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neuroanatomy2.md
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## Neural Systems
# Neural Systems
* Circuits that do the same kinds of things are grouped into 'systems', e.g. sensory systems and motor systems
* Many neurons function between these systems, called associational systems. Associational systems are the most complex and least well characterized systems.
@@ -9,8 +9,6 @@ Last time we learned some of the basic cellular anatomy of the nervous system. T
First of all it is a system of systems. In other words…
TODO: exchange pngs for jpgs in this document
---
## Major components of the nervous system and their functional relationships
@@ -368,7 +366,7 @@ From the brain stem there emerges 12 left-right pairs of cranial nerves that car
## Cranial nerves
<div style="font-size:0.6em">
<div style="font-size:0.5em">
<div></div>
number | name | function
@@ -429,6 +427,8 @@ Now you’ve all heard the phrase ‘running around like a chicken with its head
<div><iframe src="https://www.youtube.com/embed/ATz3AdbjyRI" width="420" height="315"></iframe><figcaption>Mike the headless chicken</figcaption></div>
[http://www.dailymail.co.uk/news/article-5556351/Headless-chicken-survives-WEEK-decapitated.html](http://www.dailymail.co.uk/news/article-5556351/Headless-chicken-survives-WEEK-decapitated.html)
Note:
Well here is a grotesque way of convincing you that all you need to live is your brainstem…
@@ -528,13 +528,15 @@ Note:
Thalamus is essentially the relay nuclei that routes sensory information into the cortex. This routing of information is highly organized with different subdivisions sending information in parallel pathways to different visual, auditory, and somatosensory regions of the cerebral cortex. But the connections are highly reciprocal with cortical areas, such that the thalamus is integral to many sensory, motor, and cognitive functions as well as the generation of different electrical rhythms that underly different sleep states.
Which connections gets through to neocortex without a thalamic relay? **neuromodulatory input**: cholinergic, serotonergic, histamatergic, adrengergic, dopaminergic signaling. Pathways manipulated by drugs that manipulate behavioral state and mood. More on this later in the course.
---
## Thalamus– gateway to the cerebral cortex
<div><figcaption class="big">Thalamus (brown), ventricles (blue)</figcaption><video height=300px controls loop src="figs/thalamus.m4v"></video><figcaption>[C. Krebs CC BY-NC-SA, Univ. British Columbia](http://www.neuroanatomy.ca/3D_files/3D_index.html?id=1)</figcaption></div>
<div style="width:400px"><figcaption class="big">Thalamus (brown), ventricles (blue)</figcaption><video height="250px" controls loop src="figs/thalamus.m4v"></video><figcaption>[C. Krebs CC BY-NC-SA, Univ. British Columbia](http://www.neuroanatomy.ca/3D_files/3D_index.html?id=1)</figcaption></div>
<div><figcaption class="big">Fiber stain</figcaption><img src="figs/2060_fiber-thalamus_207b466.png" height="300px"><figcaption>[Brain Biodiversity Bank MSU, NSF](https://msu.edu/~brains/brains/human/coronal/montage.html)</figcaption></div>
<div><figcaption class="big">Fiber stain</figcaption><img src="figs/2060_fiber-thalamus_207b466.png" height="250px"><figcaption>[Brain Biodiversity Bank MSU, NSF](https://msu.edu/~brains/brains/human/coronal/montage.html)</figcaption></div>
Note:
@@ -602,23 +604,6 @@ Limbic system includes the amygdala, as well as the part of the basal ganglia, p
Note:
---
## Lobes of the cerebral cortex
* frontal– planning responses to stimuli, contains: motor cortex (precentral gyrus)
* parietal– somatic sensory cortex (postcentral gyrus)
* temporal– audition and insular cortex (taste)
* occipital– vision
<div><img src="figs/Neuroscience5e-Fig-A03-1R_3474298.png" height="250px"><figcaption>Neuroscience 5e Fig. A3</figcaption></div>
<div><img src="figs/Neuroscience5e-Fig-A03-2R_c3b128c.png" height="250px"><figcaption>Neuroscience 5e Fig. A3</figcaption></div>
Note:
---
## Cortico-cortical connection pathways
@@ -637,7 +622,7 @@ Note:
<div style="margin-bottom:50px"><figcaption class="big">Fiber stain</figcaption><img src="figs/2240_fiber_d16bc49.jpg" height="200px"><figcaption>[Brain Biodiversity Bank MSU, NSF](https://msu.edu/~brains/brains/human/coronal/montage.html)</figcaption></div>
<div><figcaption class="big">Dorsal view</figcaption><img src="figs/Neuroscience5e-Fig-A11-1R_a8973d9_copy_9c648a7.jpg" height="200px"><figcaption>Neuroscience 5e Fig. A11</figcaption></div>
<div><figcaption class="big">Dorsal view</figcaption><img src="figs/Neuroscience5e-Fig-A11-1R_a8973d9_copy_9c648a7.jpg" height="200px"><figcaption>Neuroscience 5e Fig. A11</figcaption></div> <!-- .element: class="fragment fade-in"-->
<div><figcaption class="big">Dorsal view cut away</figcaption><img src="figs/Neuroscience5e-Fig-A11-3R_17d31f5_copy_406b96a.jpg" height="200px"><figcaption>Neuroscience 5e Fig. A11</figcaption></div> <!-- .element: class="fragment fade-in"-->
@@ -646,63 +631,21 @@ Note:
Note:
corpus callosum
: connections the cerebral hemispheres
: only in placental mammals (the eutherians)
: absent in monotremes and marsupials and other vertebrates (e.g. birds, reptiles, amphibians and fish)
anterior commisure
: connects temporal lobes
: connects both amygdala
: crossed projects from olfactory tracts
---
## Primary versus non-primary cortex
<div style="font-size:0.7em;">
<div></div>
* Primary cortex
* Cortical areas that are the primary projection fields targeted by the sensory input pathways
* Cortical areas that are the principal fields which have neurons that project down into the spinal cord for effecting control
* Primary visual (calcarine sulcus)
* Primary auditory
* Primary somatosensory (post-central gyrus)
* Primary motor (pre-central gyrus)
</div>
<div style="width: 400px; font-size:0.7em;">
<div></div>
* Non-primary cortex
* everything in between
* referred to collectively as association cortex
</div>
<div style="padding:0 50px;"><img src="figs/Neuroscience5e-Fig-26.01-0_copy_c5817b1.jpg" height="200px"><figcaption>Neuroscience 5e Fig. 26.1</figcaption></div>
Note:
---
## Brain organization summary
<div><img src="figs/Neuroscience5e-Fig-A12-1R_copy_020ed62.jpg" height="315px"><figcaption>Neuroscience 5e Fig. A12</figcaption></div>
<div><iframe src="https://www.youtube.com/embed/snO68aJTOpM" width="420" height="315"></iframe><figcaption>Pinky and the Brain</figcaption></div>
Note:
corpus callosum
: connections the cerebral hemispheres
: only in placental mammals (the eutherians)
: absent in monotremes and marsupials and other vertebrates (e.g. birds, reptiles, amphibians and fish)
anterior commisure
: connects temporal lobes
: connects both amygdala
: crossed projects from olfactory tracts
---
## Laminar organization of neocortex
* Cortex itself has a thickness of only about 2-4mm.
* Cortex itself has a thickness of only about 2-4mm
* 6 layers (neocortex)
* Layer IV is the primary input layer
* Layers II and III are cortico-cortical output layers
@@ -753,13 +696,19 @@ Note:
Note:
[Gyrification from constrained cortical expansion](http://www.pnas.org/content/111/35/12667)
[^Tallinen:2014] http://dx.doi.org/10.1038/nphys3632
[^Watts:1998]
---
## Which of the following is true?
1. Do specific regions of the brain control specific functions?
2. Does each part of the brain do all functions?
2. Does each part of the brain do all functions? <!-- .element: class="fragment strike" data-fragment-index="1"-->
3. Does a specific function come from many parts of the brain?
Note:
@@ -768,36 +717,26 @@ Now lets expand on how functions are organized in the brain. Which of the follow
it’s a bit of a trick question because both of these answers are partially right depending on how you define a part of the brain or what kind of function you’re talking about, but it is not the case that
<!--
## Early 1800’s Franz Joseph Gall
---
* all behavior emanates from the brain
* particular regions of the cerebral cortex controlled specific functions, i.e. the brain does not act as a single organ.
* each function grew with use such as a muscle with exercise
* this growing causes the skull to budge creating a pattern of bumps “phrenology”
## Lobes of the cerebral cortex
## Franz Joseph Gall– phrenology
* frontal– planning responses to stimuli, contains: motor cortex (precentral gyrus)
* parietal– somatic sensory cortex (postcentral gyrus)
* temporal– audition and insular cortex (taste)
* occipital– vision
Standing at his lectern, the priest stared steadily upon one man in the congregation: Franz Joseph Gall. With his angry voice echoing off the church's hallowed walls, he pronounced,"There are those amongst us, who have lost their way from our Lord's divine path. With pomposity, they state the mind is situated in an organ as mushy and insubstantial as the brain. What ludicrousness is this, when all intelligent men know that God has imbued our thinking into our very soul, whereupon no one can put his finger precisely on the spot!"
<div><img src="figs/Neuroscience5e-Fig-A03-1R_3474298.png" height="250px"><figcaption>Neuroscience 5e Fig. A3</figcaption></div>
<div><img src="figs/Neuroscience5e-Fig-A03-2R_c3b128c.png" height="250px"><figcaption>Neuroscience 5e Fig. A3</figcaption></div>
http://thevictoriantimes.blogspot.com/2011/10/galls-phrenology.html
<div><img src="figs/image21_cc3a4ac.png" height="300px"><figcaption></figcaption></div>
Note:
## Phrenology
<div><img src="figs/image22_f181430.png" height="300px"><figcaption></figcaption></div>
## Pierre Flourens (French)
* Tested Gall’s ideas by removing different parts of the brain (dogs and rabbits) and asked if specific functions were compromised.
* Showed medulla important for respiration, cerebellum important for movements.
* Lesions in cortex affected either zero or many behaviors. Concluded that the cortex was one organ and not regionalized.
-->
---
## Korbinian Brodmann (1909)
* Used subtle anatomical differences in the brain to divide it into discrete areas or regions
@@ -842,214 +781,42 @@ Note areas 4 (primary motor cortex), 1,2,3 (primary somatosensory cortex), area
*area 22 superior temporal gyrus*
---
## Paul Broca (1861)
* Believed that functions could be localized in the brain
* Studied patients with aphasia– language disorders found in patients who have had a stroke
* Had a patient that could understand language but could not speak, problems with the organizational aspects of language. Found lesion in posterior frontal lobe (Brodmann areas 44/45)
* This kind of aphasia is called a motor or expressive aphasia
* Eight patients with similar problems all had similar lesions, always on the left side
* "Nous parlons avec l’hemisphere gauche!" "We speak with the left hemisphere!"
Note:
We also define regions of the brain based on studies of brain lesions in patients. Recall the guy with the railroad spike from last lecture. Well the French physician Paul Broca in the 19th c.
--
## Broca and a patient’s brain
<div><img src="figs/image25_2d10fa8.png" height="300px"><figcaption></figcaption></div>
Note:
---
## Carl Wernicke (1874)
## Primary versus non-primary cortex
* Had a patient that could speak but not understand language. Called receptive aphasia
* Damage was to a different area– left side, posterior part of the left temporal lobe (Brodmann areas 22/39/40)
* Argued that simple perceptual and motor activities were localized to a specific area and that most functions result from interconnections between areas. Idea of "distributive processing"
Note:
---
## Major brain areas involved in the comprehension and production of language
<div><img src="figs/Neuroscience5e-Fig-27.01-0_eaf66c7_copy_1841ced.jpg" height="400px"><figcaption>Neuroscience 5e Fig. 27.1</figcaption></div>
Note:
*Arcuate fasciculus: major association fiber tract in CNS that connects Broca’s and Wernicke’s areas*
---
## Characteristics of Broca's and Wernicke's aphasias
<div><img src="figs/Neuroscience5e-Tab-27.01-0_859de7f_copy_4abca30.jpg" height="300px"><figcaption>Neuroscience 5e Table 27.1</figcaption></div>
Note:
*Broca's aphasia patients have limited writing. Loss of the ability to produce language (spoken or written)*
Apraxia
: verbal apraxia is difficulty starting and making voluntary movements (motor plans) needed for speech (with no paralysis or weakness of speech muscles)
dysarthria
: inability to move the muscles of the tongue and mouth to produce speech
agraphia
: inability to write
Agnosia
: inability to process sensory information
: affects a single modality
syntax
:the arrangement of words and phrases to create well-formed sentences in a language
Grammar
:in linguistics it is set of structural rules governing the composition of clauses, phrases, and words in any given natural language. The term refers also to the study of such rules, and this field includes morphology, syntax, and phonology, often complemented by phonetics, semantics, and pragmatics
<!-- ## Conduction aphasia
* Inability to produce appropriate responses to heard communication, even though the communication is understood.
* Can speak fluently but bad at making the connection from what has been heard to how to reply.
* Often associated with damage in the Arcuate fasiculus –an axon tract that connects wernike and broca areas.
* Difficulty repeating words
* Fluent, but with many incorrect word substitutions
* Good comprehension
<div><img src="figs/image26_0d58d77.png" height="300px"><figcaption></figcaption></div>
## Arcuate fasciculus: major association fiber tract in CNS that connects Broca’s and Wernicke’s areas
<div><img src="figs/image27_5c764df.png" height="300px"><figcaption></figcaption></div>
<div><img src="figs/ArcuatefasciculusiinCortex_1c69f77.png" height="300px"><figcaption></figcaption></div>
-->
---
## Other evidence of brain regionalization
* Fritsch and Hitzig (1870)– discrete limb movements in dogs can be produced by electrical stimulation of the contra-lateral motor cortex. Thus the right hand is controlled by the left hemisphere. 'Dominant' hemisphere
* Wilder Penfield (1950)– neurosurgeon, localized motor functions by stimulating specific areas of the brain
* Roger Sperry (1960s)– split brain patient studies
Note:
And there is lots of other evidence for localization of brain function, especially for sensory and motor information for limbs and body. In fact Fritsch…
And the Canadian physician Wilder Penfield performed classical mapping of motor function in the cerebral cortex by localized electrical stimulation.
And then there is the fascinating split brain studies of Sperry and Gazzaniga in the 1960s
---
## Penfield stimulation studies
<div><iframe src="https://www.youtube.com/embed/l1SAC1HcAzc" width="420" height="315"></iframe><figcaption>Stimululation based brain mapping</figcaption></div>
Note:
Epileptic patient. mapping the cortical tissue before resecting the site of tissue where the seizures are being generated.
*Start about minute 3*
---
## Split brain studies: Nobel prize 1981
<div style="font-size:0.9em; width:100%">
<div style="font-size:0.7em;">
<div></div>
* The corpus callosum and anterior commissure are the two axon tracts that connect the two sides of the brain. They are sometimes cut to prevent the spread of severe epilepsies
* Each side of the brain works independently from the other
* Roger Sperry showed that the left hemisphere dominates speech, writing, right hand stereognosis, analysis of right visual field
* Right hemisphere dominates, emotional coloring of language, spatial abilities, left hand stereognosis, analysis of left visual field
* Primary cortex
* Cortical areas that are the primary projection fields targeted by the sensory input pathways
* Cortical areas that are the principal fields which have neurons that project down into the spinal cord for effecting control
* Primary visual (calcarine sulcus)
* Primary auditory
* Primary somatosensory (post-central gyrus)
* Primary motor (pre-central gyrus)
</div>
<div><img src="figs/sperry_postcard_cf69954.jpg" height="200px"><figcaption>R. Sperry</figcaption></div>
<div style="font-size:0.7em; width:500px">
<div style="width: 400px; font-size:0.7em;">
<div></div>
>"for his discoveries concerning the functional specialization of the cerebral hemispheres"
* Non-primary cortex
* everything in between
* referred to collectively as association cortex
</div>
<div style="padding:0 50px;"><img src="figs/Neuroscience5e-Fig-26.01-0_copy_c5817b1.jpg" height="200px"><figcaption>Neuroscience 5e Fig. 26.1</figcaption></div>
Note:
The classic split brain studies which Roger Sperry got the Nobel for in 1981 showed the lateralized localization of language that Broca and Wernicke anticipated as well as several other higher functions. They took advance of the fact that in patients with severe epilepsies, sometimes the commissures connecting the two hemispheres are cut to prevent the spread of seizures.
And since each side of the brain to some degree can work independently of the other
* Humans are 90% right handed as a population and the degree of lateralization among individuals is strong, regardless of left or right-handedness
* 96% of right handers having left hemisphere speech, compared with 70% of left handers
* Twin studies have demonstrated some genetic influence on handedness, but 75% of the variance is nongenetic and individually specific, with only 25% explained by genes [#Bishop:2013]. Even the segregation of of handedness and language laterality suggests a complex polygenic set of factors, with 96% of right handers having left hemisphere speech, compared with 70% of left handers [#Bishop:2013].
---
## Confirmation of hemispheric specialization for language
## Mapping brain activity with human neuroimaging
<div><img src="figs/Neuroscience5e-Fig-27_split-brain_copy_8719b7e.jpg" height="500px"><figcaption>Neuroscience 5e Fig. 27.3</figcaption></div>
Note:
Here is an illustration of the experiment performed by by Sperry and his colleagues for these split brain studies.
After the corpus callosum connecting the two hemisphere was cut to alleviate epileptic seizures, the patients were asked to fixate on a point and name objects presented in each visual field.
Now you haven’t learned about the visual system yet, but just as sensory information from your left hand goes to your right hemisphere, visual information from the lateral part of your left visual field goes to your right visual cortex.
Split brain patients could not correctly name objects presented in their left visual field, presumably because that info could not reach the left hemispheres because the callosal connections were severed. But split brain patients could correctly name an object when presented in their right visual field, because that information was received by the left visual cortex and could be passed onto the language centers.
In all Sperry and his colleagues showed that language, mathematical, and logical reasoning is dominant in the left hemisphere and that shape recognition, spatial attention, emotional processing, and creativity in more dominant in the right hemisphere.
*right hemisphere: 'coloring' language with emotive tonal variation, 'prosody'. Adds additional meaning to verbal communication. Mandarin chinese. Monotone professor lecture*. Evidence suggest similar areas of the right hemisphere associate with this emotive coloring of language.
Similar areas used in sign language thus this constellation of brain regions specializes in symbolic representation and communication, rather than just spoken language.
PET:
: positron emission tomography
: detects pairs of gamma rays emitted indirectly by a radioactive tracer injected into bloodstream (positron-emitting radionuclide)
CT:
: computerized tomography
: a series of X-ray images from different angles
: computer processing to create cross-sectional images
Babbling sounds from a baby shows that there is a pattern of sounds produced sequentially that are related to the phones necessary for producing spoken language. Language imitation follows other imitations (mirror neurons?) during developmental learning and behavioral acquistion. Brain is continuously simulating the future based on past experienced training patterns.
--
## Mapping brain activity with fMRI
<figure><img src="figs/Neuroscience5e-Fig-27.06-0_2687612_copy_718a9bc.jpg" height="400px"><figcaption>Neuroscience 5e Fig. 27.6</figcaption></figure>
<figure><figcaption class="big">functional magnetic resonance imaging (fMRI)</figcaption><img src="figs/Neuroscience5e-Fig-27.06-0_2687612_copy_718a9bc.jpg" height="400px"><figcaption>Neuroscience 5e Fig. 27.6</figcaption></figure>
Note:
@@ -1058,4 +825,15 @@ Note:
- different patterns of brain activity localization depending on what the task is
- Actually sitting inside a small space magnet
---
## Brain organization summary
<div><img src="figs/Neuroscience5e-Fig-A12-1R_copy_020ed62.jpg" height="315px"><figcaption>Neuroscience 5e Fig. A12</figcaption></div>
<div><iframe src="https://www.youtube.com/embed/snO68aJTOpM" width="420" height="315"></iframe><figcaption>Pinky and the Brain</figcaption></div>
Note: