Biopsychology Study Guide

📖 Core Concepts Behavioral neuroscience – study of the biological and neural substrates of human experience and behavior. Alternative names – biological psychology, biopsychology, psychobiology. Interdisciplinary context – sits within the larger field of neuroscience; overlaps with neurobiology, neuropsychology, ethology, evolutionary biology, and comparative psychology. Primary focus – physiological, genetic, and developmental mechanisms that generate behavior. Main research topics – learning & memory, sensory processing, motivation & emotion, motor control, sleep/biological rhythms, language, decision‑making, consciousness. Cognitive neuroscience – a sub‑division emphasizing neural bases of cognition rather than overt behavior. Relationship to psychology – both study biological bases of mental functions; behavioral neuroscience stresses observable behavior, cognitive neuroscience stresses mental processes. Historical pillars – mind‑body problem, functional localization vs. equipotentiality, classic lesion case studies (e.g., Phineas Gage, Penfield’s cortical maps). --- 📌 Must Remember Definitions – behavioral neuroscience = “biology of behavior”; also called biopsychology. Key methods – lesion (permanent/temporary), TMS (lesion ↔ stimulation), electrical stimulation, psychopharmacology, genetic manipulation, neuroimaging (fMRI, PET, EEG/MEG, ECoG), single‑/multi‑unit recording. Lesion confounds – surrounding tissue damage can obscure causal interpretation. Reversibility hierarchy – TMS → temporary lesion > pharmacology → temporary block > genetic knockout → permanent (unless inducible). Imaging trade‑offs – fMRI: high spatial, indirect (blood‑flow); PET: metabolic/chemical, lower spatial; EEG/MEG: millisecond temporal, limited spatial; ECoG: better spatial than EEG, invasive. Clinical relevance – Parkinson’s, Huntington’s, Alzheimer’s, depression, schizophrenia, ASD, anxiety, drug abuse, alcoholism. --- 🔄 Key Processes Creating a lesion Choose lesion type → surgical excision / electrolytic shock / neurotoxin infusion / cooling or tetrodotoxin (temporary) → verify extent → assess behavioral change. Reversible TMS lesion Position coil → deliver brief high‑frequency pulse → induces “virtual lesion” for 10‑30 min → test behavior, then repeat with sham or excitatory protocol. Enhancing activity Electrical stimulation → set sub‑threshold current → monitor evoked behavior; Pharmacological ↑ → administer agonist or block antagonist (e.g., NMDA antagonist AP5) → observe modulation; Stimulating TMS → apply repetitive low‑frequency or patterned pulses to up‑regulate cortical excitability. Measuring neural activity Insert electrode (single‑unit) or electrode bundle (multi‑unit) → record spike trains → spike sorting → analyze firing rate/timing. fMRI → acquire BOLD series → preprocess → contrast task vs baseline → map active voxels. PET → inject radiotracer → detect emitted photons → reconstruct metabolic map. Genetic manipulation Engineer knockout/ transgenic animal → confirm genotype → phenotype assessment; For inducible systems → add/remove dietary agent → switch gene on/off → test reversible effects. Computational modeling cycle Formulate hypothesis → build mathematical/ simulation model → generate predictions → run experiments → refine model. --- 🔍 Key Comparisons Lesion vs. Stimulation Lesion: destroys or silences tissue → permanent (unless temporary). Stimulation: adds activity → reversible, often sub‑threshold. Surgical vs. Electrolytic vs. Chemical Lesions Surgical: physically removes tissue → minimal electrical artefact. Electrolytic: uses current → may damage fibers of passage. Chemical: neurotoxin (e.g., ibotenic acid) → more selective for cell bodies. fMRI vs. PET vs. EEG/MEG fMRI: indirect (BOLD), high spatial (2 mm), slower (2 s). PET: metabolic/chemical imaging, lower spatial, requires radioisotope. EEG: millisecond temporal, poor spatial (cm). MEG: similar temporal to EEG, better spatial (mm) but expensive. TMS Lesion vs. TMS Stimulation Lesion: single high‑intensity pulse → transient disruption. Stimulation: repetitive patterned pulses → up‑ or down‑regulate excitability. Behavioral vs. Cognitive Neuroscience Behavioral: emphasis on overt actions, animal models, lesion/physiology. Cognitive: focus on internal mental operations, often human imaging. Neuropsychology vs. Behavioral Neuroscience Neuropsychology: studies patients with CNS dysfunction. Behavioral neuroscience: manipulates normal or genetically altered systems to infer function. --- ⚠️ Common Misunderstandings “Lesions only affect the targeted region.” Reality: surrounding tissue and fibers of passage can be unintentionally damaged → confounds. “fMRI directly measures neuronal firing.” Reality: fMRI measures hemodynamic (blood‑flow) changes, an indirect proxy. “TMS always creates a permanent lesion.” Reality: Standard TMS is reversible; only high‑intensity single pulses act as virtual lesions. “Genetic knockouts are fully reversible.” Reality: Most are permanent; only inducible systems allow temporal control. “Behavioral neuroscience ignores cognition.” Reality: While emphasis is on behavior, many studies integrate cognitive variables (e.g., decision‑making). --- 🧠 Mental Models / Intuition Brain as hardware – lesions = removing a component; stimulation = flipping a switch on; neuroimaging = a thermal camera showing which parts heat up during a task. Genetics as software patches – knockout = deleting a line of code; inducible system = toggling a feature flag. Neural activity recording – single‑unit = listening to a single telephone line; multi‑unit = eavesdropping on a crowded call center. --- 🚩 Exceptions & Edge Cases Lesion confounds – unintended spread of damage; must use control lesions or sham surgeries. Permanent genetic manipulations – can cause developmental compensation that masks acute effects. Pharmacological reversibility – depends on drug half‑life and blood‑brain barrier; some agents linger. TMS efficacy – highly dependent on coil orientation, scalp‑brain distance, and individual cortical excitability. EEG spatial limitation – deep structures (e.g., hippocampus) generate weak scalp potentials; may be missed. --- 📍 When to Use Which | Goal | Preferred Method | Reason | |------|------------------|--------| | Causal role of a specific region | Lesion (temporary if reversible needed) | Directly removes/disable function; behavior change indicates necessity. | | Non‑invasive human study of cortical excitability | TMS (stimulatory protocol) | Safe, reversible, can up‑ or down‑regulate activity. | | Whole‑brain activity map during a task | fMRI | High spatial resolution, whole‑brain coverage. | | Temporal dynamics of stimulus processing | EEG/MEG | Millisecond resolution; ideal for event‑related potentials. | | Metabolic/ neurotransmitter imaging | PET | Directly measures radiotracer uptake (e.g., dopamine). | | Precise spike timing & coding | Single‑unit recording | Captures action potentials of individual neurons. | | Assess contribution of a specific gene | Knockout/Transgenic animal (or inducible system for reversibility) | Manipulates molecular pathway; observe behavior & physiology. | | Model testing & hypothesis generation | Computational modeling | Allows simulation of complex networks before costly experiments. | | Studying naturalistic animal behavior | Markerless pose estimation (DeepLabCut, Anipose, Keypoint‑MoSeq) | High‑throughput, minimal interference with behavior. | --- 👀 Patterns to Recognize Bidirectional affect activation – fMRI studies often show overlapping regions for savoring positive affect and rumination on negative affect. Stress‑induced structural changes – chronic stress → hippocampal shrinkage, amygdala enlargement. LTP ↔ memory – prolonged high‑frequency stimulation → long‑term potentiation → stronger synaptic efficacy → memory consolidation. Motor cortex precedes movement – early BOLD/MEG activity in primary motor area predicts upcoming limb motion. Lesion‑induced behavioral deficits – specific deficits (e.g., spatial memory loss) frequently follow hippocampal lesions; motor deficits follow cerebellar lesions. --- 🗂️ Exam Traps Distractor: “fMRI directly measures neuronal firing.” – tempting because BOLD signal looks like activation; actually measures blood oxygenation. Distractor: “All lesions are permanent.” – many labs use temporary (cooling, tetrodotoxin) or reversible TMS lesions. Distractor: “PET provides better spatial resolution than fMRI.” – PET’s resolution (4‑5 mm) is lower than modern fMRI (2 mm). Distractor: “Genetic knockouts never affect development.” – developmental compensation can mask or alter phenotypes. Distractor: “Behavioral neuroscience studies only animals.” – human studies using TMS, fMRI, EEG are core components. Distractor: “Higher brain activity always means better performance.” – increased activation may reflect inefficiency or compensatory effort. ---