Human neurophysiology Gabriel Kreiman - - PowerPoint PPT Presentation

Human neurophysiology

Gabriel Kreiman Gabriel.Kreiman@childrens.harvard.edu

Children’s Hospital Boston, Harvard Medical School McGovern Institute for Brain Research Massachusetts Institute of Technology

• Genomics, microarrays, transcriptional regulation
• Visual object recognition
• More info at http://www.mit.edu

Single neuron recordings in epileptic patients

• Patients with

pharmacologically intractable epilepsy

Kreiman, Koch, Fried (2000) Nature Neuroscience 3:946-953

Electrodes Spike sorting MRI

• Electrodes implanted

to localize seizure focus

• Targets include the

hippocampus, entorhinal cortex, amygdala and parahippocampal gyrus

Collaboration with neurosurgeon Itzhak Fried (UCLA) and Christof Koch (Caltech) Fried et al. J.Neurosurgery 1999

Inferior temporal cortex projects to frontal cortex and the medial temporal lobe (among other places)

Saleem & Tanaka. J.Neurosci.1996

• Suzuki. Sem.Neurosci. 1996
• Miller. Nat.Rev.Neurosci. 2000

Logothetis & Sheinberg. Ann.Rev.Neurosci. 1996

Individual neurons in the human MTL show visual selectivity and visual invariance

Emotional face (100) Object (51) Spatial (105) Animal (46) Car (17) Face drawing (134) Famous face (100) Pattern (54)

1000 ms

Kreiman, Koch, Fried (2000) Nature Neuroscience 3:946-953 Kreiman, Koch, Fried. Nature Neuroscience 2000

R Entorhinal Cortex

Two extreme forms of representation

Fully distributed representation Every unit responds to every object Every object is represented by the combined ensemble activity Completely sparse representation (grandmother representation) Every unit responds to only 1 object Every object is represented by 1 neuron

A neuron selective to 3 different views of Bill Clinton

n=7 n=9 n=13 n=5 n=14 n=4 n=7 n=6 n=7 n=11 n=11 n=10

1000 ms

n=4 n=6 n=7

R amygdala

A neuron selective to 7 different views of actress Jennifer Aniston

Quiroga, Reddy, Kreiman, Koch, Fried. Nature, In Press

L Parahippocampal gyrus

ROC area=1 Quian Quiroga, Reddy, Kreiman, Koch, Fried. Nature 2005

Observations in the human medial temporal lobe

• Neurons are activated during the recall of visual information (Kreiman, Koch,

Fried, Nature 2000)

N

• Neuronal activity correlates with subjective perception (Kreiman, Koch, Fried,

PNAS 2002)

• Neurons show visual selectivity (Kreiman, Koch, Fried, Nature Neuroscience 2000)
• Sparseness and invariance in the responses of single neurons (Quian

Quiroga, Reddy, Kreiman, Koch, Fried, Nature 2005)

Acknowledgments

Human Recordings

• Prof. Rodrigo Quiroga
• U. Leicester

Eve Isham UCLA Irene Wainwright UCLA

• Prof. Charles Wilson

UCLA

• Prof. Anatol Bragin

UCLA Leila Reddy Caltech

• Prof. Christof Koch

Caltech

• Prof. Itzhak Fried

UCLA

• Prof. Tomaso Poggio

MIT Patients LB, SI, YS, RZ, TD, JG, YK, HM, MS, MM, MM, DF, LA, MF, WO, RS, XV