PSYB55 Week 2 PDF

2 Cells of the Nervous System Glial cells - the glue of the nervous system - Help bind together the brain and facilitate neural functioning - Astrocytes: composes the blood brain barrier - Keeps out toxins from entering the body to protect function - Early astrocyt...

2 Cells of the Nervous System Glial cells - the glue of the nervous system - Help bind together the brain and facilitate neural functioning - Astrocytes: composes the blood brain barrier - Keeps out toxins from entering the body to protect function - Early astrocytes create a sort of scaffold to build the brain (neural development) - Plays a role is brain’s response to injury - Oligodendrocyte: support neural transmission (electrical signals) - Insulates the information highway of the neuron, the axon, to ensure that signals reach the end of the axon - Microglial cell: gobble up dead and dying neurons - Ensure ‘trash’ is being taken out - Schwann cell: support neural transmission (electrical signals) - Outside the brain and spinal cord Neurons - primary commutative unit of the nervous system - Transmits information from one part to the other - Motor neurons - Carry motor information - Sensory Neurons - Carry sensory information - Interneurons (majority) - Carry multiple informations - Powerhouse Triggering of an action potential - There is a threshold (certain ions are allowed in, some are pushed out) - A neuron receives enough excitement to reach this threshold to send a signal to other neurons - Becomes more positive - If threshold is reached > action potential > rapid decline - This either happens or it doesn’t, and it happens in the same degree everytime - More signals = louder, brighter e.t.c Electron Transmission - Axon hillock > myelin sheath (oligodendrocytes) > modes of ranvier (space between myelin and help regenerate the strength of action potential) > axon terminal - Myelin Degradation - Multiple Sclerosis (MS) - progressive myelin damage presumably due to an autoimmune disorder - Symptoms: forgetfulness, numbness, tingling, ability to walk - Depends on where the myelin is being damaged  - Amyotrophic Lateral Sclerosis (ALS) - rapidly progressing upper and lower motor disease that results in death (attack motor neurons) - Symptoms: clumsy, difficulty walking/inability to walk, hard to breathe - Mostly motor functions - Ischemia - arteries build up plaque so hard to supply blood with brain (stroke) - Neurons enter electrical failure - But prolonged oxygen deprivation could lead to neural failure or neurons will die Chemical Transmission After electrical transmission… 1. Terminal allows in calcium ions (Ca+) 2. Binds to vesicles (filled with neurochemicals) 3. Moves to end of terminal 4. Dumps in synapse 5. Neurotransmitters go to end of synapse 6. Binds to neuron it wants to communicate with 7. Binding may cause membrane potential change/excite the other neurons/inhibit e.t.c. 8. Neurotransmitters are then repackaged or resolved Neurochemicals Dopamine - Sites of production: - Substantia nigra (black substance) - Ventral tegmental area (VTA) - Links to cognition/behaviour - Higher-order cognition - Voluntary movement - Reward/reinforcement learning - Dysfunctional levels associated with - Parkinson's disease - inability to move - Psychotic thoughts/behaviours - psychosis - Addiction Norepinephrine - Sites of Production - Locus coeruleus - Links to cognition/behaviour - Cognitive arousal/attention - Memory and mental flexibility - Mood - Dysfunctional levels associated with - Alzheimer’s disease - Mood disorders  - Visuospatial neglect Serotonin - Site - Raphe nucleus - Link to cognition/behaviour - Mood - Dysfunctional levels associated with - Mood disorders - Psychotic thought/behaviour Acetylcholine (Ach) - Site - Basal forebrain - Link to cognition/behaviour - Sensory processing/attention - Learning and short-term memory - Movement (peripheral nervous system) - Dysfunctional levels associated with - Alzheimer's disease - Myasthenia gravis (skeletal muscle weakness) The challenge (when it comes to medications) * an individual’s baseline level of a neurotransmitter varies from person to person - Too little and too much = bad - Interactions with other neurotransmitters - Effect of other factors (hormones) Spinal Cord - brains extension into the body Descending tract - doing down in the body - Corticospinal tract: motor cortex > midbrain > medulla > spinal cord - Important for voluntary motor control - Rubrospinal - motor control - Tectospinal - head and neck movements - Vestibulospinal - balance - Reticulospinal - muscle tone Touch Information - Acquired from different parts of the bodies - To the spine > spinal cord > brain - 2 pathways - Medial lemniscal tract - Transmits touch info and joint stretch receptor - Lateral spinothalamic tract - Transmits temperature and pain * motor and somatosensory info are separated in the spinal cord - May damage one tract and not the other - Ventral: motor - Dorsal: somatosensory Top of spinal cord: info for entire body Bottom of spinal cord: lower half of the body Dermatomes: part of a map of the body based on nerves Gyrus - bulges in the cortex Sulcus - grooves in the cortex Grey Matter - unmyelinated parts (cell body/dendrites) White Matter - myelinated axons where signal are sent (fatty substance) Four lobes of the cerebral cortex - Frontal: motor control, speech production, higher-order cognition - Prietal: somatosensory cortex (touch info), attention - Temporal: auditory/sound, speech comprehension - Occipital: visual Primary sensory - process just one sense or control Secondary sensory - still dedicated to just one sense Association cortex - integration of sensory info Navigating the Brain Superior/Dorsal - above Inferior/Ventral - below Anterior/rostral - front Posterior caudal - back Medial - middle Lateral - outside Sagittal - side profile view Axial/horizontal/transverse - bird’s eye view Coronal - front/back view Corpus Callosum - connect left and right sides Thalamus - sensory relay station (except for smell) Amygdala - emotional processing Hippocampus - creating new memory Basal Ganglia: caudate nucleus, putamen, globus pallidus - Control of voluntary movement  - dopamine is produced - Learning how to do new skills Cerebellum - Motor control (smooth out movements) - Enunciation - Involved in memory, language, and high-order cognition Protecting the Brain - Ventricular system: set of chambers in the brain filled with fluid, keeps brain buoyant (shock protection), waste removal, nutrient delivery - Fluid system in the brain is shared with the spine, wrong in the brain = wrong in the spine - Cloudy - meningitis - All cavities are connected to each other - Lateral ventricle* - Interventricular foramen - Third ventricle* - Cerebral aqueduct - Fourth ventricle* - Cerebral vasculature - brains power supply - Oxygen comes from lungs through common carotid artery/vertebral artery - Gets to circle of willis (supplies parts of the brain) - Anterior cerebral artery* - Covers the front (medial part of the frontal and parietal cortex) - Internal carotid artery - Middle cerebral artery* - Covers the entire lateral surface of the cortex - Biggest cerebral distribution - Posterior cerebral artery* - Covers occipital lobe and most of the medial temporal lobe - Vertebral artery