Synapses and neurotransmitters. Psychology 2606. Biochemical Activity. Otto Loewi did a cool experiment in 1921 Simulated the vagus nerve is a frog’s heart Slowed the heart down Washed heart with solution, collected solution Poured solution on a second heart It slowed!!!!. - PowerPoint PPT Presentation
Text of Synapses and neurotransmitters
Synapses and neurotransmittersPsychology 2606
Biochemical ActivityOtto Loewi did a cool experiment in 1921Simulated the vagus nerve is a frogs heartSlowed the heart downWashed heart with solution, collected solutionPoured solution on a second heartIt slowed!!!!
Loewi and his frogsCalled the substance vagusstoffAcetylcholineLater stimulated heart rate, similar methodEnded up with a sped up heartEpinephrine
The SynapseGap between the axon and the dendriteNeurotransmitters are released across this gapSometimes, if all of the transmitter isnt absorbed it is taken back up, this is known as reuptake
There is lots of variation in synapsesSome are excitatory (Type I) Some are inhibitory (Type II)
More about synapsesIs the excitatory vs. inhibitory nature of a synapse due to shape?ProbablyGABA synapses are inhibitory, have less post synaptic thickeningGlutamate synapses have more thickening, more vesiclesThere are 7 types of synapses
SEVEN?Yes, SevenDepends on functionWe usually learn about axodendritic ones Easiest to think about them I guess
The Seven Steps in NeurotransmissionSynthesisStorageReleaseReceptor interactionInactivationReuptakeDegradation
The NeurotransmittersBasically, five conditions must be met before we call something a neurotransmitterPresent in terminalReleased on firingPlacing substance or organ emulates firingUptake for inactivationInactivation blocks stimulation
The NeurotransmittersAcetylcholine (Ach)MonoaminesCatecholaminesNorepinephrine (NE)Epinephrine (E)Dopamine (DA)IndoleamineSeretonin (5-Ht)OthersHistamine (H)
More neurotransmittersAmino AcidsGlutamate (universally excitatory)GABA (universally inhibitory)GlycineProlinePeptidesSubstance P
Finally.Morphine like substancesEndorphinsEnkephalinsOther peptidesInsulinProlactinHGHVasopressin
ReceptorsTransmitters bind to receptorsSort of like a lock and a keyBinding siteIon channelOne neuron (usually) has only one type of receptorGreat place for drug interaction
Synapses, neurotransmitters, learning and memoryThe Hebbian synapseWhen an axon of cell A is near enough to excite cell B and repeatedly or persistenly takes part in firing it, some growth process or metabolic change takes place in one or both cells such that As efficiency as one of the cells firing B, is increased
HabituationDecrease in the strength of a response after repeated presentation of a discreet stimulusGetting used to it, sort ofNOT sensory adaptation or simply fatigueStimulus specificOrienting responseStartle response
The rulesThompson and Spencer (1966)Gradual with timeWithhold stimulus and response will reoccurSavingsIntensityOverlearningStimulus generalization
Pokin aplysisaKendel et alGill withdrawalSeonsory -> motor pretty muchLess transmitter released into synapses!Decrease in Ca currentSimilar results in catsBecause of its generality, habituation is often thought of as the universal learning paradigm
LTPLong Term potentiationNMDA (a neuromodulator) basically allows LTP to happenBlock NMDA, block LTPBlock LTP, block learning in say a Morris water mazeBut..Deb Saucier.
Barnea and Nottebohm (1994)Chickadees store in the fall and winter, lessen off in the springHP seems to shrink and grow!!
In conclusionMuch of the interesting activity in the nervous system takes place at the synapseThis is where the electrical goes chemicalThis is where learning MAY be happeningThere is still much to learnEvery mall in Athens has a store called The Synapse