Neuroscience/Quick notes/Exam 1

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  • Cervical enlargement: C3-T1
  • Lumbosacral enlargement: L1-S2
  • Parasympathetic preganglionic neurons: CN III, CN VII, CN IX, CN X, S2-S4 (intermediolateral cell column)
  • Sympathetic preganglionic neurons: T1-L2
    • Enter sympathetic chain ganglia via white rami communicans
  • Clarke's nucleus (relay containing 2° neurons of dorsal spinocerebellar tract): T1-L2 (H:7-17)
  • Cochlear nuclei surrounds the inferior cerebellar peduncle
  • Trigeminothalamic tracts terminate in VPM of thalamus
    • Intraoral information travels in both dorsal and ventral tracts (hence its bilateral thalamic representation)
  • Mesencephalic trigeminal nucleus has no synapses
    • Contains cell bodies that receive proprioceptive info from teeth and jaw
    • Sends outputs to trigeminal motor nucleus for monosynaptic jaw reflexes
    • Derived from neural crest
  • Insula contains topographic map of visceral organs for conscious awareness from NTS
  • Spinal accessory nucleus receives ipsilateral corticobulbar input even though the nucleus is caudal to the pyramidal decussation
  • Chorda tympani is branch of CN VII that carries taste from anterior two-thirds of tongue
  • Fasciculations suggest lower motor neuron lesion
  • Cholinergic neurons in basal forebrain lost in Alzheimer's disease; treat with AChE inhibitor
  • Sarin and physostigmine (sp?) block AChE
  • Cocaine and amphetamines block catecholamine reuptake
  • Glutamate and GABA are both recycled by glia
  • Glycine's precursor is serine
    • Strichnine blocks glycine receptors
  • No reuptake for neuropeptides (instead degraded by proteases)
  • ↑Frequency → neuropeptides released; ↓frequency → other NT released
  • Benzodiazepines, barbituates, and ethanol are allosteric activators of GABA receptors
  • AMPARs desensitize rapidly
  • NMDAR has 4-5 subunits, each with 3 transmembrane domains (hence extracellular N, intracellular C)
  • β receptor
    • Agonist: isoproteronol
    • Antagonist: propranolol
  • α2 receptor
    • Agonist: phentolamine
  • Dysthymic patients respond least to treatment (of patients suffering from depressive disorders)
  • Adjustment disorders always have a precipitating event
  • Women are much more prone to major depression (prevalence is 25% in women vs. 15% in general population)
  • Depression usually involves monoamines: NE (energy, interest), 5HT (impulse), DA (drive)
  • ↓5-HIAA (a 5HT metabolite) is a marker for impulsivity
  • Lithium protects against the degeneration of neurons that often accompanies (and perhaps precipitates) stress/depression
  • Don't treat bipolar disorder with stimulants; doing so would worsen the symptoms
  • Major depressoin develops in days to weeks, dysthymia over a period of months
  • Glia use gap junctions to act as a syncytium in their buffering of K+
  • Delay in synaptic transmission is due to diffusion of neurotransmitter across synaptic cleft
  • Rostral-caudal axis
    • Henson's node is caudal organizing center: Wnt, FGF, RA
    • Anterior visceral endoderm is rostral organizing center: cerebus, dickkopf, Tlc
  • Dorsal-vendral axis
    • Roof plate is dorsalizing: BMP → alar plate
    • Floor plate, ventral mesoderm is ventralizing: Shh → basal plate
  • Segmentation: isthmus (a 2° organizing center that gives rise to the cerebellum) secretes FGF8
    • Induces DAergic neurons in mesencephalon (e.g. substantia nigra)
    • Induces 5HTergic neurons in rhombencephalon (e.g. raphe nuclei)
  • GABAergic (inhibitory) neurons only produced in the telencephalon
  • Shh induces medial and lateral ganglionic eminences in ventral neural tube
    • LGE produces local inhibitory projection neurons of the striatum (caudate and putamen)
    • MGE produces cortical interneurons
  • Only excitatory (glutamatergic) neurons radially migrate to form six-layered neocortex (GABAergic migrate tangentially)
  • Netrin-1 (chemoattractant) released by floor plate of spinal cord, attracting commissural fibers
  • Stem cell therapy is more successful in brain than spinal cord, perhaps because brain has intrinsic ability to use progenitor cells (e.g. in hippocampus and olfactory bulb) [110]
  • In muscle spindle, group Ia fiber is the same thing as a group II fiber (d'oh!) [123]
  • Gracile begins decussating before cuneate (makes sense because gracile fasciculus and nucleus beings caudal to cuneate fasciculus and nucleus) [137]
  • Dorsal spinocerebellar pathway (legs and lower body) and cuneocerebellar tract (arms and thorax) reache cerebellum via inferior cerebellar peduncle [139]
  • Complete spinal cord injuries [142]
    • C4: shrug shoulders, turn head
    • C5: flex elbow
    • C6: extend wrist
    • C7: extend elbow, very independent
    • C8: control digits somewhat, still more independent
    • T1: fully control arms (paraplegia), near complete independence
    • T2-T6: better posture and breathing
    • T7-T12: some ambulation, forced expiration (allows for productive cough that protects against respiratory infection)
    • L1-L2: hip flexion, possibly knee flexion
    • L3-L4: knee flexion, ankle dorsiflexion
    • L5 and below: complete independence
  • Incomplete spinal cord injury [146]
    • Central cord affects upper more than lower limbs (since upper limbs are medial in corticospinal tract)
    • Prognosis: Brown-Sequard syndrome (best), central cord syndrome, anterior cord syndrome (worst)
  • Corticospinal and spinothalamic tract somatotopy: lower limb is lateral, upper limb is medial [146]
  • Aδ and C fibers carry same info except that C fibers also carry chemical stimuli [150]
  • Prostaglandins enhance nociceptor sensitivity without exciting nociceptors [151]
  • Relieve pain by rubbing: large mechanoreceptors (groups Aα and Aβ) suppress nociceptive (Aδ and C) signals [153]
  • Clonidine reduces NE release to suppress pain [156]
  • GABAergic neurons especially sensitive to excitotoxicity [156]
  • Oral cavity is represented medially in the VPM
  • Aortic baroreceptors/chemoreceptors carried in CN X, carotid's carried in CN IX (makes sense because carotid is superior to aorta, and CN IX is superior to CN X) [195]
  • Smooth-pursuit movements are involuntary; saccades can be involuntary or voluntary [205]
  • Vestibulo-ocular reflex: fast, stabilizes eyes during brief head movements [205]
  • Optokinetic reflex: slow, captures image for subsequent fixation and tracking [205]
  • Horizontal gaze integrator is medial vestibular nucleus, which generates a hold signal after voluntary saccade [207]
  • Vergical gaze integrator is the interstitial nucleus of Cajal [208]
  • riMLF coordinates convergence, accommodation, and constriction [208]
  • Dorsal motor vagal nucleus receives inputs from the NTS, amygdala, and hypothalamus (cardiorespiratory and GI regulation) [231]
  • Anterior thalamic nucleus is part of Papez circuit [266]
  • Mammillary body is part of Papez circuit [268]
  • Cingulate gyrus is part of Papez circuit [282]
  • Lesioning the subthalamus (part of basal ganglia) results in hemiballismus [270]
  • Homotypic cortex is typical of association cortex (not 1° motor or sensory) [298]
  • Granular is thicker than agranular heterotypic cortex [298]
  • Ipsilateral cortical areas connected by associational efferents from layer II (some III) [301]
  • Contralateral homologous cortical areas connected by commissural efferents from layer III [301]
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