From lecture transcript to teaching system

Language is a core human capacity supported by distributed neural systems that enable comprehension, production, repetition, reading, and writing. Disruption to these systems produces clinically meaningful language disorders that vary in symptom profile, anatomical correlates, prognosis, and rehabilitation needs. This article synthesizes a practical neuropsychological framework for understanding language dysfunctions, using classical aphasiology as an organizing scaffold while incorporating contemporary clinical realities. We distinguish major aphasia syndromes---including Broca's aphasia, Wernicke's aphasia, conduction aphasia, and anomic aphasia---by emphasizing three clinically decisive dimensions: fluency, comprehension, and repetition. We further differentiate aphasia from apraxia of speech, a motor planning disorder that impairs articulation without necessarily compromising linguistic competence. The article reviews historical foundations (including associationist models of language and hemispheric lateralization), outlines lesion--symptom mapping with attention to the perisylvian network (inferior frontal gyrus, posterior superior temporal cortex, inferior parietal regions, and connecting white matter pathways), and provides guidance on bedside and formal assessment strategies. We also describe the complementary roles of neuroimaging (CT and MRI) and behavioral testing in etiological diagnosis and functional characterization. Finally, we discuss recovery trajectories in stroke, traumatic brain injury, and neurodegenerative disease, highlighting time-sensitive acute care, early spontaneous recovery, longer-term therapy-driven gains, and the constraints imposed by progressive pathology. The result is a set of lecture-based scholarly notes intended to support students, clinicians-in-training, and informed members of the public in interpreting language symptoms as indicators of underlying brain dysfunction and in reasoning about assessment and recovery.

Attention-Deficit/Hyperactivity Disorder (ADHD) is commonly presented either as a straightforward neurodevelopmental disorder best addressed by diagnosis and treatment, or as a socially constructed label that primarily serves institutional interests. Both framings capture partial truths while obscuring the deeper ethical question at stake: how diagnostic language reorganizes authority, responsibility, and the architecture of choice in education and work. Using the critical tradition associated with Thomas Szasz as a springboard, these lecture notes develop an academically grounded framework for discussing ADHD that (i) distinguishes clinical utility from political and institutional consequences of medicalization, (ii) clarifies the normative nature of diagnostic thresholds on continuous trait distributions, (iii) integrates evolutionary ``mismatch'' perspectives to contextualize attentional and motivational styles, and (iv) derives policy-relevant implications for universities and workplaces, including universal design, needs-based accommodations that reduce dependence on diagnostic credentials, and robust informed-consent norms. The central claim is not that ADHD is unreal or that treatment is illegitimate, but that defaulting to medicalized solutions as the primary administrative lever risks eroding autonomy and narrowing acceptable cognitive diversity. A humane and scientifically responsible response requires parallel investment in environmental redesign, pedagogical pluralism, and procedural safeguards that keep the person---rather than the institution---as the primary locus of decision-making.

Perception begins as physics: structured energy and matter in the environment interact with biological receptors, are transduced into neural signals, and are ultimately interpreted as conscious percepts. This article develops lecture notes on the physics of perception for an upper-level Sensation and Perception course. The central aim is to specify what, exactly, sensory systems detect---not in terms of subjective experience alone, but in terms of measurable physical variables that reach the body and can be transformed into neural codes. We articulate a three-stage analysis that helps resolve classic philosophical puzzles (e.g., the ``tree falling in a forest'') by separating (i) events in the physical world, (ii) the subset of those events that can in principle be detected by a given organism, and (iii) the organism's perceptual experience and report. We then survey core forms of environmental energy relevant to human sensation: electromagnetic radiation (vision), mechanical pressure waves (audition), mechanical and thermal interactions at body surfaces and within tissues (somatosensation, proprioception, vestibular function), and chemical structures dissolved in liquids or suspended in air (gustation and olfaction). Throughout, we emphasize that receptor systems are adaptive sampling devices: they restrict access to only a narrow band of the physical world and introduce lawful distortions (amplification, attenuation, compression, nonlinearities) that support behavioral goals rather than veridical recording. We integrate foundational psychophysics (absolute thresholds, just noticeable differences, psychometric functions, Weber fractions) and decision-theoretic signal detection theory (detection as inference under uncertainty) as methodological bridges between physics and experience. Finally, we discuss the epistemic implications of sensory envelopes for evaluating extraordinary perceptual claims and for understanding why perception is reliable enough for survival yet systematically limited and biased.