Biopsychology Exam Two Brain Damage Neuroplasticity Identify and know major causes and classes of brain damage o Brain Tumors Tumor neoplasm Mass of cells that grows independently of the rest of the body Meningiomas o 20 of brain tumors o Encased entirely within the meninges o Usually benign and often surgically removable o Typically occur between dura mater and subarachnoid space arachnoid o Compete with brain tissue for space o Pressure exerted causes headaches vomiting double vision slow heart rate membrane seizures o Can kill cells Malignant o Most brain tumors are malignant o Grow diffusely invading and infiltrating surrounding tissue o No clear membrane or boundary that encapsulates mass o Difficult to remove or destroy because they lack encapsulating membrane o About 10 are metastatic originated elsewhere Origin of tumors o Majority of tumors arise in glial cells Gliomas among the most serious highly malignant and fast growing In the basal ganglia issues with movement In the pons issues with heart rate breathing sleeping o Cerebrovascular Disorders Strokes cerebrovascular events where the brain s blood supply is disturbed by bleeding or blockage causing cell death 3rd leading cause of death most common cause of adult disability Likelihood of having stroke doubles every decade after 45 Risk Factors o High blood pressure o High cholesterol o Diabetes o Atherosclerosis o Tobacco use and smoking alcohol use o Physical inactivity o Obesity o Age Gender Race Family History Previous strokes Low socioeconomic status Two kinds o Hemorrhagic Strokes Cerebral hemorrhage bleeding in the brain Usually result from burst aneurysm weakened point in a blood vessel Usually fatal if hemorrhage affects large area greater than 5cm Often results in long term coma or severe disability o Ischemic Strokes Cerebral ischemia blockage of blood supply Plug forms in the brain Can be from blood clot air bubble etc Thrombosis Plug forms elsewhere and piece of it breaks off and moves Embolism to the brain Arteriosclerosis deposits wall of blood vessels thicken usually from fat Damage does NOT develop immediately slow Most damage results from excess release of glutamate Blood deprived neurons become OVERACTIVE and release glutamate glutamate over activates its receptors leading to dramatic influx of NA and CA2 in cells o The glutamate receptors involved are NMDA receptors Influx of NA and CA2 triggers release of MORE glutamate because cells are now depolarized cascade of reactions that kill neurons Called excitotoxicity see figure below Cannabinoids which decrease release of glutamate minimizes stroke damage most effective if taken BEFORE stroke o Closed head injuries aka Traumatic brain injuries TBI Infarct area of dead tissue neurons Brain injuries due to blows that don t penetrate the skull brain collides with skull Coup Sites of injury where brain collides directly with the skull Countercoup Site opposite to the site of injury where the brain also slams against the skull Brain sloshes backwards because of the cerebral spinal fluid CSF Contusions Damage to the cerebral circulatory system that results in a hematoma bruise Coup and countercoup injuries cause contusions Concussions Involve a change in consciousness or mental state after a blow to the head with no evidence of apparent structural damage Coup and countercoup injuries can cause concussions Post Concussion Syndrome Lack of concentration reduction in processing speed headaches deficits in higher order cognitive functions depression Serious coup countercoup injuries often result in post concussion syndrome Repeated closed head injuries often result in two conditions Chronic Traumatic Brain Injury CTBI Dementia Pugilistica Boxer s syndrome punch drunk syndrome o Syndromes Dementia and cerebral scarring Slurred speech memory impairment personality changes aggressiveness impulsiveness lack of coordination Parkinson like syndrome difficulty with voluntary movements resting tremors o Infections of the brain Brain infection is the invasion of brain tissue by microorganisms the resulting inflammation of brain tissue is called encephalitis Bacterial Infections Often lead to abscesses pockets of pus Meningitis inflammation of the meninges Treat with penicillin or other antibiotics If untreated results in paresis syndrome of dementia Viral Infections Some preferentially attack neural tissue rabies Some show no preference for neural tissue but may attack it mumps herpes Some lie dormant for years Meningitis Parasites Both bacterial and viral forms Flu like symptoms with neck stiffness inability to touch neck to chest aversion to light drowsiness depression seizures Results in neurocysticercosis Eggs hatch in stomach larvae travel in bloodstream and lodge in soft tissue producing fluid filled cysts encasing larvae o Neurotoxins Can enter from GI tract or lungs or through the skin Mercury is one toxin that results in toxic psychosis Hat makers often suffered from toxic psychosis due to mercury exposure on the job mad hatters Also lead movements Epilepsy Some antipsychotic drugs that are dopamine antagonists Producing tardive dyskinesia a motor disorder of sudden uncontrollable constant o Any disorder involving uncontrolled recurrent and spontaneous electrical disturbances in the brain o Often accompanied by changes in consciousness awareness o Primary symptom is seizures Affects 1 of population Difficult to diagnose due to diversity and complexity of seizures o When convulsions are present epilepsy is easier to diagnose Symptoms include seizures tremors clonus rigidity tonus loss of balance Many seizures involve subtle changes thought mood behavior with NO convulsive unconsciousness symptoms o Epileptic spikes in EEG Evidence of epilepsy but if they aren t present doesn t prove absence of epilepsy Auras sometimes precede seizure can suggest location of abnormal activity smells hallucinations feelings etc o Two seizure categories Partial Do NOT involve entire brain have a specific location Types o Simple o Complex Symptoms primarily sensory or motor or both Symptoms spread Often restricted to temporal lobes Patient engages in compulsive repetitive simple behaviors automatisms More complex behaviors seem normal Patients have little or no recollection of them Generalized Dostoevsky had generalized seizures Types Involve entire brain o Grand mal Loss of consciousness equilibrium Tonic clonic convulsions Rigidity tonus Tremors clonus Resulting hypoxia may cause