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62 Cards in this Set
- Front
- Back
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hippocampus has only 3 layers of cortex, is the site for
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declarative memories and processing and integration of these memories in order to transport them from short-> long term
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The hippocampal formation
is deeply folded into the |
temporal horn
of the lateral ventricle |
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Archicortex with Three Components
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Dentate Gyrus
•Hippocampus Proper (Ammon’s Horn) •Subiculum |
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Primary locusof hippocampal formation for
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the formation of declarative or episodic memories
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Papez Circuit of hypoccampus
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circuit of learning (+amygdala) = limbic system
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paperz cu trac t
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-> Mammillary bodies ->mammillothalamic fasciculus -> anterior nucleus of thalamus -> anterior limb of internal capsule -> posterior cingulate gyrus -> cingulate bundle -> entorhinal cortex (perforant and alvear paths)-> hippocampal formation (dentate gyrus -> CA4 .-> CA3 -, CA1 subiculum -> contralateral hippocampus -> fimbria -> fornix -> mammillary bodies)
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- Perforant path
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dentate gyrus and CA1 granule cells mossy fibers CA3
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- Alvear path
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ubiculum, CA1 and CA3
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medial forebrain bundle
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*locus ceruleus-> NE
*raphe nuclei-> 5HT |
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cornu Ammonis
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divisions of the hippocampus: CA1, CA2, CA3 and CA4
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Sommer's Sector
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is region CA1 of the hippocampus, a part of the human brain. It is particularly vulnerable to hypoxic or ischemic damage and is one of the first brain regions to show gross changes in cerebral hypoxia.
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- Precommissural component of fornix (exit fornix near anterior commissure) projects to
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basal forebrain (important for LT memory)
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degenerates in Alzheimer’s disease, ischemia, seizures, stroke, anoxia and it dies first
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- CA1
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Selectively degenerate in hypoglycemia
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CA3
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Degeneration of the
perforant path is an early event in |
the progression
of age-related dementias. |
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CA maintains internal connections via
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a system of collaterals
while sending projections to the contralateral hippocampus and basal forebrain via the precommissural fornix. |
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Dentate Gyrus projects to
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CA3-CA4
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CA1 projects to
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subiculum
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Subiculum projects via
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alveus
through post-commissural fornix to the mammillary bodies. |
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CA projects to contralateral hippocampus
and basal forebrain via |
precommissural fornix
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Subiculum projects via alveus
through |
post-commissural fornix
to the mammillary bodies. |
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Amygdala is in
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in anterior portion of temporal lobe
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Amygdala subdivision
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are extensions of the ventral striatum, prefrontal cortex, or olfactory system, convergence of highly processed cognitive associations and raw olfactory/visceral sensations
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Amygdala integrates
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sensations -> modulate cognitive, behavioral, and autonomic activity based on interpretation
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Amygdala can form memories from
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emotional memories from birth (unlike hippocampus which doesn’t develop until around 2-3 y/o), continuation of caudate that stretches along the ventricles and comes around to form connection with hypothalamus, ends in temporal lobe; basal ganglia surrounds it
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- Amygdala sits
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behind the uncus
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- Claustrum
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part of the basal ganglia that communicates with the insular cortex – visceral sensory function
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- Basal forebrain
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develops when lamina terminalis closes -> this is where you find your cholinergic nuclei for LT memory storage (shell of nucleus accumbens, cholinergic)
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3) 3 distinct areas of amygdala
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- Cortiomedial nucleus
- Basolateral nucleus - Extended central nucleus |
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- Cortiomedial nucleus
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olfactory part – gets olfactory input, projects to limbic cortex
o Primarily involved in regulation of appetitive and consummatory behaviors (feeding, reproduction) |
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- Basolateral nucleus
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cortical component – connections with pre-frontal cx, orbital gyrus, ventral striatum
o “executor”, plays important role in learning and memory, motivation and planning |
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- Extended central nucleus
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= striatal component – extension of basal forebrain, gets enteroceptive info and projects to brainstem, hypothalamus, and thalamus
o Involved in processing and integration of viscerosensory information (pain) |
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Pathways from amygdala
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- Stria terminalis
- Ansa lenticularis - Medial forebrain bundle - Stria medullaris |
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- Stria terminalis
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– from amygdala to anterior hypothalamus (anxiety, stress) – between caudate and thalamus
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Stria terminalis:
Associated with |
cortical
and central connections to thalamus, hypothalamus and basal forebrain. |
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Ansa lenticularis
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Associated with baso-lateral connections
to thalamus, prefrontal and cingulate cortex. |
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- Ansa lenticularis
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more integrated connects from amygdala to prefrontal cortex and temporal lobe/hippocampus (loops under lenticular nucleus)
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- Medial forebrain bundle
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bidirection traffic involving amygdala and lateral hypothalamus
o Axon bundles in prefrontal cortex, amygdala, and hypothalamus -> brainstem control centers o Viscerosensory info from brainstem -> hypothalamic and telencephalic integration centers (pleasure) |
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- Stria medullaris
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basal forebrain -> habenula, seen in midline sagittal cut
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Monoamine neurons of brainstem
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diffuse but critical modulatory influences on limbic function
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- Dopaminergic neurons (VTA) -> nucleus accumbens and prefrontal cortex function
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o Regulation of goal-driven behaviors
o Involved in pleasurable and addictive effects of drug abuse o Target for psychotropic drugs to treat schizophrenia |
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- Noradrenergic neurons (LC) -> widespread projections, it maintains
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o Maintenance of arousal and attention, mood and affect, learning and memory
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- Serotonergic neurons (Raphe nuclei) -> widespread projections to diencephalon and telencephalon function
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o Maintence of arousal and attention, mood and affect, learning and memory
o Antidepressends (ie: fluoxetine/Prozac) target this system |
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- Cholinergic neurons (basal forebrain – medial septum, bed nucleus of diagnos band of Broca and nucleus basalis of Meynert) -> widespread projections functions with
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o Work with NE and 5HT to modulate and enhance hippocampal and cortical function
o Effects on learning and memory o Severely affected (degeneration) in Alzheimer’s disease o Common target of memory enhancing drugs |
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Hypothalamus – targets for
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info processed in amygdala, important in consumatory and goal-directed behaviors
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- lamina terminalis – identifies front wall, area in front =
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preoptic area, chiasmatic zone above mamillary bodies
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Hypothalamic Nuclei – from rostral to caudal
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- Preoptic
- Anterior - Magnocellular paraventricular and supraoptic nuclei - Suprachiasmatic - Parvocellular paraventricular, arcuate nucleus and median eminence - Parvocellular paraventricular, ventromedial, and arcuate nuclei and lateral regions - Parvocellular paraventricular and lateral regions |
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The Hypothalamus functions
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the “master endocrine gland”.
• … a critical locus for the regulation of autonomic function. • … the generator or consumatory behaviors. • … the integrator of autonomic function with these goal-directed behaviors. |
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Preoptic is for
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sexual differentiation, reproductive function
and behavior |
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Anterior is for
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parasympathetic regulatory center
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- Magnocellular paraventricular and supraoptic nuclei
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vasopressin and oxytocin synthesis and release
o Cells synthesize and release vasopressin/oxytocin DIRECTLY into the posterior pituitary gland |
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- Suprachiasmatic
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at end of optic chiasm, circadian and season rhythm generator
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- Parvocellular paraventricular, arcuate nucleus and median eminence
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– production and release of pitutitary releasing factor, regulation of internal autonomic functions via projections to brainstem/SC
o Median eminence has no BBB -> regulatory factors go into anterior pituitary INDIRECTLY (via median eminence) |
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- Parvocellular paraventricular, ventromedial, and arcuate nuclei and lateral regions –
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metabolism, eating/drinking behaviors (ghrelin stimulates consummatory behavior)
o Indirect effect of leptons and insulin via median eminence (no BBB) |
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- Parvocellular paraventricular and lateral regions
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stress pathways to brain and SC, uitilze corticotrophin releasing hormone as chemical NT
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Preoptic, Anterior Hypothalamus Generator for
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goal-oriented behavior
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Preoptic, Anterior Hypothalamus are also Parasympathetic control center so they cause
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decrease blood pressure/heart rate
– regulate temperature – dissipate heat (sweating, panting, vasodilation) – respond to pyrogens - fever |
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Neurons of the anterior, arcuate and
paraventricular (parvocellular)nuclei play a dual role in the regulation of visceral function. |
1) Regulation of autonomic function
via projections to brainstem and spinal cord 2)Regulation of endocrine function via release of regulatory factors into the hypophysial portal system |
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Amygdaloid and Hypothalamic
Projections Regulate |
Autonomic Function
and Physiologic Arousal |
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Orexin and melanin
concentrating hormone (MCH) in the LH activate |
the brain’s arousal system
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Orexins – found in
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posterolateral hypothalamus
- Important part of arousal system – connections with nucleus accumbens, raphe nuclei, and LC - Knock out-> narcolepsy |
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Summary
- 1)Hippocamus - 2)Amgydala - 3)Basal forebrain - 4) Hypothalamus |
1)substrate for associative learning and cognitive interpretation
2)substrate for affect and goal oriented behavior 3)nucleus accumbens, prefrontal cortex = substrates for drive, reward, motivation, choice 4)motor unit regulating autonomic output, homeostatic control and consummatory behaviors |
