Exam Prep, Microbiota, Evolution, and Genetics

Announcements & Exam Information

• Exam 1: Scheduled for Monday, the 29th, in the usual classroom at the regular class time.

  • Format: $50$ multiple-choice questions.

  • Duration: $15$ minutes.

  • Settings: Closed book, but scrap paper is permitted after the exam has officially started.

  • Technical Requirement: Must use Top Hat on a compatible device (e.g., Chrome or Safari browser). Ensure your device and browser are set up and working before the exam day to avoid technical issues.

• Study Guide: Posted over the weekend and available via email, announcement, and in a dedicated module section ("study guides fall $2025$").

  • Purpose: A broad outline to help focus studying on heavily emphasized material for the exam, given the breadth of content.

  • Action Required: Students should start completing the study guide immediately and fill it with detailed information; simply reviewing the outline is insufficient for preparation.

• Quiz 2: The final quiz before Exam 1.

  • Availability: Will open after class today and remain open until the end of the day on Friday, as per the syllabus.

  • Content: Covers neurobiology through all physiological systems, including cardiovascular, digestive, neurobiology, and endocrinology. It will not include questions from the first two slides presented at the beginning of this lecture (but the final slide from physiological systems is fair game).

  • Format: $15$ questions to be completed in $25$ minutes, open notes once the quiz is opened.

  • Rationale: Opening the quiz later this week (instead of a couple of days prior) provides students with more flexibility, especially with another Optimal Question Assignment (OCA) due.

• Optimal Question Assignment (OCA):

  • Due: End of this week.

  • Content: Questions should relate to this week's material, including the microbiota discussion and the upcoming lecture on evolution, genetics, and behavior.

  • Format: Submit any $3$ questions following the usual guidelines.

  • Note: There will be no OCA due next week, providing a break during exam week.

  • Purpose: Designed to offer additional practice questions to aid in exam preparation.

• Exam Review: The Friday class will be dedicated entirely to exam review.

  • Resources: A review slide deck and practice questions (curated from student submissions) will be posted soon.

  • Disclaimer: Practice questions are not guaranteed to match the exact difficulty level of the actual exam questions.

Microbiota and Behavior

• The Microbiome: Consists of trillions of microorganisms living in and on the human body, a number comparable to the total number of cells in the body.

• Research Focus: Investigating how the microbiome influences human behavior, including food choices and mood.

• Precedent for Microorganism Influence on Behavior: The concept of microorganisms influencing host behavior is not new in science.

  • Rabies Virus: A deadly virus that infects animals and people (historically, only one known human survivor without immediate treatment).

    • Mechanism: The virus can cross the blood-brain barrier and directly influence brain function.

    • Behavioral Change: Infected animals become aggressive and may engage in nocturnal activity during the day (if typically nocturnal). This behavioral shift, coupled with aggression, increases the likelihood of biting other animals, effectively spreading the virus to new hosts.

  • Toxoplasma gondii (T. gondii): A parasite that requires development in the intestines of cats.

    • Life Cycle: T. gondii larvae are excreted in cat feces and, upon ingestion by rodents (e.g., mice), manipulate the rodents' behavior.

    • Behavioral Change: Infected rodents, typically terrified of cats, become sexually aroused by them. This change in behavior makes the rodents less cautious and more susceptible to being eaten by cats, thus allowing T. gondii to complete its life cycle in the cat's intestines.

    • Significance: These examples demonstrate microorganisms' ingenious ways of manipulating host behavior to ensure their own survival and propagation.

• Application to Human Microbiota: Researchers are exploring whether beneficial gut bacteria may similarly influence human behaviors related to appetite, eating, mood disorders (e.g., depression, anxiety), autism spectrum disorders, and schizophrenia.

• Physiological Systems Review: As a quick recap, the liver produces bile, which is essential for the breakdown of fats.

Evolution, Genetics, and Behavior

Evolution

• Charles Darwin: Recognized as the