Advances in Deep Brain Stimulation and Transcranial Magnetic Stimulation for Neurological Disorders

1. Neural Separability

2. Deep brain stimulation

3. DBS application • Parkinson’s disease • Clinical depression (Nucleus accumbens) • Tourette syndrome • Other application • Post-traumatic coma • Obsessive-compulsive disorder • Phantom limb pain

4. Parkinson’s disease (Symptoms) • Freezing • Postural instability • Increased muscle tone (Rigidity) • Slowness in the execution of movment (Bradykinesia) • Involuntary and unwanted movements • Resting tremor • Dystonia Levels of motor control

5. Cortico-Basal Ganglia Loop

6. Deep Brain Stimulation area for Parkinson’s disease • Subthalamic Nucleus (STN) • Freezing • Postural instability • Rigidity • Bradykinesia • Tremor • Globus Pallidus Internal (GPi) • Rigidity • Bradykinesia • Tremor • Dystonia

7. Transcranial Magnetic Stimulation (TMS)

8. Transcranial Magnetic Stimulation • Electrical flow in brain induced by magnetic field formed by the electrical flow of external coil • Increase or decrease the excitability of Neural pathways • Slow rTMS (1 Hz) increase inhibition • Fast rTMS (> 5 hz) increases excitability

9. Clinical uses of TMS • Diagnostic purpose • Interruption of ongoing neural activity to assess functional localization • Visual cortex • SMA • Motor Cortex • Cortical Physiology • Brain Plasticity: Verifying structural change • Therapeutic purpose • Parkinson’s Disease • Writer’s Cramp (dystonia) • Epilepsy • Stroke Recovery • Various psychiatric disorders

10. TMS (Good & Bad) • Strength • Can be conducted with “normal” subjects thus removing the possible confound of additional lesions • Can be performed acutely without involvement of neural plasticity or re-organization • TMS can be repeated with same subject thus introducing possibility for appropriate controls • Multiple subjects can be subjected to identical lesions thus increasing statistical power • Can target different brain regions with same subject to more precisely describe behavioral disruptions • Can execute the TMS with many different tasks to look at specificity issues • Weakness • Hard to control deep brain area • Hearing the loud click made by the TMS pulse • Some discomfort or pain reported

11. How rTMS affects the brain

12. TMS: Cerebellum pft = paced finger tapping Theoret et al., (2001). Neuroscience Letters, 306: 29-32.

13. Behavioral Findings LC = lateral cerebellum; MC medial Cerebellum; MT= site of motor threshold; Sham = reorientation of TMS Theoret et al., (2001). Neuroscience Letters, 306: 29-32.

14. TMS on M1 effects early stage of motor learning Hoterman et al., (2009). EJN

15. TMS on M1 effects early stage of motor learning Hoterman et al., (2009). EJN

16. Speech Disorders • Apraxia of speech (Plan) • Aphasia (Language) • Dysarthria • Stuttering (Flow) • Cluttering (Communication) • Articulation Disorder

17. Apraxia of Speech • Overview of Apraxia • Ideational apraxia • unable to perform due to loss of idea • Ideomotor apraxia • unable to perform due to control problem • AOS, Verbal apraxia

18. Apraxia of Speech • Definitions • An ariticulatory disorder resulting from impairment, as a result of brain damage, of the capacity to program the positioning of speech musculature and the sequencing of muscle movements for the volitional production of phonemes • Can occur without significant weakness or neuromuscular slowness, and in the absence of disturbances of thought or language

19. Aphasia • Language problem • Broca's aphasia • Damage in frontal lobe • Speak short sentence hardly & repeatedly • Wernicke's aphasia • Damage temporal lobe • speak no meaning long sentences • Anomic Aphasia (Anomia) • Impaired recall of words or names • Circumlocutions (speaking in a roundabout way) • Caused by damage to various parts of parietal or temporal lobe of the brain

20. Others • Dysarthria • Neurological Speech Disorder • Caused by disorder in the nervous system • ALS, Parkinson's disease, and cerebral palsy • Compare to AOS • Muscle weakness • Sensory loss • Comprehension deficit • Stuttering • Cluttering • Rapid speaking rate • Erratic rhythm • Words or group of words unrelated to the sentence

21. Speech problem in PD • Speech disorders in parkinson patients(Kerschan, 1998) • Functional impairment of articulation, phonation, prosody, respiration • Therapy seem useful only if no cognitive impairment • Speech motor programming in hypokinetic and ataxic dysarthria(Spencer, 2005) • Unable to maintain a programmed response or to rapidly switch between responses • Ataxic dysarthria are separable from motor execution impairments

22. Speech problem in AD • Empty speech in Alzheimer's disease(Nicholas, 1985) • Produce more empty phrases and conjunctions • Naming deficits • Compare to Wernicke's aphasia • produce more verbal, literal paraphrase • Anomic aphasia • share characteristics • Alzheimer's disease and Parkinson's disease: comparison of speech and language alterations(Cummings, 1988) • PD shows no evidence of intellectual impairment • AZ has greater language disturbances • Dementia of PD and AZ are distinguishable

23. Speech Problem in Aging • Processing speed and timing in aging adults: psychoacoustics, speech perception, and comprehension(Pickora, 2003) • auditory temporal processing differences > cognitive performance • increases quantity, reduces density of informational content and cohesive reference of narratives • increases the units of irrelevant content • Aging affects hemispheric asymmetry on a competing speech task(Greenwald, 2001)

24. Levels of Motor Contol & Speech problem • Higher • Programming (AOS) • Middle • Speech Perception (Wernicke’s) • Speech Generation (Broca’s) • Lower • Fluency, Flow • Strength and coordination of the speech muscles (Dysarthria) • Swallowing

25. Levels of motor control

26. Brain • Generalization • Obscureness • Plasticity • Taxi driver in London • Musician’s brain • Limitation • Learning new function limited by critical period