Neuroanatomy: cortical anatomy, thalamus, basal ganglia, hypothalamus, hippocampus
Anterior nucleus of thalamus
1
Central sulcus
1
Corpus callosum
1
Dorsomedial nucleus
1
Fornix
1
Frontal pole
1
Longitudinal fissure (interhemispheric fissure)
1
Paraventricular nucleus
1
Cuneus
10
Dentate gyrus of the hippocampus
10
Globus pallidus
10
Olfactory bulb
10
Optic chiasm
10
Parietooccipital sulcus
10
Superior colliculus
10
Calcarine fissure
11
Olfactory tract
11
Pulvinar
11
Stria terminalis
11
Supraoptic nucleus
11
Thalamus
11
Transverse occipital sulcus
11
Anterior ramus (of the Sylvian fissure)* *The anterior ramus of the lateral sulcus, is located at the very anterior end of the lateral sulcus (sylvian fissure), just anterior to the ascending ramus, and passes superiorly into the inferior frontal gyrus separating the pars orbitalis form the pars triangularis of the frontal operculum.
12
Habenula
12
Mammillary body
12
Occipital pole
12
Subthalamic nucleus
12
Ventromedial nucleus
12
Amygdala
13
Ascending ramus (of the Sylvian fissure)
13
Mamillary body
13
Preoptic neucleus
13
Superior parietal lobule
13
Taenia choroidea
13
Corpus callosum 13) rostrum of CC 14) genu of CC 15) body of CC 16) splenium of CC
13-16
Amygdala
14
Dorsomedial nucleus
14
Inferior parietal lobule
14
Lamina affixa
14
Parahippocampal gyrus
14
Posterior ramus (of the Sylvian fissure) (this is essentially most of the Sylvian fissure)
14
Diagonal band of Broca
15
Fornix
15
Frontal operculum
15
Optic tract
15
Postcentral gyrus
15
Frontoparietal operculum
16
Olfactory tubercle
16
Paracentral lobule The central sulcus extends into the posterosuperior aspect of the paracentral lobule in most cases. Hence, the portion lying anterior to the sulcus is frontal lobe, while the portion lying posterior is parietal lobe
16
Septum pellucidum
16
Third ventricle and choroid plexus
16
Body of the fornix
17
Lamina terminalis
17
Lateral ventricle
17
Olfactory bulb
17
Precentral gyrus
17
Superior temporal gyrus
17
Anterior commisure
18
Inferior frontal gyrus
18
Lateral ventricle and choroid plexus
18
Middle temporal gyrus
18
Septal nucleus
18
Cortex of the insula
19
Middle frontal gyrus
19
Septum pellucidum
19
Subcallosal area
19
Superior temporal sulcus
19
Area dorsalis
2
Area lateralis (lateral hypothalamic area)
2
Caudate
2
Cingulate sulcus
2
Fornix
2
Mammillothalamic tract
2
Medial frontal gyrus
2
Precentral gyrus
2
Superior margin of cerebrum
2
Anterior commissure
20
Fornix
20
Inferior temporal sulcus
20
Superior frontal gyrus
20
Inferior temporal gyrus
21
Medial forebrain bundle
21
Tela choroidea of the third ventricle
21
Choroid plexus of the third ventricle
22
Preocciptial notch
22
Occipital pole
23
Transverse cerebral fissure
23
Thalamus
24
Transverse occipital sulcus
24
Inferior parietal lobules
25
Interthalamic adhesion
25
Interventricular foramen of Monro
26
Intraparietal sulcus
26
Hypothalamus
27
Superior parietal lobule
27
Postcentral sulcus
28
Suprapineal recess and pineal body
28
Postcentral gyrus
29
Vermis of cerebellum
29
Area lateralis
3
Area medialis
3
Cingulate gyrus
3
Cingulate sucus
3
Frontal pole
3
Hypothalamic sulcus
3
Precentral sulcus
3
Stria medullaris
3
Thalamostriate vein
3
Cerebellar hemisphere
30
Supramarginal gyrus The supramarginal gyrus is horseshoe-shaped and caps the posterior ascending ramus of the lateral sulcus
30
Angular gyrus It lies as a horseshoe shaped gyrus capping the angular sulcus, a continuation of the upswing of the superior temporal sulcus. It is bound by the intraparietal sulcus superiorly, parieto-occipital sulcus caudally and supramarginal gyrus rostrally.
31
Choroid plexus of the 4th ventricle
31
Medulla
32
Pons
32
4th ventricle
33
Pyramid (medulla)
33
Olive* *The olive consists of two parts: The superior olivary nucleus, considered part of the pons and part of the auditory system, aiding the perception of sound. The inferior olivary nucleus (or 'complex'), which is a part of the olivo-cerebellar system and is mainly involved in cerebellar motor-learning and function.
34
Pons
34
Flocculus
35
Tectum and mesencephalic aqueduct of Sylvius
35
Cerebellar hemisphere
36
Mamillary body
36
Oculomotor nerve
37
Infundibular recess
38
Temporal lobe / lateral occipitotemporal gyrus
39
Habenular nucleus
4
Interthalamic adhesion
4
Posterior nucleus
4
Sulcus of the corpus callosum
4
Superior frontal gyrus
4
Superior frontal sulcus
4
Third ventricle
4
Tuberal nuclei
4
Rhinal fissure
40
Pituitary (hypophysis) with adenohypophysis (anterior lobe) and neurohypophysis (posterior lobe)
41
Optic chiasm
42
Optic nerve
43
Olfactory bulb and tract
44
Cingulate gyrus
5
Corpus callosum
5
Indusium griseum
5
Inferior frontal sulcus
5
Mamillary body
5
Optic chiasm
5
Superior frontal sulcus
5
Third ventricle
5
Fasciolar gyrus
6
Lateral sulcus (Sylvian fissure)
6
Middle frontal gyrus
6
Paracentral lobule
6
Precentral sulcus
6
Supraoptic nucleus
6
Thalamus
6
Tuberal nuclei
6
Ventromedial nucleus
6
Central sulcus
7
Claustrum
7
Fornix
7
Inferior frontal sulcus
7
Optic tract
7
Paraventricular nucleus
7
Pineal
7
Posterior lobe of pituitary gland
7
Precuneus
7
Anterior lobe of pituitary gland
8
Caudate nucleus
8
Fibria (of the hippocampus)
8
Fornix
8
Frontal pole
8
Inferior colliculus
8
Postcentral sulcus
8
Subparietal sulcus
8
Hippocampal formation
9
Infundibular nucleus
9
Intraparietal sulcus (separates the superior and inferior parietal lobules)
9
Orbitofrontal gyrus
9
Parietooccipital sulcus
9
Putamen
9
Quadrigeminal plate
9
1) Parasympathetic - anterior and medial (ventromedial) hypothalamic nuclei 2) Sympathetic - posterior and lateral hypothalamic nuclei 3) Decreasing body temp - anterior hypothalamic nucleus 4) Increasing body temp - posterior hypothalamic nucleus 5) Satiety center - medial hypothalamic nucleus 6) Feeding center - lateral hypothalamic nucleus 7) Arousal center - posterior hypothalamic nucleus In general: -anterior/medial: parasympathetic, cooling, satiety -posterior/lateral: sympathetic, heating, feeding, arousal
Describe the 7 levers of the hypothalamus (i.e. 7 aspects of hypothalamic control) and where they are located within the hypothalamus
Medial lemniscus/spinothalamic tract/trigeminothalamic tract --> VPLc/VPM (face) --> S1
Describe the basic pathway to the primary somatosensory area (S1)
Striatum = caudate + putamen Corticostriate fibers 1) Primary motor (area 4) >>> bilateral putamen 2) Premotor cortex >>> ipsilateral caudate and putamen 3) Prefrontal cortex >>> caudate
Describe the cortical input to the striatum
Paraventricular nuclei, lateral hypothalamus, and posterior hypothalamus >>> dorsal motor nucleus of X, nucleus solitarious, nucleus ambiguous, medulla, and spinal intermediolateral cell column
Describe the descending autonomic projections from the hypothalamus
Layer III (3rd from the top) The external pyramidal layer of cortex contains commissural fibers that connect the two hemispheres as well as ipsilateral cortico-cortico association fibers
Describe the fibers/projections and role of the external pyramidal layer of cortex
Layer IV (4th from the top) This is the main area of sensory input >>> enlarged in sensory cortex
Describe the fibers/projections and role of the internal granular layer of cortex
Internal pyramidal layer = layer V Main source of efferents to the brain stem and spinal cord >>> enlarged in motor cortex
Describe the fibers/projections and role of the internal pyramidal layer of cortex
Molecular = layer I (most superficial) Receives diffuse afferent fibers from the lower brain to control the excitability of the region
Describe the fibers/projections and role of the molecular layer of cortex
Multiform layer = VI (farthest from surface) Sends efferent fibers to the thalamus
Describe the fibers/projections and role of the multiform layer of cortex
Primary visual cortex Banks of the calcarine fissure Vision
Describe the functional area, location, and function of Brodmann's area 17
Secondary visual cortex Medial and lateral occipital gyri Vision, depth
Describe the functional area, location, and function of Brodmann's area 18
Tertiary visual cortex and middle temporal visual area Medial and lateral occipital gyri Vision, color, motion
Describe the functional area, location, and function of Brodmann's area 19
Visual inferotemporal area Interior temportal gyrus Form vision
Describe the functional area, location, and function of Brodmann's area 20
Visual inferotemporal gyrus Middle temporal gyrus Form vision
Describe the functional area, location, and function of Brodmann's area 21
Higher order auditory cortex (?Wernicke's versus BA 40) Superior temporal gyrus Hearing, speech
Describe the functional area, location, and function of Brodmann's area 22
Primary olfactory cortex, limbic association cortex Parahippocampal gyrus Smell, emotions
Describe the functional area, location, and function of Brodmann's area 28
Limbic association cortex Cingulate gyrus and limbic association cortex Emotions
Describe the functional area, location, and function of Brodmann's area 29, 30, 31, 32, 33
Primary olfactory cortex, limbic association cortex Parahippocampal gyrus Smell, emotions
Describe the functional area, location, and function of Brodmann's area 34, 35, 36
Parietal-temporal-occipital association cortex, middle temporal visual area Middle and inferior temporal gyri at themporo-occipital junction Perceptions, vision, reading, speech
Describe the functional area, location, and function of Brodmann's area 37
Primary olfactory cortex, limbic association cortex Temporal pole Smell, emotions
Describe the functional area, location, and function of Brodmann's area 38
Parietal-temporal-occipital association cortex Inferior parietal lobule (angular gyrus) Perception, vision, reading, speech
Describe the functional area, location, and function of Brodmann's area 39
Primary motor cortex Precentral gyrus Voluntary motor control
Describe the functional area, location, and function of Brodmann's area 4
Parietal-temporal-occipital association cortex (?Wernicke's versus BA 22) Inferior parietal lobule (supramarginal gyrus) Perception, vision, reading, speech
Describe the functional area, location, and function of Brodmann's area 40
Primary auditory cortex Heschl's gyrus and superior temporal gyrus Hearing
Describe the functional area, location, and function of Brodmann's area 41
Secondary auditory cortex Heschl's gyrus and superior temporal gyrus Hearing
Describe the functional area, location, and function of Brodmann's area 42
Gustatory cortex Insular cortex, fronto parietal operculum Taste
Describe the functional area, location, and function of Brodmann's area 43
Broca's area, lateral premotor cortex Inferior frontal gyrus (frontal operculum) Speech, movement planning
Describe the functional area, location, and function of Brodmann's area 44
Prefrontal association cortex Inferior frontal gyrus (frontal operculum) Thought, cognition, planning behavior
Describe the functional area, location, and function of Brodmann's area 45
Prefrontal association cortex (dorsolateral prefrontal cortex) Middle frontal gyrus Thought, cognition, planning behavior, eye movement
Describe the functional area, location, and function of Brodmann's area 46
Prefrontal association cortex Inferior frontal gyrus (frontal operculum) Thought, cognition, planning behavior
Describe the functional area, location, and function of Brodmann's area 47
Tertiary somatosensory cortex, posterior parietal association Superior parietal lobule Sterognosis
Describe the functional area, location, and function of Brodmann's area 5
Supplementary motor control, supplementary eye field, premotor adjacent cortex Precentral gyrus and rostral adjacent cortex Limb and eye movement planning
Describe the functional area, location, and function of Brodmann's area 6
Posterior parietal association Superior parietal lobule Visuomotor control, perception
Describe the functional area, location, and function of Brodmann's area 7
Frontal eye fields Superior and middle frontal gyri, medial frontal lobe Saccadic eye movements
Describe the functional area, location, and function of Brodmann's area 8
Primary somatosensory cortex Postcentral gyrus Touch
Describe the functional area, location, and function of Brodmann's areas 1, 2, and 3
Insular cortex Insula Involved with pain perception and speech production, processing of social emotions, autonomic function.
Describe the functional area, location, and function of Brodmann's areas 13, 14, 15, 16
Limbic association cortex Cingulate gyrus, subcallosal area, retrosplenial area, parahippocampus gyrus Emotions
Describe the functional area, location, and function of Brodmann's areas 23, 24, 25, 26, 27
Prefrontal association cortex Superior and medial frontal lobe Thought, cognition Area near frontal eye fields (medial frontal lobe) also involved in motor planning
Describe the functional area, location, and function of Brodmann's areas 9, 10, 11, 12
Amygdalostriate fibers: Amygdala to caudate + putamen
Describe the input from the amygdala to the striatum
Striatum = caudate + putamen Raphe nucleus sends inhibitory fibers (serotonin)
Describe the input from the midbrain dorsal raphe nucleus to the striatum
Striatum = caudate + putamen Nigrostriatal fibers: SN >>> caudate + putamen (?inhibitory dopamine)
Describe the input from the substantia nigra to the striatum
Striatum = caudate + putamen Thalamostriate fibers: 1) Intralaminar CM (centromedial) nucleus (largest intralaminar nucleus) >>> putamen 2) Parafascicular nucleus >>> caudate
Describe the input from the thalamus to the striatum
NSol rostral segment >>> medial hypothalamus (taste) NSol caudal segment >>> lateral hypothalamus (visceral sensation)
Describe the nucleus solitarius' (NSol) connections with the hypothalamus
1) Some fibers cross in the anterior commissure to contralateral anterior olfactory nucleus and olfactory bulb 2) Olfactory tubercle (olfactory cortex) 3) Amgydala 4a) Pyriform cortex >>> entorhinal cornex >>> hippocampus, insula, and frontal lobe via uncinate fasciculus 4b) Pyriform cortex >>> amygdala, lateral preoptic hypothalamus 4c) Pyriform cortex >>> MD thalamus >>> orbitofrontal cortex
Describe the outputs from the lateral olfactory stria (4 main -- broad strokes)
Subcallosal area Septal area (paraterminal gyrus)
Describe the outputs from the medial olfactory stria (2)
Right-handed individuals are nearly always left-brain language dominant Left-handed individuals are usually still left-brain dominant (85% of them are left dominant, 15% bilaterally dominant, rare right dominant)
Discuss handed-ness and hemispheric dominance
Nope
Do dentate fibers leave the hippocampus?
-Direct pathway neurons have excitatory D1 receptors; dopamine thus activates the direct pathway, facilitating movement -Indirect pathway neurons have inhibitory D2 receptors; dopamine thus inactivates the indirect pathway, facilitating movement
How does dopamine have its effect on the striatum?
Hippocampus >>> mamillary bodies
In broad strokes, what two man structures does the fornix connect?
1) primary olfactory cortex (pyriform cortex + periamygdaloid cortex) 2) secondary olfactory cortex (entorhinal area of anterior parahippocampus - area 28)
Name the 2 components of olfactory cortex
Lateral medullary lamina - between putamen and GP Medial medullary lamina - divides GPe and GPi Accessory medullary lamina - divides GPi itself into inner and outer segments
Name the 3 medullary laminae What do they separate?
Outputs: 1) Stria terminalis: amygdala >>> stria terminalis >>> nucleus of the stria terminalis (at caudate/thalamus junction) >> hypothalamus ("the fornix of hte amygdala") 2) ventral amygdalofugal tract: amygdala/pyriform area >> lateral preoptic area/septal area/nucleus of the diagonal band/substantia innominata/hippocampus/brainstem nucleu to regulate autonomic function (fear and stress) 3) amygdalocortical output 4) amygdalostriate (amygdala >> nucleus accumbens) ***** Inputs: literally from everything (lateral olfactory cortex, pyriform cortex, hypothalamus, paraventricular thalamus, nucleus of the solitary tract, lateral parabrachial nuclues, locus ceruleus (noradrenalin), SN and ventral tegmentum (DA), substantia innominata and lateral olfactory area (AcCh), raphe nucleus (serotonin)
Name the 4 main outputs of the amygdala Why haven't I asked about inputs to the amygdala?
1) Presubiculum 2) Subiculum 3) Prosubiculum 4) Hippocampus 5) Dentate gyrus
Name the 5 parts of the hippocampal formation
1) Parahippocampus gyrus 2) Hippocampal formation 3) Dentate gyrus 4) Cingulate gyrus 5) Insula 6) Orbitofrontal cortex
Name the 6 parts of the the limbic cortex
1) Amygdala 2) Hypothalamus 3) Septal nuclei 4) Habenular nuclei 5) Anterior and dorsomedial thalamic nuclei 6) Indusium griseum
Name the 6 subcortical limbic structures
1) Ansa lenticularis (main output tract) - from GPi AROUND the IC >>> Forel's field H1 (FFH1), the prerubral field 2) Lenticular fasciculus (FFH2 fibers) - from GPi THROUGH IC to join ansa lenticularis in Forel's field, forming the thalamic fasciculus 3) Thalamic fasciculus (FFH1 fibers) - composed of the joined ansa lenticular, lenticular fasciculus, nad cerebellothalamic tract (fibers from contralateral deep cerebelar nuclei) >>> thalamic VL and VA 4) Pallidosubthalamic fibers a) GPe >>> subthalamic nucleus (STN) b) GPi >>> stria medullaris >>> lateral habenulum
Name the four output bundles from the globus pallidus
1) Mammillothalamic tract 2) Fornix 3) Stria medullaris (thalami) 4) Stria terminalis
Name the key fiber tracts of the limbic system
From 2 oldest cortical areas 1) Pyriform cortex >>> amgydala >>> stria terminalis >>> hypothalamus and hippocampus >>> fornix >>> septum 2) Closed loop from the cingulate gyrus >>> entorhinal cortex >>> hippocampus >>> hypothalamus >>> anterior thalamic nucleus >>> cingulate gyrus
Two main inputs to the hypothalamus
1) olfactory receptors (epithelium w/ primary bipolar cells with kinocilium >>> 2) olfactory nerve (unmyelinated fibers) >>> 3) synapses on mitral cells (second neurons) in olfactory bulb (glutamate and aspartate mediated) 4) >>> olfactory tract (lateral olfactory stria** and gyrus and medial olfactory stria and gyrus) 5) >>> complex cortical connections (see other cards) **axons of the mitral and tufted cells
Walk through the olfactory pathway
3) Pars orbitalis 2) Pars triangularis 1) Pars opercularis ++ ) anterior ramus of Sylvian fissure +) ascending ramus of Sylvian fissure Broca's area considered to be formed by the pars triangularis and pars opercularis (2 and 1)
What are 1, 2, and 3? What are + and ++? What part marks up Broca's area?
Fibriae >> crura >> body >> columns
What are the 4 main components of the fornix?
I Molecular layer II External granular layer III External pyramidal layer IV Internal granular layer V Internal pyramidal layer VI Multiform layer
What are the layers of neocortex?
Caudate and putamen (striatum) They receive input from cortex (most importantly)
What are the main input nuclei of the basal ganglia? Where do they receive their most important input?
Globus pallidus and substantia nigra
What are the main output nuclei of the basal ganglia?
1) Fornix 2) Subiculum (the most inferior component of the hippocampal formation) that projects to cortex** ** subiculum is the sole direct cortical projector, may project to medial frontal cortex / cingulate / parahippocampal gyrus; may also project to cortex throguh postcommissural fornix and anterior nucleus of thalamus
What are the main outputs from the hippocampus (2)?
The fields of Forel are areas in the diencephalon. They are below the thalamus and consist of three defined, white matter areas of the subthalamus. These three regions are also named "H fields": Field H1, is the thalamic fasciculus, a horizontal white matter tract composed of the ansa lenticularis, lenticular fasciculus, and cerebellothalamic tracts between the subthalamus and the thalamus. These fibers are projections to the ventral anterior and ventral lateral thalamus from the basal ganglia (globus pallidus) and the cerebellum. H1 is separated from H2 by the zona incerta. Field H2 (synonymous with lenticular fasciculus) is also made up of projections from the pallidum to the thalamus, but these course the subthalamic nucleus (dorsal). Field H (sometimes called field H3) is a large zone of mixed grey and white matter from the pallidothalamic tracts of the lenticular fasciculus and the ansa lenticularis which combine in an area just in front of the red nucleus. The grey matter from this field is said to form a prerubral nucleus.
What are the three fields of Forel?
1) Entorhinal cortex (28) >>> hippocampus and dentate gyrus 2) Medial septal nucleus >>> fibria of hippocampus 3) Cingulate gyrus >>> cingulum >>> presubiculum/entorhinal cortex >>> hippocampus
What are the three main inputs into the hippocampus?
1) Pars tuberalis -portion of the infundibular stalk -median eminence of hypothalamus 2) Pars intermedia 3) Pars distalis (majority of the gland, has no direct blood supply >>> vulnerable)
What are the three parts of the adenohypophysis?
The three parts of the frontal operculum are the pars orbitalis, pars triangularis, and pars opercularis. (O-T-O with orbitalis in front) They result in the inferior frontal gyrus having a characteristic "M" configuration sometimes referred to as the M sign. The Sylvian fissure gives off two branches that subdivide the inferior frontal gyrus into three parts. From anterior to posterior: the anterior ramus (a.k.a. anterior horizontal ramus) separates the pars orbitalis from the pars triangularis, and the ascending ramus (aka anterior ascending ramus) separates the pars triangularis form the pars opercularis. Broca's area considered to be formed by the pars triangularis and pars opercularis.
What are the three parts of the inferior frontal gyrus? What is the relation between this region and Broca's area?
1) Pars nervosa (posterior lobe) 2) Infundibulum 3) Nuclei (supraoptic and paraventricular)
What are the three parts of the neurohypophysis?
Supplemental motor cortex (SMA, M2, area 6) There is a somatotopic organization of neurons Input is bilateral Input from S1 and input from globus pallidus (medial GP >>> ipsilateral thalamic ventroaterior pars compacta (VApc), ventrolateral pars oralis (VLo), centromedial (CM) >>> M2 and premotor (not M1)) Output to ipsilateral M1 (area 4) and parietal association cortex (areas 5 and 7); contralateral M2; bilateral spinal cord, caudate, putamen, and thalamus Lesion>>>hemiparesis/plegia, deminished spontaneous speech, may retain volitional movement with effort
What area manages programming, planning, and initiation of motor movements? Is there a somatotopic organization of neurons? Is the input unilateral or bilateral? What is the output? What does a lesion cause?
Premotor cortex (area 6) Input from cortex (M2, S1) as well as VL and VA of thalamus Also receives input from globus pallidus (medial GP >>> ipsilateral thalamic ventroaterior pars compacta (VApc), ventrolateral pars oralis (VLo), centromedial (CM) >>> M2 and premotor (not M1) Bilateral input >>> unilateral lesion causes no deficit
What area of the brain manages voluntary control for responses dependent on sensory input? What is the input from? unilateral or bilateral?
Amygdala
What defines archistriatum?
Neostriatum + paleostriatum >>> caudate, putamen, and GP
What defines corpus striatum?
Paleostriatum (GP) + subthalamic nucleus
What defines diencephalic nucleus?
Putamen and GP
What defines lentiform nuclei?
caudate and putamen
What defines neostriatum (or striatum)?
GP
What defines paleostriatum?
Gerstmann's syndrome 1) Agraphia 2) Acalculia 3) Finger agnosia 4) Right/left dissociation (inability to distinguish between the right and left sides of one's body)
What does a lesion in the dominant angular and supramarginal gyrus cause?
Neglect Anosognosia
What does a lesion in the non-dominant inferior parietal lobule cause (angular and supramarginal gyri)?
1) Anterior portion of AC connects 2 olfactory bulbs 2) Posterior portion of AC connects the two GPs, putamens, external capsules, claustrums, and inferior and middle frontal gyri
What does the anterior commissure connect (2 parts of AC)?
Cortical association areas >>> caudate >>> GP >>> thalamus >>> cortex (SMA/prefrontal cortex)
What does the cognitive basal ganglia circuit involve?
Lateral hypothalamic nucleus
What does the lateral hypothalamic area contain?
Mamillary bodies >>> midbrain ventral and dorsal tegmentum
What does the mamillotegmental tract connect?
Mamillary bodies >>> anterior thalamic nucleus
What does the mamillothalamic tract connect?
Motor/somatosensory cortex >>> putamen >>> GP >>> thalamus >>> supplementary motor area
What does the motor basal ganglia circuit involve?
Retinal ganglion cells >>> suprachiasmatic nuclei (circadian rhythms)
What does the retinohypothalamic tract connect? What does it help mediate?
Neurological circuit of historical interest Suggested involvement with emotion, combining subjective/autonomic/somatic elements Involves bidirectional connections from the subiculum <> mammillary bodies <> mammillothalamic tract <> anterior thalamic nucleus <> entorhinal cortex <> subiculum
What is Papez's Circuit?
The superior hypophyseal artery (off the supraclinoid ICA) and the inferior hypophyseal artery (branch of cavernous ICA meningohypohyseal trunk. These arteries join >>> sinusoids >>> infundibulum and anterior pituitary gland via portal system. The inferior hypophyseal artery is primary responsible for blood supply to the posterior pituitary lobe.
What is the blood supply to the pituitary?
The direct or excitatory pathway involves the disinhibition of the thalamus through the inhibition of the tonically inhibitory GPi/SNr. Overall effect of direct pathway is MORE MOVEMENT 1) Motor cortex excites (via glutamate) inhibitory neurons in the striatum 2) Inhibitory neurons in the striatum inhibit (via GABA) an inhibitory neuron in the GPi 3) Tonically inhibitory (GABAergic) neurons in GPi now no longer inhibiting thalamus 4) Thalamus now able to excite cortex and allow for movement
What is the direct pathway (components, neurotransmitters, overall effect)? Describe the direct pathway in 4 steps.
White matter tract that connects midbrain's central gray area (dorsal periaqueductal gray matter) <<<>>> periventricular hypothalamus (reciprocal)
What is the dorsal longitudinal fasciculus?
Facilitates movement
What is the effect of dopamine on the striatum?
Recent memory (not remote memory) and consolidation of short-term memory into long-term memory
What is the function of the hippocampal formation?
Controls behavior and emotion
What is the function of the limbic system?
The INHIBITORY indirect pathway allows for increased inhibition of the thalamus by the GPi thus inhibiting movement. It does so via inhibition of GPe, allowing for the disinhibition of GPi. 1) Motor cortex excites (via glutamate) inhibitory neurons in the striatum. 2) These inhibitory striatal neurons ramp up inhibition of GPe (via GABA) 3) At baseline, GPe inhibits both GPi and STN via GABA a) When GPe is inhibited per step 2, this turns down tonic GABA inhibition of GPi by GPe, thus allowing GPi to inhibit thalamus. b) When GPe is inhibited per step 2, this turns down tonic GABA inhibition of STN by GPe, thus increasing the excitatory activity of STN. 4) With increased excitatory activity of STN, STN is able to excite (the tonically inhibitory) GPi. 5) With increased activity of GPi, tonically inhibitory GPi is able to inhibit the thalamus. 6) The final result of both limbs of the indirect pathway is LESS MOVEMENT.
What is the indirect pathway (components, neurotransmitters, overall effect)? Describe the indirect pathway in 3-6 steps
Composed of supracallosal gyrus and medial and lateral longitudinal striae These are remnants of the hippocampus that course over the dorsal surface of the CC Connects the septal area with the hippocampus
What is the indusium griseum? What does it connect?
Primary related to limbic loops Input: 1) fornix 2) mamillary peduncle Output: 1) stria medularis >>> medial habenular nucleus 2) medial forebrain bundle >>> lateral hypothalamus, midbrain, and tegmentum 3) fornix >>> hippocampus
What is the input to the septal nuclei (2)? What is the output from the septal nuclei (3)?
An axon tract carrying secondary sensory information from the tegmentum of the midbrain to the mammillary body. Connects brainstem reticular formation >>> lateral mamillary nucleus
What is the mamillary peduncle?
Mamillary region = posterior portion of the medial hypothalamus It contains the mamillary bodies and the posterior hypothalamic nuclei
What is the mamillary region of the hypothalamus? What does it contain?
Runs from the basal olfactory areas, septal nuclei, periamygdala and subiculum >>> lateral preoptic and lateral hypothalamic areas >>>> hippocampus (pathway that conveys information related to basic emotional drives and smell)
What is the medial forebrain bundle?
Region of the hypothalamus where the CNS interacts with the pituitary (represents a funnel-like extension of the tuber cinereum)
What is the median eminence of the hypothalamus? What happens there?
Also called substantia innominata Located on basal forebrain (lies below the anterior part of the thalamus and lentiform nucleus) extends from olfactory tubercle to the hypothalamus (of note, the ansa lenticularis passes through this region en route from GPi to thalamus) Contains a high concentration of cholinergic neurons (it is the single major source of cholinergic fibers to the cortex) Input from amygdala, temporal lobe, pyriform cortex, and entorhinal cortex Diffuse cortical output
What is the nucleus basalis of Meynert? Where is it? What does it contain a lot of? Where does it extend? What is its input? Output?
Face is in the genu Then posterior limb contains body (organized rostral to caudal (cervical in front >>> sacral in back)
What is the orientation of motor fibers within the internal capsule?
adenohypophysis = ectodermal origin from roof of the stomodeum neurohypophysis = diencephalic origin
What is the origin of adenohypophysis? neurohypophysis
Substantia nigra pars compacta (SNpc) >>> striatum Substantia nigra pars reticulata (SNpr) >>> thalamus
What is the output (2) from the substantia nigra?
The pars marginalis (marginal sulcus) is the extension of the cingulate sulcus posterosuperiorly, separating the paracentral lobule from the precuneus of the parietal lobe on the medial surface of the cerebral hemispheres. On axial images it appears as a short sulcus, reaching the apex but not extending laterally. It is an excellent landmark to help confirm the location of the central sulcus, which is located ONE SULCUS ANTERIOR to the marginal sulcus, on the other side of the postcentral gyrus.
What is the pars marginalis? How is it useful radiographically?
Fornix divides anterior/posterior near the AC The posterior fibers (postcommissural fornix, majority of fornix fibers) pass caudal to the AC through the hypothalamus to the mammillary bodies; then to the anterior nuclei of thalamus, which project to the cingulate cortex. Pathway: Hippocampus >>> postcommissural fornix >>> mammillary bodies >>> anterior nuclei of thalamus >>> cingulate cortex (possibly to cingulum >>> presubiculum/entorhinal cortex >>> hippocampus)
What is the postcommissural fornix? Describe the pathway in which it is involved
Fornix divides anterior/posterior near the AC The anterior fibers (precommissural fornix, minority of fornix fibers) head anteriorly towards the septal nuclei and nucleus accumbens of each half of the brain. Pathway: Hippocampus >>> precommissural fornix >>> caudal septal nucleus
What is the precommisural fornix? Describe the pathway in which it is involved
Periventricular nucleus / periventricular gray of the most rostral third ventricle portion Contains medial and lateral preoptic nulcei
What is the preoptic area of the hypothalamus? What does it contain?
Part of the epithalamus. It is a fiber bundle containing afferent fibers from the septal nuclei, lateral preoptico-hypothalamic region, and anterior thalamic nuclei to the habenula. It forms a horizontal ridge on the medial surface of the thalamus, and is found on the border between dorsal and medial surfaces of thalamus. It projects to the habenular nuclei, from anterior perforated substance and hypothalamus, to habenular trigone, to habenular commissure, to habenular nucleus.
What is the stria medullaris?
Striatum = caudate + putamen Input: 1) cortex via corticostriate fibers (most important) 2) thalamic CM and parafascicular nuclei via thalmostriate fibers 3) substantia nigra via nigrostriatal fibers 4) midbrain dorsal raphe nucleus 5) lateral amygdala via amygdalostriate fibers Output (take with grain of salt) 1) striatonigral fibers: head of caudate >>> substantia nigra pars reticulata (SNpr) 2) striatopallidal fibers: caudate/putamen >>> GPi (inhibitory via gaba) 3) nigrothalamic fibers: terminate in VA, VLm, MD (inhibitory via gaba)
What is the striatum? What is its input (5)? What is its output (3)?
Supraoptic and paraventricular nuclei >>> posterior pituitary gland (releates oxytocin, vasopressin, cholecystokinin, enkephalins, glucagon, dynorphin, and angiotensin)
What is the supraoptichypophyseal tract?
The tuberal region is the middle part of the medial hypothalamus This is the region where the fornix separates the hypothalamus into medial and lateral regions
What is the tuberal region of the hypothalamus? What key division happens there?
Arcuate nucleus of the tuber region >>> median eminence and the infundibular stem (Releasing hormones are secreted into fenestrated capillaries that form the hypophyseal portal system >>> anterior pituitary gland)
What is the tuberohypophyseal tract?
Anterior thalamic nuclei (ATN) / anterior nuclear group Input from the mammillothalamic tract and fornix Output to cingulate gyrus via anterior limb of IC It is involved with the regulation of memory, emotion, visceral function (part of limbic system)
What is this nucleus or nuclear group? What is its input? Where does it project? What is it involved with?
Lateral dorsal (LD) nucleus Input from several subdivisions of visual cortex Output to cingulum (i.e. cingulate gyrus) and supralimbic parietal lobe It acts in concert with the anterior nuclei of thalamus (limbic system)
What is this nucleus or nuclear group? What is its input? Where does it project? What is it involved with?
Lateral geniculate body (LGB = light) Part of the metathalamus Primary visual relay nucleus LGB has six layers (1,2: magnocellular and 3-6: parvicellular Input from retinal ganglion cells Crossed fibers from contralateral eye >>> layers 1,4,6 Uncrossed fibers from ipsilateral eye >>> 2, 3, 5 As such, there is no binocular fusion in the LGB because layers remain separate Reciprocal connections with calcarine cortex (area 17) and pulvinar
What is this nucleus or nuclear group? What is its input? Where does it project? What is it involved with?
Lateral posterior (LP) nucleus Input from superior parietal lobe (posterior parietal association cortex) Output to areas 5 (tertiary somatosensory cortex/posterior parietal association cortex) and 7 (posterior parietal association cortex) Contributes to visual perception and eye movements, probably relating to attention to these stimuli. It acts in concert with the pulvinar.
What is this nucleus or nuclear group? What is its input? Where does it project? What is it involved with?
Medial dorsal nucleus Input from amgydala, substantia nigra, orbitofrontal cortex, temporal cortex Output to frontal association cortex and prefrontal area Also has reciprocal connects with frontal eye fields Integrates somatic and visceral activities and controls affective behavior (disconnected in prefrontal lobotomies; lesion >>> Korsakoff's psychosis)
What is this nucleus or nuclear group? What is its input? Where does it project? What is it involved with?
Medial geniculate body (MGB = music) Part of the metathalamus Input from inferior colliculus via inferior brachium Reciprocal connections with primary auditory cortex (Heschl's gyrus, area 41, transverse temporal gyrus) Both MGB and Heschl's gyrus have tonotopic organization with high frequencies medial MBG = auditory relay nucleus
What is this nucleus or nuclear group? What is its input? Where does it project? What is it involved with?
The pulvinar Input from superior colliculus, (reciprocal) connections with occipital cortex, temporal, and parietal lobes Output (as per above): occipital cortex (areas 18 and 19 - secondary and tertiary visual cortex), parietal and temporal cortex Represents part of the the extrageniculate visual pathway To review: LGB --> area 17 Inferior pulvinar >>> area 18 (extrageniculate) Lateral pulvinary >>> area 19 (extrageniculate) Contributes to visual perception and eye movements, probably relating to attention to these stimuli. It acts in concert with the LP nucleus of thalamus.
What is this nucleus or nuclear group? What is its input? Where does it project? What is it involved with?
Ventral posterolateral nucleus (VPL) Input from contralateral spinothalamic tract and contralateral medial lemniscus of posterior column-medial lemniscus pathway. Also receives some input from contralateral deep cerebellar nuclei. Output to primary somatosensory cortex (Brodmann's Areas 3, 1 and 2 in postcentral gyrus) This is a relay center for sensory information. Works on conjunction with VPM which is relay center for face sensation.
What is this nucleus or nuclear group? What is its input? Where does it project? What is it involved with?
Ventral posteromedial (VPM) nucleus "Makeup goes on your face" Input from contralateral spinothalamic tract and primary sensory nuclei of CN V as well as ipsilateral dorsal trigeminal tract Output to sensory cortex (interestingly face has bilateral VPM representation) Also taste fibers from nucleus solitarius >>> central tegmental tract uncrossed to VPMpc (pars compacta) >>> parietal operculum area 43 (gustatory cortex) This is a relay center for sensory information for face sensation and taste. Similar to VPL which is relay center for sensation for rest of body.
What is this nucleus or nuclear group? What is its input? Where does it project? What is it involved with?
Ventroanterior (VA) nucleus of the thalamus Input from globus pallidus, substantia nigra, area 6 (SMA - motor planning) and area 8 (frontal eye fields/motor planning); mammillothalamic tract also passes through VA Output to frontal cortex and intralaminar nuclei of the thalamus Involved in coordination of motor planning between cortex and BG
What is this nucleus or nuclear group? What is its input? Where does it project? What is it involved with?
Ventrolateral (VL) nucleus of the thalamus Involved in feedback signals from basal ganglia and cerebellum. BG input: VL gets input from globus pallidus and substantia nigra (as does VA) Cerebellar input: VL gets input from deep cerebellar nuclei (as does VPL) VL main output to primary motor cortex (area 4) but also to premotor and SMA Output to
What is this nucleus or nuclear group? What is its input? Where does it project? What is it involved with?
Subthalamic nucleus
What is this?
Centromedial (CM) nucleus of thalamus Part of the intralaminar nuclei Input from area 4 (primary motor) Output to putamen
What is this? Input/output? What is it involved with?
Ventral posterior inferior (VPI) nucleus of the thalamus Involved with sensory relay (neighbors VPL and VPM) Output to ipsilateral S2
What is this? What is it involved with? What is its output?
Hippocampal formation is all archipallium w/ 3 layers: 1) Molecular 2) Pyramidal 3) Polymorphic Inferior parahippocampus is isocortex w/ 6 layers
What kind of cortex is the hippocampal formation? What are the layers? How about inferior parahippocampus?
Bilateral representation
What makes face and tongue representation in S1 special?
Only sensory system without thalamic relay
What makes olfactory system unique?
Olfactory bulbs, tracts, tubercles, striae, and the anterior olfactory nucleus and pyriform cortex
What makes up the rhinencephalon?
Composed of subcallosal and the paraterminal gyrus Located on the medial surface of the cerebral hemisphere nestled inferior to the rostrum of the corpus callosum and anterior to the third ventricle and lamina terminalis. Consists of medial and lateral septal nuclei Part of the limbic system
What makes up the septal area? Where is it located? What nuclei does it contain? Why do we care?
No memory impairment
What results from unilateral injury to the mammillary body and fornix?
The only auditory commissure required for sound localization
What role does the trapezoid body
Primary motor (area 4) - 31% Premotor/supplementary motor cortex (area 6) - 29% Parietal cortex - 40%
What three main regions project (and in what proportions) to corticobulbar and corticospinal tracts?
Area 8 Caudal middle frontral gyrus Frontal eye fields initiate saccades (stimulation of this region >>> contralateral eye deviation) Pathway: eye fields >>> rostral interstial nucleus of the MLF >>> interstitial nucleus of Cajal >>> paramedian pontine reticular formation >>> superior colliculus >>> CN III, IV, VI
Where are the frontal eye fields do? What do they do? What is the pathway out of the eye fields?
Subiculum and fornix
Where do CA1 pyramidal cell axons project within the hippocampal formation?
CA1 and fornix
Where do CA3 pyramidal cell axons project within the hippocampal formation?
SNpc
Where does the dopamine that signals the striatum come from?
Primary visual cortex (BA 17) is located on the banks of the calcarine sulcus and extends around the occipital pole Input from LGB (lateral geniculate body = light) >>> geniculocalcarine fibers pass close to outer walls of lateral ventricles (external sagittal stratum) --> calcarine sulcus Output to internal sagittal stratum >>> corticofugal fibers >>> superior colliculus and LGB
Where is V1? What is its input? What is its output?
Transverse gyri of Heschl (in the superior temporal gyrus within the temporal operculum - area 41) Association area 42 surrounds 41. Input from MGB (medial geniculate body = music)* *ventral MGB has a tonotopic organization with high frequencies medial Of note, each cochlea projects b/l but more to the contralateral side
Where is primary auditory cortex? What is its input?
Precentral gyrus - area 4 The cortex is special because it is the thickest of all cortex 2/2 giant Pyramidal cells of Betz (layer V) Input from 1) ipsilateral thalamus (VL and VLo [ventrolateral pars oralis]), 2) contralateral cerebellum, 3) S1, M2 Output primarily to corticobulbar and corticospinal tracts but also has reciprocal fibers with thalamus Organization is loosely somatotopic but not perfectly so Project is bilateral except to the eye, face, and tongue
Where is primary motor cortex? What is special about this in terms of cell layers? What is the input to M1? Where does its primary output go? How is it organized -- somatotopic? unilateral? bilateral?
Located on superior bank of lateral sulcus (lower parietal lobe) Input from ipsilateral VPLc and VPM and bilateral S1 Output to ipsilateral S1 and motor cortex Bilateral information, I believe the homunculus is inverted (confirm), and there is no processing of medial lemniscus
Where is secondary somatosensory cortex located? What is its input? What is its output? What is it's representation?
Layer II (second from the top) Contains closely packed granule cells This layer is poorly myelinated
Where is the external granular layer of cortex? What is it like pathologically?
Layer III (3rd from the top) Contains pyramidal neurons, granule cells, and Martinotti cells
Where is the external pyramidal layer of cortex? What is it like pathologically?
Gustatory area 43 is on the postcentral operculum adjacent to the tongue sensory area. Ipsilateral nucleus solitarius >>> VPMpc >>> area 43
Where is the gustatory area? What is its input?
Layer IV (4th from the top) Contains closely packed stellate cells A dense horizontal myelinated plexus forms the external band of Baillarger
Where is the internal granular layer of cortex? What is it like pathologically?
Layer V (5th from the surface) Contains the largest cells (Betz cells) Contains pyramidal neurons, granule cells, and ?Martinotti cells Dense myelinated plexus forms the internal band of Baillarger
Where is the internal pyramidal layer of cortex? What is it like pathologically?
Layer I - most superficial Contains horizontal axons, Golgi type II cells, and terminal dendritic processes
Where is the molecular layer of cortex? What is it like pathologically?
Contains spindle-shaped cells
Where is the multiform layer of cortex? What is it like pathologically?
The stria terminalis runs within the terminal sulcus between the thalamus and the caudate) It connects amygdala <<<<>>> hypothalamus (anterior and preoptic nuclei) (reciprocal connection) It relays information related to emotional drives and smell *****Stria terminalis is to the amygdala as the fornix is to the hippocampus
Where is the stria terminalis? What does it do?
Supraoptic region = anterior part of medial hypothalamus Contains 1) paraventricular and supraoptic nuclei (secrete oxytocin and vasopressin) 2) anterior hypothalamic nucleus 3) suprachiasmatic nucleus (biological clock with b/l afferent input from the retinas)
Where is the supraoptic region of the hypothalamus? What does it contain? What does it do?
MD Medial dorsal nucleus
Which thalamic nucleus projects to 1?
VL Ventrolateral nucleus
Which thalamic nucleus projects to 2?
VPL/VPM Ventroposterolateral/ventroposteromedial nuclei
Which thalamic nucleus projects to 3?
LP Latereral posterior nuclei
Which thalamic nucleus projects to 4?
LGB Lateral geniculate body
Which thalamic nucleus projects to 5?
Pulvinar
Which thalamic nucleus projects to 6?
MGB Medial geniculate body
Which thalamic nucleus projects to 7?
