Functional Neuroanatomy Flashcards

1
Q

Disconnection Syndrome

A

Damage to the white matter pathways when functional brain regions are deprived of inputs and outputs through white matter damage.

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2
Q

Gray matter vs White matter

A

Gray = cell bodies of neurons
White = mostly myelinated axons

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3
Q

Unimodal cortex vs Polymodal cortex

A

Unimodal = processes information pertaining to a specific sensory modality; primary role in perception

Polymodal =processes information received from disparate modalities through afferent connections; primary role in higher order conceptual processes

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4
Q

Frontal lobe cortical divisions (3)

A

Orbitofrontal/ventromedial region
Dorsolateral region
Dorsomedial region

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5
Q

Orbitofrontal/ventromedial region

A

emotional regulation, reward monitoring, and personality

Orbitofrontal damage may cause disinhibition

ventromedial damage may cause disordered reward/punishment processing, problems making perceptual or learning experiences with reward value and emotional significance

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6
Q

Dorsolateral region

A

broad range of cognitive-executive functions

Damage produces dysexecutive syndromes, impairments in working memory and poor attentional control of behavior

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7
Q

Dorsomedial region

A

intentional and behavioral activation

Damage produces impairments in initiated behavior (in extreme cases may cause akinetic mutism - in which person is alert and awake but cannot move or speak)

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8
Q

Temporal lobe cortical areas (2)

A

Ventral temporal area
Posterior temporal area

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9
Q

Ventral temporal area

A

object recognition and discrimination

bilateral damage can produce object or face agnosia

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10
Q

Posterior temporal area

A

contains primary auditory areas and Wernicke’s area in the language-dominant hemisphere, important for language comprehension, and prosodic comprehension in the homologous non-dominant hemisphere

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11
Q

Parietal lobe cortical divisions (3)

A

Superior parietal lobe
Temporoparietal junction
Inferior parietal lobule

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12
Q

Superior parietal lobe

A

important for sensory-motor integration, body schema, and spatial processing

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13
Q

Temporoparietal junction

A

phonological and sound-based processing; language comprehension (left) and music comprehension (right)

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14
Q

Inferior parietal lobule

A

complex spatial attention, integration of tactile sensation, and self-awareness

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15
Q

Occipital lobe cortical divisions (2)

A

Ventral visual pathway
Dorsal visual pathway

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16
Q

Ventral visual pathway

A

connects occipital and temporal lobe

important for object and face recognition, item-based memory, and complex visual discrimination

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17
Q

Dorsal visual pathway

A

connects occipital and parietal lobe via superior temporal sulcus

important for spatial vision and visuomotor integration

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18
Q

Concept of functional system (processors and connectors)

A

An interconnected group of cortical and subcortical structures that each contributes to important components of complex behavior or skill. Complex behavior, such as memory or language, can be impaired by damage to the processors themselves or by damage to their connecting fibers

damage to processer = loss of function
damage to connector = disconnection syndrome, loses full ability to coordinate or communicate

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19
Q

Neuroanatomy of Vision (pathway)

A

Retinal ganglion cells in each eye > optic nerve > optic chiasm > optic tract > lateral geniculate nucleus (LGN) of the thalamus > primary visual cortex (Brodmann 17)

From LGN, pathway called “geniculostriate”

Note. A small portion of fibers bypass the LGN and terminate in the pretectal area and superior colliculus (forming the “extrageniculate” visual pathway)

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20
Q

“Dorsal” and “Ventral” pathways

A

Dorsal = (“Where”) projects to parieto-occiptal association cortex; processes spatial information. Lesions cause impairments in spatial perception, attention, and visuomotor processing

Ventral = (“What”) projects to occipito-temporal association cortex; processes structural and feature-based information. Lesions cause impairments in perceptual disturbances, poor recognition of objects/faces (agnosias)

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21
Q

Apperceptive (visual) disorder

A

a disorder results rom impairment in processing basic visual elements of objects (e.g., shapes, contour, depth)

22
Q

Associative angosia

A
23
Q

Associative agnosia

A

When the recognition disorder results from relating well-perceived stimulus to stored representations based on prior experiences with the stimulus

24
Q

Primary cortical inputs into the hippocampus (2)

A

Ventral Stream > unimodal (primarily visual) cortical areas > perirhinal cortex (PRc) -> Lateral Entorhinal cortex (L-ERc) > HC CA1 and HC CA3

Dorsal Stream > Parietal and Frontal association areas > Parahippocampal cortex (PHc) > Medial entorhinal cortex (M-ERc) > HC CA1 and HC CA3

Both end at HC CA1 and HC CA3

25
Q

Neuroanatomy of Memory: Medial (Papez) circuit

A

Hippocampus -> postcommissural fornix -> mammillary bodies -> mammillothalamic tract -> anterior thalamic nucleus -> thalamic projections -> cingulate gyrus and cingulate bundle -> cingulate bundle or cingulum -> hippocampus

26
Q

Neuroanatomy of Memory: Lateral limbic circuit

A

Amygdala -> dorsomedial nucleus of the thalamus -> orbitofrontal cortex -> uncinate fasciculus -> amygdala

27
Q

Hippocampus structure

A

Consists of dentate gyrus, sectors of Ammon’s horn (cornu Ammonis [CA] 1-4), and the subiculum

The primary internal connections comprise what is known as the ‘Trisynaptic circuit’

(entorhinal cortex > dentate granule cells (synapse 1) > CA3 via mossy fibers (synapse 2) > CA1 via Schaffer collaterals (synapse 3)

28
Q

Amygdala structure

A

two main parts: a large basolateral group of nuclei (which connect to limbic system, association cortex, and dorsomedial thalamic nucleus) and a smaller corticomedial segment (connects with basal forebrain, hypothalamus, and brainstem)

29
Q

Similar anatomical connections of amygdala and hippocampus

A

Both 1) strongly interconnected with frontal and temporal limbic cortex, 2) have indirect polymodal neocortical association areas, 3) project to basal forebrain and hypothalamus, and 4) connect directly with each other

30
Q

Anatomical Basis of Temporal Lobe Amnesia (two-system theory of amnesia)

A

Amnesia occurs when both the lateral and medial limbic circuits are damaged (explains most diencephalic and BF amnesias as well). Lesions that disrupt both cause severe amnesia, whereas lesions restricted to either pathway alone cause less severe memory disturbance

Four conclusions about temporal lobe and amnesia:
1) damage to cortical or subcortical structures within temporal lobe, whether focal or extensive, can result in amnesia
2) Amnesia most likely results from damage to both circuits
3) Damage to individual elements of these circuits can all result in amnesia, provided that both circuits are damaged
4) Hippocampus is critical for episodic memory, whereas amygdala critical for emotional aspect of cognition (including emotional memory)

31
Q

Thalamus role in Memory

A

Thalamus is primarily a sensory relay nucleus but has critical functions in high cognitive processes (alertness, behavioral activation, and memory)

Thalamic amnesia best correlates with lesions affecting the internal medullar lamina (IML) and mammillothalamic tract

32
Q

Basal Forebrain role in Memory

A

Located at the junction of the diencephalon and cerebral hemispheres (vicinity of the ventromedial fontal lobe, anterior to the caudate and putamen)

Composed of: the septal area, diagonal band of Broca, nucleus accumbens septi, olfactory tubercle, substantia innominata, bed nucleus of the stria terminals, and preoptic area.

Damage associate with profound memory loss with confabulation, the latter of which is likely associated with neighboring frontal lobe

33
Q

Approx. % of left-hemisphere language dominance

A

95% for right-hand
60-70% for left hand

34
Q

Broca’s Area

A

(BA 44, 45); dominant side of frontal lobe

Damage causes a Nonfluent Aphasia (expressive) with deficits in written or verbal expression (speech planning and production)

Connects with other frontal regions and appears necessary for processing syntax and grammatical structure of language

35
Q

Wernicke’s Area

A

(BA 22) dominant side of temporal lobe

Damage to Wernicke (BA 22) and surrounding areas (BA 37, 39, and 40) causes Fluent Aphasia (receptive) with deficits in comprehension

Reciprocally connected with supramarginal and angular gyri in the parietal lobe - important for comprehension, writing, and for mapping sounds to meaning (lexical semantics); also connections with visual areas important for recognition of word forms (important for reading)

36
Q

Arcuate Fasciculus

A

A large subcortical white matter pathway that connects Broca (BA 44, 45) and Wernicke (BA 22).

Damage produces disproportionate deficits in repetition, with relative sparing of comprehension and fluency (Conduction Aphasia)

37
Q

Prosody of Language

A

Defined as use of tone, pitch, rhythm, and other vocal intonation patterns to convey meaning and emotion

Primarily processed in the right (non-dominant) hemisphere

38
Q

Anomic Aphasia

A

Poor single word production (impaired storage or access to lexicon)

Damage to inferior parietal lobe or connections within perisylvian language areas

39
Q

Transcortical Motor Aphasia

A

Disturbed spontaneous speech similar to Broca’s; relatively preserved repetition and comprehension

A disconnection between conceptual word/sentence representations

Damage to deep white matter tracts connecting BA to parietal lobe, usually caused by anterior watershed infarcts

40
Q

Transcortical Sensory Aphasia

A

Disturbance in word comprehension (meanings) with relatively intact repetition

Damage to white matter tracts connecting parietal and temporal lobe, usually caused by posterior watershed infarcts

41
Q

Frontal Lobe network of “selective engagement”

A

Networks in the frontal lobe allow for the flexible selection and activation of cortical regions necessary to perform cognitive work

E.g., summing up the name of a friend

42
Q

Frontal-subcortical Interaction - primary loop?

A

Cortico-Striatal-Pallidal-Thalamo-Cortical Loop

43
Q

3 interconnected systems for attention (Posner & Rothbart, 2007)

A

Orientation - refers to tuning of perceptual systems to incoming stimuli so that relevant information from sensory input can be selected for further processing (primarily acetylcholine)

Alerting - state of sensitivity to incoming stimuli (primarily norepinephrine)

Executive attention - involves monitoring and resolving conflicts among thoughts, feelings, and behaviors (primarily dopamine)

44
Q

Key anatomic facts concerning Working Memory

A

1) dorsal (spatial) - ventral (object-based) distention appears to exist in the frontal working memory systems just as it does in posterior cortex

2) dorsal components of the frontal working memory system are preferentially connected to structures in the dorsal visual stream and vise-versa

45
Q

Neurotransmitter & cognitive relevance: Acetylcholine

A

Attention, memory, regulation of thalamic output

46
Q

Neurotransmitter & cognitive relevance: Norepinephrine/Noradrenaline

A

Attention shifting; arousal
Mood; sleep-wake cycle

47
Q

Neurotransmitter & cognitive relevance: Serotonin

A

Mood, arousal
Pain, respiration, temperature, motor control

48
Q

Neurotransmitter & cognitive relevance: Dopamine

A

Motor regulation; thalamic gating
Memory, reward systems
Executive function, working memory, “top-down” attention, motor initiation
Lactation, menstruation, sexual behavior

49
Q

Neurotransmitter & cognitive relevance: GABA

A

Broad neuromodulatory functions

50
Q

Neurotransmitter & cognitive relevance: Glutamate

A

Broad excitatory functions