Structure and organisation Flashcards

Question

What are the 4 lobes and their functions?

Answer 1

Frontal (personality, attention, motivation, movement) Parietal (integrating sensory information, language) Temporal (memory, sensory processing, language) Occipital (vision)

Answer 2

Lateral (separates temporal from frontal and parietal lobes) - prominent horizontal Precentral (Anterior to central sulcus) - deepest one towards the front Central (Separates frontal from parietal) - behind precentral, not as deep Parieto-occipital (Separates parietal from occipital) - back of brain

Answer 3

Inferior and Superior Colliculi Superior = part of unconscious visual system that allows us to respond quickly to stimuli Inferior = part of auditory system; play role in localising sound

Answer 4

Caudate and Putamen Striated appearance because of some white matter fibres Receives all main input to basal ganglia (glutamatergic from thalamus/cortex and dopaminergic from SNc) 90% are GABAergic medium spiny neurones - inhibitory - one very long axon to innervate other structures Striatal afferents: Corticostriatal (Glut), Thalamostriatal (Glut) and Nigrostriatal (D) Striatal efferents: Stratopallidal (GABA - direct and indirect to different part of GP) and Striatonigral (GABA)

Answer 5

Input to both GABAergic projection neurones and output from both GABAergic GPi is major output structure of BG Striatum to GPi: post-synaptic D1 receptors in striatum; Substance P and Dynorphin cotransmitters released with GABA; direct pathway Striatum to GPe: post-synaptic D2 receptors in striatum; Enkephalin released with GABA; indirect pathway

Answer 6

Made up of pars compacta (SNc) and pars reticulata (SNr) Some don't consider part of BG SNc: pigmented melanin containing cells; output to striatum (D) - 70% die before showing symptoms of PD SNr: Input from SNc (D), input from STN (glut) and output to thalamus (GABA)

Answer 7

SNc released dopamine onto striatum at D1 receptors with an excitatory effect. Some glutamate also comes from cortex (excit). GABAergic neurones in striatum with D1 receptors become more active and release GABA (inhibitory) and substance P onto GPi. GPi inhibited more, activity decreases. Less GABA released onto thalamus (less inhibition, thalamus more active). Thalamus releases more Glutamate onto cortex and striatum. More Glut released onto motor areas of cortex roughly translating to more movement

Answer 8

SNc releases Dopamine onto striatum at D2 receptors and has inhibitory effect. Less GABA released onto GPe. GPe inhibited less, activity increases. More GABA released onto STN, inhibited more. Less Glutamate released onto GPi and decreases activity. Less GABA released onto thalamus, increasing activity. More glutamate is released onto cerebral cortex and striatum. Normally indirect pathway prevents movement but addition of dopamine inhibits indirect pathway

Answer 9

Without dopamine, GPi is normally inhibited by direct and excited by indirect. Direct = GPi inhibited by GABA, releases less GABA onto thalamus so more movement. Indirect = GPi excited by glutamate releases more GABA onto thalamus so less movement.

Answer 10

Bradykinesia - slowness of voluntary movement /postural reflexes Akinesia - lack of movement Dyskinesia - abnormal involuntary movement --> Hyperkinetic = chorea --> Abnormal postures = dystonia

Answer 11

Death of SNc neurones which normally release D onto striatum. Indirect pathway isn't being inhibited as much so more GABA onto Gpe. GPe inhibited more, can't release as much GABA onto STN. STN less inhibited so more glutamate released onto GPi, making it more active. More GABA released onto Thalamus, inhibiting it even more so less Glutamate released onto cortex, less movement or inability to initiate the movement. Direct Pathway - less D so neurones aren't activated as much. Less GABA released onto GPi so inhibited less. GPi releases more GABA onto thalamus, inhibiting it more Less Glutamate onto cortex from thalamus Overall GPi is being excited more by IP and inhibites less by DP so has loads of activity

Answer 12

Still not fully understood fully why but medium spiny neurones with D2 receptors (which release GABA and Enkephalin) in striatum are more susceptible so lose IP at beginning. Less inhibition of GPe so more GABA released onto STN, inhibited it more. Less Glutamate released onto GPi, activating it less than normal. GPi releases less GABA onto thalamus, inhibiting it less. More glutamate released onto cortex, more movement (chorea) DP isn't effected in early stages

Answer 13

Entire caudate and putamen degenerates, really big ventricles, impossible to generate movement. Loss of DP Less GABA released onto GPi, inhibiting it less GPi releases more GABA onto thalamus, inhibiting it a lot more. Thalamus releases a lot less Glutamate onto cortex, no movement generated

Answer 14

Anatomically connected cortical and subcortical structures that collectively play role in the way we experience and respond to emotional, social and motivational stimuli as well as learning and memory. Dysfunction plays role in many disorders including anxiety, depression, addiction, psychosis, dementia

Answer 15

Autonomic = increased HR or sweating (hypothalamus) Subjective feelings = unconscious (amygdala, cingulate gyrus) Cognition = conscious thoughts about experience (cortex)

Answer 16

Amygala - most anterior, below thalamus, close contact with hippocampus below it, strong emotions Stria terminalis - white matter structure, posterior motion before S/A, projects to hypothalamus and nucleus accumbens Hypothalamus - collection of nuclei in area of 3rd ventricle; ANS regulation, aggression, endocrine functions Septal nuclei - regulates hypothalamus in context of aggression Olfactory bulbs - inferior to frontal lobe, giant in rodents Hippocampus - frontal lobe, types of memory Thalamus (anterior)

Answer 17

Cingulate gyrus - cognitive, attentional and emotional processing; between cingulate sulcus and corpus callosum Parahippocampal gyrus - cortex surrounding hippocampus, underneath/medial, memory, quite big Orbitofrontal cortex - above eyes in skull Insular cortices - folded inside and looks like cortex under cortex of brain Sensory association cortices

Answer 18

James Lange theory (1884) - physiological status of body triggers conscious experience of emotion (has to have physical stimulus). Cannon bard theory - physiological state and emotional experience occuring simultaneously; proposed fight or flight Removed entire cortex of cats and were angered very easily (cortex may regulated emotions a little bit but mostly elsewhere)

Answer 19

Removed anything in virus that would cause infection and filled with channel rhodopsin-2 receptor fused to enhanced yellow fluorescent protein (CHR2-EYFP) Injected into septal nuclei of rodents with a source of light. CHR2 receptor will depolarise cells when activated. Light stimulation stopped attacks by inhibiting hypothalamus that causes aggression Under normal conditions, septal nuclei excite hypothalamus

Answer 20

Proposed mechanism of emotion (1937) Injected rabies virus into rabbits' brain (acts as a tracer) Cingulate gyrus receives stimuli from sensory association cortex Projects to parahippocampal gyrus and hippocampus processes information Information fed back to cingulate via mammillary bodies and anterior nucleus of thalamus

Answer 21

Discovered by removing temporal lobe of monkeys which survived and seemed to have normal behaviour except for lack of fear and being hypersexual. Primary cause is herpes viral encephalitis. Caused by removal of temporal lobes

Answer 22

Recognised importance of orbitofrontal cortex (info from hypothalamus), amygdala (info from parahippocampal gyrus and to hypothalamus) and nucleus accumbens

Answer 23

Urbach-Wiethe disease - calcification of amygdala, unable to recognise fearful faces Fear conditioning (e.g. little albert) highlighted importance of amygdala with respect to learning to fear stimuli. Joseph LeDoux (1994): Played sound in loud chamber (BP goes up and rodent freezes) Loud sound and foot shock (BP and freezing goes up a lot) Eventually just sound causes responses like one with the shock

Answer 24

Dopaminergic neurones in midbrain project to amygdala, orbitofrontal cortex and nucleus accumbens Dopamine mediates pleasurable aspects of reward System plays a role in addiction

Answer 25

Declarative/explicit: Semantic (facts) and Episodic (personal experience) Nondeclarative/implicit: Conditioning, Procedural, skills, habits

Answer 26

Composed of dentate gyrus (smaller than CA), subiculum and Cornu Ammonis (CA) CA and DG look like interconnected hooks CA has three layers: (outside) Polymorphic, pyramidal, molecular (in) DG has three layers: (outside) Polymorphic, Granular, Molecular (in) Subiculum = transition to standard 6 layered entorhinal cortex

Answer 27

Cellular basis by which memories are stored (Bliss and Lomo, 1973). Electrodes into entorhinal cortex and recorded postsynaptic responses in CA1 Stimulation of perforant pathway (close to DG) resulting in strengthening of synaptic connections in distant CA1 region. DG to CA3 through mossy fibres. CA3 to CA1 by Schaffer collaterals Demonstrated brain's ability to undergo lasting change in response to stimulation. Suggested to be a cellular model by which memories are formed.

Answer 28

Cells that fire depending on the location of the organism in the environment. Use cues in room to navigate around the room and find the food. Different cells in hippocampus seemed to fire when the rats were in different locations in the maze. Additional evidence that hippocampus plays a role in cognitive maps came from lesion studies - rats could find platform quickly in water bath in control condition and with cortical removal but struggled with a hippocampal lesion.

Answer 29

Occurs in sub-granular zone of the DG. Quiescent undifferentiated stem cells (nestin, Sox-2, GFAP) activate and give rise to fast proliferating cells (nestin, sox-2). Neuroblasts (doublecortin) reflect the commitment towards neuronal lineage. Immature neurons begin to mature and extend dendrites into the molecular layer, and the axons project to the CA3 region 1980's: Discovery of Bromodeoxyuridine (BRDU) - thymidine analogue can be injected into rats and incorporated into DNA of newly forming cells

Answer 30

Maintains homeostasis of several physiological processes. Monitors physiological set points throughout the body and integrates autonomic responses with endocrine functions

Answer 31

Three zones with 11 nuclei Periventricular (vertical surrounding third ventricle) Medial close to 3rd ventricle Lateral on outsides

Answer 32

Paraventricular and Supraoptic - BP, water balance and electrolyte composition Preoptic - Temperature/thermoregulation Supra-chiasmatic - Circadian Arcuate, Ventromedial, Lateral and Dorsomedial - Energy and Metabolism

Answer 33

Preoptic nucleus regulates temperature via ANS Release heat (parasympathetic) by cutaneous vasodilation and sweating. Generate heat (sympathetic) by cutaneous vasoconstriction, brown fat thermogenesis and shivering.

Answer 34

Arcuate nucleus integrates gastro-intestinal, circulatory and autonomic signals from the bloodstream because it is in an area of the brain with a very thin BBB. Hunger - Low blood glucose and insulin, hormone ghrelin and 1st order neuropeptide Y and agouti-related peptide expressing neurones Ghrelin released from GI tract into blood, cycles and makes us hungry around mealtimes Satiety - High blood glucose and insulin, hormone leptin and 1st order pro-opiomelanocortin and cocaine and amphetamine transcript expressing neurones. Leptin released from adipose tissue and should make us feel less hungry Mechanoreceptors in GI tract project to brain stem and tell Vagus nerve that stomach is stretching, getting too full and need to stop eating - Vagus nerve synapses in brain stem and other nerves go to arcuate nucleus

Answer 35

Paraventricular and supraoptic nuclei regulated BP, water balance and electrolyte composition. Stimulate pituitary gland to release Vasopressin which causes vasoconstriction and promotes water-reabsorption in kidneys. Vagus nerve and brain stem signal hypotension to the paraventricular and supraoptic nuclei Osmolarity of blood is detected by organum of vasculosum laminae terminalise and subfornical organs in hypothalamus

Answer 36

Regulates unconscious visual responses Photoreceptors in retinal ganglion cells capable of light detection Projections to superior colliculus assist head movement (tectospinal tract). Projections to pretectal nuclei regulate parasympathetic component of oculomotor nerve (pupil constriction - cranial nerve 3) Suprachiasmatic nucleus contains biological clock - lesioning halts cyclic rhythmicity - Inject horseradish peroxidase into mice retina (acts as a tracer) - Nucleus lights up on scan showing retina is connected - HR and temp normally go up and down rhythmically during the day - Rod less and coneless transgenic mice can still phase shift circadian rhythms to light so doesn't need those

Answer 37

Rods and Cones > Optic Nerve (CN2) > Lateral Geniculate Nucleus > Primary visual cortex (Brodmann's area 17) Optic nerves cross over at optic chiasm to rearrange visual information then becomes optic tract once fully inside the brain. Information first stops at lateral geniculate nucleus Axons spread out (optic radiation) and go to PVC Conscious visual perception Colour produced through activation of rhodopsin pigments in cones Two processing streams: - Ventral (what) - inferior temporal lobe, object recognition, memory - Dorsal (where or how) - posterior parietal lobe, object location, object positioning

Answer 38

Input from hippocampus via fornix Output to anterior nucleus of thalamus, cingulate. Function: episodic, implicit and spatial memory

Answer 39

Midbrain, pons and medulla oblongata

Answer 40

Originated in superior colliculus of midbrain. Receives input from visual cortex and retina. Decussates quickly and descends medially, synapsing in upper cervical levels of the SC. Assists in head and neck orientation to visual stimuli.

Answer 41

Bottom of frontal lobe (easily visible) Large nerves embedded in little channels Sensory nerve Associated with sense of smell

Answer 42

Merge into Optic Chiasm which has obvious X shape Good landmark for mammillary bodies Sensory nerves Bringing information about vision to brain via primary visual system

Answer 43

Emerges from junction between pons and midbrain Associated with Oculomotor nuclei Motor - regulates 4/6 muscles that move the eye (superior/inferior/medial/inferior oblique rectus muscle - up/down/to midline/away from midline) Parasympathetic - Constricting pupils in response to light (might have persistent dilation of pupil if damaged)

Answer 44

Only nerve that comes off dorsal side of brainstem Smallest of all cranial nerves (spaghetti) Associated with Trochlear Nuclei Motor nerve Innervates superior oblique rectus muscle in eye (depresses and rotates inwards)

Answer 45

Arises from side of pons Easy to identify - stump/thick Sensory - Brings information from face Nuclei are Mesencephalic Trigemeninal and Spinal Trigeminal Motor - Controls muscles of mastication (anything requiring movement of the jaw) Associated with Trigeminal nuclei

Answer 46

Arises from junction between pons and medulla Motor nerve Regulates lateral rectus muscle in eye (active when moving eye away from midline) Associated with Abducens nuclei

Answer 47

Arises from junction between pons and medulla Part of pair 1 - more anterior Motor - Controls all muscles of face Associated with facial motor nuclei Sensory - Brings sense of taste from anterior 2/3 of tongue Associated with solitary and spinal trigeminal nuclei Parasympathetic - Involved in salivation Associated with salivatory nuclei

Answer 48

Arise from junction between pons and medulla Pair 1 - More posterior Sensory nerve Auditory and balance information to inner ear then brain Associated with Vestibular and cochlear nuclei

Answer 49

Pair 2 - More Superior Originates from side of medulla Sensory - Information about taste from posterior 1/3 of tongue Associated with solitary and spinal trigeminal nuclei Motor - Regulates muscles controlling pharynx (probably get exaggerated gag reflex if damaged) Associated with nucleus ambiguus Parasympathetic - Involved in salivation Associated with salivatory nuclei

Answer 50

Originates from side of medulla Pair 2 - More inferior Sensory - Brings information from some of the muscles in neck (pharynx and larynx) Associated with Solitary and spinal trigeminal nuclei Motor - Innervates soft palette, pharynx and other muscles in the neck Associated with nucleus ambiguus Parasympathetic - Rest and digest (e.g. HR) Associated with dorsal motor nuclei

Answer 51

Located most inferiorly Difficult to see Motor nerve Innervates trapezius and sternocleidomastoid muscles which control head rotation from side to side Associated with accessory nuclei

Answer 52

Emerges between junction between medulla and olive (lateral side of medulla) Motor nerve Innervates muscles of the tongue Associated with Hypoglossal nuclei

Answer 53

Assists with equilibrium, posture and dynamic coordination and synchronisation of muscles Communicates accuracy of movement back to the cortex Injury can result in ataxia May include postural and gait disturbance or decomposition of movements due less precise, uncontrolled and incorrectly timed movements

Answer 54

10% of total brain volume but has half of the neurons in the entire brain Tightly folded thin layer of cortex with white matter below 4th ventricle is space between cerebellum and brain stem Anterior Lobe (smallish) Primary Fissure Posterior Lobe (Largest) Posterolateral fissure Flocculonodular Lobe (Composed of nodule and flocculi, not visible until you cut it up, tucked right against brainstem) Vermis = depression directly down midline Cerebellar peduncles attach the cerebellum to the brain stem: Superior to midbrain Middle to pons Inferior to medulla oblongata

Answer 55

3 Layers: Granular (inner) - numerous granular cells that receive input Purkinje (middle) - single layer of cells, output to cerebellar nuclei Molecular (outer) - few interneurons, Purkinhje dendrites, granular axons Mossy Fibres: - Originate in spinal cord and brain stem nuclei - Each one innervates hundreds of granular cells - Granular axons ascend, send out parallel fibres (molecular) and synapse with Purkinje cells Climbing Fibres: - Originate in the olives - Axons climb and wrap around Purkinje cell bodies and dendrites - Each Purkinje cell receives input from one climbing fibre

Answer 56

Spinocerebellum (vermis and intermediate zones) Cerebrocerebellum (Lateral hemispheres) Vestibulocerebellum (Flocculonodular lobe)

Answer 57

Mediates posture, balance, some reflexes Vestibulocochlear nerve brings sound and balance information into the pons where it synapses with the Vestibulocochlear nucleus. Series of Vestibulocerebellar fibres go through the inferior cerebellar peduncle into cerebellum and synapse at granular cells of Flocculonodular lobe. Synapse with Purkinje cells. Output to Fastigial Nucleus. Fastigial fibres go out through inferior cerebellar peduncle where they make connections with the vestibulocochlear nuclei and reticular formation

Answer 58

Originates in vestibulocochlear nuclei Medial: Synapses in cervical SC with muscles that maintain head and neck position; bilateral Lateral: Synapses in many levels of SC (Cervical, thoracic, sacral) with muscles that help maintain balance and posture via extensor and anti-gravity muscles

Answer 59

Ill-defined group of inter-mingled neurons that spain the brain stem and involve a variety of neurotransmitters Medial (Raphe - Serotonin), Medial (Magnocellular) and Lateral (Parvocellular) Tract: - Originates in pontine and medullary reticular formation - Medial/Lateral: between pyramids of medulla; synapses throughout spinal cord with muscles - Assists vestibulospinal tract with controlling extensor muscles

Answer 60

Helps with planning and timing of movements. Corticopontine fibres initiate in the cortex and make their way through the internal capsule and midbrain before reaching the pons where they synapse in the pontine nucleus. Decussates to the other side of the body. Pontocerebellar fibres make their way through the middle cerebellar peduncle to granular cells in the lateral hemispheres of the cerebellum. Purkinje fibres to dentate nucleus. Dentatorubrothalamic fibres synapse in thalamus which continues to cortex and other fibres synapse in red nucleus (initiation point for rubrospinal tract).

Answer 61

Originates in red nucleus of midbrain Decussates quickly and descends laterally with corticospinal tract. Receives collaterals from corticospinal tract and provides it with assistance Flexor adjustments primarily of the upper limbs Some communication with corticospinal tract and able to compensate if there is damage

Answer 62

Sensory neurones synapse in SC; spinocerebellar tracts (mossy fibres) The Dorsal spinocerebellar tract goes through the inferior cerebellar peduncles (sensory). The Ventral spinocerebellar tract goes through the superior cerebellar peduncles (motor). Both arrive in granulae cells of vermis and intermediate zones in the cerebellum. Purkinje cells project to interposed nuclei. Interposition-rubrothalamic fibres (some make connection with red nucleus and rubrospinal tract; others go to thalamus where final thalamocortical fibres take information to the cortex)

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Structure and organisation Flashcards

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