Audition, Vision, and Alzheimer's Lecture Notes Review

A set of flashcards based on lecture notes about audition, vision, and Alzheimer's, designed to review key vocabulary and concepts.

Single-unit recording

Used to measure neural activity in animals by recording from a single neuron using a fine microelectrode.

Action potentials

Changes in voltage across the neuron's membrane due to the flow of charged ions, leading to excitation.

Depolarization

The process where incoming neural signals cause an influx of positively charged Sodium (Na+) into the axon, making the inside of the cell more positively charged.

Repolarization

The process following depolarization where Potassium (K+) flows out of the neuron, returning the cell to its original state of being slightly negatively charged.

Audition

Our sense of hearing, vital for everyday life, early warning system, and communication.

Hertz (Hz)

Cycles per second, the unit of measurement for the frequency of vibration, measured in (Hz).

Outer ear

Consists of the outer fleshy pinna, the auditory canal, and the tympanic membrane (eardrum).

Tympanic membrane (eardrum)

Vibrates with soundwaves that enter the auditory canal, transmits the signal the middle ear.

Middle ear

Conversion of physical movements to signals into the inner ear. Change in pressure gets converted into movement of eardrum, the ossicles move in response to the eardrum. Mechanical movement causes the scales to push towards the inner ear.

Ossicles

Consists of three tiny bones which move backwards and forwards in response to the eardrums.

Malleus

Hammer, connected to the tympanic membrane.

Incus

Anvil, part of the Ossicles.

Stapes

Stirrup, connected to the cochlea a structure part of the inner ear.

Cochlea

Contains the receptors for analysing sounds.

Stapes

Connected to the oval window and causes fluid to push against the fluid inside the cochlea.

Basilar membrane

Sheet of tissue that contains the auditory receptors.

Organ of Corti

A structure composed of: basilar membrane at its base, receptors in the middle called hair cells (inner and outer), neurons attached to these, rigid shelf over the top called the tectorial membrane.

Stereocilia

Tiny filaments on top of hair cells that bend and produce receptor potentials converting sound waves into neural signals.

Tip links

When the cilia bundle bends, the tension in these cause ion channels to open and close.

Spiral ganglion cells

A neurotransmitter that triggers action potentials in neurons.

Auditory nerve

Axons of many thousands of spiral ganglion cells grouped together to form the 8th cranial nerve

Place code

Different frequencies of sound are coded by particular spiral ganglion cells that are active along its length.

Tuning curve

Demonstrates the particular frequencies of a soundwave to which a neuron responds best.

Primary auditory cortex

Located in a region of the temporal lobe called the superior temporal gyrus.

Tonotopic map:

How lower frequencies are represented more anteriorly and higher frequencies more posteriorly.

Cochlear implants

Individuals with damage to the hair cells, typically due to a congenital abnormality, electrodes inserted along the basilar membrane, and Stimulation causes spiral ganglion cells to generate action potentials.

Cochlear implant

Takes information from the microphone and works out how much there is of different frequencies and breaks them up and stimulates the part of the basilar membrane replicates it.

Visible spectrum

The range of wavelengths in the electromagnetic spectrum that humans are sensitive to.

Cornea

Transparent outer layer of the eye that light enters through.

Lens

Behind the cornea and its shape can be altered to help focus the image onto the back of the eye.

Back of the eye

Lined by a light sensitive structure called the retina.

Optic disk

Rods and cones send their axons out of the eye from here.

Blindspot

A region of space from which an object is not visible, caused by there being no photoreceptors at the optic disk.

Optic Nerve

Axons that are bundled together at the optic disk.

Photoreceptors

Light sensitive (photosensitive) cells located at the back of the retina.

Cones

Most important for seeing fine detail, most active in the daylight, and encodes patterns of light.

Fovea

Concentrated in a region of the retina that is responsible for the central few degrees of our visual field.

Rods

Do not discriminate between different wavelengths, and they can't discriminate fine visual detail.

Bipolar cells

The rods and cones form synapses with these, which in turn form synapses with ganglion cells.

Horizontal cells and amacrine cells

Cell types in the middle layer of the retina, serve the function of combining messages from several photoreceptors.

Ganglion cells

Send their axons through the optic nerve that Conveys visual information to the brain, and already has a degree of pre processing.

Photopigments

Embedded in the lamellae; thin plates of membrane that make up the outer segment of photoreceptors.

Colour blindness

Genetic condition, arise from anomalies in the pigments of one or more cone types in the retina.

Red-green deficient

Poor ability in discriminating red and green affecting around 10% of males and about 1% of females.

Deuteranopia

The green cones are absent.

Protanopia

Red cones are absent.

Interactions in the retina

where plus and minus represent regions where theres excitation + and regions where theres inhibition -.

Centre-surround organisation

ON cells are excited by light in the center of their receptive field, and inhibited by light in their surrounding field; OFF cells are the opposite.

Optic chiasm

After leaving the eye the axons of retinal ganglion cells are bundled together to form the optic nerves, these project posteriorly and medially toward this.

Lateral geniculate nucleus (LGN)

Axons continue posteriorly until they form synapses with neurons in a part of the thalamus.

Retinogeniculate Pathway

The Lateral Geniculate Nucleus (LGN) contains six layers of neurons Each layer receives information from the retinal ganglion cells in the optic nerve of only one eye in a semi alternating fashion.

Magnocellular layers

Contain cells that are larger and are Important for detecting movement or change.

Parvocellular layers

Cause they look smaller, processing colour signals, and Red green processing, detail.

Koniocellular sublayers

Located below each of the magnocellular and parvocellular layers mixes in Blue information and Some form of movement.

Centre surround receptive field structure in the LGN

Active: ON centre – OFF surround-- increase neuron firing rate If light turns on that stimulates centre- sends signal to the brain saying theres light here.

Suprachiasmatic nucleus

A specific region of the hypothalamus receives light information from the environment and uses it to entrain behaviours to a 24-hour light/dark cycle.

Melanopsin cells

Retinal ganglion cells help synchronize our lives.

Bionic Eye

Can stimulate the spiral of spiral ganglia cells in a way which mimics the way the hair does their jobs.

Restoring sight after retinal disease with Bionic Eye that uses a retinal implant

Based on an understanding of the retinotopic arrangement of ganglion cells.

Primary visual cortex

Located in the medial surface of the left hemisphere And is the first cortical region to receive axons from visual cells in the lateral geniculate nucleus

Hemianopia

Damage to V1 in the right hemisphere will cause blindness in the left visual field.

Cortical magnification

Cells from the primary visual cortex being used to process information from the central region are much more than the amount used to process information in our periphery.

Lateral Geniculate Nucleus (LGN)

Magnocellular input is received by sublayer 4C α Responsive to rapid changes- flashes of movement.

Blob regions

Cells respond to colour variation-- priority of region to process located within the Cytochrome oxidase (CO) blobs receive input from one eye and are sensitive to colour.

Interblob regions

Located in the striate cortex Neurons outside the CO blob (the interblob regions) are more sensitive to orientation, movement, and binocular disparity (depth), but typically do not respond to colour.

Simple cells

Receive inputs from several LGN neurons with adjacent receptive fields gives you an extended region of excitation.

Orientation mapping in cat visual cortex by Hubel and Weisel

An electrode is lowered into the visual cortex until it is close enough to a neuron to pick up the electrical changes associated with action potentials.

Modular organization

Each area has neurons with receptive fields that tile the visual field which Focuses on a particular aspect of the visual scene.

Primary visual cortex

Cell that respond to the upper and lower visual field, cells that respond to where we are looking at, and cells that respond to patterns in our periphery that include 1. Area V4, which has neurons that are sensitive to the colour of visual inputs 2. Area MT, which is responsive to moving visual stimuli

Dorsal and ventral stream

Build up a representation of objects are where they are.

Ventral stream

Computes a detailed map of the world from visual input 'Where'.

Dorsal stream

Transforms incoming visual information for action 'What'.

Wavelength sensitivity in the retina

The range of wavelength we are sensitive to. Spectral sensitivity of L, M & S cones which occurs between 419 nm – 559 nm,. Congenital colour blindness.

R–G opponent ganglion cell

Excitatory or Inhibited by red or green light, no signal when yellow is shown due to stimulating both cones equally.

Y–B opponent ganglion cell

Excited by yellow or blue light, or some cases, no signal change comes.

V4:

Area is highly responsive to colour and also responsive to changes in shape & curvature,.

Achromatopisa:

Selective loss of colour perception, and The loss of colour vision in isolation, without any corresponding impairment of other visual abilities.

Patient DB

Lesion to V1 in the right area. Dark region corresponds to region where not pressing the button in response to visual Stimuli.

Evolutionarily older visual pathways

An only visual pathway in some animals supports ”basic” visually guided responses.

Change Blindness:

Used to support the conscious or unconscious behaviour as the patient Is required to find the small differences between two nearly identical images.

Unilateral spatial neglect:

The inability is for a failure of spatial awareness and is Due to Damage to V1 causes loss of visual awareness.

Actionable space:

Is the way the person memorise that have memory has to walk or Grasping a viewpoint.

Cognitive map:

An a representation not Unilke a physical map that you can consult and work out where you are.

Tolman

Rapidly switch to alternative path if previous path is blocked and implied that animals must have access to spatial knowledge about the environment.

Place cells

Cells fire at specific real world locations and Cells responded Vigorously when rats were in a specific location.

Grid cells

Cell has move over certain locations the neuron and would respond if Was between those nodes not response. Grid cells are thought to support coding of metric distances as the animal moves through the world.

Head direction (HD) cells

They fire on the basis of the direction the head is facing. HD cells are implicated in the tracking of heading direction.

Border/boundary cells:

Fire when the animal is at set distances from navigational boundaries facing in specific directions.

Parahippocampal place area (PPA):

Preferentially processes scenes and lies along the parahippocampal gyrus and collateral sulcus boundary between posterior parahippocampal cortex and anterior lingual gyrus

MVPA decoding of landmark identity.

To Determine if the Brain region relates to landmark identity,Related Landmark location not identity and Related at particular time.

Hippocampus volume:

Is Positively Correlates with Goal Distances During Navigation and Patterns of data showing.Hippocampal.

Henry Molaison (patient HM)

Used for long term memory- 1926 – 2008 (died aged 82). Most studied patient in history of neuroscience.

Impact on memory

Poor recollection for years prior to surgery and Could not remember events after the surgery

Retrograde amnesia

Impairment for memories created prior to injury

Anterograde amnesia

Impairment for memories created after injury.

Declarative memory (facts, events):

Conscious access to the events in the past. (e.g playing piano).

Procedural memory(skills, tasks)

Remembering ‘how to’ (e.g playing piano). (nondeclarative).

The mesial temporal lobe structures

Are essential for memory function- more essential for anterograde than retrograde memory.

consists of paired Associate Learning.

Necessary to make these association,Required to remember an association between arbitrary.

Neurotransmitter exchange:

These results from electrical changes Ions moving across the cell membrane in coordinated Way.