PSYC211 exam - quizlet

Reaction time

Choice reaction time is typically between 350-450 ms

Central nervous system

brain and spinal cord

Peripheral nervous system

the sensory and motor neurons that connect the central nervous system to the rest of the body

Somatic nervous system

Division of the PNS that controls the body's skeletal muscles.

Afferent

Input to a nerve

Efferent

output of a nerve

Cranial nerves

12 pairs of nerves that carry messages to and from the brain

Spinal nerves

31 pairs go in and out of brain, come in through dorsal (back) side and leave through ventral (front) side

Forebrain

Telencephalon - Cerebral cortex Diencephalon - subcortical

Six layers of neocortex

Molecular, External granular, external pyramidal, internal granular, internal pyramidal, multiform

Neurons

a nerve cell; the basic building block of the nervous system

Neruons - voltage

Have a negative membrane potential of -70mv while resting

Flow of ions across the membrane causes changes in potential, which creates and electrical impulse

ions involved in action potential

Sodium enters the cells, potassium leaves

Sodium concentration

Concentration gradient of sodium is into the cell Electrical gradient for sodium is also into the cell

Depolarisation

The change from a negative resting potential to a positive action potential (caused by opening of sodium channels)

Graded potential

a membrane potential that varies in magnitude in proportion to the intensity of the stimulus

Action potential

the change in electrical potential associated with the passage of an impulse along the membrane of a muscle cell or nerve cell.

Ion channels

Voltage gated sodium channels A certain voltage is required for them to open causes a positive feedback loop

Hodgin Huxley Cycle

Synaptic potential → membrane depolarises → voltage-gated ion channels open → Na flows into neuron → positive feedback → membrane depolarises

sodium-potassium pump

a carrier protein that uses ATP to actively transport sodium ions out of a cell and potassium ions into the cell

Action potential propogation

Travels along axon Travels at 0.5 to 2 metres per second

Myelin

a fatty substance that helps insulate neurons and speeds the transmission of nerve impulses Strength of action potential is boosted in nodes of ranvier boosts signal to 100m/s

multiple sclerosis

myelin sheath destruction. disruptions in nerve impulse conduction

The retina

the light-sensitive inner surface of the eye, containing the receptor rods and cones plus layers of neurons that begin the processing of visual information

Rods + cones

Named by their shape Cone mediated - high acuity colour vision in light Rod mediated - low acuity monochrome, in dark

Convergence

Cones - fed into their own individual bipolar and retinal ganglion cells

Rods - multiple rods connect to bipolar into fewer retinal ganglion cells

Distribution of rods and cones

Cones are situated in the middle of retina (macula, fovea)

Rods are mainly situated everywhere else

Number of photoreceptor cells

about 120 million rods about 6 million cones

Photosensitive retinal ganglion cells

Some ganglion cells use melanopsin to detect blue light These induce circadian rhythm Situated at bottom of eye, so they are more responsive to light from the sky

Neurotransmission

Release of chemicals across the synaptic cleft Most retina cells release glutamate, which is excitory Amacrine and horizontal cells release GABA which is inhibitory

opponent-process theory

Parts of nervous system suppress others that give competing information

complex cells

Visual cells in V-1 that respond to lines Many different specific receptive fields

Primary visual cortex

Where 90% of visual information goes first after LGN First characterised by David Hubel and Torsten Weisel

Simple cells

Cells in V1 that respond to line, or gradient, oriented in particular direction

Complex cells

Cells in V1 that give best response to moving lines of particular orientation

Cell hierarchy - visual system

Many ganglion cells feed into fewer LGN cells, which feed to fewer simple cells, leading to fewer complex cells

Columnar architecture of V1

Varying regions of V-1 respond to lines in different orientations

Retinotopic mapping

An arrangement of neurons in the visual system whereby signals from retinal ganglion cells with receptive fields that are next to each other on the retina travel to neurons that are next to each other in each visual area of the brain

Top-down processing

Cortex makes assumptions about the environment and fills in gaps

bottom-up processing

analysis that begins with the sensory receptors and works up to the brain's integration of sensory information

Parallel pathways

From v-1 information is split into the dorsal and ventral streams Ventral stream is concerned with implication of objects

v-5 motion

Ventral stream goes to V-5 Focuses on how an object is moving Cells have a preferred direction and speed

Neurological evidence of V-5

People with bilateral damage of V-5 develop akinetopsia The failure to perceive motion

What motion detection is used for

Capturing attention Computing shape of 3-d objects Estimation of direction Optic-flow: pattern of apparent motion

Sound

Pressure pulses we perceive to carry information Humans hear from 200-20,000 Hz

Cochlea

Where sound information is received Has a tonotopic map

Hair cells

Respond to movement Mechanical movement causes ion change and electrical impulses

Outer hair cells

Auditory receptor cells in the inner ear that amplify the response of inner hair cells by amplifying the vibration of the basilar membrane.

Inner hair cells

neurons in the cochlea; responsible for auditory transduction

Parallel pathways - audition

Nervous system splits into high and low frequencies This may be because large objects tended to be a threat - evolutionary

Top-down influences on A-1

66% of information to auditory complex comes from other cortical regions Helps fill in blank spots

The McGurk effect

Sound is affected by how we see people pronounce it

Representation of complex features

Occurs in ventral stream Places like inferiotemporal cortex

inferiotemporal cortex

Some cells in this area on respond to certain orientations of faces

Jennifer Aniston cells

Rodrigo Quiroga Some cells seem to respond only to Jennifer aniston This suggests every object we can perceive has it's own cell

Problems with Grandmother cells

It requires too many cells Susceptibility to damage - if cells are damaged you couldn't perceive that object anymore How do you perceive novel objects? What's the chance they found a Jennifer Aniston cell using just a couple hundred images?

Distributed encoding

The identification is spread across many cells All cells respond when you see the object

Sparseness

Sparseness of Grandmother cells maximises memory, but there is a big trade off with generalisabiltiy

Recent evidence for recognition network

Doris Tsao Recorded face patterns through temporal lobe Mapped a face and saw how neurons responded to changes

Binding

How the brain pieces information together Convergent hierarchical encoding vs. temporal binding

Convergent Hierarchical Coding

• Cells firing for each feature of an object converge on a common target cell that is representative of those collective features

• Potentially faster but inflexible and hardwired, ineffective for coding modified or novel objects or experiences, requires massive neuronal resources, and susceptible to damage

Temporal binding

• Features that occur together in time are more likely to be related

• Distributed neural responses are tied together by the coordinated timing of their firing patterns

• This synchrony can be associated with repeated, oscillatory activity -Cells that fire together, wire together

Schizophrenia

a group of severe disorders characterized by disorganized and delusional thinking, disturbed perceptions, and inappropriate emotions and actions

two-hit model of schizophrenia

Developmental issues + environmental factors Now thought to be a neurodevelopmental disorder

Effects of schizophrenia on brain

Enlarged ventricles Reduction in size of regions: frontal cortex and medial temporal lobe Excessive subcortical dopamine activity Changes in GABA neurotransmission

The dopamine hypothesis

Drugs that increase dopamine can give schizophrenia symptoms Over activation of nucleus accumbens produce positive symptoms of schizophrenia

The glutamate hypothesis

Manipulating the glutamate system has a broad effect on schizophrenia

Coherence

Neurons firing together at the same time People with schizophrenia have lower frequency osscilations of neurons

Auditory steady state response

Ossicaltions can be induced with sound ASSR is reduced in patients with schizophrenia At 20Hz neurons tend to fire twice

Donald Hebb

Wrote the organisation of behaviour Theorised that any event causes a pattern of activity within the neurons

Short term memory

Neurons fire in a closed loop reverberating manor

Long term memory

Neurons fire in a closed loop with consolidated synapses

How connections are strengthened

Donald Hebb Post-synaptic and pre-synaptic neurons fires at hte same time "cells that fire together, wire together" Allows for association of inputs

Fear induction

Pain neurons firing at the same time as neurons representing visual stimuli creates fear Crab example

Long term potentiation

an increase in a synapse's firing potential after brief, rapid stimulation. Believed to be a neural basis for learning and memory.

Why does LTP occur?

Extra stimulation causes glutamate to bind to NMDA receptor and the ion channel associataed opens and lets Mg2+ out and Ca2+ in

How to test LTP

Rat in a pool tries to find platform Those with NMDA antagonist do much worse Over activation of LTP also confuses rats

Rat on a turntable

Drug developed to turn off LTP Maintainence of LTP requires kinase ZIP causes it to decay Rats could lose memories

Mass action

The cerebral cortex acts as one in many types of learning

Equipotentiality

the idea that memory is distributed throughout the brain rather than confined to any specific location

other parts of the brain can adapt if areas are damaged

Karl lashley

Patient HM

A patient who, because of damage to medial temporal lobe structures, was unable to encode new declarative memories. Upon his death we learned his name was Henry Molaison.

HM's deficits show

Dissociation of intelligence and memory Dissociation of declarative and procedural memory Hippocampus, medial tmeporal lobe structures involved in memory

Patient RB

Ischaemic episode during open heart surgery Selective, marked anterograde amnesia and very minor retrograde amnesia Rey-osterrith task showed RB has a little bit of memory present

Patient NA

Had a mini fencing foil shoved up his nose Anterograde amnesia + visual learning deficits

Wernicke-Korsakoff syndrome

Organic brain syndrome resulting from prolonged heavy alcohol use, involving confusion, unintelligible speech, and loss of motor coordination. It may be caused by a deficiency of thiamine, a vitamin metabolized poorly by heavy drinkers. Damage occurs in mammillary bodies and dorsomedial nucleus of the thalamus

Types of explicit memory

episodic and semantic

Types of implicit memory

procedural, priming, conditioning, habituation

What can we infer from retrograde amnesia

Memories are initially stored in the hippocampus and the consolidate elsewhere

Optogenetics

Transgenic technique that combines genetics and light to control targeted cells in living tissue

Optogenetics - false memory

Animal has no reason to fear original environment, but has received a shock when neurons representing that environment were active

So it fears the environment

Egocentric space

a map of space coded relative to the position of the body

Allocentric space

the frame of reference is the external world

Beacon homing

Travelling directly towards a fixed landmark Uses egocentric cues

Dead reckoning/path integration

calculating one's current position by using a previously determined position, and advancing that position based on known or estimated speeds, elapsed time, and course

Piloting

A type of navigation using landmarks relative distance

Rat study water navigation

Rats with hippocampal damage had issues with piloting, though they were fine when using beacon homing

Food caching

when an animal acts in a way to store food for later Marsh tit does this and has smaller brain, but larger hippocampus than great tit

Human spatial memory

London taxi drivers appear to have increase volume in their posterior hippocampus, and decreased size of anterior hippocampus Whereas bus drivers had larger anterior hippocampi

Cognitive map

Tolman's term for the mental representation of the layout of a familiar environment Animals trained to follow a path and when given the option of a short cut, they were able to know it's faster

Place cells

neurons maximally responsive to specific locations in the world Place cell firing is allocentric