Psychology 224: Neuroscience Lecture Notes PDF

Psychology 224: Neuroscience Methods and Research Strategies Reading: Carlson, Chapter 5  Methods and Research Strategies Reading: Carlson, Chapter 5  Experimental Ablation  Remove or destroy tissue of a lab animal and look at consequences on behavior.  Oldest method used...

Psychology 224: Neuroscience Methods and Research Strategies Reading: Carlson, Chapter 5  Methods and Research Strategies Reading: Carlson, Chapter 5  Experimental Ablation  Remove or destroy tissue of a lab animal and look at consequences on behavior.  Oldest method used in neuroscience  Lesion studies  Methods For Producing Brain Lesions  Radio frequency lesion -Pass alternating current through a wire electrode. ventricle - Heat kills cells bodies and axons.  Methods For Producing Brain Lesions  Excitotoxic lesions Normal hippocampus - Inject a chemical through a cannula -Apply a glutamate receptor agonist (kainic acid) Lesioned hippocampus - Stimulate neurons to death - Kills cell bodies, not axons  Methods For Producing Brain Lesions  Reversible lesion - Temporary disruption of brain activity - Inject a muscimol through a cannula - Blocks action potentials by stimulating GABA receptors  Sham group - Animals that undergo surgery and have the electrode or cannula inserted - No current or chemical injected (no lesion) - Controls for incidental damage  Stereotaxic Surgery  Bregma - Junction of the sagittal and coronal bones of the skull - anterior fontanelle during infancy - closes in the first 36 months of life in humans (soft spot)  Stereotaxic Surgery  Bregma - Junction of the sagittal and coronal bones of the skull - Reference point - Use a brain atlas for coordinates necessary to target brain region -anterior-posterior -medial-lateral  Stereotaxic Surgery Stereotaxic Apparatus For Rodents Stereotaxic Apparatus For Humans  Histological Methods  Goal: Visualize the tissue as it was when the organism was alive.  Place brain tissue in a fixative (formalin) Prevents postmortem decay Preserves tissue as close to its natural state as possible Prepares tissue so it can be processed  Cut into thin sections (10-80 m thick) -1.0 m = 0.001 mm  Stain and mount sections on a glass slide  Histological Methods Microtome Cryostat These methods rely on freezing the brain so it is hard enough to be cut into thin sections.  Staining (Mouse brain) Nissl Stain Doublecortin Stain Visualize young neurons Visualize cell bodies only (neurons and glia) Requires immunocytochemistry  Immunohistochemistry  Antibodies bind specifically to GFAP Stain antigens in biological tissues  Antibodies are made by injecting animals with the protein of interest and then isolating antibodies from serum. Visualize Astrocytes  Tissue is incubated in antibodies, which bind What if we want to look inside the brain of a living person?  Visualizing The Human Brain Stroke patient CT Scan: computerized tomography - Oldest method - Involves passing X- ray beams through the head - Blood absorbs a lot of radiation and looks  Visualizing The Human Brain MRI Scan: magnetic resonance imaging -Resolution is higher than CT scan - Does not use X-rays - Involves passing a strong magnetic field through the head and radio waves  Visualizing The Human Brain Diffusion Tensor Imaging -Modification of the MRI scanner - Based on information about the movement of water Axons that project from thalamus to molecules cortex - Visualize bundles of axons  What if we want to measure neural activity?  Electrophysiological Recordings Allows for recording neural activity when the animal is performing a task