PSYCH 275 Pre-Midterm 2 Lectures (Chapters 6, 7, 8, 9)

Bottom two layers of the lateral geniculate nucleus that are composed of large body neurons -- responsive to rods and movement.

Magnocellular Layers

Top four layers of the lateral geniculate nucleus composed of small body neurons -- responsive to colour, fine detail, and slow/stationary objects.

Parvocellular Layers

Brightness contrast that enhances edges. Causes the mach bands illusion.

Contrast Enhancement

Visual stimuli is presented, subject is treated with curare, extracellular electrode is placed in one neuron and neuron's receptive field is mapped. This helps to define the area of the visual field where stimuli fire that neurons.

Hubel and Wiesel Methodology

Monocular cells that respond best to bars or edges.

Simple Striate Cells

Cells that respond best to straight lines of particular orientation.

Complex Striate Cells

Binocular cells which composed more than half of complex striate cells.

Binocular Complex Striate Cells

Neurons are organized in vertical columns and each neuron responds to stimuli from the same part of the retina. Related columns are clustered together, half of the clusters receiving input from the left eye and the other half from the right.

Hubel and Wiesel Conclusions

Component processing occurs at a receptor level; three different photopigments are recognized by cones and the ratio of cones activated at a specific spectrum creates colour differentiation.

Young and Helmholtz Trichromatic Theory

There are three classes of cells -- one becomes active more to red and less to green, one becomes more active to blue and less to yellow, and one becomes active more to bright than to dark.

Hering Opponent-Process Theory

Perceiving the same colour despite changes in the wavelengths of light, which allows objects to be distinguished in a memorable way.

Colour Constancy

The colour of an object is determined by reflectance which the visual system calculates. The reflectance corresponds to the wavelengths of three cones.

Retinex Theory

Located in the occipital lobe, receives most inputs from visual relay nuclei of the thalamus.

Primary Visual Cortex

Located in the prestriate cortex, receives input from the primary visual cortex.

Secondary Visual Cortex

Located in the inferotemporal cortex and the posterior parietal cortex, receives input from the secondary visual cortex.

Visual Association Cortex

scotomas, areas of blindness in corresponding areas of the visual field.

Damage to the primary visual cortex results in...

Information flows from the primary visual cortex, travels through the dorsal prestriate secondary visual cortex, and ends in the association cortex of posterior parietal region. Prosposed to be the "where" pathway.

Dorsal Stream

Information flows from the primary visual cortex, travels through the ventral prestriate secondary visual cortex, and ends in the association cortex of the inferior temporal region. Proposed to be the "what" pathway.

Ventral Stream

Specializes in visual spatial perception and visually guided behaviours.

Dorsal Stream Theory

Specializes in visual pattern recognition and conscious visual perception.

Ventral Stream Theory

Inability to consciously recognise faces (can recognize faces unconsciously and may be caused by damage to the fusiform face area).

Prosopagnosia

Deficiency in the ability to see smooth movement which can be triggered my damage to the medial temporal area and/or high antidepressant doses.

Akinetopsia

Area of the eye through which light enters; size is regulated by the iris and is a compromise between sensitivity and acuity.

Pupil

Focuses light on the retina; focus is called accommodation (near lens is cylindrical, far lens in flattened).

Lens

Difference in image location of an object seen by the left and right eyes, resulting from the eyes' horizontal separation (parallax). Greater for closer things and helps create depth perception.

Binocular Disparity

Front to back: retinal ganglion cells, amarcine cells, bipolar cells, horizontal cells, and receptor layer.

Retina Five Layers

Small depression in retina where visual acuity is the highest.

Fovea

Round spot on the retina formed by the passage of the axons of the retinal ganglion cells, resulting in a blind spot.

Optic Disk

Rods and cones mediate different types of vision.

Duplexity Theory

Light vision with high acuity which has low sensitivity, few receptors, and low convergence. Primarily utilises the fovea and cones.

Photopic Vision

Dark/dim vision with low acuity and has high sensitivity, many receptors, and high convergence. Useful for periphery vision and primarily utilises rods.

Scotopic Vision

from the retinal rods and cones to the geniculate in the thalamus to the striate cortex in the occipital lobe.

Visual information travels...

Nasal hemiretinas

_____________ decussate at the optic chiasm.

Temporal hemiretinas

________ stay ipsilateral.

Surface of the visual cortex is a map of the retina.

Retinotopic Layout

Primary sensory, secondary sensory, association sensory.

Three Types of Sensory Cortex

Different parts of the sensory cortexes specialize in different kinds of analysis/

Functional Segregration

The brain is organized so that information flows between structures simultaneously along multiple pathways.

Parallel Processing

determines how loud a sound will be.

Amplitude...

determines the pitch of a sound.

Frequency...

Lowest frequency produced by any particular instrument.

Fundamental Frequencies

determines timbre.

Complexity...

Study of the way general functions may be represented or approximated by sums of simpler trigonometric functions

Fourier Analysis

Separates the outer ear from the middle ear, aka the eardrum.

Tympanic Membrane

Includes the ossicles (malleus, incus, stapes). Connected to the back of the nose and throat via the eustachian tube.

Middle Ear

Part of the ear that contains organs for hearing and equilibrium. Contains the vestibule, semicircular canals, and the cochlea.

Inner Ear

A membrane covering the entrance to the cochlea in the inner ear.

Oval Window

Located within the cochlea, it contains three rows of outer hair cells and one row of inner hair cells which transduce sound waves.

Organ of Corti

Sensory receptors that transduce sound waves into electrical activity.

Hair Cells

Higher frequencies are situated closer to the oval window and lower frequencies are situated farther from the oval window.

Tonotopic Organization

Hair cells synapse on neurons --> axons enter metencephalon --> axons synapse in ipsilateral cochlear nucleus --> travel to superior olives --> travel to inferior colliculus via lateral lemniscus --> fibres ascend to medial geniculate nucleus of the thalamus --> fibres ascend to auditory cortex in the lateral fissure

Pathway from Inner Ear to Brain

Receives input from the medial geniculate nucleus. Includes the core region, belt, and parabelt areas.

Auditory Cortex

identifies sounds.

Anterior auditory pathway...

identifies where sound is.

Posterior auditory pathway...

Bilateral legions do not cause deafness but does create difficulty in localisation and recognising rapid complex sequences of sound.

Auditory Cortex Damage Effects

Mechanical deafness, e.g. damage to ossicles.

Conductive Deafness

Nerve or nerve cell deafness, e.g. damage to the cochlea or nerves.

Nerve Deafness

Receptors for mechanical (touch), thermal (temperature), and nociceptive (surface pain) stimulation.

Exteroceptive Cutaneous System

Receptors for sense of kinesthesis and body position.

Proprioceptive System

Receptors for in-body stimulations.

Interoceptive System

Pain and temperature receptors.

Free Nerve Endings

Deep fast-acting touch receptors.

Pacinian Corpuscles

Receptors for mechanical pressure, position, and deep static touch features such as shapes and edges.

Merkel Receptors

Slow adapting touch receptors.

Ruffini Corpuscles

Identification of objects by touch using fast and slow-adapting receptors.

Stereognosis

Carries information about touch and proprioception. Receptors enter the spinal cord and ascend ipsilateral dorsal columns to the dorsal column nuclei. Dorsal-column nuclei decussate and ascend medial lemnicus and then travel to the ventral posterior nucleus. Axons of the ventricular posterior nucleus ascend to the somatosensory cortex.

Dorsal-Column Medial-Lemniscus System

Mediates pain and temperature. Axons synapse as soon as they enter the spinal cord and second order axons decussate and travel along three paths: spinothalamic, spinoreticular, and spinotectal.

Anterolateral System

Projects to the ventral posterior nucleus of thalamus. Lesions here tend to lead to loss of somatosensation and sharp pain perception.

Spinothalamic Tract

Projects to the reticular formation and then to the parafascicular and intralaminar nuclei of the thalamus.

Spinoreticular Tract

Projects to the mesencephalic tectum.

Spinotectal Tract

Loss of the ability to recognise objects by touch.

Astereognosia

Loss of the ability to recognize part's of one's own body.

Asomatognosia

Gate Control Theory

Descending Pain Control: Melzack and Wall

Severe and/or chronic pain originating from no known stimulus that usually develops after injury. Glial cells may trigger hyperactivity in pain pathways.

Neuropathic Pain

Transduction in olfactory mucosa --> axons travel through cribriform plate and synapse on olfactory bulbs --> terminate in discrete clusters of neurons (olfactory glomeruli) --> axons then travel to piriform cortex and amygdala --> project to limbic system and medial dorsal nucleus of the thalamus --> then travel to orbitofrontal cortex where odour is consciously perceived

Pathway of Olfaction

Sweet (2 metabotropic receptors), sour, bitter (25 metabotropic receptors), salty, umami (1 metabotropic receptor). Salty and sour activate ionotropic receptors.

Five Primary Tastes

Transduction by taste buds in oral cavity --> single presynaptic cell integrates signals from all receptors and synapses efferent neuron --> axons project to facial, glossopharyngeal, and vagus nerves --> axons also project to solitary nucleus of medulla --> solitary nucleus projects to ventral posterior nucleus of thalamus --> travels to primary gustatory cortex and secondary gustatory cortex

Gustatory Pathway

ipsilateral

Projections from the gustatory system are largely...

Inability to smell caused by damage to the olfactory nerves as they pass through the cribriform plate and is linked to epilepsy, Down Syndrome, Parkinson's disease, multiple sclerosis, and other degenerative disorders.

Anosmia

Inability to taste which is rare and may be cause by damage to the facial nerve.

Aguesia

Images which have the possibility of being perceived in two ways (e.g. an image that is different in the dark space versus the white space).

Bistable Figures

Conscious awareness of a percept in the absence of an external stimuli, e.g. phantom limb pain.

Phantom Percepts

The problem arising from the notion that the visual system (and many other systems) disassembles incoming stimuli into different processing streams, each dealing with a separate feature such as color, orientation, or motion, in specialized regions of the cortex, but we perceive these things as belonging to the same thing without them being re-integrated in a specific area of the brain.

Binding Problem

Capacity for processing certain stimuli selectively when several occur simultaneously.

Selective Attention

Believed to be a top-down process wherein attention is voluntary, sustained, and goal-driven.

Endogenous Attention

Believed to be a bottom-up process wherein attention is passive, transient, automatic, and stimulus-driven.

Exogenous Attention

The ability to focus one's attention to a particular stimulus while filtering out a range of other background stimuli.

Cocktail Party Phenomenon

A classic example of selective attention, is the phenomenon that occurs when a stimulus undergoes a change without being noticed by the observer.

Change Blindness

Difficulty attending to more than one object at a time which occurs due to damage to the posterior parietal cortex.

Visual Simultagnosia

Hierarchically organised, motor output is guided by sensory input, learning and sensorimotor control (action start as conscious effort when you start learning and eventually become automatic).

3 Principles of Sensorimotor Function

ballistic

Only ________ movements are not guided by sensory feedback.

Association cortex gives direction to lower levels, motor neurons and muscles, which take care of the specific details. This organisation is beneficial because it allows higher levels to focus on more complex functions.

Sensorimotor System: Hierarchal Organisation

The sensorimotor system carefully monitors the external world and is able to adjust its own actions. Sensory input helps with picking things up, adjusting to unanticipated external forces, and maintaining constant force.

Sensorimotor System: Sensory Input

Initially actions are under conscious control and with practice they become integrated sequences of action. They are automatically adjusted without conscious regulation.

Sensorimotor System: Learning

Provides information on where the body parts are in relation to the external world. Receives input from visual, auditory, and somatosensory systems for which the output goes to the secondary motor cortex.

Posterior Parietal Association Cortex

posterior parietal association cortex

Stimulation of the _________ makes the subject feel as if they are performing an action.

Inability to perform certain movements due to damage in the left hemisphere (i.e. the posterior parietal association cortex).

Apraxia

Produced by very large right parietal lesions, individuals only attend to the right side of the body or or items in the environment. Individuals are capable of unconsciously perceiving objects on the left.

Contralateral Neglect

Receives projections from posterior parietal cortex; projects to the secondary motor cortex, primary cortex, and frontal eye field. Involved in assessments of external stimuli and may work alongside the posterior parietal association cortex in decisions regarding voluntary response initiation.

Dorsolateral Prefrontal Association Cortex

2 areas of premotor cortex, 3 supplemental motor areas, 3 cingulate motor cortex. They project to primary motor cortex, to each other, and to the brainstem. Produce complex movements.

8 Areas of Secondary Motor Cortex