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motor2.md
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## Upper motor neuron control
* Axons from the upper motor neurons descend to influence the local circuits in the brainstem and spinal cord that organize movements
* Upper motor pathways include several brainstem centers and a number of cortical areas in the frontal lobe
* Brainstem centers are especially important for postural control
* Motor and premotor cortex are responsible for the planning and precise control of complex sequences of voluntary movements
Note:
Upper
lower motor neurons
: are the neurons that make synapses with muscle fibers
: located in ventral horn of the spinal cord gray matter and cranial nerve nuclei of the brainstem
--
## Overall organization of neural structures that control movement
## Neural systems that control movement
<figure><img src="figs/Neuroscience5e-Fig-16.01-0_copy_c8e6e7d.jpg" height="400px"><figcaption>Neuroscience 5e Fig. 16.1</figcaption></figure>
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Today we will begin our examination of the pathways in the nervous system that modulate and give rise to volitional control of our skeletal muscles.
<!--
--
Recall–
## Midterm 2
lower motor neurons
: are the neurons that make synapses with muscle fibers
: located in ventral horn of the spinal cord gray matter and cranial nerve nuclei of the brainstem
Original stats:
```r
mean 74
median 74
std 10.5
max 97
min 45
```
TODO: replace chart
---
## Upper motor neuron control
* Upper motor neuron axons regulate the excitability of lower motor neuron circuits in the brainstem and spinal cord
* Upper motor neurons located in several brainstem centers and a number of cortical areas in the frontal lobe
* Brainstem centers are especially important for postural control
* Motor and premotor cortex are responsible for the planning and precise control of complex sequences of voluntary movements
Note:
posture
: a position of person's body when standing or sitting
: a particular post adopted by an animal, interpreted as a signal of a specific pattern of behavior
-->
---
@@ -164,7 +156,7 @@ feedforward postural control. stabilization during ongoing movements.
## Location of the reticular formation in relation to some other major landmarks
<div><img src="figs/Neuroscience5e-Fig-17.12-0_92326dc.jpg" height="400px"><figcaption>Neuroscience 5e Fig. 17.12</figcaption></div>
<!-- <div><img src="figs/Neuroscience5e-Fig-17.12-0_92326dc.jpg" height="400px"><figcaption>Neuroscience 5e Fig. 17.12</figcaption></div> -->
<div><img src="figs/Neuroscience5e-Box-17D-0R_80e2133.jpg" height="300px"><figcaption>Neuroscience 5e Box 17D</figcaption></div>
@@ -218,12 +210,12 @@ Note:
---
## Reticulospinal tract function– anticipatory maintenance of body posture
## Reticulospinal tract function– anticpate body posture control
<figure><figcaption class="big">
Upon cue (audible tone) for pulling, gastrocnemius contracts before biceps.
EMG: electromyography. Measure extracellular muscle APs
</figcaption><img src="figs/Neuroscience5e-Fig-17.13-0_60afb67.jpg" height="400px"><figcaption>Neuroscience 5e Fig. 17.13</figcaption></figure>
</figcaption><img src="figs/Neuroscience5e-Fig-17.13-0_60afb67.jpg" height="350px"><figcaption>Neuroscience 5e Fig. 17.13</figcaption></figure>
Note:
@@ -407,7 +399,7 @@ Movement encoding also applies to frontal eye fields for eye movements
## Activity of single upper motor neurons is correlated with muscle movements
<div><img src="figs/Neuroscience5e-Fig-17.06-1R_40b7eb1.jpg" height="500px"><figcaption>Neuroscience 5e Fig. 17.6</figcaption></div>
<div><img src="figs/Neuroscience5e-Fig-17.06-1R_40b7eb1.jpg" height="450px"><figcaption>Neuroscience 5e Fig. 17.6</figcaption></div>
<div><img src="figs/Neuroscience5e-Fig-17.06-2R_22d459b.jpg" height="300px"><figcaption>Neuroscience 5e Fig. 17.6. Porter and Lemon, 1993</figcaption></div>
Note:
@@ -468,11 +460,13 @@ Notice that the neuron is broadly tuned, even with this colored shading.
</div>
<div><figcaption class="big">Directional, broad range tuning
<div style="width:400px;float:left"><figcaption class="big">Directional, broad range tuning
of cortical motor neurons
</figcaption><img src="figs/Neuroscience5e-Fig-17.08-3R_6b3eda2.jpg" height="200px"><figcaption>Neuroscience 5e Fig. 17.8</figcaption></div>
</figcaption>
<img src="figs/Neuroscience5e-Fig-17.08-3R_6b3eda2.jpg" height="200px"><figcaption>Neuroscience 5e Fig. 17.8</figcaption>
</div>
<div>
<div style="width:500px; float:left; margin:0 20px;">
<figcaption class="big">
Population vector (red) for a population of simultaneously
recorded upper motor neurons (black lines indicate each id. neuron's spike rate)
@@ -549,13 +543,13 @@ thes neurons encode intention to perform a movement rather than just the movemen
---
## Mirror motor neuron activity in a ventral-anterior sector of the lateral premotor cortex
## Mirror motor neuron activity in lateral premotor cortex
<div><figcaption class="big">Monkey mirror neuron for hand reaching is active while observing a human hand reach</figcaption><img src="figs/Neuroscience5e-Fig-17.10-1R_57bd769.jpg" height="400px"><figcaption>Neuroscience 5e Fig. 17.10. Rizzolatti et al., 1996</figcaption></div>
Note:
Indeed a nice way to understand this is by examining portions of the lateral premotor cortex that contain so called mirror neurons that have been focus of a bit of attention over recent years.
A nice way to understand this is by examining portions of the lateral premotor cortex that contain so called mirror neurons that have been focus of a bit of attention over recent years.
peristimulus response histograms
@@ -569,7 +563,7 @@ Found in two cortical areas-- the posterior part of the inferior frontal cortex
---
## Mirror motor neuron activity in a ventral-anterior sector of the lateral premotor cortex
## Mirror motor neuron activity in lateral premotor cortex
<figure><figcaption class="big">Mirror neuron for hand reaching not active while observing pliers reaching</figcaption><img src="figs/Neuroscience5e-Fig-17.10-2R_a2f4703.jpg" height="400px"><figcaption>Neuroscience 5e Fig. 17.10. Rizzolatti et al., 1996</figcaption></figure>
@@ -580,7 +574,7 @@ does not respond when pliers are used to interact with food.
---
## Mirror motor neuron activity in a ventral-anterior sector of the lateral premotor cortex
## Mirror motor neuron activity in lateral premotor cortex
<figure><figcaption class="big">Mirror neuron for hand reaching active even when not observing self reaching</figcaption><img src="figs/Neuroscience5e-Fig-17.10-3R_a0ef0dd.jpg" height="400px"><figcaption>Neuroscience 5e Fig. 17.10. Rizzolatti et al., 1996</figcaption></figure>
@@ -606,7 +600,7 @@ http://nautil.us/blog/mirror-neurons-are-essential-but-not-in-the-way-you-think
Note:
image src unknown
todo: src
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Note:
see also fig. 17.11 Neurosci 6e
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First neuroimaging data
image src unknown
todo: src
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Note:
---
<!--
## The Babinski sign
<figure><img src="figs/Neuroscience5e-Fig-17.16-0_6f122b0.jpg" height="400px"><figcaption>Neuroscience 5e Fig. 17.16</figcaption></figure>
Note:
note
[https://www.youtube.com/watch?v=ZFu7bdbnZx8](https://www.youtube.com/watch?v=ZFu7bdbnZx8)
@@ -692,15 +687,16 @@ clonus
But changes in muscle tone and spasticity are different than then tremors at rest seen in Parkinson's.
---
-->
## Signs of upper and lower motor neuron lesions
<!--
Signs of upper and lower motor neuron lesions
<figure><img src="figs/Neuroscience5e-Tab-17.01-0_copy_8c62eb8.jpg" height="400px"><figcaption>Neuroscience 5e Table 17.1</figcaption></figure>
Note:
-->
---
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<div></div>
* Motor
* Output to muscles via ventral root
* Output to muscles <!-- via ventral root -->
* Two main pathways:
1. **Ventromedial system for balance, posture** and controlling head & eye movements. Important for muscles of legs & trunk needed for walking
2. **Dorsolateral system for controlling movements of upper limbs** & extremities such as fingers and toes as well as movement of facial muscles
* Sensory
* Input to primary somatosensory area via dorsal root
* Input to primary somatosensory area <!-- via dorsal root -->
* Two main pathways:
1. **Dorsal spinothalamic tract for proprioception** (body awareness and position in space) and haptic feedback (sensation of fine touch and pressure)– crosses in medulla
2. **Ventral spinothalamic tract for nocioceptive** information– crosses over in spinal cord
</div>
Note:
---