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Lecture

NROC34 Lec 4.docx

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Department
Neuroscience
Course
NROC34H3
Professor
Karen Williams
Semester
Winter

Description
NROC34 Lec 4 Poster assignment – - P = physiological basis - Submit a physical copy and a copy on turnitin - Read article AT LEAST twice - On poster  make an abstract - SUMMARIZE material in article about physiological basis - Also write about articles found that you’d want other people to read - 3 primary articles and a review article o MUST BE REFERENCED - Abstract o details - Recommended reading - References - 6 slides o 1 : name, student number, article ID o 2: Bird calls and song Chickadee responds to Owl as threat - When played back the song in a reverse direction. How would the hearer respond? - Reverse song = control; doesn’t make a call or any sense whatsoever - ZENK expression increased - Threatening call signal resulted in high ZENK expression - Birds can distinguish the song of other birds Bird songs - Vocalizations, often stereotyped communication, associated with courtship, mating or territory defence - Birds are seen as making pretty songs BUT songs might be the bird being angry - Experiment: tested by having a bird with a certain territory and taped it. Played the song in one area, sometimes of more than 1 bird. It took very long for the territory to be colonized o Paras major  Something about its song was saying get out of my territory Male birds guard against rival males - Male birds spend time guarding the female with whom he has made a nest with - He budgets his time with foraging and guarding depending on number of neighbouring males o If there are many males around, does not spend much time foraging – usually stays guarding - Do they sing songs they learned or are singing by instinct? - to know if learning was important, had to know if bird heard and made similar songs after hearing the song when it was a juvenile? - Experiment: Played the song to birds that their father sang o Then played the song to birds that were deafened - Results: Only the bird with intact hearing copied the song o In graphs: who sings?  Males – predominantly o This is why the father’s song is played o Song can be described by different motifs (picture of brain) - Could measure ZENK expression in calls - Area X is very important for bird song - LMAN - HVC = high vocal center - NCM - RA o These areas all important for songs 2.7 Changes in - looking at HVC - compared neurons in the HVC in males and females o In males, number of neurons increases while in females it decreases Male/ Female - Males have bigger robust nucleus of arcopallium (RA) than females o RA is important in the song system - Number of neurons in HVC is more in males - What makes a male different from a female bird? o Males sing o Males more attractive o Hormonal profile 2.8 the timing of gene activity in different components of the avian song control system in males - NMDA receptor in LMAN - Pattern over time after hatching: o NMDA is high after hatching in males  Is associated with learning and memory  Is it also important in birds? Molecules important for song learning - One of the molecules associated with rodent learning and memory is a receptor for GLU  NMDA-R - Hypothesis: o Sensory acquisition of a new song requires activity at NMDA receptors in the lateral magnocellular nucleus of the anterior nidopallium (lMAN) of the young zebra finch brain o Acquisition of song activates areas in these receptors of LMAN in NMDA Receptors and signals - NMDA antagonist – AP-5 o Binds to NMDA receptors, like a hormone, and changes biological response NMDARs and bird song - % of the tutors song the birds learnt o Antagonist to NMDA reduces the % of the tutor’s song the birds learnt - Different experimental conditions: o Can give birds AP-5 when bird is being tutored by another bird o Could also give AP-5 when bird is NOT learning the song o Could also give antagonist in part of the brain (cerebellum) that is not known to have effects o Could give birds saline - Measure: % of tutor songs that the birds learn - Results: there is a reduction in songs learnt when AP-5 is given o Therefore, AP-5 has an effect on that time of age, etc. Record action potentials from the HVC - HVC known to be stimulated by songs o Responds to auditory stimuli Bird songs & learning - Some birds learn between 30-90 days (zebra finches) , while some birds learn all the time (canaries)  open learners - Open learners learn songs and can change songs throughout the breeding season - Looking at swamp sparrow learning o Results: song B gave the most response - Can then ask what type of song gives these action potentials Recording from HVC neurons - Record and play in a direction the bird understands - In a forward direction, the song should be intelligible to the bird – APs fire more - In the reverse direction, AP per song per bin is much lower Fostered chicks pairing preferences - WHEN do birds actually learn? - If you cross-foster birds and put them in another birds nest (when very young), these birds will hear the songs of their host - Cross-fostered BT and GT - If young birds hear host songs all the time, they learn to recognize the songs of their host o Does it alter behaviour later in life? - 20% if GT in BT nest - If BT in a GT nest, larger % of BT mate with other BTs Few cross fostered GT.. - More BTs prefer to mate with own species How to examine imprinting? - Ability to learn something was investigated - Konrad Lorenz o Chicks followed him around like they would follow parents - Imprinting: a blob of clay/playdough where you can put a print in - Konrad Lorenz described in 1937 - Modern times: play movies to the chicks of just shapes – they approach the one they’ve been trained on. Neural mechanisms for imprinting? - NMDA receptor – look at this for learning in the imprinting phase o Bird is learning a visual image during a critical time of development – until day 4 - After day 4, birds are not able to imprint - Look at p1 and p7 o Looked at component of NMDA receptor o NR2A and NR2B o Can examine for their abundance during the time the bird is able to learn o Noted that it was more NR2B that increased during imprinting training  Up-regulated in p1 but not in p7 o NR2B increased during imprinting training - Be able to know link between human language learning and bird song - Looking at behaviour  o Listen and describe how it sounds o Measure birds response physiologically Birdsong System Controls - Pg 59-67, 93-99 Studies of bird song have relied heavilyt on male white-crowned sparrows What Is instinct? - Instinct: a behaviour pattern that appears fully functional the first time it is performed - Is bird song an instinct or learned? - E.g. of instinct o Begging behaviour of herring gull chicks to its parent’s bill o Fully begging behaviour is seen as soon as bird is born o Fixed action power – instinct – is released by an action in the parent o If mother is putting head into the nest, maybe something about the mother’s head is causing the begging behaviour - If one were to make a cardboard copy of the mother’s head, how many chicks would respond with the pecking response? o 100% if it was the full head - If just the beak was copied and put in – gives a similar response, many beg still - When putting the head and beak in, without a red dot on the beak, significantly reduces the pecking response - When putting a red pencil, the gull chicks respond as if it is the head of the mother bird o Beg a lot - RED DOT on the beak is the most important thing for the begging response to happen - Is begging “genetically determined” ? o Can say it is o What we actually mean by this, Behaviour - E.g. bird song is dependent on genetics and environment: - Have a full song and can see motifs of the song - Should be able to read spectrogram and see that these songs are different - If bird species has innately genetically determined song, how does this change from different environments? - The song of the white-crown sparrow could be environmentally determined Genes and Environment - Genetically and environmentally determined are without any clear meaning because: - Would be erroneous to say a behaviour is due JUST to genes since there are internal and external factors that could be acting on gene expression - Cannot be completely due to the environment either - Genes are transmitted from parent to offspring and DNA responds to environmental (internal/external) influences 2.7 - Male and female birds have different chromosomes – could be why they are able to sing better than
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