1. Integrates sensory inputfor motor coordination

2. Receives information from the brainstem itself

a. If you need to perform a motor act in a well-coordinated way, you need input (visual, proprioceptive, etc) to modulate the act

1. Ataxia

2. Poor balance

3. Uncoordinated movements (drunken gait)

1. Association tracts

2. Projection tract

3. Commisural tracts

1. Within the cortex

2. Connect one part of the cortex to another part of the cortex

ex. arcuate fasciculus

1. Connects cortical areas (ex. motor cortex) with subcortical areas (ex. brain stem)

1. Between hemispheres

ex. corpus callosum 

1. Internal carotid artery (from the heart)

2. Vertebral artery (from the spinal column)

3. Connect with each other at the base of the brain (Circle of Willis)

4. Extremely important as a back up mechanism

a. Blood from one arter can compensate for a blockage in the other by pumping through the circle

1. Anterior

2. Middle

3. Posterior

Three protective layers around the brain and spinal cord

1. Dura -- outer most

2. Arachnoid -- web like structure

3. Pia -- very thin layer

1. Anchor the brain with the skull/spinal cord with the column

2. Cushioning effect resuling from the CSF between the three layers

1. Produced in the choroid plexus of the ventricles

2. Travel out from the ventricles and enters the subarachnoid space (between the arachnoid and pia)

3. CSF is replenished on a daily basis

1. Cavities in the brain that produce CSF, all interconnected

a. Lateral ventricles

b. Third ventricle 

c. Fourth ventricle

1. Increase in CSF

2. Over production of CSF

3. Deficit in re-absorption of CSF in the brain

4. Openings that allow the CSF to leave the ventricles could be blocked

1. Intracellular -- within the neuron

2. Extracellular -- outside the neuron

3. Numerous openings on the neuron to allow nutrients to flow in and out

1. Chemical synapses

a. Neurotransmitters

2. Electrical synapses

a. Faster, and more rare

1. Synthesized pre-synaptically

2. Action potentials cause released of neurotransmitter

3. Attach post-synaptically to the neuron 

4. Excitatory or inhibitory

1. Functional

2. Structural

a. Invasive vs. noninvasive 

1. CT scan

2. MRI

3. DTI

4. DWI

5. PWI

1. Oldest technique (Used by Broca)

2. Levels of information

a. Gross anatomy

b. Grey and white matter (staining)

c. Neuron level (staining)

1. Examined the structure of different parts of the brain

2. Determined the cortex has six layers of cells

a. Different composition across different parts of the cortex

b. Used the compostion of the layers to categorize different parts of the brain

c. Believed the various compostions coordinated to different functions

1. Every brain has a different shape

2. The anterior and posterior commissures serve as reference points or coordinates

3. Allows us to provide (x,y) coordinates

1. Provided an atlas of the human brain

2. Brain represented as (x,y,z)

a. x: right (+) left (-)

b. y: anterior (+) posterior (-)

c. z: superior (+) inferior (-)

1. 3D reconstruction using multipe x-rays at various angles

2. Based on tissue density differences 

3. Typical resolution: 1 cm

4. Contrast CT (inject iodine as a contrast agent)

1. 3D

3. Quickly see major problems

4. Cheap

5. NOt as affected by slight movements

1. Exposure to x-rays

2. Allergy to iodine

3. Poor resolution

4. Structure but no function

1. The external magnetic field changes the spin of the protons in the body

2. Radio waves are applied and withdrawn, the protons are shifted again and release energy that is detected by the MRI

1. Limits on size and weight of person

2. Tight, enclosed spaces

3. Patient with metal implants cannot use

4. Sensitive to slight movements

5. Only structural, static brain

1. Tesla

2. Voxel

3. Pixel

Unit of magnetism

1.5 T, 3T, 4T, etc. scanner strength

(.0001 T -- earth's magnetic field)

1. Alternative to the Talairach and Tournoux atlas

2. Utilized MRI scans from many different people and averaged them together

1. MR pulse applied in six different directions

2. Sensitive to water traveling within axons

3. View white matter tracts

1. MR pulse applied in three different directions

2. Relative diffusion of water across cell membranes

3. When a cell dies, water content that orginally surrounded it flows from inside to outisde (appears as bright areas on DWI, indicating dying tissue)

4. Sensitive to early neuron damage

1. Reveals tissue with reduced blood flow

2. Functional lesion 

a.Very low blood flow causes the tissue to cease functioning, although it is still alive

3. This tissue may appear normal in other imaging techniques

4. Reveals tissue at risk of dying

1. Injection of contrast substance

2. Series of MRI scans or angiograms

3. Mean Transit Time: time to pass from arterial to venous circulation

4. Rate of blood flow is compared with the intact hemisphere

1. Electromagnetic methods

2. Magnetic methods

3. Flow techniques

Measure electrical activity

1. Cortical mapping

2. EEG

3. Evoked potentials/ERP's

1. MEG

2. TMS

1. WADA

2. CBF

3. PET

4. FMRI

1. Performed during cortical resection with local anethesia

2. Provide a small electrical current to different parts of the brain to inhibit activity in that part of the brain -- determine which parts of the brain control which movements

a. Develop cortical maps

b. Can also stimulate the activity, depending on the charge

1. Low consent rate

2. Patients typically have some neurological condition

a. Their brain may have already reorganized

3. Spatial resolution is very broad, not sure precisely where one function ends and the other begins

1. Huge contribution to neuroscience

2. Spatial resolution is also very minute, know exactly what function that point on the cortex serves

1. Normal electrical activity of neurons to communicate

2. If enough neurons fire in the same way at the same time, the current may be picked up from outside the skull

3. Measured as a potential difference between two points on the scalp using electrodes

4. Abnormal tissue is picked up as abnormal activity

1. Ease of use 

a. Can be conducted in a non-medical setting

2. Noninvasive

3. Inexpensive

4. Temportal resolution excellent

a. Time sensitive (milliseconds)

1. Poor spatial resolution

a. The skull distorts the electrical current to an extent, so increasing the number of electrodes may not improve resolution

2. Sensitive to small movements

1. Electircal activity evoked by sensory stimulation

2. Similar time scale of the EEG

3. Advantages and disadvantages similar to EEG

1. How far after presenting the stimulus does the peak occur

2. Language delayecd and other impaired populations will show reduction or leveling of peaks

1. Magnetic fields created by individual neurons

a. Scanner detects the magnetic field around your head

1. Better special localization

2. No spatial constraints

3. Noninvasive

4. Quiet

1. Will only pick up activity of axons perpendicular to the magnetic field that are in the outer-most layer

2. Acitivty occuring deep within the cortex will be washed out by other neural activity

3. Expensive

4. Sensitive to small movements

5. Easily distorted by metal implants

1. Magnetic field generated by electrical current passing through the coil

2. The underlying cortex stops functioning, and then you can witness its purpose ("virtual lesions")

1. Noninvasive

2. Inexpensive

3. Nonmedical setting

1. Only stimulates the cortex

2. Effects are extremely brief (dosage limit)

3. Clinical utility is limited

1. Most cortical neruos are within 100um of a capillary

2. If you are using a particular part of the brain continuously for any activity, blood flow will increase to meet metabolic needs

3. Indirect measures of cognitive activity

a. Difficult to make correct inferences about activity and fucntion; need to analyze the task to see what other functions are involved

1. Sodium amytal infusion (anesthetic) injected into the carotid artery

2. Used to determine hemispheric specialization

3. Effects last 2-10 minutes

1. Clinical value for determining hemispheric specialization

2. Inexpensive

1. Somewhat invasive

2. Requires trained professionals

3. Spatial resolution (whole hemisphere)