Lecture 34 Outline of Last Lecture I. Regulatory behaviors are essential for survival and nonregulatory behaviors aid in other types of tasksII. The limbic circuit relies on the flow of information among several key structuresa. Hippocampus is important in memory function and learningb. Hypothalamus produces autonomic responses to external stimulic. Amygdala and frontal lobes are responsible for perceiving subjective feelingsIII. Seeking behaviors rely on the mesolimbic dopamine systema. Medial forebrain bundle projects dopaminergic neurons from the ventral tegmental area to the nucleus accumbensb. Dopamine is released in proportion to the motivation to self-stimulatec. Increased dopamine input to the nucleus accumbens is associated with pleasurable behaviors such as eating and sexOutline of Current Lecture I. Implicit memories do not require conscious recollection, whereas explicit memories doa. Consolidation involves storing a short-term memory into a long-term oneb. Reconsolidation diminishes the accuracy of memoriesII. Emotional memories are influenced by the amygdalaIII. Spatial memories are influenced by the hippocampusIV. Forming memories involves numerous neural mechanismsa. Neurogenesisb. Synaptogenesisc. Increase in the number of AMPA receptorsd. Increase in the size of a receptive membraneCurrent Lecture- Implicit: procedural memory, implied though not directly expressed (can demonstrate knowledge without conscious recall of “how”)- Explicit: conscious recall, something you can declare- Consolidation involves storing a short-term memory into long-term recollectiono Anytime you consciously recall a previous memory, you have the ability to change it (it isn’t stable  depends on new information and context)  reconsolidationo The more times you recall, the less accurate it becomes Memory you recall the least tends to be the most accurate- Memory storageo Stored around the cortical regions that mediate their perceptionso Parietal lobe: movements, actionsThese notes represent a detailed interpretation of the professor’s lecture. GradeBuddy is best used as a supplement to your own notes, not as a substitute. NSCI 110 1st Editiono Temporal lobe: attributeso Frontal lobe: our role in events- HM epilepsy treatment  bilateral medial temporal lobe resectiono Eliminated certain parts of his brain including amygdala, part of hippocampus No expression of fear for the remainder of his lifeo After surgery could remember previous memories but could not form new ones Explicit memory impairment Anterograde amnesia- Parkinson’s Disease patients often show implicit memory deficitso Role of basal ganglia Substantia nigra dopamine input to basal ganglia is disrupted Through the ventral thalamus to the neocortex is disruptedo Implicit memory impairment Hippocampus is not necessary for implicit memory formation- Emotional memory heavily influenced by the amygdalao Amygdala has widespread connections to the: Hypothalamus (autonomic/endocrine/limbic) Medial temporal lobe (limbic) Brainstem regions for autonomic controlo Emotional arousal tends to increase formation of memories Stimuli are perceived  induces levels of arousal (activity of norepinephrine, autonomic mechanisms) and valence (how positive or negative the association is)- Spatial memory influenced by the hippocampuso Higher demand for spatial memory causes an increase in hippocampus sizeo In food-storing species the hippocampus is larger but only is used to retrieve stored food- Neural mechanisms of memoryo New neurons (neurogenesis) New synapses (synaptogenesis) Changes in synapses in response to biochemical signalso Physiological changes at synapses may store information Changes can be presynaptic, postsynaptic, or both- Receptive areas may increase, more transmitters released, increased postsynaptic response (long-term potentiation)- Seconds to minutes in duration  whether or not these changes are permanent depends on epigenetic mechanisms Increased or decreased neurotransmitter levels or receptor densities- Glutamate receptorso Hippocampus has AMPA and NMDA receptorso Glutamate activates AMPA receptors Influx of sodium induces depolarizationo NMDA receptors do not respond until enough AMPA receptors are stimulated and the neuron is partially depolarized At rest, magnesium blocks the NMDA pore When depolarized, the ion exits, glutamate binds, and calcium influxo When calcium enters through the AMPA receptor, kinases inside the cell may be activated CaMKII causes latent AMPA receptors to be incorporated back into the membrane Glutamate release from the presynaptic neuron now elicits a potentiated response in the postsynaptic neuron- Repetitive use  LTP induced- Activity dynamically regulates dendritic spines  plasticityo When CREB is phosphorylated it can enter the nucleus and act as a transcription factor More proteins that promotes synaptic function are produced as a result If one of these genes contains a cAMP response element, CREB can bind here and recruit factors that loosen histones  more