensitization–> reflex pathways
Learning and Memory depend on sensory experience
Nearly all cortical areas feed into the basal ganglia circuitry, connect many sensory experiences with each other
Multimodal association cortices code for memory recruited in reward-based behaviors:
–Insula
–Orbitofrontal cortex
Dopamine level fluctuations, both tonic and phasic, are among the most potent modulators of cue-triggered temptation
Dopamine in the VTA is released when:
Reward is unexpected
Reward is cued
*Dopamine release is inhibited when expected reward is not present:
