Week VII: Diencephalon, Cortex

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Name the 3 parts of the diencephalon: 1. thalamus
2. hypothalamus
3. epithalamus
what structure blocks the lateral growth of the thalamus during embryological development?: the internal capsule
What makes up the rostral boundary of the hypothalamus?: the lamina terminalis
What makes up the medial boundary of the hypothalamus?: the IIIrd ventricle
What makes up the inferior surface of the hypothalamus?: the floor of the IIIrd ventricle
What makes up the superior border of the hypothalamus?: The hypothalamic sulcus
What makes up the posterior border of the hypothalamus?: The beginning of the cerebral aqueduct
what structure divides the hypothalamus into the medial and lateral zones?: The fornix
Where is the medial forebrain bundle found and where does it run?: found in the lateral region of the hypothalamus. It runs between the forebrain and the reticular formation (it is bidirectional)
What are the 3 zones of the medial region of the hypothalamus?: 1. pre-optic/supra-optic
2. Tuberal
3. Mammillary
What is the function of the pre-optic and supra-optic regions?: project to the posterior lobe of the pituitary gland to release AHD and Oxytocin
What nucleus is found in the tuberal zone?: The arcuate nucleus - contains neurons that release hypothalamic releasing factors (these factors influence the anterior pituitary)
The main function of the tuberal zone, then, is _____________.: endocrine
The dorsomedial and ventromedial nuclei of the tuberal zone play a role in _____________.: regulation of appetite
What is a major characteristic of the mammillary zone?: Major location where efferent pathways leave the hypothalamus
What are the 3 efferent pathways that leave the hypothalamus via the mammillary zone? Where does each run to?: 1. mammillothalamic - to anterior thalamic nucleus
2. mammillotegmental - to midbrain reticular formation
3. dorsal longitudinal fasciculus - to brainstem reticular formation and spinal cord.
What is the autonomic function of the anterior hypothalamus?: parasympathetic functions; also heat disposal (sweating).
What is the autonomic function of the posterior hypothalamus?: sympathetic functions; also heat retention (shivering)
Hypothalamic nuclei influence the 4 F's: what are these? What system influences the 4 F's?: Feeding, Fighting, Fleeing, Fornication
The limbic system
What other connections does the hypothalamus have with the limbic system?: amygdala
ant. and dorsomedial nuclei of thalamus
Which structure makes up the medial boundary of the thalamus?: The IIIrd ventricle
Which structure makes up the lateral boundary of the thalamus?: PLIC
Which structure makes up the superior boundary of the thalamus?: transverse cerebral fissure (subarachnoid space between corpus callosum and thalamus)
Which structure makes up the inferior boundary of the thalamus?: the hypothalamus and hypothalamic sulcus
The structure that splits the thalamus into 4 groups groups of nuclei is ___________?: the internal medullary lamina
What is the thalamic reticular coat?: a surrounding structure that overlies the lateral and anterior thalamus (aka. the reticular nucleus)
The thalamus sends out 4 types of radiations - name them: 1. anterior
2. Superior
3. Posterior
4. Inferior
Regarding the anterior thalamic radiations: 1. Where do they begin 2. Run in what structure 3. Where do they project?: 1. start in anterior and medial thalamic groups
2. run in ALIC
3. project to frontal lobe
Regarding superior thalamic radiations: 1. Where do they begin 2. Run in what structure 3. Where do they project: 1. start in VPL, VPM, VL
2. run in PLIC
3. project to sensorimotor strip (areas 1, 2, 3, 4, 6)
Regarding posterior thalamic radiations? 1. Where do they begin 2. Run in which structure 3. where do they project: 1. start in LGN, Pulvinar
2. run via optic radiations
3. project to area 17; occipital lobe
Regarding Inferior thalamic radiations: 1. where do they begin? 2. run in which structure 3. project to where?: 1. MGN
2. run in auditory radiations
3. project to temporal lobe and insular cortex, Area 41
What is meant by the fact that VPM and VPL have "reciprocal connections?": VPM & VPL project to somesthetic strip (areas 1,2,3). If you knock out VPL and VPM: cortical neurons will die. If you knock out the somesthetic strip: neurons in VPM and VPL die.
Pulvinar: 1. Inputs? 2. Outputs?: 1. areas 18, 19
2. inferior parietal lobe
Dorsomedial Nucleus: 1. Inputs? 2. Outputs?: 1. Amygdaloid complex, temporal neocortex
2. Prefrontal Cortex
Anterior Nuclei: 1. Inputs? 2. Outputs?: 1. mammillothalamic tract (from hypothalamus), fornix
2. Cingulate gyrus
VA: 1. Inputs? 2. Outputs?: 1. Globus Pallidus
Substantia Nigra
2. Frontal Cortex (Area 6)
VL: 1. Inputs? 2. Outputs?: 1. Globus Pallidus
Substantia Nigra
Dentate Nucleus (from cerebellum)
2. Area 4 (Motor Cortex)
VPL: 1. Inputs? 2. Outputs?: 1. Medial Lemniscus
Spinothalamic tracts
2. Areas 1, 2, 3 - sensory cortex
VPM: 1. Inputs? 2. Outputs?: 1. Trigeminothalamic nucleus
2. Areas 1,2,3 - sensory cortex
LD Output? LP Output?: To Caudate Nucleus
To Superior parietal lobe
LGN: 1. Inputs? 2. Outputs?: 1. Optic Tract
2. Optic Radiations to Area 17
MGN: 1. Inputs? 2. Outputs?: 1. Inferior colliculus, lateral lemniscus
2. Auditory Radiations to Areas 41, 42
Branches of the internal carotid supply which portion of the thalamus?: The anterior nuclear group
What is the blood supply to anteromedial aspect of the thalamus?: Posteromedial striatal arteries (aka. thalamoperforant arteries): branches from PCmA
What is the blood supply to VPM, VPL, LGN, MGN?: posterolateral striatal arteries (aka. thalamogeniculate arteries): branches of the PCA
the _____cortex covers the cerebral hemispheres; it has six distinct cellular layers: neocortex
the ______cortex is also known as the hippocampus; it has four cellular layers: Archicortex
the _____cortex is found on the ventral surface of the cortex and the parahippocampal gyrus; it has three cellular layers: Paleocortex
There are three basic types of neurons in the cerebral cortex. Name them.: 1. Projection Neurons
2. Association Neurons
3. Commissural neurons
Elaborate on projection neurons: send axons to areas of the CNS that lie outside of the cortex
Elaborate: association neurons: connect cortical regions to the same hemisphere
Elaborate: commissural neurons: connect cortical regions to the contralateral hemisphere
General rule: projection fibers arise from _________, while association and commissural fibers arise from _________.: deep neocortex
superficial cortex
What are the largest and most prominent neurons in the cortex? What type of fibers do they give rise to?: *pyramidal neurons
*association fibers or projection fibers
What characterizes a stellate nueron and where are these neurons found?: Stellate neurons have extensive dendrites projecting from all directions of the cell body. THey are found in layer IV (internal granular)
Where are fusiform neurons found? What type of nerve fibers do they form?: In the deepest cortical layers.
They form projection fibers
What are the Horizontal Cells of Cajal AND the Cells of Martinitti?: Other types of neurons found in the cortex
In general: cortical efferent fibers originate in layer (lamina) _____, while thalamic projections originate in ____.: cortical efferent fibers - lamina VI
Thalamic projections - lamina V
List the cellular Cortical layers from superficial to deep.: I. Molecular
II. External granular layer
III.External pyramidal layer
IV. Internal granular layer
V. Internal pyramidal layer
VI. Fusiform layer
The molecular layer contains mainly _________ fibers.: horizontal
The external granular layer is comprised of _________.: small densely packed granule cells
What is notable about layer III?: This is a very prominent layer and consists of pyramidal neurons arranged in two sub-layers.
The two sub layers of the external pyramidal layer are made up of ________ and _______.: outer layer - medium sized neurons
inner layer - larger pyramidal cells
The external pyramidal layer (III) gives rise to what type of fibers?: Association and commissural fibers.
What makes up the internal granular layer (IV)?: densely packed stellate neurons and bands of Baillarger (horizontal fiber layer)
What makes up the internal pyramidal layer (V): pyramidal neurons, granule neurons, neurons of Martinotti, and internal band of Baillarger.
Which type of fibers does the internal pyramidal layer (V) give rise to?: projection fibers
What makes up the fusiform layer (VI): small fusiform nuerons with dendrites that project to other cortical layers.
The fusiform layer gives rise to what type of fibers?: Projection fibers
What is characteristic of visual cortex nerve firing patterns?: The visual cortex has functional columnar units - the whole column fires at once.
Radial fibers project from _______ to ________.: from inside to out. (medullary region to cortex)
Tangential fibers project ________, parallel with the _________.: horizontally, parallel with the cortical surface.
List the three basic types of circuits in the neocortex.: 1. point to point
2. local
3. divergent
Point to point circuits are major __________ and _________ pathways such as the __________ (2 categories): afferent and efferent
cortico-cortical circuits
Thalamo-cortical circuits
Are point to point circuits (+) or (-)?: (+)
Point to point circuits are well suited to transfer what type of informations?: precise, topographically organized information
Are local circuits (+) or (-): (-) or (+) (although there is more (-) than (+)).
Inhibitory local circuits use __________ as a neurotransmitter.: GABA
Divergent circuits use ___________ as a neurotransmitter.: Monoamines
Divergent circuits are well suited for __________________.: activites that involve cohesive activity of large areas of neocortex such as attention, arousal, mood.
Cortico-cortico projections connect _______________. Example?: cortices within hemispheres. Ie. frontal cortex with visual cortex
Commissural Cortical Fibers connect ________________.: the hemispheres via the anterior and posterior commissures or the corpus callosum
There are two anatomical differences between the R and L hemispheres of the brain. What are they?: 1. L tempo-parietal cortex has more tissue
2. L lateral fissure is longer (at a shallower angle)
1. The use of sodium amytal in the early days? 2. What kind of a drug is sodium amytal?: 1. injected into internal carotid to find out hemispheral dominance (it temporarily "paralyzes" neurons in that area.
2. barbituate
What is the result of amytal injected into the dominant lobe?: Loss of ability to speak
Amytal injected in the left ICA will produce __________, whereas amytal injected into the right ICA will produce __________/: left - depression
right - euphoria
if there is cortical damage to a child sparing the right hemisphere - what will be the influence on language?: Damage to the R hemisphere in children is not so significant: they "adapt" so their speech is adequate. Above the age of 6 this observation is not seen.
In general, will cortical damage to the right hemisphere effect language skills?: No
What is the operculum and where is it located?: associated with 2 main areas of language (Broca's & Wernicke's). It is located in the area around the lateral sulcus overlying the insula.
What area of the brain is called the writing area? Where is this located?: Exner's area - superior to Broca's area in premotor cortex.
What are the two parts of Wernicke's area? What is their main function?: 1. traditional Wernicke's area (anterior) - spoken language
2. angular gyrus (btwn visual and auditory cortex) - written language
T/F: The arcuate fasciculus is bidirectional.: True
The "modern" view of language areas lists 3 area networks. What are they?: 1. Conceptual - concepts from higher cortices
2. mediational - intermediary btwn. conceptual and implementation.(around B & W)
3. Implementation - controls articulation and grammar. (B, W, insula, basal ganglia)
In regards to the temporal cortex: 1. place/people's names go here 2. tools/utensil names go here 3. Common names (dog) go here.: 1. anterior
2. posterior
3. inferior
What is the insula responsible for in regards to language function? What would a lesion in this location look like?: motor planning for speech. A lesion would result in trouble saying words accurately.
What is the medial frontal cortex responsible for in regards to language function? What would a lesion in this location look like?: "desire" to communicate
lesion results in mutism
What are CN nuclei responsible for in regards to language function?: motor, sensory and parasympathetic aspects of speech
Define prosity Where is this function found?: timing, intonation and stress of language. Function found in right cortex.
Define pragmatics. Where is this function found?: language appropriate to social settings. (a lesion will cause innapropriate actions and inability to "get" jokes). Found in right cortex
The area of the brain responsible for familiar voices, music and rythm is _____________.: The right cortex
Communication vs. language What is thinking?: communication: transmit ideas
language: transmit abstract ideas
thinking = the ability to have ideas
1. define phonology 2. define morphology 3. Define syntax 4. define semantics: 1. speech sounds (phonics)
2. combining sounds into words
3. combining words to form sentences
4. relation of phonology and syntax to meaning
T/F: intelligence correlates with language.: False. Language is separate from intelligence.
Aphasia is an UMN problem. name the two types of aphasia: 1. expressive aphasia - cannot transform thought into spoken or written information
2. receptive aphasia - cannot transform spoken or written information into thoughts.
define logorrhea: excessive output of words
Conduction aphasia is damage to ____________. How does it present?: arcuate fasciculus
can comprehend and produce meaningful speech: have word finding problems, cannot repeat sentences
1. Damage to higher cortical areas that initiate speech is _____________ aphasia. 2. How would this present?: 1. transcortical motor aphasia (info does not pass from higher centers)
2. presents as: intact comprehension, can repeat long sentences, trouble initiating speech.
1. Damage to the posterior end of the lateral sulcus would result in ____________ aphasia. 2. How would this patient present?: 1. Transcortical sensory aphasia (info does not pass to higher centers)
2. fluent speech, can repeat long sentences, echolalia, anomic aphasia, can repeat sentences (vs. Wernicke's - can't repeat sentences)
1. What is global aphasia? 2. How would this patient present?: 1. damage to the Left hemisphere and basal ganglia.
2. severe impairment of understanding and language expression. may retain automatic speech (ie. counting)
What is anomic aphasia?: trouble finding a name for objects
define: alexia: lack reading. damage in angular gyrus: disrupt pathways to language centers.
define: agraphia: lack writing. damage to Exner's area
Define: dysarthria: motor speech problem (LMN) located in brainstem or CN nuclei of fibers. Only affects muscles
define: apraxia: disorder of programming muscles of articulation. (cannot combine sounds to form a word)
define: dysphonia: disorder of the larynx
define: amusia: lesion of Right parietal, occipital or temporal cortex resulting in inability to recognize familiar voices, music and rythm.
define: akinetic mutism: lose motivation to speak (usually temporary). Damage is to medial frontal cortex
define: agnosia: lack of sensory recognition of speech (due to lesioned sensory association areas)
What is a characteristic of lesions to the Right hemisphere? This finding is characteristic of a __________ lobe lesion.: Contralateral Neglect (fail to act with or acknowledge left side of body). This is characteristic of a parietal lobe lesion.
Failure to respond to stimuli on one side of the body is known as __________.: inattention. If stimulus in strong enough pt. will respond
How can you confirm inattention in a patient?: by double simultaneous stimulation. Elicit a moderate stimuli on both sides - results in extinction of inattention side.
Extinction is defined as:: failure of the inattention side to respond to double simultaneous stimulation.
How can extinction and innattention be overcome?: by elicing a strong stimulus: that will be noticed on the inattention side.
Regarding music: if you are untrained it is percieved in the ___(1)________ cortex. If trained (professional) it is perceived in the ____(2)_____ cortex. If you are singing it comes from the ______(3)____ cortex.: 1. Right
2. Left
3. right
What are the three components of the 3 neuroaxis model of brain functioning?: 1. Right-Left Axis
2. Anterior-Posterior Axis
3. Up-Down Axis
What are the three components to a functioning memory?: 1. Encoding
2. Storage
3. Retrieval
Cortical dementias would be a problem in which component of memory?: Storage
Test Anxiety is a classic example of which component of memory?: Retrieval
In adults, a common aquired neurological problem of the LH is __________. In children it is __________.: Adults - aphasia
Children - dyslexia
reading comprehension, prosodic expression and comprehension, Calculation of spacial alignment: these are all characteristics of which hemisphere?: RH
Which hemisphere of the brain allows us to apply "affect" to our statements?: RH
Damage to which hemisphere results in a more severe spacial attention loss (severe contralateral neglect): Damage to the RH.
What is meant by executive functions?: control or self-regulatory functions that ORGANIZE and DIRECT all cognitive activity, emotional response and overt behavior.
What is a disorder that has problems with executive function?: ADHD
Executive functions have to do with __________. Examples of this include self regulation, planning and organization, social adaptation: Performance
'Knowing what to do is not the same as doing what you know' Knowing is a function of which area? What about doing?: knowing - posterior based
doing - frontal based
The relationship between ______ functions and ______ functions is like the relationship between athletes and their coach.: cognitive functions
executive functions
The up-down axis mediates communication between __________ and _________. *give an example: Cortical gray matter and Subcortical White matter
*frontal system vs. brainstem, hippicampus. (executive functions vs. arousal, attention, motivation)
What are some roles of white matter in human behavior?: speed of processing
integration
retrieval of memories/knowl.
organization
multitasking
Would a disturbance in white matter result in a disturbance of IQ?: NO.
What % of PD pts develop dementia?: 10-30%
Neuroimaging tells you about the _____________ of the brain: neuropsychological eval. tells you about the __________ .: structural
function
(Structural damage does not always correlate with functional ability)
What is pragmatic damage?: Talking too much: taking the "scenic route" to expain or define something.
Where is the damage in global aphasia?: in both Broca's and Wernicke's areas.
Which hemisphere stroke is at a higher risk for developing depression?: LH
An indifference reaction is often observed following a ____ hemisphere CVA. Symptoms?: RH or bilateral
Sx. undue cheerfulness, apathy.
A frontal heteromodal syndrome of unawareness presents as unawareness of ________? (2): social innapropriatness
planning or anticipation
A parietal heteromodal syndrome of unawareness presents as unawareness of _____________? (2): impaired sensory function
hemiplegia, hemi-neglect
Catastrophic reaction syndrome is often observed following a ____ CVA. Symptoms?: Left anterior-subcortical
Sx: axiety, tears, verbal, physical aggression
a left frontal or a basal ganglia lesion often results in ________________. Pt. presents as irritated, anxious, sad, weight loss, trouble sleeping.: Depression
What is the disease/problem? - memory dysfunction - neglect - problems with "affect" - cause sometimes HTN, DM: Subcortical Vascular disease
The following are all risk factors for what? hypertension Cardiac disease TIA's Smoking, ETOH, drug abuse Elevated lipids: Vascular Cognitive Impairment
What is one of the earliest symptoms of cardiovascular disease?: HTN
Can there be cognitive decline after CABG?: Yes: due to precedures, equipment used.
Mixed dementia is defined as...: coexistance of AD and Vascular Dementia (VaD)
Development of AD plaques & tangles may be due to ____________.: Ischemia from CV disease
What is the pathophysiology of seizures and epilepsy?: Unknown (65-75%)
What are the indications and the MOA of Phenytoin and Carbamezepine?: indications: epilepsy
MOA: enhance Na+ activation: result - reduce firing rates
Define paroxysmal: sudden outburst or alteration of behavior, movement or sensation
Define: ictal: during a seizure
Define: post-ictal: after a seizure
Define: interictal: between seizures
What are the three main classifications for seizures?: 1. Partial (small area)
2. Generalized (both hemisph)
3. Unclassified
Partial Seizures can be further subdivided into two types: Simple (Focal) seizures and Complex seizures. What is difference between the two?: Simple (focal) seizures are partial seizures without alteration of consciousness.
Complex Seizures involve an alteration of consciousness.
T/F: Partial seizures never evolve to secondary generalized seizures.: FALSE. They can evolve.
What is the most common type of epilepsy?: Generalized seizure epilepsy
Define: generalized seizures: uncontrollable discharge of neurons on both sides of the brain. (they start in one side and spread across the brain)
Do generalized siezures result in a loss of consciousness?: Yes. People w/ this type of epilepsy do not remember having a seizure.
Define: myoclonic seizure: generalized seizure that involves the motor cortex. (causes twitching and jerking)
What is status epilepticus?: A period of frequent, long-lasting seizures WITHOUT regaining consciousness between attacks. Can be fatal; req. medical attention
What are 3 known causes of epilepsy?: 1. Genetic (defect in genes that encode ion channels)
2. Structural (tumor, infection, excess CSF, Scar tissue)
3. Metabolic (hypoglycemia, hypocalcemia, drug use or abuse)
seizures that develop in old age are known as _________?: Neurodegerative seizures (often secondary to CVA)
In an EEG: what is the source of current that causes fluctuating scalp potential?: Pyramidal neurons
(These are the neurons most prone to seizure activity)
What is basic epileptogenesis?: Thought to be a biologic event that alters balance between (+) and (-) in neural networks.
Why are EEGs so useful in diagnosing seizures?: They are very good at measuring synchronicity of cell firing. In a seizure all the cells fire at once.
T/F: An EEG can read one pyramidal neuron when it fires an AP.: FALSE. It takes many thousands of neurons firing at once to generate a signal large enough to detect w/EEG
What is the major EEG rythm seen in normal relaxed adults? (Eyes must be closed): Alpha rythm
What is the major EEG rythm that is normal in infants and sleep: if seen in an adult, it indicates pathology.: Theta activity
What is the major EEG rythm that is normal when eyes are open and patients are alert?: Beta activity
Spikes, Sharp Waves and Polyspikes on an EEG are known as __________ and are due to ____________.: Epileptiform discharges
synchrony of thousands and thousands of firing neurons
There are three basic mechanisms used by AEDs. What are they?: 1. Increased inactivation of Na+ channels - reduces sustained firing
2. Act on synaptic transmission ((+) of (-) neurotransmission or vice versa)
3. Act on NT receptors: enhance GABA receptor action
reduce glutamate receptor action
The MOA of the older AEDs was/is ____________, whereas the newer drugs are starting to target _____________. Advantage?: Na+ channel inactivation
GABA and NMDA receptors
Targets are more specific - causes less adverse effects
What are 3 other treatment modalities used for seizures?: 1. Ketogenic diet
2. Vagus Nerve Stimulation
3. Biofeedback
T/F: 25-30% of epilepsy patients on AEDs still have inadequate seizure control.: True
There are four functional "groups" of the reticular formation. Name them and where they would be found...: 1. Parvocellular (Lateral, small) Group
2. Magnocellular (medial, large) group
3. Paramedian group (PPRF)
4. Raphe group (midline: "Raphe" = seam)
What is the function of the Lateral group of the pontomedullary reticular formation?: function: local "circuit" control of CN functions. (visceral and motor coordination)
What is the function of the Medial group of the pontomedullary reticular formation?: descending: movement and posture, pain modulation
ascending: cortical arousal
What is the function of the Paramedian group of the pontomedullary reticular formation?: PPRF - controls voluntary horizontal conjugate gaze.
What is the function of the Raphe group of the pontomedullary reticular formation?: descending: pain modulation
ascending: cortical arousal, affective behavior
There are 3 monoaminergic systems that arise from the brainstem reticular formation. Name them.: 1. Noradrinergic
2. Seratonergic
3. Dompaminergic
The Noradrenergic projections arise from ____________ and project to ________. Functions?: Locus ceruleus
project all over the brain
function: maintain attentiveness, sleep-wake states and mood.
The Seratonergic projections arise from _________ and project to ________. Functions?: from midline raphe nuclei
project all over brain.
functions:
descending: pain modulation, regulation of motor systems
ascending: cortical arousal, affective behaviors
The Dopaminergic projections arise from two locations. What are they?: 1. Substantia Nigra
2. Ventral Tegmental Area of midbrain
Name the 3 dopaminergic projections, where they start and end, functions.: 1. mesostriatal - substantia nigra to striatum. (Motor)
2. Mesolimbic - ventral tegmental area to limbic system (emotion, thought memory).
3. mesocortical - ventral tegmental area to prefrontal cortex. (emotion, thought, memory).
Cholaminergic projections seem to be involved in _______________?: cortical arousal
alertness
learning
memory
The dementia in Alzheimer's disease is contributed to cholinergic projections from ______________.: the Basal Nucleus of Meynert. (It has widespread cortical connections)
Histaminergic projections arise from the ___________ and project to the ___________. Function?: hypothalamus to the forebrain
function: maintainance of an alert state
How does the reticular formation carry out sensory modulation?: PAIN MODULATION: they send a descending "reticulospinal" projection to the spinal dorsal horn - influence inhibitory interneurons by releasing enkephalin. Pain neuron transmission inhibited.
What do the pontine and medullary reticulospinal pathways regulate? How?: regulate tone and posture
they have descending influences on alpha and gamma motor neurons
The descending tectobulbar projections carry out what function of the reticular formation?: PPRF = controls voluntary conjugate movement of the eyes.
How does the reticular formation modulate arousal and consciousness?: via the RAS. (Reticular activating system)
Alteration of consciousness or arousal states involving bilateral lesions to the reticular formation results in___________.: either a coma or persistant vegitative state.

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