Brain and Behavior

O RGANIZATION OF THE C EREBRAL C ORTEX Gray matter –Cell bodies and dendrites Most common type: Pyramidal cells –Organized into columns and layers 2

O RGANIZATION OF THE C EREBRAL C ORTEX White matter –Axons travelling down into the brain Myelination appears white (fatty tissue) –Includes communication between hemispheres Corpus callosum Anterior commissure 3

T ERMINOLOGY : A NATOMICAL T ERMS Gyrus –“Bump” on the brain’s surface Sulcus –Fold / groove between gyri Fissure –A long, deep sulcus 4

M AJOR G YRI AND S ULCI Sylvian fissure aka Lateral sulcus Separates temporal lobe from frontal and parietal lobes 5

M AJOR G YRI AND S ULCI Parieto occipital sulcus aka Calcarine fissure Separates parietal and occipital lobes 6

M AJOR G YRI AND S ULCI Longitudinal fissure Divides the two hemispheres 7

M AJOR G YRI AND S ULCI Central sulcus One of deepest sulci in cortex Divides frontal and parietal lobes 8

M AJOR G YRI AND S ULCI Precentral gyrus aka Primary Motor Cortex Posterior part of frontal lobe Anterior to central sulcus Control of fine movements 9

M AJOR G YRI AND S ULCI Postcentral Gyrus aka Primary Somatosensory Cortex Anterior part of parietal lobe Posterior to central sulcus Touch sensation 10

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Homunculus = “little man” Primary somatosensory cortex 12

Prefrontal Cortex Everything in front of the motor areas All sensory info goes to the frontal cortex CEO of the brain

PFC 3 divisions: – Dorsolateral PFC Cognitive, conscious, deliberate thinking – Orbital (ventral medial) PFC Automatic, quick, emotional behavior Most frequently damaged – Medial PFC

PFC Challenges of PFC damage – Planning in advance – Selecting from multiple stimuli – Ignoring extraneous stimuli – Memory

Temporal Lobe Limbic system – Amygdala – Hippocampus Organizing sensory input Auditory perception Language and speech production Memory association and formation

Temporal Lobe Damage can result in Wernicke’s aphasia – Rapid and fluent speech – Use content and function words – Good prosody – MEANINGLESS SPEECH – Don’t seem to be aware of deficit

Obtaining pictures of the brain May examine: –Structure –Functioning N EUROIMAGING 18

Computerized axial tomography (CAT/CT Scan) –X-rays from different angles –Useful for: brain tumors, brain injuries, structural abnormalities –Disadvantage: radiation exposure N EUROIMAGING : S TRUCTURAL T ECHNIQUES 19

Normal CT N EUROIMAGING : S TRUCTURAL T ECHNIQUES 20

Epidural bleed (A) Brain tumors (B) N EUROIMAGING : S TRUCTURAL T ECHNIQUES 21

Magnetic resonance imaging (MRI) –High-strength magnetic field –Signals excite and relax hydrogen atoms –Lighter/Darker sections indicate lesions or damage N EUROIMAGING : S TRUCTURAL T ECHNIQUES 22

Normal brain MRI N EUROIMAGING : S TRUCTURAL T ECHNIQUES 23

Kwon et al.,

Positron Emission Tomography (PET) Scan –Tracer substance is injected Substance interacts with blood, oxygen, or glucose –Shows active parts of brain Use more blood, oxygen, and glucose N EUROIMAGING : F UNCTIONAL T ECHNIQUES 25

Normal PET vs. Alzheimer’s PET N EUROIMAGING : F UNCTIONAL T ECHNIQUES 26

Single photon emission computed tomography (SPECT) –Similar to PET (different tracer) –Less accurate than PET, but less expensive N EUROIMAGING : F UNCTIONAL T ECHNIQUES 27

functional MRI (fMRI) –More popular than PET/SPECT in research –Measures immediate reactions to brief events Moment-to-moment oxygen use and blood flow N EUROIMAGING : F UNCTIONAL T ECHNIQUES 28

fMRI normal vs. ADHD N EUROIMAGING : F UNCTIONAL T ECHNIQUES 29

N EUROIMAGING : PET VS. F MRI PET is faster than fMRI fMRI has better resolution than PET 30