PS267(A) Intro to Cognitive Neuroscience Lecture Notes PDF

PS267(A): Intro to Cognitive Neuroscience Dr. Melanie Stollstorf Lecture #1 September 10: Neuroanatomy The Neuron Axon: Information t...

PS267(A): Intro to Cognitive Neuroscience Dr. Melanie Stollstorf Lecture #1 September 10: Neuroanatomy The Neuron Axon: Information transferred across, if action potential occurs then information is passed onto next neuron Dendritic Tree: Receives input from other cells Cell Body: Contains nucleus and other apparatuses that sustain functioning: The Brain Gray Matter: Neuronal cell bodies White Matter: Neuronal myelinated axons Ventricles contain cerebro-spinal fluid (CSF) Navigating the Brain: Different planes are used to view the brain in scans like CT scans, MRI, and fMRI (coronal; right and left hemispheres, horizontal;also see both hemispheres but from a different angle, sagittal; one hemisphere- hippocampus) TERMS: Superior: above Dorsal: toward the top Posterior: behind Caudal: towards tail Inferior: below Ventral: toward bottom Anterior: front Rostral: Towards nose Major Divisons of the Nervous System The Cortex 80% of brain volume 2 2500𝑐𝑚 Thinkness → 1.5-3.0mm Gyrus: the protruding rounded surface Sulcus: the enfolded regions that appear as lines and creases (fissure) Higher Order Functions: planning, attention, memory, language, etc Separated into 2 divisions: Anatomical Characteristics and Functional Characteristics 1. Anatomical Characteristics: What can be seen  Four Lobes: - Frontal Lobe: motor cortex, association cortex, Broca’s Area - Parietal Lobe: somatosensory complex, association complex - Occipital Lobe: visual complex - Temporal Lobe: auditory complex, Wrenicke’s Area Brodmann’s Areas: 52 areas that correspond with diverse functions including sensation motor control and cognition Brodmann’s Map: Divides areas of cortex according to their laminar organization (layers) and cell characteristics ○ If a region has the same cellular organisation as another then it was put in the same area by Brodmann Based on anatomy not function, but sometimes there is a correlation All regions have 5 or 6 layers (laminae) of cells Based on anatomy (structure) not function Cytoarchitecture - Sensory areas of the brain have a larger layer IV (Input) - Motor areas of the brain have larger V and VI layers (output) - Association layers (I-III) are roughly the same 2. Functional Characteristics Divide by the function each region serves Important Distinction: ○ Primary, secondary, tertiary (association) regions Primary Sensory Cortex (Organizational Principles) Specific aspects of the real world are mapped onto specific brain tissue ○ Ie. specific region of the body is controlled by a specific region of the brain Maps are distorted relative to the real world ○ Reflects relative distribution of receptors  Ie. the fovea gets more receptors and gets mire mapping than the peripheral retinal areas The world is mapped upside down and backwards (vision, touch and motor control) ○ Ie. info from upper right portion of is processed by the bottom left hemisphere Lecture #2 September 12: Neuroanatomy Frontal Cortex Contains motor cortex Everything anterior to motor strip is the Prefrontal Cortex ○ Prefrontal Cortex: the region infront of the motor cortex in the frontal lobes ○ Proportionately larger in humans compared to other species Evolutionarily late to develop ○ Latest brain structure to mature (develops until age 30) ○ Most variable anatomical structure between individuals  Cognitive-Emotional Distinction Cognition occurs in the dorsolateral PFC (top, outside) Emotion occurs in the ventromedial PFC (bottom, middle) Anatomical Highlights: ○ Dorsolateral prefrontal cortex (ie. working memory) ○ Broca’s Area (Language production) ○ Orbital Frontal Cortex (Phineas Gage) Temporal Cortex Contains auditory cortex Neurons code objects (“what” are they) Medial temporal lobes → memory center ○ Surround hippocampus Parietal Cortex Contains somatosensory cortex Neurons are sensitive to the “how” ○ Ie. linking an object and motion, or an object and a location Alexia, Agraphia, Apraxia Occipital Cortex Contains the visual cortex ○ Primary Visual Cortex: V1– lines (“V1”, “striate cortex”) ○ Extrastriate Cortex: V2– simple features (more complex than V1), V4–colour, V5–motion Limbic System Includes the following structures: ➔ Hippocampus ➔ Amygdala ➔ Cingulate ➔ Mamillary Bodies ➔ Olfactory Bulb ➔ Hypothalamus Important for and involved in the regulation of emotion and memory Lecture #3 September 17: Neurosignaling The neuron Action Potential The Synapse Neurotransmitters Myelination Neuron Sodium-Potassium Pump Resting Potential - 3 Na+ out, 2 K+ in - Ion channels open or close depending on if NT has it do so Synaptic Potentials Excitatory Postsynaptic Potential (EPSPs) ○ Makes neuron more likely to fire Inhibitory Postsynaptic Potential (IPSPs) ○ Makes neuron less likely to fire Sums at axon hillock to either trigger an action potential (or not) Action Potential Resting potential = approx. -70mV Action potential follows an “all-or-none” principle Neuron depolarizes past -55mV→ action potential will occur Na+ in, then K+ out Propogates down axon 1. Voltage gated Na+ channels open, Na+ rushes in (depolarizes cell→ more positie) 2. Voltage gated K+ channels open allowing K+ to rush out → repolarizes cell, more negative) 3. Na+ channels snap shut, K+ continues repolarizing Neuronal Communication: The Synapse Neurotransmitters: synthesized in the cell body, transported down the axon, to the axon terminal Receptors: NTs bind to the receptors to affect postsynaptic neuron (IPSPs or EPSPs) Action potential occurs, neurotransmitters are released into synapse (voltage gated Ca+ channels cause synaptic vesicles to fuse with the membrane), travel across synapse and bind to receptors on the next neuron (postsynaptic neuron), either to inhibit or excite it. Ionotropic Receptor H Metabotropic Receptor H Neurotransmitters Glutamate ○ Major excitatory NT ○ Receptors: NMDA (change biochemical & structural properties of synapse; memory!) AMPA (EPSP) Kainate (EPSP) Metabotropic ○ Epilepsy: exitotoxicity (rapid release of glutamate; cells can fire to death) GABA ○ Major inhibitory NT (40% of CNS receptors are GABAergic ○ Puts on the brakes, allowing for precision firing of neurons ○ 𝐺𝐴𝐵𝐴𝐴 receptor (ionotropic); 𝐺𝐴𝐵𝐴𝐵 receptor (metabotropic) ○Barbituates, benzodiazepines, alcohol are GABA agonists Reduce seuzures, induce sleep, anxiolytic effects Acetylcholine ○ Basal Forebrain Nucleus Projects very diffusely all over cortex ○ Septal Nuclei Projects to hippocampus ○ Has a general effect on neuronal and mental functioning (excitability, general attention and memory) ○ Two types of receptors: Ionotropic (nicotinic receptor: nicotine agonist) Metabotropic (muscarinic receptor) Dopamine ○ Nigrostriatal, mesolimbic and mesocortical ○ Metabotropic receptors only (𝐷1 − & 𝐷2 − alike D1 and D5: increase cyclic AMP D2, D3, D4: decrease cyclic AMPD ○ Different receptors in different regions of the brain contribute to various aspects of cognitive and emotional processing Eg. Schizophrenia & ADHD Nigrostriatal System: from the substantia nigra to striatum ○ Motor control and Parkinsons Mesolimbic System: from ventral tegmental area to nucleus accumbens, ventral striatum, hippocampus, amygdala, and prefrontal cortex ○ Reward and addiction Mesocortical System: to cortex ○ Executive function Noradrenaline ○ Also called norepiniephrine (NE)  ○ Produced in locus coeruleus and projects to thalamus, hypothalamus, and cortex (PFC) ○ 4 receptor types ( all metabotropic, excitatory and inhibitory depending on where) α1 & α2 (arousal and attention) β1 & β2 (long-term emotional memory) Serotonin (5-HT) ○ “5-hydroxytryptamine” ○ Produced in raphe nuclei of the midbrain, pons, and medulla to the cortex, thalamus, cerebellum, striatum (ie. the whole brain!) Arousal, mood, anxiety and aggerssion, control of eating, sleeping and dreaming, pain, sexual behaviour, memory ○ 14 receptors (7 subtypes) Can be excitatory or inhibitory depending on the subtype ○ Selective Serotinin Reuptake Inhibtors (SSRIs) treat depression After Neurotransmitter Release 1. Reuptake (eg. dopamine transporter “DAT”) 2. Enzymatic breakdown (eg. AChE, MAO, “-ase”) 3. Diffusion out of cleft 4. Autoreceptors 5. Glial cell degradation - Treatment for neuropsychiatric disorders alter NT functioning - SSRIs - MAOIs - Ritalin (DAT blocker)