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Neuron Structure

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Neuron Structure. Synapse. The Synapse. Synthesis of neurotransmitter (NT) Storage and transport of NT within vesicles NT Release Activation of postsynaptic receptors Termination of transmitter effect (e.g. reuptake). Resting Potential. - PowerPoint PPT Presentation

Text of Neuron Structure

  • Neuron Structure

  • Synapse

  • The SynapseSynthesis of neurotransmitter (NT)Storage and transport of NT within vesiclesNT ReleaseActivation of postsynaptic receptorsTermination of transmitter effect (e.g. reuptake)

  • Resting Potential

    Sodium ions are concentrated on the outside of the axon membrane.Potassium ions are concentrated on the inside of the axon membrane.Ion channels are closed.The inside of the axon membrane is more negative that is the outside.

  • Action PotentialAction potential occurs when the membrane potential rapidly shifts from -70 to +40 mVIon channels open in the membrane, allowing sodium ions to enter the axonSodium entry shifts the membrane potential toward a positive valuePotential is restored when other channels open, allowing potassium ions to exit the axon

  • MyelinMyelin is a fatty, waxy substance coating the axon of some neurons.Functions:Speeds neurotransmissionInsulates neurons from each otherMakes neurotransmission more efficient

  • NeurotransmittersSerotonin AcetylcholineDopamineNorepinephrineEpinephrineGABAEndorphins

  • Midline Brain View

  • BrainstemBrainstem is a primitive portion of brainPons: involved in respiration, sleep regulation, dreamingMedulla: involved in life support functions such as respiration and heart rateReticular activating system is an arousal system within the brainstem

  • Subcortical Brain AreasCorpus callosum: band of axons that interconnects the hemispheresThalamus: sensory relay areaLimbic system: involved in emotionalityHypothalamus: feeding, fleeing, mating, fighting, homeostasisCerebellum: involved in motor control

  • Limbic System: Seat of Motivation, Emotions

  • Cerebral CortexCortex refers to the outer covering of the brainConsists of left and right hemispheres

    Cortex is divided into lobesFrontal: Self-awareness, planning, voluntary movement, emotional control, speech, working memoryParietal: Body sensationsOccipital: VisionTemporal: Hearing, language comprehension

    Localization of function: do discrete circuits carry out different functions?

  • Cortical Lobes

  • Cerebral Cortex

  • Motor and Somatosensory Cortex

  • Language areas: Broca & Wernicke

  • Primary Visual Pathways

  • Primary Visual Pathways

  • Secondary Visual Pathways: Dorsal and Ventral Streams

  • Dorsal and Ventral Visual Pathways

  • Auditory Pathways

  • LeDouxs two pathways of emotion

  • Nee, et al., STM/LTM articleDamage to Medial Temporal produced LTM deficits while leaving STM in tact. Inferior Temporal = LT visual pattern recognition deficits

  • Medial and Inferior Temporal lobes

  • Perisylvian cortex: STM disruptions

  • Behavioral data confirming STM/LTM distinctionPresentation rate affects primacy but not recency effectIncreased delay affects recency but not primacy effect. (Glanzer & Cunitz, 1966)Med. Temporal activation for early probes in serial recall paradigmR infer. parietal for late probes (Talmi, Grady, Goshen-Gottstein, & Moscovitch (2005)

  • STM/LTM distinction or novelty (MTL) and resistance to distraction (frontal)Ranganath & Blumenfeld (2005) argue that MTL binds novel items together in single representation. STM storage can be disrupted in patients with MT damage when items are novel (novel items rarely used in most STM studies)Furthermore patients with frontal damage can perform STM task when distractions are minimized. Sakai, Rowe, & Passingham (2002), subject did STM spatial task found greater frontal activity on correct trials, less on error trials suggesting frontal areas important for filtering distractions. Similar findings for words and pseudo words. Other evidence suggesting that phonological deficits are found in patients with perisylvian damage, thus this area may not be specifically for STM, but may STM tasks may typically require phonological rehearsal. STM is attentionally mediated activation of LTM representations.

  • Episodic retrieval and STM retrievalSimilar processes may exist in LTM, STM processes. Cabeza, et al., 2002 episodic retrieval: Subs judge probe word as remembered from earlier list, known or not seen before. STM: yes/no to probe after studySame areas of left frontal active in both cases. Anterior frontal may play a monitoring role.

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