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.