Forebrain part 2 Flashcards Preview

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Flashcards in Forebrain part 2 Deck (70):
1

Diencephalon is located

at the center of the cerebrum

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Diencephalon is composed of ___ parts:

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~thalamus
~hypothalamus
~subthalamus
~epithalamus

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Thalamus is a

large nuclear complex

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Thalamus can be have____ or _____ descriptions

anatomical or functional descriptions

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Thalamus- anatomical description

~there are lateral nuclei to the internal medullary lamina, medial nuclei that is medial to the lamina, anterior nucleus that is anterior to the lamina, and the intralaminar nuclei within the lamina
~the large number of lateral nuclei are divided into dorsal and ventral tier of nuclei

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Thalamus- functional description

~relay nuclei
~association nuclei
~regulatory nuclei

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Relay Nuclei of Thalamus (function)

~function to relay information from different brain regions to cerebral cortex

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Relay Nuclei of Thalamus (parts)

~Anterior nucleus
~Ventral Lateral and Ventral Anterior
~Ventral Posterior
~Lateral and Medial Geniculate nuclei

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Relay Nuclei- Anterior Nucleus

~relays information from reticular formation of brainstem to the prefrontal cortex
~this relayed information id important in linking emotional content to sensory input

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Relay Nuclei- Ventral Lateral (VL) and Ventral Anterior (VA)

~relay information from the basal nuclei (ganglia) and cerebellum to motor cortex

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Relay Nuclei- Ventral Posterior nucleus (parts)

~ventroposterolateral
~ventroposteromedial

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Relay Nuclei- Ventral Posterior nucleus- ventroposterolateral

~relays somatosensory information from the body (via connections in the spinal cord)

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Relay Nuclei- Ventral Posterior nucleus- ventroposteromedial

~relays somatosensory information from the head and face (via connections in the brainstem)

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Relays Nuclei- Lateral and Medial Geniculate nuclei (location)

~located very posterior in the thalamus

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Relays Nuclei- Lateral and Medial Geniculate nuclei

~lateral- relays visual information from primary visual input to the primary visual cortex of the occipital cortex
~medial- relays auditory information as part of the primary auditory to the primary auditory cortex of the temporal lobe

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Association nuclei of Thalamus (include)

~midline (medial nuclei)
~interlaminar nuclei (Dorsomedian and Centromedian)
~pulvinar

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Association nuclei of Thalamus (information from)

There connect structures like (to the cerebral cortex):
~basal nuclei
~brainstem reticular activating system
~various sensory systems

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Association nuclei of Thalamus (information to)

Send this information to:
~the limbic cortex
~prefrontal cortex
~posterior parietal cortex
*and diffuse through the rest of the cerebral cortex

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Association nuclei of Thalamus (function)

~providing emotional components of sensory input
~reticular activating system providing alertness and wakefulness
~visual pathways to posterior parietal areas for spatial coordination

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Reticular nucleus of Thalamus (functions)

~regulate excitability of other thalamic nuclei

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Reticular nucleus of Thalamus (parts)

~Reticular nucleus (outer lateral coat of thalamus)
~Zona Incerta (inferior to thalamus contiguous with reticular nucleus)

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Hypothalamus (location)

~large group of nuclei located just below the thalamus

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Hypothalamus (parts)

~Anterior (supraoptic)
~Middle (tuberal)
~Posterior (mammillary)

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Hypothalamus- Anterior

above the optic chiasm

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Hypothalamus- Middle

above the pituitary gland

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Hypothalamus- Posterior

most posterior group over level of mammillary bodies

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Hypothalamus (function)

~regulates endocrine and autonomic function
~chief effector of the limbic system
~body temperature regulation
~sleep- wakefulness cycle
~emotional and behavioral functional

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Hypothalamus (input-7)

~cerebral cortex, midbrain, brainstem, hipcampus, amygdala, septal nuclei, & cicumventricular sensory organs
*theses last are chemosensitive areas that sense toxin in the cerebrospinal fluid and trigger emesis

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Hypothalamus (output-7)

~cerebral cortex, midbrain, hippocampus, amygdala, septal nuclei, brainstem, and spinal cord

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Control from the anterior pituitary gland on the hypothalamus

*anterior pituitary can be easily described as part of the endocrine system but it has a neuroendocrime component
~Neuroendocrine- neurons from the nuclei release hormones in median eminence
~Endocrine- hormones circulate to anterior pituitary via hypothalamic- hypophysical (pituitary) portal system of vessels
~triggers release of hormones

31

Control form the posterior pituitary gland on the hypothalamus

~neurons in two nuclei, specifically the supraoptic and paraventricular nuclei of the hypothalamus send axon to posterior pituitary
~release hormones

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What hormones do the anterior pituitary gland release?

~Adrenocorticotropic hormone (ACTH)
~Growth hormone
~Thyroid stimulating hormone (TSH)
~Gonadotropic hormone (FSH and LH)
~Prolactin

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What hormones do the posterior pituitary gland release?

~oxytocin
~antidiuretic hormone (ADH)

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Hypothalamus- control of ANS

~referred to as "head nucleus" of sympathetic division of ANS
~descending control of spinal sympathetic pre-ganglionic neurons
~regulation of blood floe and blood pressure particularly during exercise
~thermal regulation
~some parasympathetic funation- emesis (vomiting) reflexes

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Epithalamus (composed of)

~pineal gland
~associated structures

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Epithalamus- pineal gland

~located posterior to the thalamus and superior to superior colliculus
~Neuroendocrine function- releases melatonin

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Melatonin (what is it for, etc)

~the release of melatonin follow a Circadian rhythm and is thought to have a role in sleep/wakefulness cycles

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Subthalamus (location)

~a wedge-shaped nucleus to the thalamus between thalamus and middbrain

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Subthalamus (what is it for)

~a nucleus of basal nuceli (ganglia) and has an important role in motor function

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Why is the cerebellum call the "little brain"?

it is small in size, but high in neuron density

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Where is the cerebellum located?

~posterior cranial fossa
~superior to brainstem (pons and medulla)
~inferior to occipital lob of cerebrum

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Cerebellum has functions in (3) domains

~motor
~cognitive/affective
~visceral

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Cerebellum- motor functions

*the control of the motor system predominates
~normal muscle tone
~smooth, accurate, and coordinated movements
~postural stability
~motor coordination

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What are the two major motor roles in the cerebellum?

Feedback comparator and feed forward controller

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Cerebellum- motor control (feedback)

~takes the signal after it has been processed and brains it BACK into the process
~comparator function of the cerebellum is hen it compares the intended motor performance with the motor performance (movement) that actually occurs
~allows for error detection and correction
~allows the cerebellum to provide coordination, regulation, and modulation of motor behavior

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Cerebellum- motor control (feed forward)

~a control signal that enters the process for the first time, PRIOR to the process of completing the task
~role of cerebellum is involved in the cerebellum's role in the learning and performance of smooth, complex movements

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Cerebellum- divided into

~central vermis and hemispheres
~also anterior and posterior lobes (separated by the primary fissure) and the flocculonodular lobes which is separated from the posterior lobe by the posterolateral fissure
*lobes can be further divided into lobules

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Folia

folds in the cerebellar cortex

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The cerebellum is surround by

deep white matter surrounded by a thin outer mantle of cerebellar cortex

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Cerebellum: the inner white matter is called

arbor vitae

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Cerebellum: the deep white matter has (_) bilateral pairs of deep nuclei

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~Fastigial nucleus
~Nucleus interpositus- Globose nucleus
~Nucleus interpositus- Emboliform nucleus
~Dentate nucleus

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In the cerebellum, there are 3 distinct layers

~molecular layer
~Purkinje cell layer
~granule cell layer

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Cerebellum: molecular layer

~dense arborization of Purkinje cell dendrites, all of which are in a plane perpendicular to direction of folia
~excitatory input fibers (climbing and parallel fibers)- climbing fibers wrap around the Purkinje cells and their dendrites while parallel fibers run in parallel to the direction of the folia (each parallel fiber would run through thousands of Purkinje cell dendritic fields)
~inhibitory interneurons called stellate and basket cells

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Cerebellum: Purkinje cell layer

~regularly spaced Purkinje neurons
~excitatory climbing fibers

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Cerebellum: Granular cell layer

~Granule cells form excitatory parallel fibers of the molecular layer
~mossy fiber inputs
~inhibitory Golgi cells

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Cerebellar peduncles (what is it)

Afferents and efferents leave the cerebellum through here

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Cerebellar peduncle (parts)

~Inferior
~Middle
~Superior

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Cerebellar peduncle- Inferior

(restiform body)
~afferent from spinal cord and vestibular system and inferior olive
~efferent to vestibular nuclei and reticular formation

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Cerebellar peduncle- Middle

(brachium pontis)
~afferents from pontine nuclei of the pons

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Cerebellar peduncle- Superior

(brachium conjunctivum)
~mostly efferents from cerebellum to thalamus and brainstem
~however, the ventral spinocerebellar tract enter through here as well

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Cerebellum: what are the 3 functional divisions?

~vestibulocerebellum
~spinocerebellum
~pontocerebellum

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Cerebellum: Vestibulocerebellum

*also called Archicerebellum
~composed of the Flocculonodular lobe
~it is interconnected with (both afferents from and efferents to) the vestibular nuclei
~the principle deep nucleus which provides efferent fibers from this region is the fastigial nucleus

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Cerebellum: Spinocerebellum

*Also called Paleocerebellum
~composed of the vermis and paravermal cortex
~highly interconnected with spinal cord and brainstem
~principal deep output nuclei from this region are the fastigial and interposed nuclei

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Cerebellum: Pontocerebellum

*also called Neocerebellum or cerebrocerebellum
~composed of lateral cerebellar hemisphere
~highly interconnected with motor cortex
~the principal deep output nucleus is dentate nucleus

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Cerebellum: Vestibulocerebellum (function)

~regulation of muscle tone, posture, balance, and gait

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Cerebellum: Spinocerebellum (function)

~skilled movement, tone, posture of ipsilateral LE and gait

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Cerebellum: Pontocerebellum (function)

~skilled movement, tone, posture of ipsilateral UE and motor learning

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Cerebellum: Vestibulocerebellum (damage)

~dysequilibrium and loss of balance

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Cerebellum: Spinocerebellum (damage)

~staggering ataxic gait, and wide base of support

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Cerebellum: Pontocerebellum (damage)

~loss of skilled movement, uncoordinated, ataxic movement, intention tremor, and dysdiadochokinesia