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Flashcards in Forebrain part 1 Deck (72):
1

Cerebral cortex (details)

~most complex area of the brain
~has about 20 billion neurons and 200-500 trillion synapses

2

Cerebral cortex (organized)

~Organized functionally by regional differences and within each functional region is organized by columns and layers

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The cerebrum is divided into the ____ and ____ hemisphere

left and right hemispheres

4

Lobes in the cerebrum

~frontal
~parietal
~temporal
~occipital

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Frontal Lobe- specific gyri

~pre-central
~superior, middle, and inferior frontal
~orbital

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Temporal Lobe- specific gyri

~superior, middle, and inferior temporal
~parahippocampal

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the three types of connections within the cerebral cortex and

~projection fibers
~association fibers
~commissural fibers

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Projection fibers

~connections leaving the cerebral cortex going to other structures in thee neural axis
~EX: the corticospinal and corticobulbar tracts going to the spinal cord and brain stem respectively

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Association fibers

~connections between adjacent areas of same hemisphere
~EX: the arcuate fasciculus between language centers of the cortex

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Commissural fibers

~connection between the two hemisphere
~EX: corpus callosum

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Parietal Lobe- specific gyri

~post-central
~superior parental
~angular
~supra-marginal

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Neocortex has _ layers

6

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Numbered fro, 1 (most____) to 6 (most ____)

1- most superficial
6-most deep; nearest deep white matter

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Each layer had unique distribution of different____

types of cortical neurons & inputs & outputs

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Large pyramidal cells of layer ____ have axons which form:

layer 5
~form the principal projection output from the cerebral cortex

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Smaller pyramidal cells of layer ____ have axons which form _______ and layer ____ form _____

~layer 3 have axons which form commissural output
~layer 2 pyramidal cells axons for association output fibers

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Input from outside the cerebral cortex, specifically the thalamus enter and end in the ____ layer

layer 4

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Input from other cortical areas both association and commissural fibers primary enter and end in neurons in layers ____

1, 2, 4, & 5

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Brainstem reticular activating system input into ___ layers

all layers

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there are ___ different histological regions

52 different regions

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Each region is defined by

~different patterns of cells in each of the layers

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Brodmanns areas

~roughly corresponds to functional areas

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Caveats

~not all individuals are the same (variation in size and shape of each Brodmann area from person to person)
~Boundaries of Brodmann areas are not distantly shown
~Brain plasticity can reshape the Brodmann regions, expanding some regions and contracting others so even for one individual these areas are continuously changing through their life

24

Cortical Columns

~neurons of similar functions organized in the same functional cortical columns
~extend from pial surface to white matter
~within a column there is a dense interconnection of neurons between layers
~most distinct cortical columns are in the primary motor and sensory cortices

25

Parts of the frontal lobe

~Primary motor area
~Pre-motor cortex
~Supplementary motor area (SMA)
~Broca's Motor Speech
~Frontal Eye Field
~Prefrontal cortex
~Anterior cingulate gyrus

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Primary motor area is located

along the pre-central gyrus

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Primary motor area (details)

~Pyramidal cells here have axons which are projection fibers that form the motor tracts to contralateral spinal cord lower motor neurons (LMN) (corticospinal tract) and to contralateral brain stem lower motor neurons (corticobulbar tract)
~has somatotopic organization (body map)

28

Primary motor area- somatatotopic organization

(motor homunculus)
~the size of the body parts in the homunculus represents the number of cortical neurons that are innervating LMN in the spinal cord or brainstem
~the greater areas of the homunculus represents a greater fine motor control of the muscles in that area
~greatest in hands and face
~least in trunk and lower extremities

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Primary motor area- lesion in this area causes..

A lesion to primary motor area causes voluntary paralysis of opposite side of the body and facial expression
**this occurs in stroke

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Pre-motor cortex is located

just anterior to the primary motor cortex

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Pre-motor cortex

~when stimulated, the result is not single muscle contraction as with the primary motor cortex but activates groups of similar muscle (synergistic muscles)

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Supplementary motor area (SMA) is located

superior and medial to the pre-motor cortex

33

Supplementary motor area (detail)

~appears to be the site of the storage of motor memory
~when movements are initiated, activity in the SMA occurs up to 120 ms before movement occurs
~suggests that the SMA may develop the motor plans that are acted upon by the primary motor cortex

34

Supplementary motor area- lesion

~lesions to the SMA produces defects in motor planning (called apraxia)
~lesions produce the loss of memory of how to preform tasks
~this is an inability to preform tasks, not a paralysis of the muscles that produce these movements

35

Broca's Motor Speech Area- location

anterior to the primary motor cortex
**only in left hemisphere in 90% of individuals, but in some in right hemisphere, and some bilateral

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Broca's Motor Speech Area (what does it do)

~devoted to the control of the muscles of the face and larynx

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Broca's Motor Speech Area (damage)

~damage to this area produces expressive aphasia- a paucity or lack of speech production

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Frontal Eye Field- location

anterior to the pre-motor cortex

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Frontal Eye Field (what does it do)

~produces conjugate eye movements and smooth visual pursuit
~controls the brainstem areas which produce conjugate eye movements

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Prefrontal Cortex- location

rostral, inferior, and medial to the Broca's area

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Prefrontal Cortex (what does it do)

roles on thinking, planning, social behaviors- both cognitive and emotional responses

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Prefrontal Cortex (3 distinct areas)

~dorsolateral
~ventromedial
~orbitofrontal

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Prefrontal Cortex- Dorsolateral frontal cortex (what does it do)

~involved in analytical thinking, problem solving, keeping focus and attention, and planning

44

Prefrontal Cortex- Dorsolateral frontal cortex (damage)

~damage to this area results in disordered thinking and disorganized behavior with an inability to maintain focus and being easily distracted

45

Prefrontal Cortex- Ventromedial frontal cortex (what does it do)

~involved in motivation, gaining emotional pleasure form life experiences and connecting to emotions and thoughts

46

Prefrontal Cortex- Ventromedial frontal cortex (damage)

~damage to this area produces apathy, anhedonia, flat emotional affects, inability to report preferences, hyperactivity in this area in mania and less active in clinical depression

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Prefrontal Cortex- Orbitofrontal cortex (what does it to)

~involved in impulse control, socially acceptable behaviors, and planning

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Prefrontal Cortex- Orbitofrontal cortex (damage)

~damage produces irresponsible, impulsive behavior, lack of planning, focus, and organized skills
~hyperactivity in this area is associated with OCD

49

Anterior cingulate gyrus is sometimes considered part of the...

"limbic lobe"

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Anterior cingulate gyrus (what does it do)

~appears to help integrate sensation, emotions, and thought with motivation and attentiveness

51

Anterior cingulate gyrus (damage)

~damage to this area results in feeling of apathy and aimlessness
~hyperactivity corresponds to anxiety and OCD

52

Parts of the Temporal Lobe

~Primary Auditory Cortex
~Auditory association cortex
~Wernicke's receptive speech area
~Inferotemporal cortex
~medial temporal cortex (3 parts)

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Primary Auditory Cortex (location)

~located along the medial aspect of the superior temporal gyrus
~pulling back on the parietal and frontal lobes to look into the insula only the superior temporal gyrus
**surrounded by the auditory association cortex

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Primary Auditory Cortex (what does it do)

~tonotopically organized and maps low frequencies rostral and high frequencies more posterior

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Auditory association cortex (location)

~inferior, lateral, and posterior to the primary auditory cortex

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Auditory association cortex (what does it do)

~gives rise to our complex auditory experience, including the recognition of sounds and the complex analysis of sounds

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Wernicke's receptive speech area (location)

~just posterior to the auditory association area
**it is in the left hemisphere in most but can be bilateral in 5-10% of individuals

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Wernicke's receptive speech area (what does it do)

~important for understanding language, including written, sign, and verbal/spoken language
*in the non-dominant hemisphere, this area of the posterior temporal lobe is responsible for interpretation of nonverbal language, gestures, and body language

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Wernicke's receptive speech area (damage)

~damage produces a highly verbal who does not understand language
~lots of words, but you cannot understand what they are saying/ lots of random words

60

how is the Wernick's area connected to the Broca's motor area?

connected by arcuate fasciculus

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Inferotemporal Cortex (location)

lateral and inferior temporal lobe

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Inferotemporal Cortex (what does it do)

responsible for the recognition of faces, objects, and colors

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Inferotemporal Cortex (damage)

dames produces prosopagnosia- inability to recognize faces of familiar individuals

64

Medial temporal cortex (what's in it-3)

~Primary olfactory cortex
~Amygdala
~Hippocampus
*best seen from a mid-sagittal section of the brain

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Primary olfactory cortex

~damage to this area will cause anosmia- loss of sense of smell

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Amygdala (location)

~a group of nuclei at rostral tip of the temporal lobe

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Amygdala (what does it do)

~generally associated with fear and anger
~parts that are active with any strong emotion

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rich connections with hypothalamus and amygdala produce

the physiological responses of strong emotion including increased heart rate, respiratory rate, and blood pressure

69

Where did the name hippocampus come from?

named from its shape- its shaped like a sea horse

70

Hippocampus (location)

along the ventromedial aspect of the temporal lobe

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Hippocampus (what does it do)

~principal function is the consolidation of memory- conversation of short-term to long-term

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Hippocampus (damage)

produces anterograde amnesia- inability to produce new memories