Neuroscience Lecture: Sensation, Perception, Language, and Self-Identity

Comprehensive vocabulary flashcards covering the chemical senses, the auditory system and language neuroanatomy, visual streams and attentional systems, face/object recognition disorders, and hemispheric lateralization.

Gustation

The sense of taste, initiated when chemicals from food dissolve in saliva and activate taste receptor cells within taste buds.

Five Basic Tastes

The five fundamental modalities detected by taste receptor cells: sweet, salty, sour, bitter, and umami (savory).

Olfaction

The sensory sense of smell, initiated when odor molecules activate olfactory receptor neurons in the nose.

Olfactory Bulb

An early sensory structure that receives signals from olfactory receptor neurons and sends olfactory projections to cortical areas without relaying first through the thalamus.

Mitral Cells

The principal output neurons of the olfactory bulbs that receive input from olfactory receptor neurons/glomeruli and relay odor information to cortical regions, including the piriform cortex.

Piriform Cortex

A major component of the olfactory cortex located in the temporal/ventral forebrain that processes odor information, aids in identifying scents, and registers olfactory signals into conscious awareness.

Primary Gustatory Cortex

The cortical structure located primarily within the insula and frontal operculum that processes taste information.

Blindsight

A phenomenon in which individuals with lesions in the primary visual cortex can respond to certain visual stimuli without having conscious awareness of seeing them.

Thalamus

The subcortical 'neural gatekeeper' that modulates and relays sensory input before it reaches conscious awareness, with the exception of olfaction.

Vomeronasal Organ

A specialized group of molecule-sensing receptors inside the nostril highly responsive to pheromones, whose functional presence in humans remains debated.

Pheromones

Chemical messengers secreted by organisms to communicate with and alter the behavior of conspecifics, influencing mating, sexual selection, aggression, and social interactions.

Vasopressin

A neuropeptide influencing social behavior; blocking it from reaching olfactory receptors in rats impairs individual recognition, rendering them 'socially blind' within their colony.

Oxytocin

A hormone ('quick birth' / 'love hormone') that promotes labor contractions and whose intranasal administration can enhance trust and in-group social bonding, while also increasing aggression toward out-group individuals.

Mirror Neuron System

A network of neurons (predominantly in the frontal cortex) that fire both when an individual executes an action and when observing another individual perform that same action.

Ventral Premotor Cortex

A motor-planning region commonly associated with mirror neurons in monkeys, showing neural activity prior to action execution and during observation of that action.

William James's Bear

An illustration of William James's 1884 counterintuitive theory of emotion stating that physiological bodily reactions precede and generate emotional feeling (e.g., seeing a bear causes trembling/running, which then triggers the feeling of fear).

Pseudobulbar Affect

A neurological condition caused by brain lesions or psychiatric disorders marked by uncontrollable, involuntary emotional outbursts (such as pathological laughing or crying) that do not match the situational context.

Scent Tracking (Jess Porter)

Research demonstrating that humans can follow scent trails across terrain, improve with practice, and that tracking performance correlates with higher sniff frequency.

Tympanic Membrane

The eardrum; a thin membrane that vibrates in response to incoming sound pressure waves.

Basilar Membrane

A cochlear structure that decomposes complex sound into individual frequency components; it is narrower and stiffer at the base (high frequencies) and wider and less stiff at the apex (low frequencies).

Primary Auditory Cortex

Located in the superior temporal lobe on Heschl's gyrus; organizes acoustic information tonotopically, representing lower frequencies anteriorly and higher frequencies posteriorly.

Heschl's Gyrus

A prominent anatomical ridge of gray matter in the superior temporal lobe that houses the primary auditory cortex.

Echolocation

A perceptual navigation method utilizing self-generated vocal/clicking sounds and their returning echoes to map the spatial location of objects.

Daniel Kish

A completely blind individual with prosthetic eyes who navigates and perceives space through learned human echolocation using tongue clicks.

Positron Emission Tomography (PET)

A functional neuroimaging technique measuring changes in regional blood flow and metabolic consumption (glucose and oxygen) during specific tasks, such as Braille reading.

Transcranial Magnetic Stimulation (TMS)

A non-invasive technique using rapidly changing magnetic fields to temporarily disrupt local cortical activity; demonstrated that disrupting the visual cortex impairs Braille reading in blind individuals.

Brainstem Auditory Evoked Potential (BAEP)

A diagnostic electrophysiological hearing assessment developed by Galambos using scalp EEG electrodes to evaluate auditory brainstem pathway integrity in newborns.

Superior Temporal Gyrus

A temporal lobe structure critical for auditory processing and speech comprehension, containing parts of Wernicke's area within the left hemisphere.

Wernicke's Area

A cortical region situated around the temporoparietal junction and posterior superior temporal gyrus (typically in the left hemisphere) critical for the comprehension of spoken and written language.

Wernicke's Aphasia

A receptive language disorder characterized by impaired language comprehension with preserved, fluent, but often nonsensical or incoherent speech production.

Broca's Area

A region in the inferior frontal gyrus (frontal lobe), described by Paul Pierre Broca, responsible for speech and motor language production.

Broca's Aphasia

An expressive language disorder characterized by effortful, non-fluent speech production and grammatical deficits, with relatively preserved language comprehension.

Telegraphia

A pattern of non-fluent speech consisting primarily of content words and fragmented phrases while omitting connecting syntax and grammatical filler words.

Arcuate Fasciculus

A prominent white matter axon tract that bidirectionally connects Wernicke's area in the temporal lobe with Broca's area in the frontal lobe.

Conduction Aphasia

A language deficit resulting from damage to the arcuate fasciculus, characterized by a severe difficulty in repeating spoken words and phrases despite preserved comprehension and fluent spontaneous speech.

Wada Test

A pre-surgical procedure developed by Juhn Atsushi Wada where sodium amobarbital is injected into one internal carotid artery to anesthetize an entire hemisphere, determining hemispheric language lateralization.

Hair Cells

The mechanoreceptor sensory cells of the inner ear cochlea that convert fluid vibrations into receptor potentials and auditory action potentials.

Tip Links

Elastic molecular filaments connecting adjacent stereocilia on hair cells that mechanically pull open ion channels upon stereociliary deflection, depolarizing the cell.

Auditory Pathway

The neural route of acoustic transmission: cochlea $\rightarrow$ vestibulocochlear nerve ($\text{CN VIII}$) $\rightarrow$ cochlear nucleus $\rightarrow$ lateral lemniscus $\rightarrow$ inferior colliculus $\rightarrow$ medial geniculate nucleus $\rightarrow$ primary auditory cortex.

Spatial Attention

The cognitive mechanism of focusing conscious awareness onto a specific coordinate or region in the visual environment, functioning like an adjustable spotlight.

Cortical Blindness

Visual loss resulting from bilateral damage to the visual processing regions of the brain (such as V1) despite intact, functional eyes and retinas.

Retina

The light-sensitive neural tissue lining the back of the eye containing photoreceptor cells, intermediate interneurons, and ganglion cells.

Photoreceptors

Specialized retinal cells (rods and cones) that transduce incident photons of light into electrochemical signals.

Optic Disk

The point of retinal egress where retinal ganglion cell axons converge to form the optic nerve; contains no photoreceptors and constitutes the physiological blind spot.

Optic Chiasm

The X-shaped junction where optic nerve fibers originating from the nasal hemiretina of each eye cross contralaterally to the opposing hemisphere.

Lateral Geniculate Nucleus (LGN)

A laminated sensory relay nucleus within the thalamus that receives retinal inputs via the optic tract and projects to the primary visual cortex.

Optic Radiations

Broad bundles of axonal projections carrying retinotopic visual information from the lateral geniculate nucleus of the thalamus to the primary visual cortex in the occipital lobe.

Primary Visual Cortex (V1)

The striate cortex located in the occipital lobe that creates topographic visual maps of the contralateral visual hemifield.

Extrastriate Cortex

The secondary visual areas surrounding V1 that process higher-order visual dimensions such as color, curvature, form, and movement with increasingly large receptive fields.

Receptive Field

The specific region of sensory space (or visual field) that, when stimulated, alters the firing rate of a particular sensory neuron.

Ventral Visual Stream

The 'what' processing pathway extending from the occipital lobe into the inferior temporal cortex, responsible for object, scene, and facial identification.

Dorsal Visual Stream

The 'where' or 'how' visual processing pathway projecting from the occipital lobe to the posterior parietal cortex, involved in spatial localization, visually guided action, and integrating visual space with proprioception.

Proprioception

The somatosensory awareness of the physical position, orientation, and movement of one's own body parts in space.

Balint's Syndrome

A triad of visuospatial deficits resulting from bilateral occipitoparietal lesions, consisting of simultanagnosia, psychic paralysis of gaze, and optic ataxia.

Simultanagnosia

The inability to visually perceive more than one discrete visual object at a single time.

Psychic Paralysis of Gaze

A visual deficit characterized by an inability to voluntarily direct, initiate, and maintain fixational eye movements onto a target visual stimulus.

Optic Ataxia

A visuomotor disorder characterized by severe spatial misreaching when attempting to manually grasp objects under visual guidance, despite intact motor strength.

Hemispatial Neglect

A syndrome caused by unilateral parietal or temporoparietal lesions characterized by a failure to perceive, attend to, or orient toward stimuli presented in contralesional space.

Disengagement Deficit

An attentional impairment identified by Michael Posner wherein an individual cannot disengage visual attention from an already attended target to shift to a new target.

Bottom-up Attention Capture

Exogenous, stimulus-driven allocation of attention triggered automatically by salient external environmental stimuli (e.g., a sudden bright flash or loud sound).

Top-down Attention Control

Endogenous, goal-directed voluntary modulation of attention that allows sustained focus on a target while actively suppressing extraneous environmental distractions.

Fornix

A C-shaped tract of white matter that originates at the mammillary bodies and arches forward to connect with the hippocampus.

Capgras Delusion

A delusional misidentification syndrome characterized by the persistent false conviction that familiar individuals (such as close relatives or partners) have been replaced by identical imposters.

Prosopagnosia

A neurological condition ('face blindness') marked by an inability to recognize familiar human faces despite preserved general visual acuity and object recognition.

Prosopometamorphopsia

A visual perceptual distortion where the geometric proportions and features of human faces appear warped, melted, or displaced.

Fusiform Face Area (FFA)

A specialized region within the ventral temporal fusiform gyrus dedicated to holistic face perception and configuration.

Parahippocampal Place Area (PPA)

A sub-region of the ventral visual stream within the parahippocampal cortex selectively engaged in recognizing environmental scenes, landscapes, and buildings.

Superior Temporal Sulcus (STS)

A visual-auditory association region situated superior to the FFA implicated in decoding dynamic facial expressions, biological motion, and perceived emotion.

Optic Aphasia

A selective syndrome where patients can recognize visually presented objects and faces, but are unable to verbally name objects when presented visually.

Cotard's Delusion

A rare neuropsychiatric delusion ('walking corpse' or 'zombie delusion') wherein an affected individual holds the false belief that they are deceased, non-existent, putrefying, or devoid of internal organs.

Alien Hand Syndrome

A neurological motor condition where an upper limb performs autonomous, purposeful, and goal-directed actions outside of the patient's conscious intent.

Callosal Alien Hand Syndrome

A variant of alien hand syndrome arising from surgical or ischemic damage to the corpus callosum, resulting in competitive intermanual conflict between the hands.

Asomatognosia

A neurological loss of body ownership, frequently associated with lesions of the right parietal lobe, causing patients to deny ownership of their contralateral arm or leg.

Corpus Callosum

The largest commissural white matter tract interconnecting the left and right cerebral hemispheres, facilitating interhemispheric transfer of neural data.

Ramón y Cajal's Cross-Wiring Hypothesis

The evolutionary hypothesis proposing that crossed sensory and motor pathways reduce behavioral reaction time by allowing a hemisphere detecting a lateral threat to immediately command contralateral motor responses.

Anterior Commissure

A tract of nerve fibers crossing near the anterior third ventricle (rostral to the fornix) connecting hemispheric structures involved in olfaction, emotion, and memory.

Posterior Commissure

A commissural bundle crossing the midline superior to the midbrain colliculi near the posterior third ventricle, mediating consensual pupillary light reflexes and bilateral eye movements.

Claustrum

A thin sheet of subcortical gray matter situated between the insular cortex and putamen, proposed to coordinate multi-system cortical information and regulate attention.