Chapter2 - Notes.docx

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Konstantine Zakzanis

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-0PSYC31 chpt 2 notes -Neurological exams have been historically been the usual clinical approach to brain dysfunction which includes extensive study of behavior (brains chief product) -Neurologist examine strength, efficiency , reactivity and appropriateness of responses to commands, questions, discrete stimulation of particular neural subsystems and challenges to specific muscle groups and motor patterns. -Neurologist also examine body structures in search for evidence of brain dysfunction. - Ex swellin of retina or atrophied muscles due to insufficient stimulation. -Scanning techniques introduces in mid-1970s -CT(computerized tomography) and MRI reconstruct different densities and constituents of internal structures into clinically useful shadow pictures of intracranial anatomy. Neuropsychological Assessment is another useful method of examining the brain; by studying its behavioral products -relies on same techniques, assumptions and theories as does psychological assessment because subject matter of N-A is behavior. -like psych assessment, N-A involves intensive study of behavior via interviews, standardized scaled test and questionnaires, that provide relatively precice and sensitive indices of behavior. -A behavioral study whether clinical or research based is neuropsychological in nature as long as the questions that promted it, the central issues, the findings or the inferences drawn from them ultimately relate to brain function. !! -newer examination techniques rely upon indirect, noninvasive methods. -Earliest instruments for studying brain function and continue to be used are electrophysiological.. These include: electroencephalogram (EEG)patterns are affected by many brain diseases (ex. High frequency= attentional activity Electrodermal activity (skin conductance or galvanic skin response) reflects autonomic Nervous system functioning, provides a measure of emotional response. And has demonstated recognition in the absence of conscious perception. Evoked and event-related potential (EP, ERP)..both EP and ERP have demonstrated hemispheric specialization and processing speed and efficiency. Magnetoencephalographyrecords magnetic rather than electrical fields (like in EEG.) Brain mapping..displaying quantified data on a stylized head or brain image or MRI Using EP/EEG brain mapping techniques have been controversial due to numerous methodological and technological problems in this practice.leading to high rate of erroneous interpretations. Functional brain imaging: allows for viewing of brain activityuseful for exploring both normal brain functioning and the nature of specific brain disorders. Regional cerebral blood flow (rCBF): reflects brain metabolic activity indirectly as changes in the magnitude of blood flow in diff brain regionsrelatively inexpensive Positron emission tomography (PET) visualizes brain metabolism directly as glucose radioisotopes emit decay signals, their quantity indicates the level of brain activity in an areaLimitations: relies on radio isotope w/ short half-life..and high cost.. Single photon emission computed tomography (SPECT) similar to PET but less expensive .involves a contrast agent that is readily availablecomparisons of interictal and ictal SPECT scans in epilepsy surgery candidates has been valuable for identifying seizure onset.Limitation: does not have necessary temporal and spatial resolution for use in activation studies of cognition. fMRI.most widely used now clinical need to Identify cerebral language and memory dominance in neurosurgery candidates led to development of the ..WADA test(intracarotid injection of amobarbital for temporary pharmacological inactivation of one side of the brain) and electrical cortical stimulation mapping to reduce the surgical risk to these functions.**ARE BOTH INVASIVE. Questions addressed by the WADA and ECSM in patients may be answered using noninvasive techniques such as.: Transcranial magnetic stimulation (TMS)..functional transcranial Doppler..magnetoencephalography/ magnetic source imaging.. BRAIN DAMAGE and ORGANICITY Brain damage = organicity or organic impairment In 30s 40s and 50s clinicians treated brain damage and if it were a unitary phenomenonorganicitymuch work done on brain damaged ppl was based on the assumption that organicity was characterized by one central and therefore universal behavioral defect. No one behavioral phenomenon could be found that was shared by all brain injured persons but by no one else In neuropsychologies next evolution stage (2.0?)brain damage was still treated as a unitary phenomenon but was given measurable extensionthis basis for provided by Karl Lashley (law of mass action and principle of equipotentiality.).his rat studies led him to believe that the effectiveness of an animals behavior and the extent to which its cortex was intact were directly correlated regardless of the site of damage..and that contributions of diff parts of the cortex were interchangeable LF Chapman and wolff.**.the sheeer extent of cortical loss played a greater role in determining the amount of cog impairment than did the site of the lesion. -behavioral repercussions of brain damage vary with the nature, extent, location, and duration of the lesion; with age, sex, physical condition and psychosocial background and status of the patientand with individual neuroanatomical and physiological differences.. --2 ppl with similar pathology and lesion sites may have distinctly different neuropsychological profiles.In contrast patients with damage at diff sites may present similar deficits.. Therefore brain damage only becomes meaningful in terms of specific behavioral dysfunctions and their implications regarding underlying brain pathology.. Concerning terminology Constructional defects or constructional impairment is used ?? -apraxia; refers to a special class of dysfunction characterized by a breakdown in the direction or execution of complex motor acts. -Dimensions of Behavior -3 functional systems conceptualizing behavior..: 1. Cognition; information handling aspects of behavior 2. Emotionality; concerns feelings and motivation 3. Executive function; have to do with how behavior is expressed **each can be conceptualized and treated separately** --- **greeks were first to think of the tri-part division of behaviorsoul governed the Rational.appetitive and animating aspects of behavior --cognitive aspects have has more attn...than EMO and control systems.because Cog. Defects in brain injured patients can be prominent in their symptomatology... ..partly because they can readily be conceptualized, measured and correlated with neuroanatomically identifiable systems.ANDpartyl because structured nature of most medical and psychological exams do not provide much opportunity for subtle EMO and control deficits to become evident.HOWEVER ..brain damage rarely affects just one of these systems**the disruptive effects of most brain lesions, regardless of size or location, usually involves all 3 systems Examplekorsakoffs psychosis.associated with sever alcoholism.amnesia..disoriented in space/time.flat affectlack of impulse to initiate activityunable to organize plan of action for a goal.. Right hemisphere damage also reflect involvement of all 3 systems Cognitive functions: cog abilities/disabilities are functional properties of the individual that are not directly observed but instead are inferred from behavior. --4 classes of Cog function:input.storageprocessing.output 1. Receptive functions:ability to select, acquire, classify and integrate information.. 2. Memory and Learning..: refer to information storage and retrieval
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