Biopsych Psychopathology

Inverse Association Between Serotonin Levels and Aggression

  - Higher serotonin levels correlate with lower aggression levels, particularly in males.
  - Presence of sufficient testosterone enables aggressive behaviors, but higher serotonin mitigates aggression.
  - This relationship can be described as a threshold effect—beyond a certain serotonin level, aggression levels are not significantly influenced.

Key Mechanisms Affecting Serotonin and Aggression

  - Psilocybin: A hallucinogen that has negligible effects on serotonin levels as a mechanism to modulate aggression.
  - SSRIs (Selective Serotonin Reuptake Inhibitors):
    - Mechanism: SSRIs block the serotonin transporter, which prolongs the presence of serotonin in the synaptic cleft, enhancing postsynaptic effects.
    - Predicted outcome: SSRIs are likely to decrease aggression due to increased serotonin availability.
  - Amphetamine:
    - Mechanism: Blocks VMAT (Vesicular Monoamine Transporter) 2, leading to elevated free neurotransmitter levels in the terminal.
    - Methamphetamine reverses the dopamine transporter, increasing dopamine levels externally.
    - However, these effects do not relate directly to aggression as discussed.

Key Enzymes and Their Functions

  - Tryptophan Hydroxylase: Enzyme that converts tryptophan to serotonin.
    - Blocking this enzyme is predicted to reduce serotonin and increase aggression.
  - Hydroxylase: The specific role is to convert biochemical precursors into neurotransmitters, fundamental for understanding aggression's biochemical basis.

Class Review and Self-Assessment

  - Importance of understanding core concepts and mechanisms affecting aggression to avoid poor academic performance (grades of D or F).
  - Engagement is critical: If there are doubts about understanding, seeking help from TAs or tutors is encouraged.

Cued Emotional Response and Conditioning

  - Cued Emotional Response: Training an animal to associate a tone (conditioned stimulus) with a shock (unconditioned stimulus), leading to a conditioned response:
    - Unconditioned Response: Jumping and squeaking following shock.
    - Conditioned Response: Freezing when hearing the tone.
  - Importance of understanding these concepts in the context of emotional responses.

Neurophysiology Basics

  - Removal of sodium from intracellular fluid leads to decreased positive charges:
    - This results in hyperpolarization, making the neuron less likely to fire.
  - Key Brain Structures and Functions:
    - Cerebellum: Coordinates movement; not primarily related to emotion.
    - Medial Temporal Lobe: Contains the hippocampus, primarily involved in memory, but has some links to emotional regulation.
    - Cingulate Cortex: Essential in emotional processing and is the best fit among the structures discussed that would disrupt emotional behavior when damaged.
    - Hypothalamus: Involved in hormone regulation, motivated behaviors, thirst, and more, but not as significantly in emotion as the cingulate cortex.
    - Suprachiasmatic Nucleus: Regulates circadian rhythms, unrelated to aggression or emotion.

Workshop and Review Sessions

  - Workshops are scheduled every Wednesday and Saturday, covering various topics, including synaptic processes and potential learning mechanisms.
  - Worksheets: Provided for practice, answers to be verified with instructors or peers.
  - Syllabus and Examination Schedules: Exams are TBA and can be found in HUB; students must check for their specific schedules.

Cellular Basis of Learning

  - Discussed habituation and adaptation; the necessity to understand these concepts for exams.
  - Gills Withdrawal Reflex:
    - Electrical activity measurement in the sensory neuron shows habituation.
    - Sensory neuron response diminishes upon repetitive stimulation due to neurotransmitter release decrease.
    - Importance of the model organism (aplysia) for detailed mechanistic studies.

Sensitization vs. Habituation

  - Habituation: A decreased response to a repeated stimulus.
  - Sensitization: Enhanced response due to prior stimulation (e.g., sensitivity after a sunburn).

Long-Term Potentiation (LTP)

  - Identified as a primary molecular mechanism of learning and memory.
  - Any manipulation facilitating LTP is expected to enhance learning, while anything inhibiting it reduces learning potential.
  - Key structures involved in studies of LTP, including:
    - Hippocampus: Critical for LTP and thus learning.
  - Experimental Setup for Inducing LTP:
    - Employing stimulating electrodes and recording electrodes in vitro; stimulating the perforant pathway and recording responses in the dentate gyrus.
    - Calcium influx is crucial for the induction of LTP and linked to changes in neurotransmitter release and receptor availability.

Mechanism of NMDA Receptors in LTP

  - NMDA receptors are crucial for calcium ions flow; their complex gating mechanism must be understood for LTP.
    - Two requirements: Depolarization to remove magnesium block and the presence of ligand (glutamate).
    - They are both voltage and ligand-gated ionotropic receptors.
  - Actions post-LTP induction include increased neurotransmitter release and receptor insertion, leading to enhanced postsynaptic effects.
    - Nitric Oxide: Functions as a retrograde signal, promoting increased neurotransmitter release at the presynaptic cell.

Types of Memory and Learning Processes

  - Reviewed types of learning, focusing on declarative and non-declarative memories.
  - Spatial Memory: Testing through paradigms like the Morris water maze.
  - Rats rely on the hippocampus for learning in such tasks, showing deficits with hippocampal damage.

Genetic Manipulations and Neurodevelopment

  - Increasing NMDA receptor availability in genetically modified animal models to enhance learning potentially increases susceptibility to seizures, highlighting the balance needed between excitatory and inhibitory neurotransmission.

Psychological Disorders Overview

  - Discussion included the DSM V diagnostic criteria for various psychological disorders such as schizophrenia, their treatment mechanisms, and neural correlates.
  - Examination of patient cases for practical understanding of theoretical aspects and ethical considerations in psychological and medical practice.
  - Importance of maintaining professionalism when discussing real patient cases in classroom settings.