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Biophysics, Dendrites & Neural Computation

 

We seek to understand how the biophysical features of neurons give rise to the computational power of the brain.

Our laboratory is located in the McGovern Institute for brain research and the department of brain and Cognitive Sciences at MIT in Cambridge, MA.

 

 

 

 

HARNETT LAB @ MIT

 

We have three main directions of research, each centered around dendritic processing:

 

Dendrites & computation

Our laboratory studies how the biophysical features of neurons, including ion channels, receptors, and membrane electrical properties, endow neural circuits with powerful processing capabilities, ultimately allowing them to perform the complex computations required to drive adaptive behavior.  We focus on the role of dendrites, the elaborate tree-like structures where neurons receive the vast majority of afferent input.  Due to the spatial arrangement of synaptic contacts on dendrites and the presence of particular biophysical mechanisms a complex array of interactions among synapses can take place.  Elementary input-output operations that manifest as coincidence detection, pattern recognition, input comparison, and simple logical functions can all be carried out even in small dendritic subunits.  Our hypothesis is that computations in neural circuits are built out of these fundamental integrative operations conducted at dendrites. The goal is to provide mechanistic explanations for how the neural circuits underlying sensory processing and navigation create complex, abstract representations of the environment and past experiences to ultimately guide behavior.

 

plasticity

If neural circuits use integrative operations at single neurons as the building blocks for computations, then synaptic and cellular plasticity provide a potent means for either reinforcing or changing neural processing algorithms.  Dendritic mechanisms governing input transformations likely impose plasticity induction rules distinct from the canonical spike-timing dependent plasticity framework, which currently dominates learning models.  Using electrical and optical recording in behaving rodents as well as in vitro preparations we hope to understand the mechanisms and functional consequences of plasticity in dendrites to ultimately relate changes in synaptic and cellular function to the alterations in computations that occur during learning to modify behavior.

 

Disorders of Cognition

Many cognitive disorders, including Autism, are characterized by conspicuous changes in the number, distribution, and/or morphology of dendritic spines, the anatomical locus of the majority of excitatory synapses in the brain. However, there is limited functional data on how, or even if, these morphological changes effect neural circuit operation.  We plan to address the relationship between anatomical aberrations observed in mouse models and the functional consequences for synaptic efficacy, plasticity, and integration to identify disease-associated mechanistic loci.  Manipulation of these processes during behavior is hoped to causally link changes in synapse anatomy and cellular function with potentially ectopic computations in the relevant microcircuit and behavioral alterations in these animals. We hope this novel research plan will shed new light on these complicated and currently intractable disorders.

 
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HARNETT LAB @ MIT

 

Publications

Harnett MT, Magee JC, Williams SR (2015) Distribution and function of HCN channels in the apical dendritic tuft of neocortical pyramidal neurons. Journal of Neuroscience 35(3):1024-37

Harnett MT, Xu N, Magee JC, Williams SR (2013) Potassium channels control the interaction between active dendritic integration compartments in layer 5 cortical pyramidal neurons. Neuron 79(3):516-29                                                                                   *Preview article in Neuron by Dax Hoffman, p409

Marvin JS, Borghuis BG, Tian L, Cichon J, Harnett MT, Akerboom J, Gordus A, Renninger SL, Chen T, Bargmann CI, Orger MB, Schreiter ER, Demb JB, Gan W, Hires SA, Looger LL (2013) An optimized fluorescent probe for visualizing glutamate neurotransmission. Nature Methods 10(2):162-70

Xu N, Harnett MT, Williams SR, Huber D, O’Connor, DH, Svoboda K, Magee JC (2012) Nonlinear dendritic integration of sensory and motor input produces an object localization signal. Nature 492(7428):247-51

Harnett MT*, Makara J*, Kath W, Spruston N, Magee JC (2012) Synaptic amplification by dendritic spines enhances input cooperativity. Nature 491(7425):599-602

 
 
 

HARNETT LAB NEWS

 

January 5, 2017 - Mateo has named the quad patch amplifiers

Its almost a full blown party!

Its almost a full blown party!

 

November 8, 2016 - Mark elected to the Allen Institute's Next Generation Leaders Council

 

October 13, 2016 - wearing your heart on your sleeve (kind of)

S1 adult mouse barrel cortex dendritic rec...

S1 adult mouse barrel cortex dendritic rec...

...transformed into the height of fashion via the wonders of the internet.

...transformed into the height of fashion via the wonders of the internet.

 

October 1, 2016 - Jakob officially joins the lab! 

and we yet again forget to take a picture...

 

August 16, 2016 - lou de-noises

Or maybe he's concerned about the NSA stealing his ideas...

Or maybe he's concerned about the NSA stealing his ideas...

 

August 3, 2016 - last day of Quique's summer program!

You couldn't possibly ask for more from a summer student.  Quique was nothing short of fantastic.

You couldn't possibly ask for more from a summer student.  Quique was nothing short of fantastic.

So we ate bulgogi to celebrate a job well done!

So we ate bulgogi to celebrate a job well done!

Must grill more...

Must grill more...

July 15, 2016 - mark becomes the Fred and Carole Middleton Career Development Assistant Professor!

July 1, 2016 - Harnett lab retreat at Mark's house

BBQ, beverages, and badminton.

BBQ, beverages, and badminton.

Time for some science...

Time for some science...

Enough science!

Enough science!

Vardhan takes a well deserved rest.

Vardhan takes a well deserved rest.

Lou lays out his thesis project.

Lou lays out his thesis project.

...more games!

...more games!

June 15, 2016 - The lab is awarded MIT research support committee funding through the NEC Corporation Fund for Research in Computers and Communications!

Thank you School of Science and NEC!

 

June 9, 2016 - Brain and cognitive sciences departmental retreat in Newport, RI

The Harnett Lab on walkabout in the streets of Newport.

The Harnett Lab on walkabout in the streets of Newport.

Vardhan enjoying the vistas.

Vardhan enjoying the vistas.

Looking for shade...

Looking for shade...

Derrick notices Mateo taking his picture.

Derrick notices Mateo taking his picture.

Derrick, Quique, and Mark on the cliffwalk.

Derrick, Quique, and Mark on the cliffwalk.

Marie also enjoying the cliffwalk.

Marie also enjoying the cliffwalk.

King Lou attempts to command the denizens of the sea to do his bidding.

King Lou attempts to command the denizens of the sea to do his bidding.

"You ready Derrick?"

"You ready Derrick?"

"I was born ready."

"I was born ready."

Lobster boil!!!

Lobster boil!!!

 

May 25, 2016 - Marie, Lukas and Derrick enjoying the spring weather

Lunch on the terrace.

Lunch on the terrace.

 

april 26, 2016 - the never-ending fussball struggle continues

Intensity and competitive spirit - we got those.

Intensity and competitive spirit - we got those.

Handwriting skills - not so much.

Handwriting skills - not so much.

 

April 19, 2016 - Marie's rotation dinner

Mateo poses for the camera.

Mateo poses for the camera.

"Why a spoon?"

"Why a spoon?"

Derrick and Vardhan ponder then menu.

Derrick and Vardhan ponder then menu.

"Because its dull!"

"Because its dull!"

April 9, 2016 - Party at Mark's house to celebrate lou joining the lab!

It was too cold outside to BBQ...

It was too cold outside to BBQ...

It wasn't too cold for bocce though!

It wasn't too cold for bocce though!

A good time was had by all!

A good time was had by all!

...so we had tacos and tortas from Tenoch!

...so we had tacos and tortas from Tenoch!

There was copious trash talking.

There was copious trash talking.

HARNETT LAB POSITIONS

 

Graduate students

We are currently accepting graduate students for rotations.  Please contact Mark directly.

 

undergraduate students

We are currently looking for MIT UROPs for the spring term.  We are particularly interested in undergrads with a neuroscience research background or programming/computer science/engineering expertise.  Please contact Mark directly.

 

 

 

HARNETT LAB CONTACT INFORMATION

McGovern Institute for Brain Research &        Department of Brain and Cognitive Sciences

MIT Bldg 46-6143
43 Vassar St
Cambridge, MA 02139

harnett@mit.edu

617.324.6989

 
 
 

 

 

 

 

© 2015 Mark Harnett.  All rights reserved