Ch4 neuroanatomy and neuropharmacology Flashcards
Human nervous system is composed of
central nervous system (CNS) and peripheral nervous system (PNS)
central nervous system (CNS) includes
brain and spinal cord
peripheral nervous system (PNS) includes
everything except brain and spinal cord
the brain is divided into which 3 main components?
forebrain, midbrain, hindbrain
forebrain includes which 2 parts?
cerebral hemisphere and diencephalon
hindbrain are comprised of which 3 parts?
medulla, pons, cerebellum
In terms of orientation, what is another term from “front-back”?
ventral-dorsal
Ventral is toward the…
belly
In terms of orientation, what is another term from “up-down”?
rostral/superior - caudal/inferior
Above the spinal cord, ventral/dorsal means
inferior/superior in the brain
Below the spinal cord, ventral/dorsal means
front and back in the spinal cord
Below the spinal cord, rostral/caudal means
toward the head/toes in the cord
Above the spinal cord, rostral/caudal means
anterior/posterior in the brain
Gray matter
cell bodies of neurons
White matter
myelinated axons
What does white matter do?
provide communication among cortical areas and between cortical and subcortical structures over longer distances
Damage to the white matter pathways when functional brain regions are deprived of input and output through white matter damage
Disconnection syndromes
unimodal cortex
- an association area that primarily deals with information from one sense modality.
- For example, visual association cortex is devoted to the integration of different types of visual information.
- plays a prominent role in perception
polymodal cortex
- processes information received from disparate modalities through afferent connections
- involved in higher order conceptual processes that are less dependent on concrete sensory information than on abstract features extracted from multiple inputs
Frontal lobe can be subdivided into the following 3 regions
1) orbitofrontal/ventromedial region
2) dorsalateral region
3) dorsomedial region
Orbitofrontal/ventromedial region is responsible for
- emotional regulation
- reward monitoring
- personality
- decision making
Damage to the orbitofrontal/ventromedial region results in
- disordered reward/punishment processing
- problems making perceptual and learning experiences with reward value and emotional significance
- poor decision making
Dorsolateral region is responsible for
- cognitive executive functions, executive attention
Damage to the dorsalateral regions results in
- dysexecutive syndromes
- impairments in working memory
- poor attentional control of behavior
Dorsomedial region is responsible for
- intentional and behavioral activation
Damage to the dorsomedial prefrontal cortex results in
- impairments in initiated behavior including akinetic mutism
- apathy
Akinetic mutism means
person is alert and awake, not comatose, but cannot speak or move
Temporal lobes can be divided into which 3 regions?
1) Temporal polar cortical areas
2) Ventral temporal areas
3) Posterior temporal region
Temporal polar cortical areas are responsible for
intersensory integration and semantic memory
Ventral temporal areas are responsible for
object recognition and discrimination
Bilateral damage to ventral temporal areas can result in
object or face agnosia
Posterior temporal regions are comprised of which sulci?
middle and superior temporal sulci
Which part of temporal lobe is Wernicke’s area (brodmann area 22) located?
Superior temporal gyrus
Posterior temporal regions are responsible for:
- language comprehension in the language dominant hemisphere
- prosodic comprehension in the homologous non-dominant hemisphere
Parietal Lobe can be divided into which 3 regions?
1) Superior parietal lobule
2) Temporoparietal junction
3) Inferior Parietal lobule
Superior parietal lobule is responsible for:
sensory-motor integration
body schema
spatial processing
Temporoparietal junction is responsible for
phonological and sound-based processing language comprehension (left) music comprehension (right)
Inferior parietal lobule is responsible for
complex spatial attention
integration of tactile sensation
self awareness
Occipital lobe contains which 2 cortex?
- Primary visual cortex
- Visual association cortex
Damage to the primary visual cortex results in
- cortical blindness
- Anton’s syndrome (denial of cortical blindness)
- blindsight (detection of unconsciously perceived stimuli in the blind field)
Partial damage to the primary visual cortex results in
- visual field defects
Occipital lobe is the origin of which 2 main visual-cortical pathways?
- Ventral visual pathway
- Dorsal visual pathway
What does the ventral visual pathway do?
- connects occipital and temporal lobe
- object and face recognition
- item based memory
- complex visual discrimination
What does the dorsal visual pathway do?
- connects the occipital and parietal lobes
- important for spatial vision and visuomotor integration
How many Brodmann areas are there?
52
Disconnection syndrome occurs when
fiber damage causes functional processors to lose their ability to communicate or coordinate in performing a complex task of behavior
What are the name of the cells of our eyes that send their axons into the optic nerve?
Retinal ganglion cells
What do retinal ganglion cells do?
They send their axons into the optic nerve
Where does the optic nerve project to?
Optic nerve projects posteriorly and comes together at the optic chiasm
Where do optic tracts originate?
Optic chiasm
Discuss what happens at the visual pathway, how information travels from the eye to the visual cortex
1) retinal ganglion cells in each eye send their axons into the optic nerve
2) optic nerves projects posteriorly, comes together at optic chiasm
3) optic tracts originate at optic chiasm, then terminate at Lateral Geniculate Nucleus (LGN)
4) then projects to brodmann area 17/primary visual cortex
5) small proportion of fibers bypass LGN, terminate in pretectal area and superior colliculus, then project to parietal and frontal association cortex
Where does visual information crossover?
Optic Chiasm
Tectopulvinar system
prectectal and collicular fibers project to parietal and frontal association cortex via relays in pulvinar nucleus of thalamus
What is the tectopulvinar system responsible for?
pupillary light reflex
attention-directed eye movements
general orientation to visual stimuli
Extrageniculate or Extrastriate visual pathways refer to
the small proportion of visual fibers that bypass lateral geniculate nucleus and terminate in the pretectal area and superior colliculus
Dorsal pathway in human vision projects to…
parietal occipital association cortex
What does the dorsal/parieto-occipital association cortex do?
processes spatial information
visuomotor integration in the environment
What does the ventral/occipito-temporal association cortex do?
processes structural and feature based information for analysis and recognition of visual form (e.g. faces and objects)
Dorsal lesions may cause
impairments in spatial perception, attention, visuomotor processing
Ventral lesions may cause
perceptual disturbances
disorders of recognition of familiar objects or faces (AGNOSIA)
Apperceptive Agnosia
- results from extensive damage to visual association areas
- impairments in processing basic visual elements of objects (e.g. shape, contour, depth)
Associative Agnosia
- difficulty understanding the meaning of what is seen
- patients can draw or copy but do not know what they drew
- perception of form is okay, but cannot recognize or identify
Memory disorders can result from damage to which 3 areas?
1) medial/mesial temporal lobe
2) medial diencephalon
3) basal forebrain
Definition of agnosia
an inability to recognize and identify objects or persons while perception or senses may be intact
What does the limbic system include?
hippocampal formation amygdala septal nuclei cingulate cortex entorhinal cortex perirhinal cortex parahippocampal cortex
Which 3 cortical areas form the temporal lobe?
entorhinal cortex
perirhinal cortex
parahippocampal cortex
What does the hippocampal formation include?
- dentate gyrus
- the hippocampus proper (i.e., cornu ammonis)
- subicular cortex
- entorhinal cortex
Hippocampus is also called
cornu ammonis or Ammon’s Horn
Where is hippocampus located?
Temporal lobe
Amygdala’s functions are
an integrative center for emotions, emotional behavior, and motivation
Where is amygdala located?
adjacent to the hippocampus
Hippocampus can be divided into 4 histological regions
CA1, CA2, CA3, CA4
Function of dendate gyrus
Episodic memories
Exploration of new environments
Subicular complex
- the most inferior structure of the hippocampal formation
- responsible for working memory
Circuit of papez
- begins and ends at the hippocampus
- information received from perirhinal and parahippocampal cortex -> hippocampus -> (via fornix) mammillary bodies -> (via mammillothalamic tract) anterior thalamus -> cingulate gyrus -> hippocampus
Which 2 cortices receive a majority of the cortical input to the temporal lobe memory circuit?
- perirhinal cortex
- parahippocampal cortex
What information does perirhinal cortex receive?
More anterior temporal non-spatial information
What information does parahippocampal cortex receive?
More posterior medial spatial information
Describe the lateral circuit
perirhinal and parahippocampal cortex -> amygdala -> dorsomedial nucleus of the thalamus -> orbitofrontal cortex -> uncinate fasciculus ->amygdala
What does the case of H.M illustrate?
removal of uncus and amygdala caused no memory loss, but more posterior resections involving the hippocampus and parahippocampal gyrus produced amnesia more severe
two-system theory of amnesia explains that
amnesia occurs when both the lateral AND medial limbic circuit (papez) are damaged
lesions that interrupt both the fornix (papez circuit) AND ventral amygdalofugal pathways (lateral circuit) will result in
severe amnesia
Each memory system can carry on the function of the other because…
lesions affecting only one system result in memory loss that is far less severe than if both systems are damaged
Damages to Perirhinal and parrahippocampal cortex can cause more severe memory impairment than…
when there are impairments of the lateral and medial limbic circuits
Damage to cortical or subcortical of temporal lobe results in
amnesia
Amnesia most likely results from damage to which circuits?
BOTH hippocampal-based medial limbic (papez) and amygdala-based lateral limbic circuits
Hippocampus is critical what kind of memory?
Episodic memory
Amygdala is responsible for what kind of memory?
Emotional memory
Emotional aspects of cognition
Function of thalamus
Sensory relay nucleus
alertness
behavioral activation
memory
Thalamic lesions can result in
- impaired connections to hippocampus
- disconnection with frontal lobes
Wernicke-Korsakoff is associated with
amnesia related to dorsomedial thalamic lesions
Damage to cholinergic neurons in Basal Forebrain
causes memory loss
Alzheimer’s Disease is associated with
substantial loss of neurons containing acetylcholine in the basal forebrain (BF), affecting recognition memory
Which parts of the brain is amnesia associated with?
medial temporal
thalamic
basal forebrain
parahippocampal gyrus damage
In the brain, gray matter is found…
in the outer most layer of the brain
In the spinal cord, gray matter is found
inside
In the spinal cord, white matter is found
in the outer layer
Which parts does the brainstem include?
midbrain, pons, medulla
Functions of afferent neurons
carry information from sensory receptors of the skin and other organs to the central nervous system (i.e., brain and spinal cord)
Functions of efferent neurons
carry motor information away from the central nervous system to the muscles and glands of the body
Name 2 sulci found in the temporal lobe
Superior temporal sulcus
Inferior temporal sulcus
Name the 3 gyri found in the temporal lobe
Superior temporal gyrus
Middle temporal gyrus
Inferior temporal gyrus
Functions of parietal lobe
processing sensations of touch, pain, pressure
Primary Somatosensory cortex (brodmann area 3) is housed in which area of the parietal lobe?
Postcentral gyrus of the parietal lobe
Name the notable lobules, gyrus and sulcus in the parietal lobe
superior parietal lobule inferior parietal lobule angular gyrus supramarginal gyrus post central gyrus
Hemispatial neglect is caused by damage to which part of the brain?
Right parietal lobe
Trisynaptic circuit
- pattern of synaptic transmission within hippocampus
- entorhinal cortex -> dentate gyrus -> CA3 -> CA1
DLPFC functions include
top down executive attention
Lesions in dorsal medial prefrontal cortex can result in
apathy and akinetic mutism
Dorsomedial nucleus is a part of …
thalamus
Parts of basal forebrain
septal area
substantia innominata
red nucleus of the stria terminalis
